Merge branch 'development' into chru-atomic-constexpr

.bazelrc

@@ -0,0 +1,26 @@
+# Bazel settings for ETL
+build --enable_bzlmod
+build --cxxopt=-std=c++17
+
+# Cross-compilation: build flags + QEMU (mirrors .devcontainer/run-tests.sh)
+# Each config sets CC + tool env vars so Bazel's auto-configured toolchain
+# finds the full cross-tool suite, and --run_under for QEMU execution.
+build:armhf    --repo_env=CC=arm-linux-gnueabihf-gcc --repo_env=AR=arm-linux-gnueabihf-ar --repo_env=LD=arm-linux-gnueabihf-ld --repo_env=NM=arm-linux-gnueabihf-nm --repo_env=STRIP=arm-linux-gnueabihf-strip --repo_env=OBJDUMP=arm-linux-gnueabihf-objdump
+build:armhf    --cxxopt=-std=c++23 --copt=-DETL_NO_STL --copt=-O0
+test:armhf     --run_under=/usr/bin/qemu-arm-static
+
+build:i386     --repo_env=CC=i686-linux-gnu-gcc --repo_env=AR=i686-linux-gnu-ar --repo_env=LD=i686-linux-gnu-ld --repo_env=NM=i686-linux-gnu-nm --repo_env=STRIP=i686-linux-gnu-strip --repo_env=OBJDUMP=i686-linux-gnu-objdump
+build:i386     --cxxopt=-std=c++23 --copt=-DETL_NO_STL --copt=-O0
+test:i386      --run_under=/usr/bin/qemu-i386-static
+
+build:powerpc  --repo_env=CC=powerpc-linux-gnu-gcc --repo_env=AR=powerpc-linux-gnu-ar --repo_env=LD=powerpc-linux-gnu-ld --repo_env=NM=powerpc-linux-gnu-nm --repo_env=STRIP=powerpc-linux-gnu-strip --repo_env=OBJDUMP=powerpc-linux-gnu-objdump
+build:powerpc  --cxxopt=-std=c++23 --copt=-DETL_NO_STL --copt=-O0
+test:powerpc   --run_under=/usr/bin/qemu-ppc
+
+build:riscv64  --repo_env=CC=riscv64-linux-gnu-gcc --repo_env=AR=riscv64-linux-gnu-ar --repo_env=LD=riscv64-linux-gnu-ld --repo_env=NM=riscv64-linux-gnu-nm --repo_env=STRIP=riscv64-linux-gnu-strip --repo_env=OBJDUMP=riscv64-linux-gnu-objdump
+build:riscv64  --cxxopt=-std=c++23 --copt=-DETL_NO_STL --copt=-O0
+test:riscv64   --run_under=/usr/bin/qemu-riscv64-static
+
+build:s390x    --repo_env=CC=s390x-linux-gnu-gcc --repo_env=AR=s390x-linux-gnu-ar --repo_env=LD=s390x-linux-gnu-ld --repo_env=NM=s390x-linux-gnu-nm --repo_env=STRIP=s390x-linux-gnu-strip --repo_env=OBJDUMP=s390x-linux-gnu-objdump
+build:s390x    --cxxopt=-std=c++23 --copt=-DETL_NO_STL --copt=-O0
+test:s390x     --run_under=/usr/bin/qemu-s390x-static

.bazelversion

@@ -0,0 +1 @@
+8.5.1

.clang-tidy

@@ -0,0 +1,182 @@
+---
+# TODO: Enable these checks in smaller steps
+# cppcoreguidelines-*,
+# portability-* if needed
+# readability-*, -readability-magic-numbers,
+# misc-*, -misc-no-recursion,
+# modernize-*, -modernize-use-trailing-return-type,
+# performance-*,
+
+Checks: >-
+    cert-*, -cert-dcl37-c, -cert-dcl51-cpp,
+    clang-analyzer-*,
+    bugprone-*,
+    -bugprone-easily-swappable-parameters,
+    cppcoreguidelines-pro-type-vararg,
+    cppcoreguidelines-pro-type-reinterpret-cast,
+    llvm-*,-llvm-header-guard,-llvm-include-order,
+    google-readability-casting
+ExtraArgs: ['-Wno-unknown-warning-option']
+HeaderFileExtensions: ['h', 'hpp']
+HeaderFilterRegex: '.*include/etl/.*'
+ImplementationFileExtensions: ['cpp']
+UseColor: true
+# TODO: Enable these when readability check is enabled
+# CheckOptions :
+#  - key: readability-identifier-naming.AbstractClassCase
+#    value: snake_case
+#  - key: readability-identifier-naming.AbstractClassPrefix
+#    value: I
+#  - key: readability-identifier-naming.AbstractClassSuffix
+#    value: ''
+#  - key: readability-identifier-naming.ClassCase
+#    value: snake_case
+#  - key: readability-identifier-naming.ClassPrefix
+#    value: ''
+#  - key: readability-identifier-naming.ClassSuffix
+#    value: ''
+#  - key: readability-identifier-naming.GlobalConstantCase
+#    value: UPPER_CASE
+#  - key: readability-identifier-naming.GlobalConstantPrefix
+#    value: ''
+#  - key: readability-identifier-naming.GlobalConstantSuffix
+#    value: ''
+#  - key: readability-identifier-naming.ConstantCase
+#    value: snake_case
+#  - key: readability-identifier-naming.ConstantPrefix
+#    value: ''
+#  - key: readability-identifier-naming.ConstantSuffix
+#    value: ''
+#  - key: readability-identifier-naming.ConstantMemberCase
+#    value: snake_case
+#  - key: readability-identifier-naming.ConstantMemberPrefix
+#    value: k
+#  - key: readability-identifier-naming.ConstantMemberSuffix
+#    value: ''
+#  - key: readability-identifier-naming.StaticConstantCase
+#    value: snake_case
+#  - key: readability-identifier-naming.StaticConstantPrefix
+#    value: k
+#  - key: readability-identifier-naming.StaticConstantSuffix
+#    value: ''
+#  - key: readability-identifier-naming.EnumCase
+#    value: snake_case
+#  - key: readability-identifier-naming.EnumPrefix
+#    value: ''
+#  - key: readability-identifier-naming.EnumSuffix
+#    value: ''
+#  - key: readability-identifier-naming.EnumConstantCase
+#    value: snake_case
+#  - key: readability-identifier-naming.EnumConstantPrefix
+#    value: ''
+#  - key: readability-identifier-naming.EnumConstantSuffix
+#    value: ''
+#  - key: readability-identifier-naming.GlobalVariableCase
+#    value: snake_case
+#  - key: readability-identifier-naming.GlobalVariablePrefix
+#    value: g
+#  - key: readability-identifier-naming.GlobalVariableSuffix
+#    value: ''
+#  - key: readability-identifier-naming.LocalVariableCase
+#    value: snake_case
+#  - key: readability-identifier-naming.LocalVariablePrefix
+#    value: ''
+#  - key: readability-identifier-naming.LocalVariableSuffix
+#    value: ''
+#  - key: readability-identifier-naming.StructCase
+#    value: aNy_CasE
+#  - key: readability-identifier-naming.StructPrefix
+#    value: ''
+#  - key: readability-identifier-naming.StructSuffix
+#    value: ''
+#  - key: readability-identifier-naming.FunctionCase
+#    value: snake_case
+#  - key: readability-identifier-naming.FunctionPrefix
+#    value: ''
+#  - key: readability-identifier-naming.FunctionSuffix
+#    value: ''
+#  - key: readability-identifier-naming.MethodCase
+#    value: snake_case
+#  - key: readability-identifier-naming.MethodPrefix
+#    value: ''
+#  - key: readability-identifier-naming.MethodSuffix
+#    value: ''
+#  - key: readability-identifier-naming.ParameterCase
+#    value: snake_case
+#  - key: readability-identifier-naming.PrivateMethodCase
+#    value: snake_case
+#  - key: readability-identifier-naming.PrivateMethodPrefix
+#    value: ''
+#  - key: readability-identifier-naming.PrivateMethodSuffix
+#    value: ''
+#  - key: readability-identifier-naming.PublicMethodCase
+#    value: snake_case
+#  - key: readability-identifier-naming.PublicMethodPrefix
+#    value: ''
+#  - key: readability-identifier-naming.PublicMethodSuffix
+#    value: ''
+#  - key: readability-identifier-naming.MemberCase
+#    value: snake_case
+#  - key: readability-identifier-naming.MemberPrefix
+#    value: _
+#  - key: readability-identifier-naming.MemberSuffix
+#    value: ''
+#  - key: readability-identifier-naming.PrivateMemberCase
+#    value: snake_case
+#  - key: readability-identifier-naming.PrivateMemberPrefix
+#    value: _
+#  - key: readability-identifier-naming.PrivateMemberSuffix
+#    value: ''
+#  - key: readability-identifier-naming.PublicMemberCase
+#    value: snake_case
+#  - key: readability-identifier-naming.PublicMemberPrefix
+#    value: ''
+#  - key: readability-identifier-naming.PublicMemberSuffix
+#    value: ''
+#  - key: readability-identifier-naming.NamespaceCase
+#    value: lower_case
+#  - key: readability-identifier-naming.NamespacePrefix
+#    value: ''
+#  - key: readability-identifier-naming.NamespaceSuffix
+#    value: ''
+#  - key: readability-identifier-naming.InlineNamespaceCase
+#    value: lower_case
+#  - key: readability-identifier-naming.InlineNamespacePrefix
+#    value: ''
+#  - key: readability-identifier-naming.InlineNamespaceSuffix
+#    value: ''
+#  - key: readability-identifier-length.IgnoredParameterNames
+#    value: ^(n|id|a|b|x|y)$
+#  - key: readability-identifier-length.IgnoredLoopCounterNames
+#    value: ^[ijkxy_]$
+#  - key: readability-identifier-naming.GlobalFunctionCase
+#    value: snake_case
+#  - key: readability-identifier-naming.GlobalFunctionPrefix
+#    value: ''
+#  - key: readability-identifier-naming.GlobalFunctionSuffix
+#    value: ''
+#  - key: readability-identifier-naming.TemplateParameterCase
+#    value: CamelCase
+#  - key: readability-identifier-naming.TemplateParameterPrefix
+#    value: ''
+#  - key: readability-identifier-naming.TemplateParameterSuffix
+#    value: ''
+#  - key: readability-identifier-naming.TemplateTemplateParameterCase
+#    value: CamelCase
+#  - key: readability-identifier-naming.TemplateTemplateParameterPrefix
+#    value: 'TPL'
+#  - key: readability-identifier-naming.TemplateTemplateParameterSuffix
+#    value: ''
+#  - key: readability-identifier-naming.TypeTemplateParameterCase
+#    value: CamelCase
+#  - key: readability-identifier-naming.TypeTemplateParameterPrefix
+#    value: 'T'
+#  - key: readability-identifier-naming.TypeTemplateParameterSuffix
+#    value: ''
+#  - key: readability-identifier-naming.ValueTemplateParameterCase
+#    value: UPPER_CASE
+#  - key: readability-identifier-naming.ValueTemplateParameterPrefix
+#    value: ''
+#  - key: readability-identifier-naming.ValueTemplateParameterSuffix
+#    value: ''
+...

.devcontainer/Dockerfile

@@ -36,15 +36,32 @@ RUN set -eux \
     && apt-get -y install --no-install-recommends \
         python3-full \
         python3-pip \
+        python3-cogapp \
         git \
         wget \
         cmake \
-    && rm -rf /var/lib/apt/lists/* \
-    && if pip help install | grep -q '\-\-break-system-packages'; then \
-           pip install --no-cache-dir --break-system-packages cogapp; \
-       else \
-           pip install --no-cache-dir cogapp; \
-       fi
+        clang-format \
+        clang-format-18 \
+        lcov \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN set -eux; \
+    VERSION="2.4.1"; \
+    case "$(uname -m)" in \
+        x86_64)  ARCH="amd64"; SHA256="bdaa2c0fbee03e5c2f99e605d9419386ce5d558440baac2017398faada839e04" ;; \
+        aarch64) ARCH="arm64"; SHA256="0a09e1f04a0f8a86fd4e709552613f5d82adf6bc72f0a4b5e217670894e79fbf" ;; \
+        *) echo "Unsupported architecture: $(uname -m)"; exit 1 ;; \
+    esac; \
+    wget -O treefmt.tar.gz "https://github.com/numtide/treefmt/releases/download/v${VERSION}/treefmt_${VERSION}_linux_${ARCH}.tar.gz" \
+    && echo "${SHA256} treefmt.tar.gz" | sha256sum -c \
+    && tar xzf treefmt.tar.gz treefmt \
+    && install -m 755 treefmt /usr/bin/treefmt \
+    && rm treefmt.tar.gz treefmt
+
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
 
 RUN set -eux \
     && echo "Pip version: " \

.devcontainer/armhf/Dockerfile

@@ -0,0 +1,61 @@
+# armhf Test Environment for ETL
+# Uses QEMU user-mode emulation to run armhf binaries on x64 host
+FROM debian:trixie
+
+# Avoid prompts from apt
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Install QEMU user-mode emulation and armhf cross-compilation tools
+RUN dpkg --add-architecture armhf && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    qemu-user-static \
+    qemu-user \
+    binfmt-support \
+    gcc-arm-linux-gnueabihf \
+    g++-arm-linux-gnueabihf \
+    cmake \
+    make \
+    ninja-build \
+    git \
+    wget \
+    ca-certificates \
+    file \
+    libc6:armhf \
+    libstdc++6:armhf \
+    libatomic1:armhf \
+    && rm -rf /var/lib/apt/lists/*
+
+# Create non-root user with stable UID/GID
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=1000
+
+RUN groupadd --gid ${USER_GID} ${USERNAME} && \
+    useradd --uid ${USER_UID} --gid ${USER_GID} --shell /bin/bash --create-home ${USERNAME}
+
+# Set working directory
+WORKDIR /workspaces/etl
+
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
+
+# Verify QEMU and cross-compilation setup
+RUN echo "=== Host Architecture ===" && \
+    uname -m && \
+    echo "" && \
+    echo "=== armhf Cross Compiler ===" && \
+    arm-linux-gnueabihf-gcc --version && \
+    echo "" && \
+    echo "=== QEMU arm ===" && \
+    qemu-arm-static --version | head -n1
+
+# Ensure workspace directory ownership for non-root user
+RUN mkdir -p /workspaces/etl && chown -R ${USERNAME}:${USERNAME} /workspaces
+
+# Switch to non-root user
+USER ${USERNAME}
+
+# Default command
+CMD ["/bin/bash"]

.devcontainer/armhf/devcontainer.json

@@ -0,0 +1,29 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/cpp
+{
+  "name": "armhf (Debian)",
+  "build": {
+    "dockerfile": "./Dockerfile",
+    "context": "."
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-vscode.cpptools",
+        "ms-vscode.cmake-tools"
+      ],
+      "settings": {
+        "cmake.sourceDirectory": "${workspaceFolder}/test",
+        "cmake.configureArgs": [
+          "-DCMAKE_TOOLCHAIN_FILE=${workspaceFolder}/.devcontainer/armhf/toolchain-armhf.cmake",
+          "-DBUILD_TESTS=ON",
+          "-DNO_STL=OFF",
+          "-DETL_CXX_STANDARD=23"
+        ],
+        "cmake.buildDirectory": "${workspaceFolder}/build-armhf",
+        "cmake.generator": "Ninja"
+      }
+    }
+  },
+  "remoteUser": "root"
+}

.devcontainer/armhf/toolchain-armhf.cmake

@@ -0,0 +1,21 @@
+# CMake toolchain file for armhf cross-compilation
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR arm)
+
+# Specify the cross compiler
+set(CMAKE_C_COMPILER arm-linux-gnueabihf-gcc)
+set(CMAKE_CXX_COMPILER arm-linux-gnueabihf-g++)
+set(CMAKE_AR arm-linux-gnueabihf-ar)
+set(CMAKE_RANLIB arm-linux-gnueabihf-ranlib)
+set(CMAKE_STRIP arm-linux-gnueabihf-strip)
+
+# Search for programs in the build host directories
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+
+# For libraries and headers in the target directories
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+# Set QEMU for running tests
+set(CMAKE_CROSSCOMPILING_EMULATOR /usr/bin/qemu-arm-static CACHE FILEPATH "Path to the emulator for cross-compiled binaries")

.devcontainer/context/reinstall-cmake.sh

@@ -1,291 +0,0 @@
-#!/usr/bin/env bash
-
-# For more detailed debugging, uncomment the next line
-# set -x
-
-# Explicitly set CMAKE_VERSION from first argument, default to "none"
-CMAKE_VERSION=${1:-"none"}
-
-# --- Configuration ---
-DOWNLOAD_ATTEMPTS=3
-DOWNLOAD_RETRY_DELAY=5 # seconds
-
-# --- Global Variables ---
-TMP_DIR="" # Initialize TMP_DIR, will be set by mktemp
-# Filenames used within TMP_DIR
-CMAKE_INSTALLER_SCRIPT_LOCAL_NAME="cmake-installer.sh"
-CMAKE_CHECKSUM_FILE_LOCAL_NAME="cmake-checksums.txt"
-# This will be the actual name of the CMake binary, derived from version and arch
-# It's important for matching against the checksum file.
-DERIVED_CMAKE_BINARY_FILENAME=""
-
-# --- Cleanup Function ---
-# This trap will execute on EXIT, ERR, SIGINT, SIGTERM
-# It's crucial for debugging to see the state of TMP_DIR if things go wrong.
-cleanup() {
-    # $? is the exit code of the last command before the trap was triggered
-    # or the argument to exit if the script called exit explicitly.
-    LAST_EXIT_CODE=$?
-    echo # Newline for readability
-
-    # Only proceed with detailed cleanup if TMP_DIR was actually created
-    if [[ -n "${TMP_DIR}" && -d "${TMP_DIR}" ]]; then
-        echo "--- Cleanup: Temporary Directory Inspector (${TMP_DIR}) ---"
-        echo "Listing contents of TMP_DIR:"
-        ls -la "${TMP_DIR}"
-
-        # Check and display checksum file content
-        if [[ -f "${TMP_DIR}/${CMAKE_CHECKSUM_FILE_LOCAL_NAME}" ]]; then
-            echo "--- Content of downloaded checksum file (${CMAKE_CHECKSUM_FILE_LOCAL_NAME}) ---"
-            cat "${TMP_DIR}/${CMAKE_CHECKSUM_FILE_LOCAL_NAME}"
-            echo "--- End of checksum file ---"
-        else
-            echo "Checksum file (${CMAKE_CHECKSUM_FILE_LOCAL_NAME}) not found in TMP_DIR."
-        fi
-
-        # Check and display head of (potentially) installer script
-        # Useful to see if it's an HTML error page
-        if [[ -f "${TMP_DIR}/${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}" ]]; then
-            echo "--- First 10 lines of downloaded installer script (${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}) ---"
-            head -n 10 "${TMP_DIR}/${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}"
-            echo "--- End of installer script head ---"
-        elif [[ -f "${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}" ]]; then
-             # If it was renamed
-            echo "--- First 10 lines of downloaded installer script (${DERIVED_CMAKE_BINARY_FILENAME}) ---"
-            head -n 10 "${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}"
-            echo "--- End of installer script head ---"
-        else
-            echo "Installer script not found in TMP_DIR (checked for ${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME} and ${DERIVED_CMAKE_BINARY_FILENAME})."
-        fi
-
-        echo "Attempting to remove temporary directory: ${TMP_DIR}"
-        rm -Rf "${TMP_DIR}"
-        echo "Temporary directory removed."
-        echo "--- End of Cleanup ---"
-    else
-        echo "--- Cleanup: TMP_DIR was not set or not a directory, no temp files to inspect or clean. ---"
-    fi
-
-    # Ensure the script exits with the LAST_EXIT_CODE observed by the trap
-    # unless it was 0 and the script is exiting due to an explicit non-zero exit.
-    # The 'exit' command within the trap will override the script's natural exit code.
-    # So, if the script was going to exit 0, but cleanup had an issue, this could change it.
-    # However, for debugging an exit code 8, we want to preserve the code that *caused* the trap.
-    echo "Script finished with exit code: ${LAST_EXIT_CODE}."
-    exit "${LAST_EXIT_CODE}"
-}
-trap cleanup EXIT ERR SIGINT SIGTERM
-
-# Immediately turn on `set -e` after trap setup
-set -e
-
-# --- Helper Functions ---
-# Function to download a file with retries and basic validation
-download_file() {
-    local url="$1"
-    local output_filename="$2"
-    local attempts_left=$DOWNLOAD_ATTEMPTS
-    local wget_exit_code=0
-
-    while [ $attempts_left -gt 0 ]; do
-        echo "Downloading: ${url}"
-        echo "Saving to: ${TMP_DIR}/${output_filename}"
-        echo "Attempt $((DOWNLOAD_ATTEMPTS - attempts_left + 1)) of ${DOWNLOAD_ATTEMPTS}..."
-
-        # Use wget with:
-        # -O: specify output file
-        # --timeout: connection/read timeout
-        # --tries: number of retries (wget's own retry, distinct from this loop)
-        # --quiet: suppress normal output, but errors still go to stderr
-        # --show-progress: if not quiet, shows a progress bar (optional)
-        # Using -q for less verbose logs, but on failure, we need to know.
-        wget -O "${TMP_DIR}/${output_filename}" --timeout=30 --tries=1 "${url}"
-        wget_exit_code=$?
-
-        if [ ${wget_exit_code} -eq 0 ]; then
-            echo "Download command successful for ${output_filename}."
-            if [ -s "${TMP_DIR}/${output_filename}" ]; then # -s: file exists and has a size greater than 0
-                # Basic check for common HTML error page indicators
-                # This is a heuristic and might not catch all error pages.
-                if head -n 5 "${TMP_DIR}/${output_filename}" | grep -Eiq '<html|<head|<!doctype html|404 Not Found|Error'; then
-                    echo "WARNING: Downloaded file '${output_filename}' might be an HTML error page."
-                    echo "First 5 lines of ${output_filename}:"
-                    head -n 5 "${TMP_DIR}/${output_filename}"
-                    # Consider this a failure for critical files
-                    return 1 # Treat as failure
-                fi
-                echo "File ${output_filename} downloaded and is not empty."
-                return 0 # Success
-            else
-                echo "ERROR: Downloaded file ${output_filename} is empty."
-                # No need to rm here, loop will retry or fail
-            fi
-        else
-            echo "ERROR: wget failed to download ${url} with exit code ${wget_exit_code}."
-        fi
-
-        attempts_left=$((attempts_left - 1))
-        if [ $attempts_left -gt 0 ]; then
-            echo "Retrying in ${DOWNLOAD_RETRY_DELAY} seconds..."
-            sleep $DOWNLOAD_RETRY_DELAY
-        else
-            echo "ERROR: Failed to download ${url} after ${DOWNLOAD_ATTEMPTS} attempts."
-            return 1 # Explicit failure
-        fi
-    done
-    return 1 # Should be unreachable if loop logic is correct, but as a fallback
-}
-
-# --- Main Script Logic ---
-
-if [ "${CMAKE_VERSION}" = "none" ]; then
-    echo "No CMake version specified by argument, skipping CMake reinstallation."
-    exit 0
-fi
-echo "CMake version to install: ${CMAKE_VERSION}"
-
-# 1. Ensure wget is available
-echo "Checking for wget..."
-if ! command -v wget > /dev/null; then
-    echo "wget not found. Attempting to install wget via apt-get..."
-    if command -v apt-get > /dev/null; then
-        apt-get update -y
-        apt-get install -y --no-install-recommends wget
-        echo "wget installed."
-    else
-        echo "ERROR: apt-get not found. Cannot install wget. Please install wget manually."
-        exit 1
-    fi
-else
-    echo "wget is available."
-fi
-
-# 2. (Optional) Remove existing CMake installed via apt
-echo "Attempting to remove any existing CMake installed via apt..."
-if command -v apt-get > /dev/null; then
-    if dpkg -s cmake &> /dev/null; then # Check if cmake package is actually installed
-        apt-get -y purge --auto-remove cmake
-        echo "cmake package purged."
-    else
-        echo "cmake package not found via dpkg, skipping purge."
-    fi
-else
-    echo "apt-get not found, skipping removal of CMake via apt."
-fi
-
-# 3. Create installation and temporary directories
-echo "Creating CMake installation directory /opt/cmake..."
-mkdir -p /opt/cmake
-
-TMP_DIR=$(mktemp -d -t cmake-install-XXXXXXXXXX)
-echo "Temporary directory created: ${TMP_DIR}"
-# Crucial: subsequent operations needing temp files should happen in or relative to TMP_DIR
-# We will cd into TMP_DIR later, or use full paths like ${TMP_DIR}/filename
-
-# 4. Determine system architecture
-echo "Determining system architecture..."
-architecture=$(dpkg --print-architecture)
-case "${architecture}" in
-    arm64) ARCH="aarch64" ;;
-    amd64) ARCH="x86_64" ;;
-    *)
-        echo "ERROR: Unsupported architecture '${architecture}' reported by dpkg."
-        exit 1
-        ;;
-esac
-echo "Detected architecture: ${architecture} (mapped to CMake arch: ${ARCH})"
-
-# 5. Define CMake download URLs and the filename expected by checksum
-DERIVED_CMAKE_BINARY_FILENAME="cmake-${CMAKE_VERSION}-linux-${ARCH}.sh"
-CMAKE_BINARY_URL="https://github.com/Kitware/CMake/releases/download/v${CMAKE_VERSION}/${DERIVED_CMAKE_BINARY_FILENAME}"
-CMAKE_CHECKSUM_FILE_URL="https://github.com/Kitware/CMake/releases/download/v${CMAKE_VERSION}/cmake-${CMAKE_VERSION}-SHA-256.txt"
-
-# 6. Download CMake binary and checksum file
-echo "--- Downloading Files ---"
-if ! download_file "${CMAKE_BINARY_URL}" "${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}"; then
-    echo "ERROR: Failed to download CMake binary installer. See messages above."
-    exit 1
-fi
-
-if ! download_file "${CMAKE_CHECKSUM_FILE_URL}" "${CMAKE_CHECKSUM_FILE_LOCAL_NAME}"; then
-    echo "ERROR: Failed to download CMake checksum file. See messages above."
-    exit 1
-fi
-echo "Downloads complete."
-echo "--- End of Downloading Files ---"
-echo # Newline for readability
-
-# Before checksum, rename the downloaded installer to its derived name,
-# as the checksum file refers to this specific name.
-echo "Renaming downloaded installer from '${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}' to '${DERIVED_CMAKE_BINARY_FILENAME}' for checksum verification."
-mv "${TMP_DIR}/${CMAKE_INSTALLER_SCRIPT_LOCAL_NAME}" "${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}"
-if [ ! -f "${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}" ]; then
-    echo "ERROR: Failed to rename installer script for checksum. File '${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}' does not exist after move."
-    exit 1
-fi
-
-# 7. Verify checksum
-echo "--- Verifying Checksum ---"
-echo "Checksum file is: ${TMP_DIR}/${CMAKE_CHECKSUM_FILE_LOCAL_NAME}"
-echo "Binary file to check is: ${TMP_DIR}/${DERIVED_CMAKE_BINARY_FILENAME}"
-
-# Ensure the checksum file actually contains an entry for our binary
-# This is important because the SHA-256.txt file contains checksums for *all* release assets
-echo "Checking if checksum file contains entry for '${DERIVED_CMAKE_BINARY_FILENAME}'..."
-if ! grep -q "${DERIVED_CMAKE_BINARY_FILENAME}" "${TMP_DIR}/${CMAKE_CHECKSUM_FILE_LOCAL_NAME}"; then
-    echo "ERROR: The downloaded checksum file '${CMAKE_CHECKSUM_FILE_LOCAL_NAME}' does NOT contain an entry for '${DERIVED_CMAKE_BINARY_FILENAME}'."
-    echo "This strongly suggests that the CMAKE_VERSION ('${CMAKE_VERSION}') or ARCH ('${ARCH}') is incorrect, or the specified version does not provide a .sh installer for this architecture."
-    echo "Please verify the version and available files at https://github.com/Kitware/CMake/releases/tag/v${CMAKE_VERSION}"
-    exit 1
-fi
-echo "Checksum file contains an entry for '${DERIVED_CMAKE_BINARY_FILENAME}'."
-
-# Perform the checksum. We need to be in the directory where the files are.
-echo "Changing directory to ${TMP_DIR} for checksum verification."
-cd "${TMP_DIR}" # <<<<<<< IMPORTANT: sha256sum -c needs to find files
-
-echo "Verifying checksum of '${DERIVED_CMAKE_BINARY_FILENAME}' using '${CMAKE_CHECKSUM_FILE_LOCAL_NAME}'..."
-# The --ignore-missing flag is good, as the .txt file has many checksums.
-# The --strict flag would cause it to error if there are improperly formatted lines.
-# We rely on the grep check above to ensure our specific file is mentioned.
-if sha256sum -c --ignore-missing "${CMAKE_CHECKSUM_FILE_LOCAL_NAME}"; then
-    echo "Checksum verification successful for '${DERIVED_CMAKE_BINARY_FILENAME}'."
-else
-    SHA_EXIT_CODE=$?
-    echo "ERROR: Checksum verification FAILED for '${DERIVED_CMAKE_BINARY_FILENAME}' with exit code ${SHA_EXIT_CODE}."
-    # Cleanup trap will show file contents.
-    exit 1 # Critical failure
-fi
-echo "--- End of Verifying Checksum ---"
-echo # Newline for readability
-
-# 8. Install CMake
-echo "--- Installing CMake ---"
-echo "Making the CMake installer script '${DERIVED_CMAKE_BINARY_FILENAME}' executable..."
-chmod +x "${DERIVED_CMAKE_BINARY_FILENAME}" # Still in TMP_DIR
-
-echo "Executing CMake installer script: ./${DERIVED_CMAKE_BINARY_FILENAME} --prefix=/opt/cmake --skip-license"
-# Execute the script. If this script exits with 8, this is our culprit.
-if ./"${DERIVED_CMAKE_BINARY_FILENAME}" --prefix=/opt/cmake --skip-license; then
-    echo "CMake installer script executed successfully."
-else
-    INSTALLER_EXIT_CODE=$?
-    echo "ERROR: CMake installer script FAILED with exit code ${INSTALLER_EXIT_CODE}."
-    # This is the most likely place for an exit code 8 if downloads and checksums were okay.
-    # The trap will handle cleanup. The script will exit with INSTALLER_EXIT_CODE due to the trap.
-    exit ${INSTALLER_EXIT_CODE} # Explicitly exit with the installer's code
-fi
-echo "--- End of Installing CMake ---"
-echo # Newline for readability
-
-# 9. Create symlinks
-echo "Creating symbolic links for cmake and ctest in /usr/local/bin/..."
-ln -sf /opt/cmake/bin/cmake /usr/local/bin/cmake
-ln -sf /opt/cmake/bin/ctest /usr/local/bin/ctest
-echo "Symbolic links created."
-
-echo # Newline for readability
-echo "SUCCESS: CMake ${CMAKE_VERSION} installation and setup complete."
-
-# The script will exit with 0 here. The trap will run, see $? is 0, and then exit 0.
-exit 0

.devcontainer/i386/Dockerfile

@@ -0,0 +1,61 @@
+# i386 Test Environment for ETL
+# Uses QEMU user-mode emulation to run i386 binaries on x64 host
+FROM debian:trixie
+
+# Avoid prompts from apt
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Install QEMU user-mode emulation and i386 cross-compilation tools
+RUN dpkg --add-architecture i386 && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    qemu-user-static \
+    qemu-user \
+    binfmt-support \
+    gcc-i686-linux-gnu \
+    g++-i686-linux-gnu \
+    cmake \
+    make \
+    ninja-build \
+    git \
+    wget \
+    ca-certificates \
+    file \
+    libc6:i386 \
+    libstdc++6:i386 \
+    libatomic1:i386 \
+    && rm -rf /var/lib/apt/lists/*
+
+# Create non-root user with stable UID/GID
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=1000
+
+RUN groupadd --gid ${USER_GID} ${USERNAME} && \
+    useradd --uid ${USER_UID} --gid ${USER_GID} --shell /bin/bash --create-home ${USERNAME}
+
+# Set working directory
+WORKDIR /workspaces/etl
+
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
+
+# Verify QEMU and cross-compilation setup
+RUN echo "=== Host Architecture ===" && \
+    uname -m && \
+    echo "" && \
+    echo "=== i386 Cross Compiler ===" && \
+    i686-linux-gnu-gcc --version && \
+    echo "" && \
+    echo "=== QEMU i386 ===" && \
+    qemu-i386-static --version | head -n1
+
+# Ensure workspace directory ownership for non-root user
+RUN mkdir -p /workspaces/etl && chown -R ${USERNAME}:${USERNAME} /workspaces
+
+# Switch to non-root user
+USER ${USERNAME}
+
+# Default command
+CMD ["/bin/bash"]

.devcontainer/i386/devcontainer.json

@@ -0,0 +1,29 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/cpp
+{
+  "name": "i386 (Debian)",
+  "build": {
+    "dockerfile": "./Dockerfile",
+    "context": "."
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-vscode.cpptools",
+        "ms-vscode.cmake-tools"
+      ],
+      "settings": {
+        "cmake.sourceDirectory": "${workspaceFolder}/test",
+        "cmake.configureArgs": [
+          "-DCMAKE_TOOLCHAIN_FILE=${workspaceFolder}/.devcontainer/i386/toolchain-i386.cmake",
+          "-DBUILD_TESTS=ON",
+          "-DNO_STL=OFF",
+          "-DETL_CXX_STANDARD=23"
+        ],
+        "cmake.buildDirectory": "${workspaceFolder}/build-i386",
+        "cmake.generator": "Ninja"
+      }
+    }
+  },
+  "remoteUser": "root"
+}

.devcontainer/i386/toolchain-i386.cmake

@@ -0,0 +1,21 @@
+# CMake toolchain file for i386 cross-compilation
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR i386)
+
+# Specify the cross compiler
+set(CMAKE_C_COMPILER i686-linux-gnu-gcc)
+set(CMAKE_CXX_COMPILER i686-linux-gnu-g++)
+set(CMAKE_AR i686-linux-gnu-ar)
+set(CMAKE_RANLIB i686-linux-gnu-ranlib)
+set(CMAKE_STRIP i686-linux-gnu-strip)
+
+# Search for programs in the build host directories
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+
+# For libraries and headers in the target directories
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+# Set QEMU for running tests
+set(CMAKE_CROSSCOMPILING_EMULATOR /usr/bin/qemu-i386-static CACHE FILEPATH "Path to the emulator for cross-compiled binaries")

.devcontainer/powerpc/Dockerfile

@@ -0,0 +1,85 @@
+# powerpc Test Environment for ETL
+# Uses QEMU user-mode emulation to run powerpc binaries on x64 host
+FROM debian:sid-20260406
+
+# Avoid prompts from apt
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Install QEMU user-mode emulation and powerpc cross-compilation tools
+RUN dpkg --add-architecture powerpc && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    binfmt-support \
+    gpg \
+    ca-certificates \
+    cmake \
+    make \
+    ninja-build \
+    git \
+    wget \
+    file \
+    debian-ports-archive-keyring \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN cat <<EOF > /etc/apt/sources.list.d/debian.sources
+Types: deb
+URIs: http://snapshot.debian.org/archive/debian/20260406T000000Z
+Suites: sid
+Components: main
+Signed-By: /usr/share/keyrings/debian-archive-keyring.pgp
+EOF
+
+RUN cat <<EOF > /etc/apt/sources.list.d/powerpc.sources
+Types: deb
+URIs: http://snapshot.debian.org/archive/debian-ports/20260406T000000Z
+Suites: sid
+Components: main
+Architectures: powerpc
+Signed-By: /usr/share/keyrings/debian-ports-archive-keyring.gpg
+EOF
+
+RUN echo 'Acquire::Check-Valid-Until "false";' > /etc/apt/apt.conf.d/99no-check-valid
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    qemu-user-static \
+    qemu-user \
+    gcc-powerpc-linux-gnu \
+    g++-powerpc-linux-gnu \
+    libc6:powerpc \
+    libstdc++6:powerpc \
+    libatomic1:powerpc \
+    && rm -rf /var/lib/apt/lists/*
+
+# Create non-root user with stable UID/GID
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=1000
+
+RUN groupadd --gid ${USER_GID} ${USERNAME} && \
+    useradd --uid ${USER_UID} --gid ${USER_GID} --shell /bin/bash --create-home ${USERNAME}
+
+# Set working directory
+WORKDIR /workspaces/etl
+
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
+
+# Verify QEMU and cross-compilation setup
+RUN echo "=== Host Architecture ===" && \
+    uname -m && \
+    echo "" && \
+    echo "=== powerpc Cross Compiler ===" && \
+    powerpc-linux-gnu-gcc --version && \
+    echo "" && \
+    echo "=== QEMU powerpc ===" && \
+    qemu-ppc-static --version | head -n1
+
+# Ensure workspace directory ownership for non-root user
+RUN mkdir -p /workspaces/etl && chown -R ${USERNAME}:${USERNAME} /workspaces
+
+# Switch to non-root user
+USER ${USERNAME}
+
+# Default command
+CMD ["/bin/bash"]

.devcontainer/powerpc/devcontainer.json

@@ -0,0 +1,29 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/cpp
+{
+  "name": "powerpc (Debian)",
+  "build": {
+    "dockerfile": "./Dockerfile",
+    "context": "."
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-vscode.cpptools",
+        "ms-vscode.cmake-tools"
+      ],
+      "settings": {
+        "cmake.sourceDirectory": "${workspaceFolder}/test",
+        "cmake.configureArgs": [
+          "-DCMAKE_TOOLCHAIN_FILE=${workspaceFolder}/.devcontainer/powerpc/toolchain-powerpc.cmake",
+          "-DBUILD_TESTS=ON",
+          "-DNO_STL=ON",
+          "-DETL_CXX_STANDARD=23"
+        ],
+        "cmake.buildDirectory": "${workspaceFolder}/build-powerpc",
+        "cmake.generator": "Ninja"
+      }
+    }
+  },
+  "remoteUser": "root"
+}

.devcontainer/powerpc/toolchain-powerpc.cmake

@@ -0,0 +1,21 @@
+# CMake toolchain file for powerpc cross-compilation
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR powerpc)
+
+# Specify the cross compiler
+set(CMAKE_C_COMPILER powerpc-linux-gnu-gcc)
+set(CMAKE_CXX_COMPILER powerpc-linux-gnu-g++)
+set(CMAKE_AR powerpc-linux-gnu-ar)
+set(CMAKE_RANLIB powerpc-linux-gnu-ranlib)
+set(CMAKE_STRIP powerpc-linux-gnu-strip)
+
+# Search for programs in the build host directories
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+
+# For libraries and headers in the target directories
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+# Set QEMU for running tests
+set(CMAKE_CROSSCOMPILING_EMULATOR /usr/bin/qemu-ppc CACHE FILEPATH "Path to the emulator for cross-compiled binaries")

.devcontainer/riscv64/Dockerfile

@@ -0,0 +1,61 @@
+# riscv64 Test Environment for ETL
+# Uses QEMU user-mode emulation to run riscv64 binaries on x64 host
+FROM debian:trixie
+
+# Avoid prompts from apt
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Install QEMU user-mode emulation and riscv64 cross-compilation tools
+RUN dpkg --add-architecture riscv64 && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    qemu-user-static \
+    qemu-user \
+    binfmt-support \
+    gcc-riscv64-linux-gnu \
+    g++-riscv64-linux-gnu \
+    cmake \
+    make \
+    ninja-build \
+    git \
+    wget \
+    ca-certificates \
+    file \
+    libc6:riscv64 \
+    libstdc++6:riscv64 \
+    libatomic1:riscv64 \
+    && rm -rf /var/lib/apt/lists/*
+
+# Create non-root user with stable UID/GID
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=1000
+
+RUN groupadd --gid ${USER_GID} ${USERNAME} && \
+    useradd --uid ${USER_UID} --gid ${USER_GID} --shell /bin/bash --create-home ${USERNAME}
+
+# Set working directory
+WORKDIR /workspaces/etl
+
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
+
+# Verify QEMU and cross-compilation setup
+RUN echo "=== Host Architecture ===" && \
+    uname -m && \
+    echo "" && \
+    echo "=== riscv64 Cross Compiler ===" && \
+    riscv64-linux-gnu-gcc --version && \
+    echo "" && \
+    echo "=== QEMU riscv64 ===" && \
+    qemu-riscv64-static --version | head -n1
+
+# Ensure workspace directory ownership for non-root user
+RUN mkdir -p /workspaces/etl && chown -R ${USERNAME}:${USERNAME} /workspaces
+
+# Switch to non-root user
+USER ${USERNAME}
+
+# Default command
+CMD ["/bin/bash"]

.devcontainer/riscv64/devcontainer.json

@@ -0,0 +1,29 @@
+// For format details, see https://aka.ms/devcontainer.json. For config options, see the
+// README at: https://github.com/devcontainers/templates/tree/main/src/cpp
+{
+  "name": "riscv64 (Debian)",
+  "build": {
+    "dockerfile": "./Dockerfile",
+    "context": "."
+  },
+  "customizations": {
+    "vscode": {
+      "extensions": [
+        "ms-vscode.cpptools",
+        "ms-vscode.cmake-tools"
+      ],
+      "settings": {
+        "cmake.sourceDirectory": "${workspaceFolder}/test",
+        "cmake.configureArgs": [
+          "-DCMAKE_TOOLCHAIN_FILE=${workspaceFolder}/.devcontainer/riscv64/toolchain-riscv64.cmake",
+          "-DBUILD_TESTS=ON",
+          "-DNO_STL=OFF",
+          "-DETL_CXX_STANDARD=23"
+        ],
+        "cmake.buildDirectory": "${workspaceFolder}/build-riscv64",
+        "cmake.generator": "Ninja"
+      }
+    }
+  },
+  "remoteUser": "root"
+}

.devcontainer/riscv64/toolchain-riscv64.cmake

@@ -0,0 +1,20 @@
+# CMake toolchain file for riscv64 cross-compilation
+set(CMAKE_SYSTEM_NAME Linux)
+set(CMAKE_SYSTEM_PROCESSOR riscv64)
+
+# Specify the cross compiler
+set(CMAKE_C_COMPILER riscv64-linux-gnu-gcc)
+set(CMAKE_CXX_COMPILER riscv64-linux-gnu-g++)
+set(CMAKE_AR riscv64-linux-gnu-ar)
+set(CMAKE_RANLIB riscv64-linux-gnu-ranlib)
+set(CMAKE_STRIP riscv64-linux-gnu-strip)
+# Search for programs in the build host directories
+set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
+
+# For libraries and headers in the target directories
+set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
+set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
+
+# Set QEMU for running tests
+set(CMAKE_CROSSCOMPILING_EMULATOR /usr/bin/qemu-riscv64-static CACHE FILEPATH "Path to the emulator for cross-compiled binaries")

.devcontainer/run-tests.sh

@@ -0,0 +1,56 @@
+#!/bin/bash
+#
+# Run tests inside the separately created docker container for different hardware architecture
+#
+# Strategy:
+# * Create docker image
+# * Enter image
+# * Cross build tests
+# * Run tests via QEMU
+#
+
+set -e
+
+usage()
+{
+  echo "Usage: run-tests.sh <architecture>"
+  echo "Architecture: armhf|i386|powerpc|riscv64|s390x"
+  echo "(run from project root)"
+}
+
+ARCHLIST="armhf i386 powerpc riscv64 s390x"
+
+if [[ " $ARCHLIST " =~ " $1 " ]] ; then
+  ARCH=$1
+else
+  echo "Unsupported architecture: $1"
+  usage
+  exit 1
+fi
+
+if [ "$2" = "" ] ; then
+  echo "Creating docker image..."
+  docker build -t $ARCH .devcontainer/$ARCH
+
+  echo "Entering container..."
+  docker run -it --rm -v "$PWD":/workspaces/etl -w /workspaces/etl $ARCH /bin/bash .devcontainer/run-tests.sh $ARCH inside_container
+
+elif [ "$2" = "inside_container" ] ; then
+  echo "Cross building tests..."
+  mkdir -p build-$ARCH
+  cd build-$ARCH
+  cmake -DCMAKE_TOOLCHAIN_FILE=../.devcontainer/$ARCH/toolchain-$ARCH.cmake \
+        -DBUILD_TESTS=ON -DNO_STL=ON -DETL_CXX_STANDARD=23 \
+        -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_OPTIMISATION=-O0 -DETL_ENABLE_SANITIZER=OFF -DETL_MESSAGES_ARE_NOT_VIRTUAL=OFF \
+        ../test
+  export CMAKE_BUILD_PARALLEL_LEVEL=$(nproc)
+  cmake --build .
+
+  echo "Running tests via CTest (using QEMU emulator from toolchain)..."
+  ctest -V --output-on-failure
+  echo "Tests successful."
+else
+  echo "Invalid second argument: $2"
+  usage
+  exit 1
+fi

.devcontainer/s390x/Dockerfile

@@ -7,7 +7,7 @@ ENV DEBIAN_FRONTEND=noninteractive
 
 # Install QEMU user-mode emulation and s390x cross-compilation tools
 RUN dpkg --add-architecture s390x && \
-    apt-get update && apt-get install -y --no-install-recommends\
+    apt-get update && apt-get install -y --no-install-recommends \
     qemu-user-static \
     qemu-user \
     binfmt-support \
@@ -18,14 +18,29 @@ RUN dpkg --add-architecture s390x && \
     ninja-build \
     git \
     wget \
+    ca-certificates \
     file \
     libc6:s390x \
     libstdc++6:s390x \
+    libatomic1:s390x \
     && rm -rf /var/lib/apt/lists/*
 
+# Create non-root user with stable UID/GID
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=1000
+
+RUN groupadd --gid ${USER_GID} ${USERNAME} && \
+    useradd --uid ${USER_UID} --gid ${USER_GID} --shell /bin/bash --create-home ${USERNAME}
+
 # Set working directory
 WORKDIR /workspaces/etl
 
+# Install Bazelisk as 'bazel'
+RUN ARCH=$(uname -m | sed 's/x86_64/amd64/;s/aarch64/arm64/') && \
+    wget -qO /usr/local/bin/bazel https://github.com/bazelbuild/bazelisk/releases/latest/download/bazelisk-linux-${ARCH} && \
+    chmod +x /usr/local/bin/bazel
+
 # Verify QEMU and cross-compilation setup
 RUN echo "=== Host Architecture ===" && \
     uname -m && \
@@ -36,5 +51,11 @@ RUN echo "=== Host Architecture ===" && \
     echo "=== QEMU s390x ===" && \
     qemu-s390x-static --version | head -n1
 
+# Ensure workspace directory ownership for non-root user
+RUN mkdir -p /workspaces/etl && chown -R ${USERNAME}:${USERNAME} /workspaces
+
+# Switch to non-root user
+USER ${USERNAME}
+
 # Default command
 CMD ["/bin/bash"]

.devcontainer/s390x/devcontainer.json

@@ -18,7 +18,7 @@
           "-DCMAKE_TOOLCHAIN_FILE=${workspaceFolder}/.devcontainer/s390x/toolchain-s390x.cmake",
           "-DBUILD_TESTS=ON",
           "-DNO_STL=OFF",
-          "-DETL_CXX_STANDARD=17"
+          "-DETL_CXX_STANDARD=23"
         ],
         "cmake.buildDirectory": "${workspaceFolder}/build-s390x",
         "cmake.generator": "Ninja"

.devcontainer/ubuntu-26.04/Dockerfile

@@ -0,0 +1,20 @@
+FROM ubuntu:26.04
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update && apt-get install -y \
+    build-essential \
+    cmake \
+    git \
+    ninja-build \
+    python3 \
+    python3-pip \
+    clang \
+    docker.io \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN useradd -m -s /bin/bash vscode
+
+WORKDIR /etl
+
+CMD ["/bin/bash"]

.github/workflows/bazel-gcc-c++23-no-stl.yml

@@ -0,0 +1,22 @@
+name: bazel-gcc-c++23-no-stl
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-bazel-gcc-cpp23-no-stl:
+    name: Bazel GCC C++23 Linux - No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build
+      run: bazel build //test:etl_tests --cxxopt=-std=c++23 --copt=-DETL_NO_STL
+
+    - name: Run tests
+      run: bazel test //test:etl_tests --cxxopt=-std=c++23 --copt=-DETL_NO_STL --test_output=all

.github/workflows/clang-c++11.yml

@@ -25,7 +25,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -47,7 +47,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v

.github/workflows/clang-c++14.yml

@@ -25,7 +25,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -47,7 +47,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v

.github/workflows/clang-c++17.yml

@@ -25,7 +25,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -47,7 +47,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v

.github/workflows/clang-c++20.yml

@@ -32,7 +32,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./
         clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v
@@ -61,7 +61,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -90,7 +90,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -112,7 +112,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -134,7 +134,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -156,7 +156,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -178,7 +178,7 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v

.github/workflows/clang-c++23.yml

@@ -13,26 +13,19 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
 
-    # Temporary fix. See https://github.com/actions/runner-images/issues/8659
-    - name: Install newer Clang
-      run: |
-        wget https://apt.llvm.org/llvm.sh
-        chmod +x ./llvm.sh
-        sudo ./llvm.sh 17
-
     - name: Build
       run: |
-        export CC=clang-17
-        export CXX=clang++-17
+        export CC=clang
+        export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=OFF -DETL_CXX_STANDARD=23 ./
-        clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v
@@ -42,26 +35,19 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
 
-    # Temporary fix. See https://github.com/actions/runner-images/issues/8659
-    - name: Install newer Clang
-      run: |
-        wget https://apt.llvm.org/llvm.sh
-        chmod +x ./llvm.sh
-        sudo ./llvm.sh 17
-
     - name: Build
       run: |
-        export CC=clang-17
-        export CXX=clang++-17
+        export CC=clang
+        export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
-        clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -71,26 +57,19 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
 
-    # Temporary fix. See https://github.com/actions/runner-images/issues/8659
-    - name: Install newer Clang
-      run: |
-        wget https://apt.llvm.org/llvm.sh
-        chmod +x ./llvm.sh
-        sudo ./llvm.sh 17
-
     - name: Build
       run: |
-        export CC=clang-17
-        export CXX=clang++-17
+        export CC=clang
+        export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
-        clang-17 --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -110,9 +89,9 @@ jobs:
         export CC=clang
         export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=OFF -DETL_CXX_STANDARD=23 ./
+        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -132,9 +111,9 @@ jobs:
         export CC=clang
         export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=OFF -DETL_CXX_STANDARD=23 ./
+        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -154,9 +133,9 @@ jobs:
         export CC=clang
         export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
+        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -176,9 +155,9 @@ jobs:
         export CC=clang
         export CXX=clang++
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
-        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
+        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v

.github/workflows/clang-c++26.yml

@@ -0,0 +1,185 @@
+name: clang-c++26
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-clang-cpp26-linux-stl:
+    name: Clang C++26 Linux - STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./ && \
+          clang --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-clang-cpp26-linux-no-stl:
+    name: Clang C++26 Linux - No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./ && \
+          clang --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-clang-cpp26-linux-stl-force-cpp03:
+    name: Clang C++26 Linux - STL - Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./ && \
+          clang --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-clang-cpp26-linux-no-stl-force-cpp03:
+    name: Clang C++26 Linux - No STL - Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./ && \
+          clang --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-clang-cpp26-osx-stl:
+    name: Clang C++26 OSX - STL
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-26]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build
+      run: |
+        export CC=clang
+        export CXX=clang++
+        export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
+        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+    - name: Run tests
+      run: ./test/etl_tests -v
+
+  build-clang-cpp26-osx-no-stl:
+    name: Clang C++26 OSX - No STL
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-26]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build
+      run: |
+        export CC=clang
+        export CXX=clang++
+        export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
+        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+    - name: Run tests
+      run: ./test/etl_tests -v
+
+  build-clang-cpp26-osx-stl-force-cpp03:
+    name: Clang C++26 OSX - STL - Force C++03
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-26]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build
+      run: |
+        export CC=clang
+        export CXX=clang++
+        export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
+        cmake -D BUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+    - name: Run tests
+      run: ./test/etl_tests -v
+
+  build-clang-cpp26-osx-no-stl-force-cpp03:
+    name: Clang C++26 OSX - No STL - Force C++03
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [macos-26]
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build
+      run: |
+        export CC=clang
+        export CXX=clang++
+        export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
+        cmake -D BUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./
+        clang --version
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+    - name: Run tests
+      run: ./test/etl_tests -v

.github/workflows/clang-syntax-checks.yml

@@ -23,10 +23,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=03 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp03-linux-No-STL:
-    name: Syntax Check - Clang C++03 Linux No STL 
+    name: Syntax Check - Clang C++03 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -41,7 +41,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=03 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp11-linux-STL:
     name: Syntax Check - Clang C++11 Linux STL
@@ -59,10 +59,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp11-linux-No-STL:
-    name: Syntax Check - Clang C++11 Linux No STL 
+    name: Syntax Check - Clang C++11 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -77,7 +77,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp11-linux-STL-Force-CPP03:
     name: Syntax Check - Clang C++11 Linux STL Force C++03
@@ -95,7 +95,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=11 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp11-linux-No-STL-Force-CPP03:
     name: Syntax Check - Clang C++11 Linux No STL Force C++03
@@ -113,7 +113,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=11 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp14-linux-STL:
     name: Syntax Check - Clang C++14 Linux STL
@@ -131,10 +131,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp14-linux-No-STL:
-    name: Syntax Check - Clang C++14 Linux No STL 
+    name: Syntax Check - Clang C++14 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -149,7 +149,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp14-linux-STL-Force-CPP03:
     name: Syntax Check - Clang C++14 Linux STL Force C++03
@@ -167,7 +167,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=14 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp14-linux-No-STL-Force-CPP03:
     name: Syntax Check - Clang C++14 Linux No STL Force C++03
@@ -185,7 +185,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=14 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp17-linux-STL:
     name: Syntax Check - Clang C++17 Linux STL
@@ -203,10 +203,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp17-linux-No-STL:
-    name: Syntax Check - Clang C++17 Linux No STL 
+    name: Syntax Check - Clang C++17 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -221,7 +221,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp17-linux-STL-Force-CPP03:
     name: Syntax Check - Clang C++17 Linux STL Force C++03
@@ -239,7 +239,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=17 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp17-linux-No-STL-Force-CPP03:
     name: Syntax Check - Clang C++17 Linux No STL Force C++03
@@ -257,7 +257,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=17 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp20-linux-STL:
     name: Syntax Check - Clang C++20 Linux STL
@@ -275,10 +275,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp20-linux-No-STL:
-    name: Syntax Check - Clang C++20 Linux No STL 
+    name: Syntax Check - Clang C++20 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -293,7 +293,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp20-linux-STL-Force-CPP03:
     name: Syntax Check - Clang C++20 Linux STL Force C++03
@@ -311,7 +311,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp20-linux-No-STL-Force-CPP03:
     name: Syntax Check - Clang C++20 Linux No STL Force C++03
@@ -329,7 +329,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp23-linux-STL:
     name: Syntax Check - Clang C++23 Linux STL
@@ -347,10 +347,10 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp23-linux-No-STL:
-    name: Syntax Check - Clang C++23 Linux No STL 
+    name: Syntax Check - Clang C++23 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -365,7 +365,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp23-linux-STL-Force-CPP03:
     name: Syntax Check - Clang C++23 Linux STL Force C++03
@@ -383,7 +383,7 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-clang-cpp23-linux-No-STL-Force-CPP03:
     name: Syntax Check - Clang C++23 Linux No STL Force C++03
@@ -401,4 +401,84 @@ jobs:
         export CXX=clang++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 ./test/syntax_check
         clang --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+  build-clang-cpp26-linux-STL:
+    name: Syntax Check - Clang C++26 Linux STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          clang++ --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-clang-cpp26-linux-No-STL:
+    name: Syntax Check - Clang C++26 Linux No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          clang++ --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-clang-cpp26-linux-STL-Force-CPP03:
+    name: Syntax Check - Clang C++26 Linux STL Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          clang++ --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-clang-cpp26-linux-No-STL-Force-CPP03:
+    name: Syntax Check - Clang C++26 Linux No STL Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=clang && \
+          export CXX=clang++ && \
+          cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          clang++ --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"

.github/workflows/clang-tidy.yaml

@@ -0,0 +1,29 @@
+name: clang-tidy
+
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+  clang-tidy:
+    name: clang-tidy
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Install dependencies
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y --no-install-recommends clang clang-tidy
+          clang --version
+          clang-tidy --version
+          run-clang-tidy --version || true
+
+      - name: Run clang-tidy
+        run: |
+          test/run-clang-tidy.sh

.github/workflows/coverage.yml

@@ -65,8 +65,4 @@ jobs:
     steps:
     - name: Deploy to GitHub Pages
       id: deployment
-      uses: actions/deploy-pages@v4
-
-# GitHub Repository settings
-# -> Settings -> Pages
-# -> Source: gh actions
+      uses: actions/deploy-pages@v5

.github/workflows/deploy_documentation.yml

@@ -0,0 +1,39 @@
+name: Deploy documentation to www.etlcpp.com
+
+on:
+  push:
+    branches:
+      - master
+
+    workflow_dispatch:
+
+jobs:
+  build_deploy:
+    name: build and deploy
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          submodules: true
+          fetch-depth: 0
+
+      - name: Setup Hugo
+        uses: peaceiris/actions-hugo@v3
+        with:
+          hugo-version: '0.147.1'
+          extended: true
+
+      - name: Build
+        working-directory: hugo
+        run: hugo --minify --cleanDestinationDir --baseURL "https://www.etlcpp.com/"
+
+      # Deploys the site via the deploy script in the ci directory
+      - name: Deploy
+        run: source $GITHUB_WORKSPACE/scripts/deploy_documentation.sh
+        env:
+          ACTIONS_DEPLOY_KEY: ${{ secrets.DOCS_BDEPLOY_KEY }}
+          SSH_USERNAME: ${{ secrets.DOCS_SSH_USER }}
+          SERVER_ADDRESS: ${{ secrets.DOCS_SSH_SERVER }}
+          SERVER_DESTINATION: ${{ secrets.DOCS_DEST_DIR }}
+          SSH_PORT: ${{ secrets.DOCS_SSH_PORT }}

.github/workflows/gcc-c++11.yml

@@ -26,7 +26,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v
@@ -49,7 +49,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v

.github/workflows/gcc-c++14.yml

@@ -25,7 +25,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v
@@ -47,7 +47,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v

.github/workflows/gcc-c++17.yml

@@ -25,7 +25,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v
@@ -47,7 +47,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v

.github/workflows/gcc-c++20.yml

@@ -25,7 +25,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v
@@ -47,7 +47,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v
@@ -69,7 +69,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -91,7 +91,7 @@ jobs:
         export CXX=g++
         cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v

.github/workflows/gcc-c++23-armhf.yml

@@ -0,0 +1,29 @@
+name: gcc-c++23-armhf
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp23-linux-no-stl-armhf:
+    name: GCC C++23 Linux - No STL - armhf
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-armhf -f .devcontainer/armhf/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-armhf bash -c "\
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF \
+           -DETL_CXX_STANDARD=23 -DCMAKE_TOOLCHAIN_FILE=.devcontainer/armhf/toolchain-armhf.cmake \
+           -DEXTRA_TESTING_FLAGS=-v \
+           ./ && \
+          cmake --build . -- -j \$(getconf _NPROCESSORS_ONLN) && \
+          ctest -V"

.github/workflows/gcc-c++23-i386.yml

@@ -0,0 +1,29 @@
+name: gcc-c++23-i386
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp23-linux-no-stl-i386:
+    name: GCC C++23 Linux - No STL - i386
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-i386 -f .devcontainer/i386/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-i386 bash -c "\
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF \
+           -DETL_CXX_STANDARD=23 -DCMAKE_TOOLCHAIN_FILE=.devcontainer/i386/toolchain-i386.cmake \
+           -DEXTRA_TESTING_FLAGS=-v \
+           ./ && \
+          cmake --build . -- -j \$(getconf _NPROCESSORS_ONLN) && \
+          ctest -V"

.github/workflows/gcc-c++23-powerpc.yml

@@ -0,0 +1,29 @@
+name: gcc-c++23-powerpc
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp23-linux-no-stl-powerpc:
+    name: GCC C++23 Linux - No STL - powerpc
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-powerpc -f .devcontainer/powerpc/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-powerpc bash -c "\
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF \
+           -DETL_CXX_STANDARD=23 -DCMAKE_TOOLCHAIN_FILE=.devcontainer/powerpc/toolchain-powerpc.cmake \
+           -DEXTRA_TESTING_FLAGS=-v \
+           ./ && \
+          cmake --build . -- -j \$(getconf _NPROCESSORS_ONLN) && \
+          ctest -V"

.github/workflows/gcc-c++23-riscv64.yml

@@ -0,0 +1,29 @@
+name: gcc-c++23-riscv64
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp23-linux-no-stl-riscv64:
+    name: GCC C++23 Linux - No STL - riscv64
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-riscv64 -f .devcontainer/riscv64/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-riscv64 bash -c "\
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF \
+           -DETL_CXX_STANDARD=23 -DCMAKE_TOOLCHAIN_FILE=.devcontainer/riscv64/toolchain-riscv64.cmake \
+           -DEXTRA_TESTING_FLAGS=-v \
+           ./ && \
+          cmake --build . -- -j \$(getconf _NPROCESSORS_ONLN) && \
+          ctest -V"

.github/workflows/gcc-c++23-s390x.yml

@@ -0,0 +1,29 @@
+name: gcc-c++23-s390x
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp23-linux-no-stl-s390x:
+    name: GCC C++23 Linux - No STL - s390x
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-s390x -f .devcontainer/s390x/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-s390x bash -c "\
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF \
+           -DETL_CXX_STANDARD=23 -DCMAKE_TOOLCHAIN_FILE=.devcontainer/s390x/toolchain-s390x.cmake \
+           -DEXTRA_TESTING_FLAGS=-v \
+           ./ && \
+          cmake --build . -- -j \$(getconf _NPROCESSORS_ONLN) && \
+          ctest -V"

.github/workflows/gcc-c++23.yml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
@@ -23,9 +23,9 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         export CC=gcc
         export CXX=g++
-        cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=OFF -DETL_CXX_STANDARD=23 ./
+        cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v
@@ -35,7 +35,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
@@ -45,9 +45,9 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         export CC=gcc
         export CXX=g++
-        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=OFF -DETL_CXX_STANDARD=23 ./
+        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v
@@ -57,7 +57,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
@@ -67,9 +67,9 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         export CC=gcc
         export CXX=g++
-        cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
+        cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
     - name: Run tests
       run: ./test/etl_tests -v
@@ -79,7 +79,7 @@ jobs:
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        os: [ubuntu-22.04]
+        os: [ubuntu-24.04]
 
     steps:
     - uses: actions/checkout@v4
@@ -89,9 +89,9 @@ jobs:
         export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0
         export CC=gcc
         export CXX=g++
-        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03=ON -DETL_CXX_STANDARD=23 ./
+        cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 -DETL_OPTIMISATION=-O3 ./
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
     
     - name: Run tests
       run: ./test/etl_tests -v

.github/workflows/gcc-c++26.yml

@@ -0,0 +1,97 @@
+name: gcc-c++26
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-gcc-cpp26-linux-stl:
+    name: GCC C++26 Linux - STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./ && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-gcc-cpp26-linux-no-stl:
+    name: GCC C++26 Linux - No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./ && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-gcc-cpp26-linux-stl-force-cpp03:
+    name: GCC C++26 Linux - STL - Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./ && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"
+
+  build-gcc-cpp26-linux-no-stl-force-cpp03:
+    name: GCC C++26 Linux - No STL - Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build and run tests
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export ASAN_OPTIONS=alloc_dealloc_mismatch=0,detect_leaks=0 && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DBUILD_TESTS=ON -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./ && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN) && \
+          ./test/etl_tests -v"

.github/workflows/gcc-syntax-checks.yml

@@ -23,10 +23,10 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=03 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp03-linux-No-STL:
-    name: Syntax Check - GCC C++03 Linux No STL 
+    name: Syntax Check - GCC C++03 Linux No STL
     runs-on: ${{ matrix.os }}
     strategy:
       matrix:
@@ -41,7 +41,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=03 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp11-linux-STL:
     name: Syntax Check - GCC C++11 Linux STL
@@ -59,7 +59,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp11-linux-No-STL:
     name: Syntax Check - GCC C++11 Linux No STL 
@@ -77,7 +77,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=11 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp11-linux-STL-Force-CPP03:
     name: Syntax Check - GCC C++11 Linux STL Force C++03
@@ -95,7 +95,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=11 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp11-linux-No-STL-Force-CPP03:
     name: Syntax Check - GCC C++11 Linux No STL Force C++03
@@ -113,7 +113,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=11 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp14-linux-STL:
     name: Syntax Check - GCC C++14 Linux STL
@@ -131,7 +131,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp14-linux-No-STL:
     name: Syntax Check - GCC C++14 Linux No STL 
@@ -149,7 +149,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=14 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp14-linux-STL-Force-CPP03:
     name: Syntax Check - GCC C++14 Linux STL Force C++03
@@ -167,7 +167,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=14 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp14-linux-No-STL-Force-CPP03:
     name: Syntax Check - GCC C++14 Linux No STL Force C++03
@@ -185,7 +185,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=14 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp17-linux-STL:
     name: Syntax Check - GCC C++17 Linux STL
@@ -203,7 +203,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp17-linux-No-STL:
     name: Syntax Check - GCC C++17 Linux No STL 
@@ -221,7 +221,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=17 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp17-linux-STL-Force-CPP03:
     name: Syntax Check - GCC C++17 Linux STL Force C++03
@@ -239,7 +239,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=17 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp17-linux-No-STL-Force-CPP03:
     name: Syntax Check - GCC C++17 Linux No STL Force C++03
@@ -257,7 +257,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=17 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp20-linux-STL:
     name: Syntax Check - GCC C++20 Linux STL
@@ -275,7 +275,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp20-linux-No-STL:
     name: Syntax Check - GCC C++20 Linux No STL 
@@ -293,7 +293,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=20 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp20-linux-STL-Force-CPP03:
     name: Syntax Check - GCC C++20 Linux STL Force C++03
@@ -311,7 +311,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp20-linux-No-STL-Force-CPP03:
     name: Syntax Check - GCC C++20 Linux No STL Force C++03
@@ -329,7 +329,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=20 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp23-linux-STL:
     name: Syntax Check - GCC C++23 Linux STL
@@ -347,7 +347,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp23-linux-No-STL:
     name: Syntax Check - GCC C++23 Linux No STL 
@@ -365,7 +365,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=23 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp23-linux-STL-Force-CPP03:
     name: Syntax Check - GCC C++23 Linux STL Force C++03
@@ -383,7 +383,7 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
 
   build-gcc-cpp23-linux-No-STL-Force-CPP03:
     name: Syntax Check - GCC C++23 Linux No STL Force C++03
@@ -401,4 +401,84 @@ jobs:
         export CXX=g++
         cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=23 ./test/syntax_check
         gcc --version
-        make -j $(getconf _NPROCESSORS_ONLN)
+        make -j "$(getconf _NPROCESSORS_ONLN)"
+
+  build-gcc-cpp26-linux-STL:
+    name: Syntax Check - GCC C++26 Linux STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-gcc-cpp26-linux-No-STL:
+    name: Syntax Check - GCC C++26 Linux No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=OFF -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-gcc-cpp26-linux-STL-Force-CPP03:
+    name: Syntax Check - GCC C++26 Linux STL Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DNO_STL=OFF -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"
+
+  build-gcc-cpp26-linux-No-STL-Force-CPP03:
+    name: Syntax Check - GCC C++26 Linux No STL Force C++03
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: Build Docker image
+      run: docker build -t etl-ubuntu-2604 -f .devcontainer/ubuntu-26.04/Dockerfile .
+
+    - name: Build
+      run: |
+        docker run --rm --user root -v ${{ github.workspace }}:/workspaces/etl etl-ubuntu-2604 bash -c "\
+          cd /workspaces/etl && \
+          export CC=gcc && \
+          export CXX=g++ && \
+          cmake -DNO_STL=ON -DETL_USE_TYPE_TRAITS_BUILTINS=OFF -DETL_USER_DEFINED_TYPE_TRAITS=OFF -DETL_FORCE_TEST_CPP03_IMPLEMENTATION=ON -DETL_CXX_STANDARD=26 ./test/syntax_check && \
+          gcc --version && \
+          make -j \$(getconf _NPROCESSORS_ONLN)"

.github/workflows/generator.yml

@@ -14,12 +14,11 @@ jobs:
     steps:
     - uses: actions/checkout@v4
 
-    - name: Generate
+    - name: Install dependencies
       run: |
         sudo apt-get update
         sudo apt-get install -y python3-cogapp
-        cd include/etl/generators && bash generate.bat
 
-    - name: Check Generated Headers For Changes
+    - name: Run generator_test.py
       run: |
-        git diff --exit-code
+        cd scripts && python3 generator_test.py

.github/workflows/meson-gcc-c++23-no-stl.yml

@@ -0,0 +1,31 @@
+name: meson-gcc-c++23-no-stl
+on:
+  push:
+    branches: [ master, development, pull-request/* ]
+  pull_request:
+    branches: [ master, development, pull-request/* ]
+    types: [opened, synchronize, reopened]
+
+jobs:
+
+  build-meson-gcc-cpp23-no-stl:
+    name: Meson GCC C++23 Linux - No STL
+    runs-on: ubuntu-24.04
+
+    steps:
+    - uses: actions/checkout@v6
+
+    - name: Install Meson
+      run: sudo apt-get install -y meson
+
+    - name: Configure
+      run: |
+        export CC=gcc
+        export CXX=g++
+        meson setup builddir -Duse_stl=false -Dcpp_std=c++23
+
+    - name: Build
+      run: meson compile -C builddir
+
+    - name: Run tests
+      run: meson test -C builddir -v

.gitignore

@@ -419,3 +419,5 @@ hugo/resources
 hugo/.hugo_build.lock
 docs/*.html
 test/build-coverage
+include/etl/iterator.h~RFfd5eda.TMP
+test/vs2022/Build

BUILD.bazel

@@ -0,0 +1,9 @@
+load("@rules_cc//cc:defs.bzl", "cc_library")
+
+package(default_visibility = ["//visibility:public"])
+
+cc_library(
+    name = "etl",
+    hdrs = glob(["include/**/*.h"]),
+    includes = ["include"],
+)

DOCUMENTATION.md

@@ -0,0 +1,144 @@
+# Viewing the documentation locally
+
+The documentation for this project is built using [Hugo](https://gohugo.io/), a static site generator.
+This guide will walk you through installing Hugo and running the documentation site on your machine.
+
+---
+
+## Prerequisites
+
+- You must have already cloned this repository, including its submodules (the Hugo themes are stored as submodules).
+- If you cloned without submodules, run this first:
+```bash
+  git submodule update --init --recursive
+```
+
+---
+
+## Step 1: Install Hugo Extended
+
+This project requires the **extended** version of Hugo, which includes support for additional features such as SCSS/Sass processing.  
+Make sure you install the extended version, not the standard one.
+
+### Windows
+
+1. The easiest way to install Hugo on Windows is via [Chocolatey](https://chocolatey.org/). If you have it installed, open a command prompt as Administrator and run:
+```bash
+   choco install hugo-extended -y
+```
+2. If you don't have Chocolatey, you can download Hugo Extended directly from the [Hugo releases page](https://github.com/gohugoio/hugo/releases).  
+Download the file named `hugo_extended_x.x.x_windows-amd64.zip`, extract it, and add the folder to your system PATH.
+3. Verify the installation by opening a new command prompt and running:
+```bash
+   hugo version
+```
+   You should see the word **extended** in the output, for example: `hugo v0.x.x+extended`.
+
+### macOS
+
+1. The easiest way to install Hugo Extended on macOS is via [Homebrew](https://brew.sh/). Homebrew installs the extended version by default. If you have it installed, open a terminal and run:
+```bash
+   brew install hugo
+```
+2. If you don't have Homebrew, you can install it first by following the instructions at [brew.sh](https://brew.sh/), then run the command above.
+3. Verify the installation by running:
+```bash
+   hugo version
+```
+   You should see the word **extended** in the output, for example: `hugo v0.x.x+extended`.
+
+### Linux
+
+1. Package managers often provide an older or non-extended version of Hugo, so the recommended approach is to download the latest extended release directly from the [Hugo releases page](https://github.com/gohugoio/hugo/releases).
+   Download the file named `hugo_extended_x.x.x_linux-amd64.tar.gz`, then run:
+```bash
+   tar -xzf hugo_extended_x.x.x_linux-amd64.tar.gz
+   sudo mv hugo /usr/local/bin/
+```
+2. Verify the installation by running:
+```bash
+   hugo version
+```
+   You should see the word **extended** in the output, for example: `hugo v0.x.x+extended`.
+
+---
+
+## Step 2: Run the documentation site
+
+1. Open a terminal (or command prompt on Windows) and navigate to the `hugo` directory inside the project:
+```bash
+   cd hugo
+```
+
+2. Start the Hugo development server:
+```bash
+   hugo server
+```
+
+3. Hugo will start a local web server. You will see output similar to:
+```
+   Web Server is available at http://localhost:1313/
+```
+
+4. Open your browser and go to **http://localhost:1313/** to view the documentation.
+
+---
+
+## Stopping the server
+
+To stop the Hugo server, go back to your terminal and press **Ctrl+C**.
+
+---
+
+## Editing the Documentation
+
+The documentation source files are located in the `/docs` directory at the root of the repository —
+**not** inside the `hugo` directory. Hugo is configured to mount this directory automatically via
+`hugo.toml`, so any changes you make to files in `/docs` will be picked up by the Hugo development
+server straight away.
+
+Here is a quick overview of where things live:
+```
+hugo/
+├── layouts/        # HTML templates (you probably won't need to touch these)
+├── themes/         # The Hugo theme (managed as a git submodule)
+└── hugo.toml       # Hugo configuration file (includes the /docs content mount)
+
+docs/
+└── section-name/   # Each subdirectory becomes a section in the documentation
+    ├── _index.md   # The landing page for that section
+    └── my-page.md  # Individual pages within the section
+```
+
+### Adding or Editing a Page
+
+All documentation pages are written in **Markdown** (`.md` files). To edit an existing page, open
+the relevant `.md` file in the `/docs` directory and make your changes.
+
+The documentation is written in [Goldmark](https://github.com/teekennedy/goldmark-markdown) markdown.
+
+Hugo uses [Goldmark](https://github.com/teekennedy/goldmark-markdown) as its default Markdown processor for versions 0.60.0 and newer.  
+It is built into Hugo, providing high-performance and fully [CommonMark](https://commonmark.org/)-compliant rendering, along with support for [GitHub](https://docs.github.com/en/get-started/writing-on-github/getting-started-with-writing-and-formatting-on-github/basic-writing-and-formatting-syntax) Markdown.
+
+### Starting a New Page
+
+A template file is provided at `docs/page-template.md` to use as a starting point. Copy it to the
+appropriate section directory, rename it, and edit the front matter, in particular, change the
+`title` and remove the `draft: true` line, otherwise Hugo will not include your page in the
+documentation.
+
+### Previewing Your Changes
+
+If you have the Hugo development server running (see [Step 2](#step-2--run-the-documentation-site)),
+your changes will appear in the browser automatically as soon as you save the file. There is no need
+to restart the server.
+
+### Images and Other Assets
+
+If you need to include images in your documentation, place them in the `hugo/static/` directory and
+reference them in your Markdown like so:
+```markdown
+![Alt text](/my-image.png)
+```
+
+The site will automatically refresh in your browser whenever you save changes to the documentation files.

MODULE.bazel

@@ -0,0 +1,7 @@
+module(
+    name = "etl",
+    version = "0.0.0",
+)
+
+bazel_dep(name = "platforms", version = "0.0.11")
+bazel_dep(name = "rules_cc", version = "0.1.1")

MODULE.bazel.lock

@@ -0,0 +1,205 @@
+{
+  "lockFileVersion": 24,
+  "registryFileHashes": {
+    "https://bcr.bazel.build/bazel_registry.json": "8a28e4aff06ee60aed2a8c281907fb8bcbf3b753c91fb5a5c57da3215d5b3497",
+    "https://bcr.bazel.build/modules/abseil-cpp/20210324.2/MODULE.bazel": "7cd0312e064fde87c8d1cd79ba06c876bd23630c83466e9500321be55c96ace2",
+    "https://bcr.bazel.build/modules/abseil-cpp/20211102.0/MODULE.bazel": "70390338f7a5106231d20620712f7cccb659cd0e9d073d1991c038eb9fc57589",
+    "https://bcr.bazel.build/modules/abseil-cpp/20230125.1/MODULE.bazel": "89047429cb0207707b2dface14ba7f8df85273d484c2572755be4bab7ce9c3a0",
+    "https://bcr.bazel.build/modules/abseil-cpp/20230802.0.bcr.1/MODULE.bazel": "1c8cec495288dccd14fdae6e3f95f772c1c91857047a098fad772034264cc8cb",
+    "https://bcr.bazel.build/modules/abseil-cpp/20230802.0/MODULE.bazel": "d253ae36a8bd9ee3c5955384096ccb6baf16a1b1e93e858370da0a3b94f77c16",
+    "https://bcr.bazel.build/modules/abseil-cpp/20230802.1/MODULE.bazel": "fa92e2eb41a04df73cdabeec37107316f7e5272650f81d6cc096418fe647b915",
+    "https://bcr.bazel.build/modules/abseil-cpp/20240116.1/MODULE.bazel": "37bcdb4440fbb61df6a1c296ae01b327f19e9bb521f9b8e26ec854b6f97309ed",
+    "https://bcr.bazel.build/modules/abseil-cpp/20240116.1/source.json": "9be551b8d4e3ef76875c0d744b5d6a504a27e3ae67bc6b28f46415fd2d2957da",
+    "https://bcr.bazel.build/modules/bazel_features/1.1.1/MODULE.bazel": "27b8c79ef57efe08efccbd9dd6ef70d61b4798320b8d3c134fd571f78963dbcd",
+    "https://bcr.bazel.build/modules/bazel_features/1.11.0/MODULE.bazel": "f9382337dd5a474c3b7d334c2f83e50b6eaedc284253334cf823044a26de03e8",
+    "https://bcr.bazel.build/modules/bazel_features/1.15.0/MODULE.bazel": "d38ff6e517149dc509406aca0db3ad1efdd890a85e049585b7234d04238e2a4d",
+    "https://bcr.bazel.build/modules/bazel_features/1.17.0/MODULE.bazel": "039de32d21b816b47bd42c778e0454217e9c9caac4a3cf8e15c7231ee3ddee4d",
+    "https://bcr.bazel.build/modules/bazel_features/1.18.0/MODULE.bazel": "1be0ae2557ab3a72a57aeb31b29be347bcdc5d2b1eb1e70f39e3851a7e97041a",
+    "https://bcr.bazel.build/modules/bazel_features/1.19.0/MODULE.bazel": "59adcdf28230d220f0067b1f435b8537dd033bfff8db21335ef9217919c7fb58",
+    "https://bcr.bazel.build/modules/bazel_features/1.30.0/MODULE.bazel": "a14b62d05969a293b80257e72e597c2da7f717e1e69fa8b339703ed6731bec87",
+    "https://bcr.bazel.build/modules/bazel_features/1.30.0/source.json": "b07e17f067fe4f69f90b03b36ef1e08fe0d1f3cac254c1241a1818773e3423bc",
+    "https://bcr.bazel.build/modules/bazel_features/1.4.1/MODULE.bazel": "e45b6bb2350aff3e442ae1111c555e27eac1d915e77775f6fdc4b351b758b5d7",
+    "https://bcr.bazel.build/modules/bazel_features/1.9.1/MODULE.bazel": "8f679097876a9b609ad1f60249c49d68bfab783dd9be012faf9d82547b14815a",
+    "https://bcr.bazel.build/modules/bazel_skylib/1.0.3/MODULE.bazel": "bcb0fd896384802d1ad283b4e4eb4d718eebd8cb820b0a2c3a347fb971afd9d8",
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README.md

@@ -2,7 +2,7 @@
 
 ![GitHub release (latest by date)](https://img.shields.io/github/v/release/jwellbelove/etl)
 [![Release date](https://img.shields.io/github/release-date/jwellbelove/etl?color=%231182c3)](https://img.shields.io/github/release-date/jwellbelove/etl?color=%231182c3)
-[![Standard](https://img.shields.io/badge/c%2B%2B-98/03/11/14/17/20/23-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization)
+[![Standard](https://img.shields.io/badge/c%2B%2B-98/03/11/14/17/20/23/26-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization)
 [![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://opensource.org/licenses/MIT)
 ![GitHub contributors](https://img.shields.io/github/contributors-anon/ETLCPP/etl)
 ![GitHub forks](https://img.shields.io/github/forks/ETLCPP/etl?style=flat)
@@ -15,6 +15,7 @@
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-c++17.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-c++20.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-c++23.yml/badge.svg?branch=master)
+![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-c++26.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/gcc-syntax-checks.yml/badge.svg?branch=master)
 
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-c++11.yml/badge.svg?branch=master)
@@ -22,6 +23,7 @@
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-c++17.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-c++20.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-c++23.yml/badge.svg?branch=master)
+![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-c++26.yml/badge.svg?branch=master)
 ![CI](https://github.com/ETLCPP/etl/actions/workflows/clang-syntax-checks.yml/badge.svg?branch=master)
 
 [![Codacy Badge](https://api.codacy.com/project/badge/Grade/3c14cd918ccf40008d0bcd7b083d5946)](https://www.codacy.com/manual/jwellbelove/etl?utm_source=github.com&utm_medium=referral&utm_content=ETLCPP/etl&utm_campaign=Badge_Grade)
@@ -49,7 +51,7 @@ Its design goals include:
 -	Offering APIs that closely resemble those of the STL, enabling familiar and consistent usage.
 
 -	Maintaining compatibility with C++98 while implementing many features introduced in later standards
-(C++11/14/17/20/23) where possible.
+(C++11/14/17/20/23/26) where possible.
 
 -	Ensuring deterministic behavior, which is critical in real-time and resource-constrained environments.
 

arduino/Embedded_Template_Library.h

@@ -18,6 +18,22 @@
     #define ARDUINO_BOARD "Teensy 3.5"
   #elif defined(__MK66FX1M0__)
     #define ARDUINO_BOARD "Teensy 3.6"
+  #elif defined(ARDUINO_TEENSY40)
+    #define ARDUINO_BOARD "Teensy 4.0"
+  #elif defined(ARDUINO_TEENSY41)
+    #define ARDUINO_BOARD "Teensy 4.1"
+  #elif defined(ARDUINO_TEENSY_MICROMOD)
+    #define ARDUINO_BOARD "Teensy MicroMod"
+  #else
+    #define ARDUINO_BOARD "Unknown"
+  #endif
+
+#elif defined(CORE_ARDUINO_PICO)
+
+  #if defined(PICO_RP2040)
+    #define ARDUINO_BOARD "RP2040"
+  #elif defined(PICO_RP2350)
+    #define ARDUINO_BOARD "RP2350"
   #else
     #define ARDUINO_BOARD "Unknown"
   #endif

docs/IO/_index.md

@@ -0,0 +1,6 @@
+---
+title: "IO"
+weight: 100
+---
+
+Classes that address access to hardware.

docs/IO/bip_buffer_spsc_atomic.md

@@ -0,0 +1,152 @@
+---
+title: "bip_buffer_spsc_atomic"
+---
+
+{{< callout >}}
+  Header: `bip_buffer_spsc_atomic.h`  
+  Since: tbc
+{{< /callout >}}
+
+A fixed capacity bipartite buffer.  
+
+A bipartite buffer is a memory buffer design that uses two contiguous halves of the same underlying memory block to create a seamless, wraparound-free view of a circular/ring buffer's contents.
+
+**The Problem It Solves**  
+Ring buffers are efficient for streaming data, but when data wraps around the end of the buffer back to the beginning, reading a contiguous chunk across that boundary normally requires two separate reads or a temporary copy.
+
+**How It Works**  
+A bipartite buffer allocates a backing array that is twice the needed capacity. The two halves (the "bipartite" part) are mapped to the same physical memory, so:
+
+The first region covers indices 0 to N-1
+The second region covers indices N to 2N-1, but maps to the same memory as the first
+
+This means any contiguous slice of up to N bytes can always be read as a single, linear pointer — no wraparound, no copying, no splitting.
+
+```cpp
+etl::bip_buffer_spsc_atomic<typename T, 
+                            size_t SIZE, 
+                            size_t MEMORY_MODEL = etl::memory_model::MEMORY_MODEL_LARGE>
+```
+
+Inherits from `etl::ibip_buffer_spsc_atomic<T>`.  
+
+`etl::ibip_buffer_spsc_atomic` may be used as a size independent pointer or reference type for any `etl::bip_buffer_spsc_atomic instance`.
+
+## Member types
+
+`value_type`  
+`size_type`  
+`reference`  
+`const_reference`  
+`rvalue_reference`  
+
+## Static Constants
+
+`MAX_SIZE`  The maximum size of the circular_buffer.
+
+## Constructor
+```cpp
+etl::bip_buffer_spsc_atomic<typename T, 
+                            size_t SIZE, 
+                            size_t MEMORY_MODEL = etl::memory_model::MEMORY_MODEL_LARGE>();
+```
+
+## Capacity
+
+```cpp
+bool empty() const
+```
+**Description**  
+Returns `true` if the size of the circular buffer is zero, otherwise `false`.
+
+---
+
+```cpp
+bool full() const
+```
+**Description**  
+Returns `true` if the size of the circular buffer is `SIZE`, otherwise `false`.
+
+---
+
+```cpp
+size_t size() const
+```
+**Description**  
+Returns the size of the circular buffer.
+
+---
+
+```cpp
+size_t max_size() const
+```
+**Description**  
+Returns the maximum possible size of the circular buffer.
+
+---
+
+```cpp
+size_t capacity() const
+```
+**Description**  
+Returns the maximum possible size of the circular buffer.
+
+---
+
+```cpp
+size_t available() const
+```
+**Description**  
+Returns the remaining available capacity in the circular buffer.
+
+## Modifiers
+
+```cpp
+etl::span<T> read_reserve(size_type max_reserve_size = numeric_limits<size_type>::max())
+```
+**Description**  
+Reserves a memory area for reading (up to the `max_reserve_size`).
+
+```cpp
+void read_commit(const etl::span<T> &reserve)
+```
+**Description**  
+Commits the previously reserved read memory area
+the reserve can be trimmed at the end before committing.
+Throws `bip_buffer_reserve_invalid`.
+
+---
+
+```cpp
+etl::span<T> write_reserve(size_type max_reserve_size)
+```
+**Description**  
+Reserves a memory area for writing up to the `max_reserve_size`.
+
+---
+
+```cpp
+etl::span<T> write_reserve_optimal(size_type min_reserve_size = 1U)
+```
+**Description**  
+Reserves an optimal memory area for writing. The buffer will only wrap
+around if the available forward space is less than `min_reserve_size`.
+
+---
+
+```cpp
+void write_commit(const etl::span<T> &reserve)
+```
+**Description**  
+Commits the previously reserved write memory area
+the reserve can be trimmed at the end before committing.
+Throws `bip_buffer_reserve_invalid`
+
+---
+
+```cpp
+void clear()
+```
+**Description**  
+Clears the buffer, destructing any elements that haven't been read.
+

docs/IO/buffer_descriptors.md

@@ -0,0 +1,277 @@
+---
+title: "buffer_descriptors"
+---
+
+{{< callout >}}
+  Header: `buffer_descriptors.h`  
+  Since: All versions  
+{{< /callout >}}
+
+A set of descriptors to a collection of buffers.
+
+```cpp
+template <typename TBuffer,      // The type to store in the buffer.
+          TSize    BUFFER_SIZE,  // The size of each buffer.
+          size_t   N_BUFFERS,    // The total number of buffers.
+          typename TFlag = bool> // The 'in use' flag type.
+class buffer_descriptors
+```
+
+The type used for the 'in use' flag depends on how the buffer descriptors class is used.
+For interrupts and multi-threaded code, either the flag  type must force a fence (by using an atomic type) or the calls to allocate and release must ensure that they are not re-ordered by the compiler or processor.
+
+## Member types
+| Type          |                                                                      |
+| ------------- | -------------------------------------------------------------------- |
+| value_type    | The type that is stored in the buffers                               |
+| size_type     | An unsigned integral type                                            |
+| flag_type     |                                                                      |
+| pointer       |                                                                      |
+| descriptor    | A nested class that encapsulates the details of an individual buffer |
+| notification  | A nested class that is sent to the user defined callback function    |
+| callback_type | `etl::delegate<void(notification)>`                                  |
+
+## Static Constants  
+| Value       |                                                           |
+| ----------- | --------------------------------------------------------- |
+| N_BUFFERS   | The number of buffers that the buffer descriptor controls |
+| BUFFER_SIZE | The number of elements in each buffer                     |
+
+## Constructors  
+```cpp
+buffer_descriptors(pointer pbuffers)
+```
+**Description**  
+Construct with a pointer to the start of the buffers to control.
+This storage should be contiguous and large enough to hold `N_BUFFERS`.
+
+---
+
+```cpp
+buffer_descriptors(pointer pbuffers, const callback_type& callback)
+```
+**Description**  
+Construct with a pointer to the start of the buffers to control and the callback.
+
+## Member functions  
+
+```cpp
+void set_callback(const callback_type& callback)
+```
+**Description**  
+Set the callback for notification.
+
+---
+
+```cpp
+bool is_valid() const
+```
+**Description**  
+Returns true if class contains valid buffers.
+
+---
+
+```cpp
+void notify(notification n)
+```
+**Description**  
+Calls the user defined callback with the descriptor and buffer size.
+Used when the buffer has been filled and is ready for processing via the callback.
+
+---
+
+```cpp
+descriptor allocate()
+```
+**Description**  
+Returns a new descriptor. 
+If all descriptors are in use then the descriptor will be invalid.
+
+---
+
+```cpp
+descriptor allocate(value_type fill)
+```
+**Description**  
+Returns a new descriptor and fills the buffer with fill. 
+If all descriptors are in use then the descriptor will be invalid.
+
+---
+
+```cpp
+void clear()
+```
+**Description**  
+Clears by releasing all allocated descriptors.
+
+```cpp
+descriptor
+```
+**Description**  
+A nested class that encapsulates the details of an individual buffer.
+
+---
+
+```cpp
+const size_type MAX_SIZE
+```
+**Description**  
+The maximum size of the buffer.
+
+---
+
+```cpp
+descriptor()
+```
+**Description**  
+Default constructor.
+
+---
+
+```cpp
+ETL_CONSTEXPR pointer data() const
+```
+**Description**  
+Returns a pointer to the start of the buffer.
+
+---
+
+```cpp
+ETL_CONSTEXPR size_type max_size() const
+```
+**Description**  
+Returns the maximum size of the buffer.
+
+---
+
+```cpp
+bool is_valid() const
+```
+**Description**  
+Returns true if the descriptor points to a valid buffer.
+
+---
+
+```cpp
+bool is_allocated() const
+```
+**Description**  
+Returns true if the descriptor has been allocated.
+
+---
+
+```cpp
+bool is_released() const
+```
+**Description**  
+Returns true if the descriptor has been released.
+
+---
+
+```cpp
+void release()
+```
+**Description**  
+Releases the descriptor.
+
+---
+
+```cpp
+notification
+```
+**Description**  
+A nested class that is sent to the user defined callback function.
+
+---
+
+```cpp
+notification()
+```
+**Description**  
+Default contructor.
+Initialises to a default constructed descriptor and a count of zero.
+
+---
+
+```cpp
+notification(descriptor desc, size_t count)
+```
+**Description**  
+Construct with the supplied parameters.
+
+---
+
+```cpp
+descriptor get_descriptor() const
+```
+**Description**  
+Gets the descriptor.
+
+---
+
+```cpp
+size_t get_count() const
+```
+**Description**  
+Gets the count.
+
+## Example
+*Very simplified.*  
+Assumes that there is a DMA driver class called DMA.  
+In the real world the descriptor would be queued in the callback and handled in a foreground thread.  
+The handler in the thread would release the descriptor.
+
+```cpp
+constexpr size_t BUFFER_SIZE = 256U;
+constexpr size_t N_BUFFERS   = 8U;
+
+// Define the buffer descriptors type.
+using BD = etl::buffer_descriptors<char, BUFFER_SIZE, N_BUFFERS, std::atomic_char>;
+
+// The buffers to use with it.
+char buffers[N_BUFFERS][BUFFER_SIZE];
+
+// The function to call when a buffer is ready.
+void Callback(BD::notification notification)
+{
+  // Process the buffer in the descriptor here.
+  ProcessData(notification.get_descriptor().data(), notification.get_count());
+
+  // Finished with the descriptor now, so release it back.
+  notification.get_descriptor().release();
+}
+
+// Create the buffer_descriptors.
+BD bd(&buffers[0][0], BD::callback_type::create<Callback>());
+
+// The current dma descriptor.
+BD::descriptor dma_descriptor;
+
+// An object that controls the DMA.
+DMA dma;
+
+// Call to start the DMA.
+void DMAStart()
+{
+  // Get a new descriptor.
+  dma_descriptor = bd.allocate();
+
+  if (dma_descriptor.is_valid())
+  {
+    // Link the buffer to the DMA channel.
+    dma.Start(dma_descriptor.data());
+  }
+  else
+  {
+    // No valid descriptors available.
+    LogError("No Descriptor Available");
+  }
+}
+
+// Called when the DMA has completed (usually an interrupt).
+void DMAComplete()
+{
+  // DMA is complete. Notify the callback.
+  bd.notify(BD::notification(dma_descriptor, dma.GetTransferredSize()));
+}
+```

docs/IO/debounce.md

@@ -0,0 +1,246 @@
+---
+title: "debounce"
+---
+
+{{< callout type="info">}}
+  Header: `debounce.h`  
+  Since: `TBC`  
+{{< /callout >}}
+
+A class to debounce signals.
+
+It can detect signal hold, and generate auto repeat.
+
+```cpp
+etl::debounce<uint16_t Valid_Count  = 0, 
+              uint16_t Hold_Count   = 0, 
+              uint16_t Repeat_Count = 0>
+```              
+
+There are four variants of the class which are selected at compile time according to the supplied template parameters.
+All of the template parameters are optional. 
+
+If the first parameter is supplied then the debouncer acts as a simple signal debounce.  
+The signal will become valid after `VALID_COUNT` identical samples have been added.  
+
+If the second parameter is supplied then the debouncer will detect the signal being held true for `HOLD_COUNT` samples after becoming valid.  
+
+If the third parameter is supplied then the debouncer will indicate that a change has occurred for the signal being held true for each `REPEAT_COUNT` that occurs after entering the hold state.  
+
+If no template parameters are supplied then the template variant using internal variables is used.  
+This has similar parameters supplied to the constructor or the `set` member function.  
+
+The diagram below shows the effect of the various parameters.
+
+![Debounce sequence](debounce.png)
+
+## Functions
+
+```cpp
+debounce(bool initial_state = false)
+```
+**Description**  
+Default constructor.  
+
+`etl::debounce<Valid_Count, Hold_Count, Repeat_Count>`
+
+The initial state defaults to:  
+
+Initial state = `false`  
+Valid count   = `Valid_Count`  
+Hold count    = `Hold_Count`  
+Repeat count  = `Repeat_Count`  
+
+---
+
+`etl::debounce<Valid_Count, Hold_Count>`
+
+The initial state defaults to:  
+
+Initial state = `false`  
+Valid count   = `Valid_Count`  
+Hold count    = `Hold_Count`  
+Repeat count  = `0` (Disabled)  
+
+---
+
+`etl::debounce<Valid_Count>`
+
+The initial state defaults to:  
+
+Initial state = `false`  
+Valid count   = `Valid_Count`  
+Hold count    = `0` (Disabled)  
+Repeat count  = `0` (Disabled)  
+
+---
+
+`etl::debounce<>`
+
+The initial state defaults to:  
+
+Initial state = `false`  
+Valid count   = `1`  
+Hold count    = `0` (Disabled)  
+Repeat count  = `0` (Disabled)  
+
+---
+
+```cpp
+debounce(bool     initial_state,
+         uint16_t valid_count  = 1, 
+         uint16_t hold_count   = 0, 
+         uint16_t repeat_count = 0)
+```
+**Description**  
+The constructor available when no template parameters are supplied.
+
+Valid count   = `1`  
+Hold count    = `0` (Disabled)   
+Repeat count  = `0` (Disabled)  
+
+---
+
+```cpp
+bool add(bool sample)
+```
+**Description**  
+Adds a new signal sample. Returns true if the state of the debouncer becomes valid, held or repeating.
+
+```cpp
+bool has_changed() const
+```
+**Description**  
+Returns `true` if the state of the debouncer became valid, held or repeating after the last sample
+
+---
+
+```cpp
+bool is_set() const
+```
+**Description**  
+Returns `true` if the debouncer is set, `false` if cleared.
+
+---
+
+```cpp
+bool is_held() const
+```
+**Description**  
+Returns `true` if the debouncer signal is being held.
+
+---
+
+```cpp
+bool is_repeating() const
+```
+**Description**  
+Returns `true` if the debouncer signal is repeating.
+
+---
+
+```cpp
+void set(uint16_t valid_count, uint16_t hold_count = 0, uint16_t repeat_count = 0)
+```
+**Description**  
+Sets the debouncer parameters.  
+Only available when no template parameters are supplied.
+
+## Examples
+```cpp
+etl::debounce<20> debouncer;
+```
+**Description**  
+Simple debounce.  
+Valid after 20 identical samples.
+
+---
+
+```cpp
+etl::debounce<20, 1000> debouncer;
+```
+**Description**  
+Key debounce.  
+Valid after 20 identical samples.  
+Hold detection after 1000 'set' samples.
+
+---
+
+```cpp
+etl::debounce<20, 1000, 100> debouncer;
+```
+**Description**  
+Key debounce with hold and auto repeat. 
+Valid after 20 identical samples.  
+Hold detection after 1000 'set' samples.  
+Repeat every 100 samples after hold.  
+
+---
+
+```cpp
+etl::debounce<> debouncer;
+debouncer.set(20, 1000, 100);
+```
+**Description**  
+Key debounce with hold and auto repeat.  
+Runtime parameters.
+
+---
+
+The example below targets the Arduino hardware.
+
+```cpp
+//***********************************************************************************
+// A debounce demo that reads a key and toggles the LED.
+// Set the pin to the correct one for your key.
+//***********************************************************************************
+
+#include <debounce.h>
+
+// The sample time in ms.
+const int Sample_Time = 1;    
+
+// The number of samples that must agree before a key state change is recognised.
+// 50 = 50ms for 1ms sample time.
+const int Debounce_Count = 50;
+
+// The number of samples that must agree before a key held state is recognised.
+// 1000 = 1s for 1ms sample time.
+const int Hold_Count = 1000;   
+
+// The number of samples that must agree before a key repeat state is recognised.
+// 200 = 200ms for 1ms sample time.
+const int Repeat_Count = 200;     
+
+// The pin that the key is attached to.
+const int Key = XX;
+
+void setup()
+{
+  // Initialize LED pin as an output.
+  pinMode(LED_BUILTIN , OUTPUT);
+  digitalWrite(LED_BUILTIN, LOW);
+  
+  // Initialize KEY pin as an input.
+  pinMode(KEY, INPUT);
+}
+
+void loop()
+{
+  static int led_state = LOW; 
+  static etl::debounce<Debounce_Count, Hold_Count, Repeat_Count> key_state;
+
+  // Assumes 'HIGH' is 'pressed' and 'LOW' is 'released'.
+  if (key_state.add(digitalRead(KEY) == HIGH))   
+  {
+    if (key_state.is_set())
+    {
+      // Toggle the LED state on every validated press or repeat.
+      led_state = (led_state == LOW ? HIGH : LOW); 
+      digitalWrite(LED_BUILTIN, led_state);
+    }
+  }
+  
+  delay(1); // Wait 1ms
+}
+```

docs/IO/io_port.md

@@ -0,0 +1,411 @@
+---
+title: "io_port"
+---
+
+{{< callout type="info">}}
+  Header: `io_port.h`  
+  From: `20.39.0`  
+{{< /callout >}}
+
+A set of templates for building interface classes to memory mapped hardware ports.
+They avoid the need to directly map carefully packed (and possibly non-portable) structures onto memory addresses.
+
+>A read from a write-only, or write to a read-only port will result in a compile time error.
+
+**Defines classes for the following IO types**  
+Read / Write.  
+Read only.  
+Write only.  
+Write only with shadow register.  
+
+With a shadow register the value written is stored locally and may be read back.  
+
+The port may either have an address fixed at compile time or set at runtime. The compile time versions require no extra overhead compared to a plain memory mapped structure.  
+
+Ports may be sent as parameters to algorithms that expect iterators, except the runtime address version of `io_port_wos`, which must use the built-in iterator if the shadow value is to be correctly updated for writes.  
+
+All classes define the following typedefs.
+
+| Type name         | Maps to             |
+| ----------------- | ------------------- |
+| `value_type`      | `T`                 |
+| `pointer`         | `volatile T*`       |
+| `const_pointer`   | `volatile const T*` |
+| `reference`       | `volatile T&`       |
+| `const_reference` | `volatile const T&` |
+
+## Read/write port
+```cpp
+io_port_rw<typename T, uintptr_t Address>
+```
+**Description**  
+Compile time port address.
+
+---
+
+**Types**  
+iterator  
+const_iterator  
+
+---
+
+```cpp
+operator T() const
+```
+**Description**  
+Read the value.  
+Conversion operator to T.
+
+---
+
+```cpp
+iterator iter()
+```
+**Description**  
+Get an iterator to this port.
+
+---
+
+```cpp
+const_iterator iter() const
+const_iterator citer() const
+```
+**Description**  
+Get a const_iterator to this port.
+
+---
+
+```cpp
+T read() const
+```
+**Description**  
+Read the value.
+
+---
+
+```cpp
+void write(T value)
+```
+**Description**  
+Write the value.
+
+---
+
+```cpp
+io_port_rw& operator =(T value)
+```
+**Description**  
+Write the value.
+
+---
+
+```cpp
+pointer get_address()
+const_pointer get_address() const
+```
+**Description**  
+Gets the address of the port.
+
+---
+
+```cpp
+io_port_rw& operator |=(value_type value)
+```
+**Description**  
+Or-Equals operator.
+
+---
+
+```cpp
+io_port_rw& operator &=(value_type value)
+```
+**Description**  
+And-Equals operator.
+
+---
+
+```cpp
+io_port_rw& operator ^=(value_type value)
+```
+**Description**
+Exclusive-Or-Equals operator.
+
+---
+
+```cpp
+io_port_rw& operator <<=(int shift)
+```
+**Description**  
+Left-Shift-Equals operator.
+
+---
+
+```cpp
+io_port_rw& operator >>=(int shift)
+```
+**Description**  
+Right-Shift-Equals operator.
+
+---
+
+```cpp
+value_type operator ~() const
+```
+**Description**  
+Not operator.
+
+## Read only port
+```cpp
+io_port_ro<typename T, uintptr_t Address>
+```
+
+---
+
+**Types**  
+```cpp
+const_iterator
+```
+
+---
+
+```cpp
+operator T() const
+```
+**Description**  
+Read the value. Conversion operator to T.
+
+---
+
+```cpp
+const_iterator iter() const
+const_iterator citer() const
+```
+**Description**
+Get a const_iterator to this port.
+
+---
+
+```cpp
+T read() const
+```
+**Description**  
+Read the value.
+
+---
+
+```cpp
+const_pointer get_address() const
+```
+**Description**  
+Gets the address of the port.
+
+## Write only port
+```cpp
+io_port_wo<typename T, uintptr_t Address>
+```
+
+---
+
+**Types**  
+iterator
+
+---
+
+```cpp
+iterator iter()
+```
+**Description**  
+Get an iterator to this port.
+
+---
+
+```cpp
+void write(T value)
+```
+**Description**  
+Write the value.
+
+---
+
+```cpp
+io_port_wo& operator =(T value)
+```
+**Description**  
+Write the value.
+
+---
+
+```cpp
+pointer get_address()
+```
+**Description**  
+Gets the address of the port.
+
+## Write only port, with shadow register
+```cpp
+io_port_wos<typename T, uintptr_t Address>
+```
+
+---
+
+**Types**  
+```cpp
+iterator
+const_iterator
+```
+
+---
+
+```cpp
+operator T() const
+```
+**Description**  
+Read the value. Conversion operator to `T`.
+
+---
+
+```cpp
+iterator iter()
+```
+**Description**
+Get an iterator to this port.
+
+---
+
+```cpp
+const_iterator iter() const
+const_iterator citer() const
+```
+**Description**  
+Get a `const_iterator` to this port.
+
+---
+
+```cpp
+T read() const
+```
+**Description**  
+Read the value.
+
+---
+
+```cpp
+void write(T value)
+```
+**Description**  
+Write the value.
+
+---
+
+```cpp
+io_port_rw& operator =(T value)
+```
+**Description**
+Write the value.
+
+---
+
+```cpp
+pointer get_address()
+const_pointer get_address() const
+```
+**Description**  
+Gets the address of the port.
+
+---
+
+```cpp
+io_port_rw& operator |=(value_type value)
+```
+**Description**  
+Or-Equals operator.
+
+---
+```cpp
+io_port_rw& operator &=(value_type value)
+```
+**Description**  
+And-Equals operator.
+
+---
+
+```cpp
+io_port_rw& operator ^=(value_type value)
+```
+**Description**  
+Exclusive-Or-Equals operator.
+
+---
+
+```cpp
+io_port_rw& operator <<=(int shift)
+```
+**Description**  
+Left-Shift-Equals operator.
+
+---
+
+```cpp
+io_port_rw& operator >>=(int shift)
+```
+**Description**  
+Right-Shift-Equals operator.
+
+---
+
+```cpp
+value_type operator ~() const
+```
+**description**  
+Not operator.
+
+## Example serial port
+
+The example uses a port at a compile time address.
+
+| Variable  | Description                                                |
+| --------- | ---------------------------------------------------------- |
+| `rxdata`  | An 8 bit read only port                                    |
+| `txdata`  | An 8 bit write only port                                   |
+| `control` | A 16 bit write only port, with shadow register             |
+| `status`  | A 16 bit read only port. It shares an address with control |
+| `option`  | An 8 bit read/write port                                   |
+
+```cpp
+template <uintptr_t Address>
+struct serial_port
+{
+  etl::io_port_ro<char,      Address>     rxdata;  // Read only rx data register.
+  etl::io_port_wo<char,      Address + 1> txdata;  // Write only tx register.
+  etl::io_port_wos<uint16_t, Address + 2> control; // Write only, with shadow, control register.
+  etl::io_port_ro<uint16_t,  Address + 2> status;  // Read only status register.
+  etl::io_port_ro<char,      Address>     option;  // Read/Write register.
+};
+
+serial_port<0x800> port; // A serial port at address 0x800
+
+// Read Rx data
+char data   = port.rxdata;
+
+// Write Tx data
+port.txdata = 'A';
+
+// Compile error! txdata is write only.
+data = port.txdata;
+
+// Write to the control register and read back what we wrote.
+port.control = 0x1234;
+uint16_t control = port.control;
+
+// Flip bit 3 of the control register.
+port.control ^= 0x0080;
+
+// Read from the status register.
+uint16_t status = port.status;
+
+// Copy data from a buffer to the Tx data port.
+std::copy(txBuffer.begin(), txBuffer.end(), serial_port.txdata.iter());
+
+// Copy data from the Rx data port to a buffer.
+std::copy_n(serial_port.rxdata, serial_port.status, std::back_inserter(rxBuffer)); 
+```

docs/Is the ETL free.md

@@ -0,0 +1,75 @@
+---
+title: "Is the ETL free?"
+# Force it to the top of the list
+weight: 1
+# Disable the Table of Contents entirely for this page
+toc: false
+---
+
+The ETL is free for you or your company to use, including in commercial applications.  
+
+*However, it is not free for me to create or maintain.*
+
+## Why Open Source Needs Support
+
+Development, support, documentation, testing, and hosting all require time and resources.  
+*Currently, this work is carried entirely by me, usually without compensation.*
+
+As the ETL has grown in functionality and popularity, so has the workload. In some weeks, maintaining the project takes over 30 hours. Without financial support, this is difficult to sustain alongside paid work and personal obligations.
+
+## Why Sponsor the Embedded Template Library (ETL)?
+
+The Embedded Template Library (ETL) is a modern, high-performance C++ library designed specifically for embedded systems. It provides STL-like functionality for environments where efficiency, reliability, and low overhead are essential.
+
+The ETL is used by hobbyists, engineers, and international companies developing commercial embedded products. Yet it is maintained by a single developer in their spare time.
+
+If the ETL has helped your project or become part of your development toolset, please consider supporting its continued growth.
+
+## Why Sponsorship Matters
+
+- **Sustainability**  
+Ongoing support helps keep the library maintained and up to date.
+- **Reliability**  
+Sponsorship allows for regular testing, bug fixes, and improvements.
+- **Responsibility**  
+Supporting the tools you depend on strengthens the software ecosystem.
+- **Recognition**  
+Sponsors can be publicly acknowledged if desired.
+
+Whether you use the ETL in personal projects or commercial products, your support helps keep it available and improving.
+
+The ETL began as a way to share years of embedded development experience. Since 2014, it has grown into a feature-rich and widely used library.  
+*But it is still powered by one developer, without corporate funding.*
+
+If you or your company benefit from the ETL, please consider becoming a sponsor. Even small contributions help cover hosting, tools, and time spent supporting the library and its users.
+
+[Why CFOs should care about Open Source software](https://opensourcepledge.com/blog/CFOs-care-about-OSS/)
+
+## How to sponsor
+
+There are two ways that you can help me with the maintenance and further development of the library.
+
+**Through the GitHub donations link.**  
+[Github sponsors](https://github.com/sponsors/ETLCPP)
+
+---
+
+**By direct bank transfer**  
+  Donations are accepted in many world currencies.  
+  AED, AUD, BGN, CAD, CHF, CLP, COP, CZK, DKK, EGP, EUR, GBP, HKD, HUF, ILS, INR, ISK, JPY, KRW, 
+  KZT, MAD, MXN, NOK, NZD, PHP, PLN, QAR, RON, RSD, SAR, SEK, SGD, THB, TRY, USD, ZAR 
+
+  I can supply invoices for companies that require one for accounting and tax purposes. 
+
+**UK**  
+Beneficiary   John Wellbelove  
+Account       12655643  
+Sort code     04-00-75
+
+**Swift (International)** 
+Beneficiary  John Wellbelove  
+IBAN         GB17 REVO 0099 7000 7513 26  
+BIC          REVOGB21  
+
+Many thanks for any support you can give to keep this project actively supported,  
+*John Wellbelove*

docs/Messaging/_index.md

@@ -0,0 +1,23 @@
+---
+title: "Messaging"
+weight: 100
+---
+
+## Headers
+
+- `message.h`  
+  Defines the core message model. etl::imessage is the base interface (virtual or non-virtual, depending on `ETL_HAS_VIRTUAL_MESSAGES`). `etl::message<ID>` provides typed messages with static IDs. Type traits (`is_message`, `is_message_type`, etc.) and ID comparison utilities support compile-time validation.  
+- `message_router.h`  
+  Defines `etl::imessage_router`, the central routing interface with receive, accepts, and router identity. Provides message_router<TDerived, ...> that statically dispatches by message ID (contiguous IDs optimized). Includes null_message_router and message_producer helpers, plus send_message utilities.  
+- `message_bus.h`  
+Implements `etl::imessage_bus`, a router that manages a sorted list of subscribed routers and forwards messages based on destination ID (broadcast or addressed). Supports subscription limits and forwards to successors.  
+- `message_broker.h`  
+  Implements etl::message_broker, a router with explicit subscription objects mapping routers to message ID lists (span). It routes only to subscribers that match both message ID and destination ID, then forwards to any successor.
+- `message_packet.h`  
+  A type-erased, in-place container for a fixed set of message types. Validates message ID acceptance, supports copy/move, and exposes `get()` as `etl::imessage&`. Uses aligned storage sized to the largest message type.  
+- `shared_message.h`  
+  Reference-counted wrapper around pooled messages (`ireference_counted_message_pool`). Supports copy/move semantics with automatic release when the last reference drops.
+
+## Basic architecture
+
+![message-framework](images/message-framework.png)

docs/Messaging/message-broker.md

@@ -0,0 +1,217 @@
+---
+title: "message_broker"
+weight: 6
+---
+
+{{< callout type="info">}}
+  Header: `message_broker.h`  
+{{< /callout >}}
+
+Message Broker  
+
+A variant of the observer pattern in that message routers and derived types are be able to subscribe to selected sets of messages. The message_broker is similar to the message_bus, but it provides more control over the routing of messages.  While the message_bus simply broadcasts every message to all subscribers, the message_broker allows you to specify which subscribers should receive each message.  
+
+Derived from `imessage_router`.
+
+## Types
+
+```cpp
+message_id_span_t    etl::span<const etl::message_id_t>
+```
+
+## subscription
+A nested class of `etl::message_broker`.
+The base for broker subscription information.  
+Derive from this to define your subscription class.  
+See Example.
+
+---
+
+```cpp
+subscription(etl::imessage_router& router)
+```
+Constructor.
+
+---
+
+```cpp
+virtual message_id_span_t message_id_list() const = 0;
+```
+Override this to return a span of message ids.
+
+## message_broker
+
+```cpp
+message_broker()
+```
+The broker is constructed with an id of `etl::imessage_router::MESSAGE_BROKER`.
+
+---
+
+```cpp
+message_broker(etl::imessage_router& successor)
+```
+The broker is constructed with an id of `etl::imessage_router::MESSAGE_BROKER`.  
+Sets the successor.
+
+---
+
+```cpp
+message_broker(etl::message_router_id_t id)
+```
+The broker is constructed with the specified id.
+
+---
+
+```cpp
+message_broker(etl::message_router_id_t id, etl::imessage_router& successor)
+```
+The broker is constructed with the specified id.  
+Sets the successor.
+
+---
+
+```cpp
+void subscribe(etl::imessage_router& router)
+```
+Subscribes an `etl::imessage_router` derived class to the broker.  
+A subscription object must have a lifetime of at least the same as the broker.  
+A subscription cannot be shared with another broker.
+
+---
+
+```cpp
+void unsubscribe(etl::imessage_router& router)
+```
+Unsubscribes the specified `etl::imessage_router` derived class from the bus.  
+Does not unsubscribe from nested buses.
+
+---
+
+```cpp
+void receive(const etl::imessage& message)
+void receive(etl::shared_message message)
+```
+Receives a message and distributes it to all subscribers that have registered to receive the message type.  
+Forwards the message to any successor.  
+
+Override this in a derived class if you wish to capture messages sent to the broker.  
+Call the base receive function from here to allow normal operation to continue.
+
+---
+
+```cpp
+bool accepts(etl::message_id_t id) const
+```
+Always returns `true`.
+
+---
+
+```cpp
+void clear()
+```
+Clears the broker of all subscribers.
+
+---
+
+```cpp
+ETL_DEPRECATED bool is_null_router() const ETL_OVERRIDE
+```
+Always returns `false`.
+
+---
+
+```cpp
+bool is_producer() const ETL_OVERRIDE
+```
+Always returns `true`.
+
+---
+
+```cpp
+bool is_consumer() const ETL_OVERRIDE
+```
+Always returns `true`.
+
+---
+
+```cpp
+bool empty() const
+```
+Returns `true` is the are are no subscribers.
+
+## Example
+```cpp
+// Some router ids.
+enum
+{
+  ROUTER_ID_1,
+  ROUTER_ID_2,
+};
+
+// Custom subscription type.
+class Subscription : public etl::message_broker::subscription
+{
+public:
+
+  Subscription(etl::imessage_router& router, std::initializer_list<etl::message_id_t> id_list_)
+    : etl::message_broker::subscription(router)
+    , id_list(id_list_)
+  {
+  }
+
+  etl::message_broker::message_id_span_t message_id_list() const override
+  {
+    return etl::message_broker::message_id_span_t(id_list.begin(), id_list.end());
+  }
+
+  std::vector<etl::message_id_t> id_list;
+};
+
+// Instances of messages.
+Message1 message1;
+Message2 message2;
+Message3 message3;
+Message4 message4;
+
+// Custom broker.
+class Broker : public etl::message_broker
+{
+public:
+
+  using etl::message_broker::receive;
+
+  // Hook incoming messages and translate Message4 to Message3.
+  void receive(const etl::imessage& msg) override
+  {
+    if (msg.get_message_id() == Message4::ID)
+    {
+      etl::message_broker::receive(Message3());
+    }
+    else
+    {
+      etl::message_broker::receive(msg);
+    }
+  }
+};
+
+// Instances of message routers.
+Router1 router1;
+Router2 router2;
+
+// The subscriptions.
+Subscription subscription1{ router1, { Message1::ID, Message2::ID } };
+Subscription subscription2{ router2, { Message2::ID, Message3::ID } };
+
+// Instance of message broker.
+etl::message_broker broker;
+
+// Subscribe router1 and router1 to the broker.
+broker.subscribe(subscription1);
+broker.subscribe(subscription2);
+
+broker.receive(message1); // Received by router1
+broker.receive(message2); // Received by router1 and router2
+broker.receive(message3); // Received by router2
+broker.receive(message4); // Received by router2 as a Message3
+```

docs/Messaging/message-bus.md

@@ -0,0 +1,207 @@
+---
+title: "message_bus"
+weight: 5
+---
+
+{{< callout type="info">}}
+  Header: `message_broker.h`  
+  From: `20.33.0`
+{{< /callout >}}
+
+Message Bus  
+
+This page documents version `20.0.0` and above.  
+
+A variant of the observer pattern in that message routers and derived types are be able to subscribe to messages on a bus. The messages can be either broadcast, to be automatically picked up by any router that has a handler, or addressed to a particular router or router id. Message buses may be nested  by setting a successor.  
+
+## imessage_bus
+Derived from imessage_router.  
+
+The base for all message buses.  
+Inherits publicly from `etl::imessage_router`.  
+Message buses are therefore also a type of  router.  
+Objects of type `etl::imessage_bus` cannot be directly constructed.  
+
+## Member functions
+
+```cpp
+bool subscribe(etl::imessage_router& router)
+```
+Subscribes an `etl::imessage_router` derived class to the bus.  
+Returns `true` on success.
+
+---
+
+```cpp
+void unsubscribe(etl::imessage_router& router)
+```
+Unsubscribes the specified `etl::imessage_router` derived class from the bus.  
+Does not unsubscribe from nested buses.
+
+---
+
+```cpp
+void unsubscribe(etl::message_router_id_t id)
+```
+Unsubscribes routers with the specified id from the bus.  
+Does not unsubscribe from nested buses.  
+
+`etl::imessage::MESSAGE_BUS` will unsubscribe all message buses.  
+`etl::imessage::ALL_MESSAGE_ROUTERS` will unsubscribe all routers and buses. Equivalent to calling `clear()`.
+
+---
+
+```cpp
+void receive(const etl::imessage& message)
+void receive(etl::shared_message message)
+```
+Receives a message and distributes it to all subscribers.  
+Forwards the message to any successor.  
+
+The routers are called first, in order of ascending router id.  
+Routers with the duplicate ids will be called in subscribe order.  
+Any nested message buses are called in subscribe order.
+
+---
+
+```cpp
+void receive(etl::message_router_id_t destination_router_id, 
+             const etl::imessage&     message);
+void receive(etl::message_router_id_t destination_router_id, 
+             etl::shared_message message)
+```
+Receives a message and distributes it to all subscribers that have the specified router id.  
+Forwards the message to any successor.  
+
+Routers with the duplicate ids will be called in subscribe order.  
+Any nested message buses are called in subscribe order.  
+
+Override this in a derived class if you wish to capture messages sent to the bus.  
+Call the base receive function from here to allow normal operation to continue.
+
+---
+
+```cpp
+bool accepts(etl::message_id_t id) const
+```
+Always returns `true`.
+
+---
+
+```cpp
+size_t size() const
+```
+Returns the number of subscribers.
+
+---
+
+```cpp
+void clear()
+```
+Clears the bus of all subscribers.  
+
+Message buses inherit all of the public functions of `etl::imessage_router`.
+
+## Errors
+
+```cpp
+message_bus_exception
+```
+Base error class for `etl::message_bus`. Inherits from `etl::exception`.
+
+---
+
+```cpp
+message_bus_too_many_subscribers
+```
+Emitted when the number of subscribers exceeds the capacity. Inherits from `etl::message_bus_exception`.
+
+## message_bus
+Derived from `imessage_bus`.
+
+```cpp
+template <const uint_least8_t MAX_ROUTERS>
+class message_bus
+```
+`MAX_ROUTERS` The maximum number of routers that can be subscribed.
+
+## Member functions
+
+```cpp
+message_bus()
+```
+Constructs a message bus.  
+Message buses always have a router id of `etl::imessage::MESSAGE_BUS`.
+
+```cpp
+message_bus(etl::imessage_router& successor)
+```
+Constructs a message bus and sets the successor.  
+Message buses always have a router id of `etl::imessage::MESSAGE_BUS`.
+
+## Example
+```cpp
+// Some router ids.
+enum
+{
+  ROUTER_ID_1,
+  ROUTER_ID_2,
+  ROUTER_ID_3
+};
+
+// Instances of messages.
+MessageA messageA;
+
+// Instances of message routers.
+RouterA routerA(ROUTER_ID_1);
+RouterB routerB(ROUTER_ID_1);
+RouterC routerC(ROUTER_ID_2);
+RouterD routerD(ROUTER_ID_3);
+RouterE routerE(ROUTER_ID_1);
+
+// Instances of message buses.
+etl::message_bus<4> bus1;
+etl::message_bus<2> bus2;
+etl::message_bus<1> bus3;
+
+// Subscribe bus2 & bus3 to bus1.
+bus1.subscribe(bus3);
+bus1.subscribe(bus2);
+
+// Subscribe routerB & routerA to bus1.
+bus1.subscribe(routerB);
+bus1.subscribe(routerA);
+
+// Subscribe routerD & routerC to bus2.
+bus2.subscribe(routerD);
+bus2.subscribe(routerC);
+
+// Subscribe routerE to bus3.
+bus3.subscibe(routerE);
+
+// Assume all routers accept the same messages.
+
+// Broadcast messageA to everyone.
+bus1.receive(messageA);
+
+// The call order will be...
+// routerB
+// routerA
+// routerE
+// routerC
+// routerD
+
+// Address messageA to routers with id ROUTER_ID_1.
+bus1.receive(ROUTER_ID_1, messageA);
+
+// The call order will be...
+// routerB
+// routerA
+// routerE
+
+// Address messageA to routers with id ROUTER_ID_3.
+bus1.receive(ROUTER_ID_3, messageA);
+
+// The call order will be...
+// routerD
+```

docs/Messaging/message-packet.md

@@ -0,0 +1,155 @@
+---
+title: "message_packet"
+---
+
+{{< callout type="info">}}
+  Header: `message_packet.h`  
+{{< /callout >}}
+
+A container for more than one type of message.  
+The messages must have been derived from `etl::imessage`.
+
+The messages types that the packet may contain are listed as template parameters.  
+e.g. `etl::message_packet<Message1, Message2, Message3>`  
+
+From `20.40.0` message types are not required to have a virtual destructor.
+
+---
+
+```cpp
+message_packet()
+```
+Default constructs a message packet.  
+`is_valid()` returns `false`.
+
+---
+
+```cpp
+explicit message_packet(const etl::imessage&)
+```
+Constructs a message packet from an `etl::imessage` reference.  
+Asserts an `etl::unhandled_message_exception` error if the parameter is not one listed in the template parameter list.  
+
+---
+
+```cpp
+explicit message_packet(etl::imessage&&) C++11
+```
+Move constructs a message packet from an `etl::imessage` rvalue reference.  
+Emits an `etl::unhandled_message_exception` error if the parameter is not one listed in the template parameter list.
+
+---
+
+```cpp
+template <typename TMessage>
+explicit message_packet(const TMessage&)
+```
+Constructs a message packet from a `TMessage` reference.
+Emits a compile time static assert if the parameter is not one listed in the template parameter list.  
+From: `20.22.0`
+
+---
+
+```cpp
+template <typename TMessage>
+explicit message_packet(TMessage&&)
+```
+Move constructs a message packet from a `TMessage` rvalue reference.
+Emits a compile time static assert if the parameter is not one listed in the template parameter list.  
+From: `20.22.0`
+
+---
+
+```cpp
+message_packet(const message_packet&)
+```
+Constructs a message packet from an `message_packet` reference.  
+Emits an `etl::unhandled_message_exception` error if the parameter is not one listed in the template parameter list.
+
+---
+
+```cpp
+message_packet(message_packet&&)
+```
+Move constructs a message packet from an `message_packet` rvalue reference.  
+Emits an `etl::unhandled_message_exception` if the parameter is not one listed in the template parameter list.
+
+---
+
+```cpp
+message_packet& operator =(const message_packet&)
+```
+Assigns a message packet from an `message_packet` reference.  
+Emits an `etl::unhandled_message_exception` error if the parameter is not one listed in the template parameter list.
+
+---
+
+```cpp
+message_packet& operator =(message_packet&&)
+```
+Move assigns a message packet from an `message_packet` rvalue reference.  
+Emits an `etl::unhandled_message_exception` error if the parameter is not one listed in the template parameter list.
+
+---
+
+```cpp
+etl::imessage& get()
+const etl::imessage& get() const
+```
+Returns a reference to an `etl::imessage`.
+
+---
+
+```cpp
+bool is_valid() const
+```
+Returns `true` if the packet contains a valid message, otherwise `false`.
+
+---
+
+## Constants
+
+`SIZE`      The size of the largest message.
+`ALIGNMENT` The largest message alignment.
+
+---
+
+## Example
+```cpp
+enum
+{
+  MESSAGE1,
+  MESSAGE2,
+  MESSAGE3
+};
+
+struct Message1 : public etl::message<MESSAGE1>
+{
+};
+
+struct Message2 : public etl::message<MESSAGE2>
+{
+};
+
+struct Message3 : public etl::message<MESSAGE3>
+{
+};
+
+using Packet = etl::message_packet<Message1, Message2>
+
+Message1 message1;
+Message2 message2;
+Message3 message3;
+
+Packet packet1(message1);
+Packet packet2(message2);
+Packet packet3(message3); // Runtime time error! Packet does not support Message3 type.
+
+etl::imessage& m1 = message1;
+Packet packet4(m1); // Construct from an etl::imessage reference.
+
+etl::imessage& m3 = message3;
+Packet packet4(m3); // Asserts etl::unhandled_message_exception! Packet does not support Message3 type.
+
+etl::imessage& m = packet2.get(); // Get a reference to an etl::imessage from the packet.
+```

docs/Messaging/message-router-registry.md

@@ -0,0 +1,180 @@
+---
+title: "message_router_registry"
+weight: 4
+---
+
+{{< callout type="info">}}
+  Header: `message_router_registry`  
+  From: `20.6.0`  
+{{< /callout >}}
+
+A class that will act as a registry for all message router types.  
+When iterating through the registry, routers with identical IDs are ordered by insertion.  
+
+**Defines the following classes**  
+```cpp
+etl::imessage_router_registry
+etl::message_router_registry
+```
+
+## imessage_router_registry
+
+The base class for all router registries.  
+
+### Iterators
+```cpp
+iterator
+const_iterator
+```
+
+### Member functions
+
+```cpp
+iterator begin()
+const_iterator begin() const
+const_iterator cbegin() const
+```
+Get the beginning of the registry.
+
+---
+
+```cpp
+iterator end()
+const_iterator end() const
+const_iterator cend() const
+```
+Get the end of the registry.
+
+---
+
+```cpp
+iterator lower_bound(etl::message_router_id_t id)
+const_iterator lower_bound(etl::message_router_id_t id) const
+```
+Get the lower bound in the registry of the router with the specified ID.
+
+---
+
+```cpp
+iterator upper_bound(etl::message_router_id_t id)
+const_iterator upper_bound(etl::message_router_id_t id) const
+```
+Get the upper bound in the registry of the router with the specified ID.
+
+---
+
+```cpp
+etl::imessage_router* find(etl::message_router_id_t id)
+const etl::imessage_router* find(etl::message_router_id_t id) const
+```
+Returns a pointer to the first router with the specified ID, or `ETL_NULLPTR` if it cannot be found.
+
+---
+
+```cpp
+void add(etl::imessage_router& router)
+void add(etl::imessage_router* p_router)
+```
+Registers a router.  
+If the registry is full then an ETL assert is emitted (`etl::message_router_registry_full`).  
+Duplicate routers will be ignored.
+
+---
+
+```cpp
+template <typename TIterator>
+void add(TIterator first, const TIterator& last)
+```
+Registers a collection of routers.  
+If the registry becomes full then an ETL assert is emitted (`etl::message_router_registry_full`).  
+Duplicate routers will be ignored.
+
+---
+
+```cpp
+void remove(etl::message_router_id_t id)
+```
+Unregisters a router.
+
+---
+
+```cpp
+bool contains(const etl::message_router_id_t id) const
+bool contains(const etl::imessage_router* const p_router) const
+bool contains(const etl::imessage_router& router) const
+```
+Returns `true` if the registry contains a router that has the specified ID or object.
+
+---
+
+```cpp
+bool empty() const
+```
+Returns `true` if the registry is empty, otherwise `false`.
+
+---
+
+```cpp
+bool full() const
+```
+Returns `true` if the registry is full, otherwise `false`.
+
+---
+
+```cpp
+size_t size() const
+```
+Returns the size of the registry.
+
+---
+
+```cpp
+size_t available() const
+```
+Returns the available size of the registry.
+
+---
+
+```cpp
+size_t max_size() const
+```
+Returns the maximum size of the registry.
+
+---
+
+## message_router_registry
+
+```cpp
+message_router_registry()
+```
+Default constructor.
+
+---
+
+```cpp
+template <typename TIterator>
+message_router_registry(TIterator first, const TIterator& last)
+```
+Constructs from an iterator range.
+
+---
+
+```cpp
+message_router_registry(std::initializer_list<etl::imessage_router*> init)
+```
+Initializer_list constructor.  
+Enabled for C++11 or above.
+
+---
+
+```cpp
+message_router_registry(const message_router_registry& rhs)
+```
+Copy constructor.
+
+---
+
+```cpp
+message_router_registry& operator =(const message_router_registry& rhs)
+```
+Assignment operator.

docs/Messaging/message.md

@@ -0,0 +1,112 @@
+---
+title: "message"
+weight: 1
+---
+
+{{< callout type="info">}}
+  Header: `message.h`  
+{{< /callout >}}
+
+Message types used for many of the framework classes.
+
+---
+
+```cpp
+etl::message_id_t
+```
+The type used for message ids.  
+By default can hold a value between 0 and 255.  
+If `ETL_MESSAGE_ID_TYPE` is defined then this type will be used instead.
+
+---
+
+```cpp
+etl::message_router_id_t
+```
+The type used for message router ids.  
+Can hold a value between 0 and 255.
+
+---
+
+The message classes are the common communication method across all of the message capable frameworks.
+They are identified by a unique id number that specialises the base class.
+
+## imessage
+
+The base class for messages. 
+It is this class that is passed around, usually by const reference.  
+The class is abstract.  
+
+---
+
+```cpp
+etl::message_id_t get_message_id() const ETL_NOEXCEPT = 0;
+```
+Returns the id of the message.
+
+---
+
+## message
+
+```cpp
+message<size_t ID, typename TParent = etl::imessage>
+```
+Requires an integral id as the template parameter.  
+Inherits from `TParent`, which defaults to `etl::imessage`.  
+`TParent` allows additional base interfaces or  functionality to be included.  
+static asserts if `TParent` is not a base of `etl::imessage`.
+
+---
+
+```cpp
+ID
+```
+The id of the message as an enum.
+Can be accessed by `etl::message` instances.
+
+---
+
+```cpp
+TParent
+```
+The class that it inherits from. It must ultimately derive from `etl::imessage`.  
+The default is `etl::imessage`.
+
+---
+
+## Example
+
+```cpp
+enum
+{
+  START,
+  STOP,
+  SET_SPEED
+};
+
+struct MyInterface : public etl::imessage
+{
+  virtual void DoStuff() = 0;
+};
+
+// Start implements MyIterface
+struct Start : public etl::message<START, MyInterface>
+{
+  void DoStuff() override
+  {
+    // Do stuff here.  
+  }
+};
+
+struct Stop : public etl::message<STOP>
+{
+  bool isEmergencyStop;
+};
+
+struct SetSpeed : public etl::message<SET_SPEED>
+{
+  uint32_t speed;
+};
+
+void Receive(const etl::imessage& msg);
+```

docs/Messaging/reference-counted-message-pool.md

@@ -0,0 +1,139 @@
+---
+title: "reference_counted_message_pool"
+---
+
+{{< callout type="info">}}
+  Header: `reference_counted_message_pool.h`  
+  Header: `ireference_counted_message_pool.h`  
+{{< /callout >}}
+
+Allocates `etl::ireference_counted_message` types that are used by `etl::shared_message`.  
+Uses a supplied `memory_block allocator` derived from `etl::imemory_block_allocator`.  
+
+## ireference_counted_message_pool.h  
+Defines the following class.  
+`etl::ireference_counted_message_pool`  
+
+## reference_counted_message_pool.h
+Defines the following classes.  
+`etl::reference_counted_message_pool_exception`
+`etl::reference_counted_message_pool_allocation_failure`
+`etl::reference_counted_message_pool_release_failure`
+
+
+## ireference_counted_message_pool
+
+```cpp
+etl::ireference_counted_message_pool
+```
+
+The interface for reference counted message pools.  
+```cpp
+virtual ~ireference_counted_message_pool() {}
+```
+```cpp
+virtual void release(const etl::ipool_message& msg) = 0;
+```
+
+Virtual `lock()` and `unlock()` functions are defined. The default action is to do nothing.  
+A derived class may override these functions to provide a thread or interrupt safe pool.  
+`virtual void lock()`
+`virtual void unlock()`
+
+## reference_counted_message_pool
+
+```cpp
+etl::reference_counted_message_pool<TCounter>
+```
+The concrete reference counted message pool.  
+
+```cpp
+reference_counted_message_pool(imemory_block_allocator& memory_block_allocator)
+```
+Constructs the pool and assigns the memory block allocator to it.  
+
+---
+
+```cpp
+template <typename TMessage>
+etl::reference_counted_message<TMessage, TCounter>* allocate()
+```
+Returns a pointer to a pool message that holds a `TMessage`.  
+The message is default constructed.  
+ETL_ASSERT if one cannot be allocated and returns `ETL_NULLPTR`.
+
+---
+
+```cpp
+template <typename TMessage>
+etl::reference_counted_message<TMessage, TCounter>* allocate(const TMessage& message)
+```
+Returns a pointer to a pool message that holds a `TMessage`.  
+ETL_ASSERT if one cannot be allocated and returns `ETL_NULLPTR`.
+
+---
+
+```cpp
+void release(const etl::ireference_counted_message& rcmessage)
+```
+Returns the reference counted to a pool message that holds a `TMessage`.  
+`ETL_ASSERT` if it cannot be released. Reasons can include the message not belonging to the pool.
+
+## pool_message_parameters
+
+**C++03**  
+The C++03 version defines the largest size and alignment of up to 8 types at a time.  
+
+```cpp
+template <typename TMessage1,              typename TMessage2  = TMessage1, 
+          typename TMessage3  = TMessage1, typename TMessage4  = TMessage1,
+          typename TMessage5  = TMessage1, typename TMessage6  = TMessage1,
+          typename TMessage7  = TMessage1, typename TMessage8  = TMessage1>
+struct pool_message_parameters
+```
+
+---
+
+```cpp
+static const size_t max_size;
+```
+The maximum size.
+
+---
+
+```cpp
+static const size_t max_alignment;
+```
+The maximum alignment.
+
+**C++11 or above**  
+The C++11 version defines the largest size and alignment of a set of message types.  
+
+```cpp
+template <typename TMessage1, typename... TMessages>
+struct pool_message_parameters
+```
+
+---
+
+```cpp
+static constexpr size_t max_size
+```
+The maximum size.  
+
+---
+
+```cpp
+static constexpr size_t max_alignment;
+```
+The maximum alignment.
+
+---
+
+**For C++11, with atomic support.**  
+
+```cpp
+template <typename TObject>
+using atomic_counted_message_pool = etl::reference_counted_message_pool<etl::atomic_int32_t>;
+```
+Defines an alias to a reference counted message pool that uses an atomic.

docs/Messaging/reference-counted-messages.md

@@ -0,0 +1,197 @@
+---
+title: "reference_counted_message"
+---
+
+{{< callout type="info">}}
+  Header: `reference_counted_message.h`  
+{{< /callout >}}
+
+Reference counted message types that are used by `etl::shared_message`.  
+
+**Defines the following classes**  
+
+```cpp
+etl::ireference_counted_message
+```
+The interface of all reference counted message types.
+
+---
+
+```cpp
+etl::reference_counted_message<typename TMessage, typename TCounter>
+```
+Derived from `etl::ireference_counted_message`.
+
+```cpp
+etl::persistent_message<typename TMessage>
+```
+Derived from `etl::ireference_counted_message`.
+
+## ireference_counted_message
+
+```cpp
+etl::ireference_counted_message
+```
+The interface of all reference counted message types.
+
+---
+
+```cpp
+virtual ~ireference_counted_message()
+```
+
+---
+
+```cpp
+ETL_NODISCARD virtual etl::imessage& get_message() = 0;
+```
+Get a reference to the message.
+
+---
+
+```cpp
+ETL_NODISCARD virtual const etl::imessage& get_message() const = 0;
+```
+Get a const reference to the message.
+
+---
+
+```cpp
+ETL_NODISCARD virtual etl::ireference_counter& get_reference_counter() = 0;
+```
+Get a reference to the reference counter.
+
+---
+
+```cpp
+ETL_NODISCARD virtual const etl::ireference_counter& get_reference_counter() const = 0; 
+```
+Get a const reference to the reference counter.
+
+---
+
+```cpp
+virtual void release() = 0;
+```
+Release back to the owner.
+
+## reference_counted_message
+
+```cpp
+etl::reference_counted_message<typename TMessage, typename TCounter>     
+```
+The implementation of reference counted messages owned by a pool.  
+Will static assert if TMessage is no derived from etl::imessage.
+
+---
+
+```cpp
+reference_counted_message(const TMessage& message, etl::ireference_counted_message_pool& owner)
+```
+Constructs from a message and the pool from which the reference counted message is allocated.  
+The message is copied.
+
+---
+
+```cpp
+reference_counted_message(etl::ireference_counted_message_pool& owner)
+```
+Constructs from a message and the pool from which the reference counted message is allocated.  
+The message is default constructed.
+
+---
+
+```cpp
+ETL_NODISCARD TMessage& get_message() ETL_OVERRIDE
+```
+Get a reference to the message.
+
+---
+
+```cpp
+ETL_NODISCARD const TMessage& get_message() const ETL_OVERRIDE
+```
+Get a const reference to the message.
+
+---
+
+```cpp
+ETL_NODISCARD etl::ireference_counter& get_reference_counter() ETL_OVERRIDE
+```
+Get a reference to the reference counter.
+
+---
+
+```cpp
+ETL_NODISCARD const etl::ireference_counter& get_reference_counter() const ETL_OVERRIDE
+```
+Get a const reference to the reference counter.
+
+---
+
+```cpp
+void release() ETL_OVERRIDE
+```
+Release back to the owner pool.
+
+## persistent_message
+
+```cpp
+etl::persistent_message<typename TMessage>     
+```
+
+The implementation of reference counted messages not owned by a pool.  
+It's counter type is `void`.  
+Will static assert if `TMessage` is not derived from `etl::imessage`.
+
+---
+
+```cpp
+persistent_message(const TMessage& message)
+```
+Constructs from a message.  
+The message is copied.
+
+---
+
+```cpp
+ETL_NODISCARD TMessage& get_message() ETL_OVERRIDE
+```
+Get a reference to the message.
+
+---
+
+```cpp
+ETL_NODISCARD const TMessage& get_message() const ETL_OVERRIDE
+```
+Get a const reference to the message.
+
+---
+
+```cpp
+ETL_NODISCARD etl::ireference_counter& get_reference_counter() ETL_OVERRIDE
+```
+Get a reference to the reference counter.
+
+---
+
+```cpp
+ETL_NODISCARD const etl::ireference_counter& get_reference_counter() const ETL_OVERRIDE
+```
+Get a const reference to the reference counter.
+
+---
+
+```cpp
+void release() ETL_OVERRIDE
+```
+Does nothing for a persistent message.
+
+## For C++11, with atomic support.
+
+```cpp
+template <typename TMessage>
+using atomic_counted_message = etl::reference_counted_message<TMessage, etl::atomic_int32_t>;
+```
+Defines an alias to a reference counted message that uses an atomic.
+

docs/Messaging/shared-message.md

@@ -0,0 +1,79 @@
+---
+title: "shared_message"
+weight: 2
+---
+
+{{< callout type="info">}}
+  Header: `shared_message.h`  
+{{< /callout >}}
+
+Shared Messages  
+
+The type used to encapsulate reference counted messages.  
+Shared messages are usually passed by value.  
+
+See the Shared Message Tutorial  
+
+---
+
+```cpp
+template <typename TPool, typename TMessage>
+shared_message(TPool& owner, const TMessage& message)
+```
+Static asserts if `TPool` is not derived from `etl::ireference_counted_message_pool`
+Static asserts if `TMessage` not derived from `etl::imessage`.  
+
+Requires that `TPool` implements the following member function to allocate from the pool.  
+
+```cpp
+template <typename TMessage>
+etl::ireference_counted_message* allocate(const TMessage& message)
+```
+---
+
+```cpp
+explicit shared_message(etl::ireference_coutnted_message& message)
+```
+Construct from a reference counted message.
+
+---
+
+```cpp
+shared_message(const etl::shared_message& other)
+```
+Copy constructor.
+
+---
+
+```cpp
+shared_message& operator =(const etl::shared_message& other)
+```
+Assignment operator.
+
+---
+
+```cpp
+~shared_message()
+```
+Destructor.
+
+---
+
+```cpp
+ETL_NODISCARD etl::imessage& get_message()
+```
+Gets a reference to the contained message.
+
+---
+
+```cpp
+ETL_NODISCARD const etl::imessage& get_message() const
+```
+Gets a const reference to the contained message.
+
+---
+
+```cpp
+ETL_NODISCARD uint32_t get_reference_count() const
+```
+Gets the current reference count for this shared message.

docs/_config.yml

@@ -1,6 +0,0 @@
-plugins:
-  - jekyll-relative-links
-relative_links:
-  enabled: true
-include:
-  - manchester.md

docs/_index.md

@@ -0,0 +1,131 @@
+---
+title: "Embedded Template Library"
+weight: 998
+type: hextra-home
+---
+
+<div class="not-prose badges">
+
+<div>
+    <img src="https://img.shields.io/github/v/release/jwellbelove/etl" alt="release">
+    <img src="https://img.shields.io/github/release-date/jwellbelove/etl?color=%231182c3" alt="date">
+    <img src="https://img.shields.io/badge/c%2B%2B-98/03/11/14/17/20/23-blue.svg" alt="standard">
+    <img src="https://img.shields.io/badge/license-MIT-blue.svg" alt="license">
+    <img src="https://img.shields.io/github/contributors-anon/ETLCPP/etl" alt="contributors">
+    <img src="https://img.shields.io/github/forks/ETLCPP/etl?style=flat" alt="forks">
+    <img src="https://img.shields.io/github/stars/ETLCPP/etl?style=flat" alt="stars">
+  </div>
+
+  <div>
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/msvc.yml/badge.svg?branch=master" alt="CI MSVC">
+  </div>
+
+  <div>
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/gcc-c++11.yml/badge.svg?branch=master" alt="CI GCC 11">
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/gcc-c++14.yml/badge.svg?branch=master" alt="CI GCC 14">
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/gcc-c++17.yml/badge.svg?branch=master" alt="CI GCC 17">
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/gcc-c++20.yml/badge.svg?branch=master" alt="CI GCC 20">
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/gcc-c++23.yml/badge.svg?branch=master" alt="CI GCC 23">
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/gcc-syntax-checks.yml/badge.svg?branch=master" alt="CI GCC syntax">
+  </div>
+
+  <div>
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/clang-c++11.yml/badge.svg?branch=master" alt="CI Clang 11">
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/clang-c++14.yml/badge.svg?branch=master" alt="CI Clang 14">
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/clang-c++17.yml/badge.svg?branch=master" alt="CI Clang 17">
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/clang-c++20.yml/badge.svg?branch=master" alt="CI Clang 20">
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/clang-c++23.yml/badge.svg?branch=master" alt="CI Clang 23">
+    <img src="https://github.com/ETLCPP/etl/actions/workflows/clang-syntax-checks.yml/badge.svg?branch=master" alt="CI Clang syntax">
+  </div>
+
+  <div>
+    <a href="https://github.com/ETLCPP/etl/actions/workflows/coverage.yml"><img src="https://github.com/ETLCPP/etl/actions/workflows/coverage.yml/badge.svg" alt="coverage"></a>
+    <a href="https://www.codacy.com/manual/jwellbelove/etl"><img src="https://api.codacy.com/project/badge/Grade/3c14cd918ccf40008d0bcd7b083d5946" alt="Codacy"></a>
+  </div>
+  
+  <div>
+    <a href="https://www.etlcpp.com/sponsor.html"><img src="https://img.shields.io/static/v1?label=Sponsor&message=%E2%9D%A4&logo=GitHub&color=%23fe8e86" alt="Sponsor"></a>
+  </div>
+
+</div>
+
+## Version
+This documents version **{{< version >}}**.
+
+## Motivation
+
+C++ is a powerful language for embedded systems development, with templates offering a great deal of flexibility and type safety. While the C++ Standard Library provides a wealth of well-tested functionality, it’s often not well suited to environments with strict deterministic behavior and limited resources.  
+
+In many embedded applications, dynamic memory allocation is discouraged or outright prohibited, making standard STL containers and many other components impractical or unusable.  
+
+What’s needed is a template library specifically designed for embedded systems — one that allows developers to define fixed or maximum sizes for containers and other objects at compile time. Additionally, since many older (but still in use) embedded toolchains lack full support for standards beyond C++03, it's valuable to have access to a library that backports select features from later versions of the C++ Standard Library.  
+
+## About the ETL
+
+The Embedded Template Library (ETL) is not intended as a full replacement for the C++ Standard Template Library (STL), but rather as a complementary solution tailored specifically for embedded systems.  
+
+**Its design goals include**
+
+- Providing a set of containers with fixed or maximum sizes defined at compile-time.
+- Offering APIs that closely resemble those of the STL, enabling familiar and consistent usage.
+- Maintaining compatibility with C++98 while implementing many features introduced in later standards
+(C++11/14/17/20/23/26) wherever possible.
+- Ensuring deterministic behavior, which is critical in real-time and resource-constrained environments.
+- Introducing additional components and utilities useful in embedded contexts but absent from the STL.
+- The ETL avoids dynamic memory allocation entirely; the heap is never used. All non-intrusive containers have a fixed capacity, allowing memory requirements to be fully determined at compile-time. This makes the ETL ideal for lower-resource embedded applications where predictability, performance, and memory control are essential.
+
+The library is compatible with any compiler that supports C++03 or later.
+
+Help on integrating the ETL with your project may be found here.
+
+## Key Features of the ETL
+ 
+- Actively Maintained: Developed and maintained on GitHub since 2014.
+- Open Source: MIT licensed.
+- No STL Dependency: Designed to operate independently of the C++ Standard Template Library.
+- No Dynamic Memory Allocation: All storage is allocated either at compile-time or on the stack; heap usage is entirely avoided.
+- RTTI and Virtual Functions: No runtime type information (RTTI) is required. Virtual functions are used sparingly and only when strictly necessary.
+- Header-Only Library: All functionality is provided via header files; No separate compilation needed.
+- Fixed-Capacity Containers: Offers STL-like containers with fixed or maximum capacity, plus additional non-standard container types.
+- Cache Efficiency: Containers use contiguous memory layouts for optimal cache performance.
+- Compact Codebase: Shared base classes (based on type) help reduce overall container code size.
+- Compile-Time Features:  
+Templated compile-time constants
+Template-based design pattern base classes (e.g., Visitor, Observer)
+Type-safe smart enumerations
+Type-safe typedefs and constants
+- Embedded System Frameworks:  
+Message routing  
+Finite state machines  
+Task scheduling  
+- C++11 Backports:  
+Implements many C++11 features (type traits, algorithms, containers) for use in C++03 environments.
+- Utilities:  
+CRC calculations (8, 16, 32 & 64-bit)  
+Checksums and hash functions
+- Variants (type-safe unions)
+- Extensive template support utilities
+- Robust Error Handling: Configurable error checking using asserts, exceptions, error handlers, or no checks; user’s choice.
+- Thoroughly Tested:  
+Over 10,000 unit tests
+Tested with Visual Studio 2022, GCC 12, and Clang 14
+Continuous integration via GitHub Actions.
+- Readable and Well-Documented: Clean, maintainable source code with clear documentation.
+- Support: Free email support available. A Slack group is available. Paid support on request.
+- Archived: A snapshot of the ETL is preserved in the Arctic Code Vault for long-term digital preservation.
+
+## Support the ETL
+Maintaining the ETL can take a lot of man-hours of work, but unfortunately it doesn't pay the bills. When I have to take on paying work, the ETL gets a lot less attention. So if you have found the library is an important component in your work and you would like to help out, then please consider by supporting the project.
+
+---
+
+[**Is the ETL free?**]({{< relref "is the ETL free.md" >}})
+
+---
+
+Any help porting the library to work under different platforms and compilers would be gratefully received.  
+I am especially interested in people who are using Keil, IAR, Green Hills, TI Code Composer etc, bare metal
+or RTOS, and DSPs.
+
+Many thanks.  
+John.

docs/about.md

@@ -0,0 +1,56 @@
+---
+title: "About"
+weight: 3002
+---
+
+## About me
+I have been involved in technology and computer systems for all of my working life and have amassed considerable knowledge of designing and implementing systems that are both performant and correct.  
+My role normally encompasses the entire project life-cycle, from specification to maintenance phase. 
+
+Most systems I have worked on have required high speed and deterministic performance, often within a highly constrained platform. I am experienced in designing and adapting algorithms to solutions that are both space and time efficient, avoiding the normal overheads of standard solutions.
+
+Acting as a mentor for colleagues has often been a significant, though unofficial, part of my role.  
+
+## Why write this library?
+I wrote this library, and all the others I have written over the
+years, because I'm lazy.
+
+Yes, lazy!
+
+One of the things I really hate when writing software is having to do the same, or something almost the same, over and over again. The first thing I think when presented with a problem that requires a specific set of functionality is "Is this a specific case of a more generic problem?". Surprisingly, I can say "yes" more often than you would expect. Even if not all of the problem can be seen as generic, there are almost certainly parts that are. In every job I've had I've left an extensive code library behind me.
+
+Reinventing the wheel every time is a bad idea, for many reasons.
+
+- **Compile-Time Features:**  
+Templated compile-time constants
+Template-based design pattern base classes (e.g., Visitor, Observer)
+Type-safe smart enumerations
+Type-safe typedefs and constants
+- **Code Bloat**  
+Multiple instances of slight variations of a theme results in an increase in code size due to no commonality of functionality.  
+Testing, more testing or no testing.  
+Are all the variants tested to the same degree?  
+Are some tested at all?
+- **Variable functionality**  
+Not all the variants are going to have the same level of functionality, or the same API.
+Ad-hoc solutions are invariably only going to solve the little bit of the problem that was needed at the time.  
+This goes against the YAGNI principle, but...  
+*I think that YAGNI can often be just another way of saying ISEP.*  
+*I believe in GIRFT.*  
+*I have over three decades of empirical proof.*  
+- **No collective knowledge base**  
+Without commonality every new variant has to be learnt. The underlying principles may be understood (i.e. Linked list), but each implementation has to be understood separately, along with its particular caveats and foibles.  
+Documentation is likely to be patchy, if it exists at all.  
+- **Octopus code**  
+The application is liable to have a close coupling with the solution. For example, I've often seen code using linked lists directly accessing the node pointers. Ad-hoc solutions are liable to have lazy (the bad kind) implementations.
+
+>YAGNI - You Aren't Going To Need It  
+>ISEP  - It's Somebody Else's Problem  
+>GIRFT - Get It Right First Time
+
+## Why not use 'C'?
+**Greenspun's Tenth Rule** has an unofficial C corollary:  
+*"Any sufficiently advanced C program contains an ad hoc, informally specified, bug-ridden, slow implementation of half of C++."*
+
+I spent 12 years programming in pure C.  
+I discovered that I had been reverse engineering C++ all that time.  

docs/binary/_index.md

@@ -0,0 +1,6 @@
+---
+title: "Binary utilities"
+weight: 100
+---
+
+Classes and functions that define and manipulate binary data.

docs/binary/binary.md

@@ -0,0 +1,574 @@
+---
+title: binary
+---
+
+{{< callout type="info">}}
+  Header: `binary.h`  
+  Since: `TBC`  
+{{< /callout >}}
+
+Utility functions for manipulating binary numbers.
+
+## Rotate
+Rotate the bits in the value left or right.
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T rotate_left(T value)
+```
+**Return**  
+`value` rotated left by one bit.
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T rotate_left(T value, size_t distance)
+```
+**Return**  
+`value` rotated left by `distance`.
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T rotate_right(T value)
+```
+**Return**  
+`value` rotated right by one bit.
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T rotate_right(T value, size_t distance)
+```
+**Return**  
+`value` rotated right by `distance`.
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T rotate(T value, typename etl::make_signed<size_t>::type distance)
+```
+**Parameters**  
+`distance` Positive is left, negative is right.  
+**Return**  
+`value` rotated left or right by `distance`.  
+
+## reverse_bits
+Reverse the order of the bits in a value.
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T reverse_bits(T value)
+```
+
+The structures below define a member constant value that is Value reversed in bits.
+```cpp
+template <int8_t Value>
+struct reverse_bits_const<int8_t, Value>
+```
+```cpp
+template <uint8_t Value>
+struct reverse_bits_const<uint8_t, Value>
+```
+```cpp
+template <int16_t Value>
+struct reverse_bits_const<int16_t, Value>
+```
+```cpp
+template <uint16_t Value>
+struct reverse_bits_const<uint16_t, Value>
+```
+```cpp
+template <int32_t Value>
+struct reverse_bits_const<int32_t, Value>
+```
+```cpp
+template <uint32_t Value>
+struct reverse_bits_const<uint32_t, Value>
+```
+```cpp
+template <int64_t Value>
+struct reverse_bits_const<int64_t, Value>
+```
+```cpp
+template <uint64_t Value>
+struct reverse_bits_const<uint64_t, Value>
+```
+
+Defines `value`  The reversed bits.
+
+## reverse_bytes
+Reverse the order of the bytes in a value.
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T reverse_bytes(T value)
+```
+
+## gray_to_binary
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T gray_to_binary(T value)
+```
+Converts a gray code value to binary.
+
+## binary_to_gray
+```cpp
+template <typename T>
+ETL_CONSTEXPR T binary_to_gray(T value)
+```
+Converts a binary value to the gray code equivalent.
+
+## count_bits
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 uint_least8_t count_bits(T value)
+```
+**Return**  
+The number of set bits in `value`.
+
+## parity
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 uint_least8_t parity(T value)
+```
+**Return**  
+`1` if the parity of the value is odd, `0` if it is even.
+
+## max_value_for_nbits
+```cpp
+template <size_t NBits>
+struct max_value_for_nbits
+```
+**Return**  
+Maximum unsigned value a particular number of bits can represent.
+
+`value_type` The type for the value.
+`value`      The maximum value.
+
+## fold_bits
+```cpp
+template <typename TReturn, size_t NBits, typename TValue>
+ETL_CONSTEXPR14 TReturn fold_bits(TValue value)
+```
+**Description**  
+Fold a binary number down to a set number of bits using XOR.  
+
+**Example**  
+`0xE8C9AACCBC3D9A8F` folded down to 20 bits = `0x998E8`  
+
+```cpp
+uint32_t result = etl::fold_bits<uint32_t, 20>(0xE8C9AACCBC3D9A8F);
+```
+
+## sign_extend
+Sign extends a binary number.  
+
+```cpp
+template <typename TReturn, size_t NBits, typename TValue>
+ETL_CONSTEXPR14 TReturn sign_extend(TValue value)
+```
+**Description**  
+Converts an N bit binary number, where bit N-1 is the sign bit, to a signed integral type.
+
+---
+```cpp
+template <typename TReturn, size_t NBits, size_t Shift, typename TValue>
+ETL_CONSTEXPR14 TReturn sign_extend(TValue value)
+```
+**Description**  
+Converts an N bit binary number, where bit N-1 is the sign bit, and `Shift` is the right shift amount, to a signed integral type.
+
+---
+
+```cpp
+template <typename TReturn, typename TValue>
+ETL_CONSTEXPR14 TReturn sign_extend(TValue value, size_t nbits)
+```
+**Description**  
+Converts an N bit binary number, where bit N-1 is the sign bit, to a signed integral type.
+
+---
+
+```cpp
+template <typename TReturn, typename TValue>
+ETL_CONSTEXPR14 TReturn sign_extend(TValue value, size_t nbits, size_t shift)
+```
+**Description**  
+Converts an N bit binary number, where bit N-1 is the sign bit, and shift is the right shift amount, to a signed integral type.
+
+## count_leading_zeros
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 uint_least8_t count_leading_zeros(T value)
+```
+**Description**  
+Counts the number of leading zeros in a binary number
+
+## count_trailing_zeros
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 uint_least8_t count_trailing_zeros(T value)
+```
+**Description**  
+Counts the number of trailing zeros in a binary number
+
+## count_leading_ones
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 uint_least8_t count_leading_ones(T value)
+```
+**Description**  
+Counts the number of leading ones in a binary number
+
+## count_trailing_ones
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 uint_least8_t count_trailing_ones(T value)
+```
+**Description**  
+Counts the number of trailing ones in a binary number
+
+## first_set_bit_position
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 uint_least8_t first_set_bit_position(T value)
+```
+**Description**  
+Finds the index of the first set bit from lsb.
+
+## first_clear_bit_position
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 uint_least8_t first_clear_bit_position(T value)
+```
+**Description**  
+Finds the index of the first clear bit from lsb.
+
+## first_bit_position
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 uint_least8_t first_bit_position(bool state, T value)
+```
+**Description**  
+Finds the index of the first bit in the specified state, from lsb.
+
+## binary_fill
+```cpp
+template <typename TResult, typename TValue>
+ETL_CONSTEXPR TResult binary_fill(TValue value)
+```
+Fills a value of the specified width with a repeating binary pattern.  
+*Run time*  
+
+Generate `0x12121212`  
+```cpp
+etl::binary_fill<uint32_t>(uint8_t(0x12));
+```
+
+---
+
+```cpp
+template <typename TResult, typename TValue, TValue Value>
+ETL_CONSTEXPR TResult binary_fill()
+```
+*Partial compile time*  
+
+Generate `0x12121212`
+```cpp
+etl::binary_fill<uint32_t, uint8_t, 0x12>();
+```
+
+## has_zero_byte
+```cpp
+template <typename TValue>
+ETL_CONSTEXPR14 bool has_zero_byte(TValue value)
+```
+*Run time*  
+Checks to see if a value contains a byte of value zero.
+
+**Example**  
+`etl::has_zero_byte(uint32_t(0x01234567)) == false`  
+`etl::has_zero_byte(uint32_t(0x01230067)) == true`
+
+---
+
+```cpp
+template <typename TValue, TValue Value>
+ETL_CONSTEXPR14 bool has_zero_byte()
+```
+Checks to see if `Value` contains a byte of value zero.
+*Compile time value*
+
+## has_byte_n
+Checks to see if a value contains a byte of a particular value.
+
+```cpp
+template <typename TValue>
+ETL_CONSTEXPR14 bool has_byte_n(TValue value, uint8_t n)
+```
+*Run time*  
+
+```cpp
+etl::has_byte_n(uint32_t(0x01234567), 0x12) == false
+etl::has_byte_n(uint32_t(0x01234567), 0x45) == true
+```
+
+---
+
+```cpp
+template <typename TValue, TValue Value>
+ETL_CONSTEXPR14 bool has_byte_n(TValue value)
+```
+*Partial compile time*  
+
+```cpp
+etl::has_byte_n<0x12>(uint32_t(0x01234567)) == false
+etl::has_byte_n<0x45>(uint32_t(0x01234567)) == true
+```
+
+## binary_merge
+Merges two binary values according to a mask.  
+Bits set in the mask select bits in the first value, clear bits select those in the second.
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR T binary_merge(T first, T second, T mask)
+```
+```cpp
+uint8_t first  = 0x12;
+uint8_t second = 0x34;
+
+const uint8_t mask = 0xF0;
+
+etl::binary_merge(first, second, mask) Equals 0x14
+```
+
+---
+
+```cpp
+template <typename T, T Mask>
+ETL_CONSTEXPR T binary_merge(T first, T second)
+```
+
+```cpp
+uint8_t first  = 0x12;
+uint8_t second = 0x34;
+
+const uint8_t mask = 0xF0;
+
+etl::binary_merge<uint8_t, mask>(first, second) Equals 0x14
+```
+
+## binary_interleave
+Interleaves two values such that bits abcd and efgh will result in eafbgchd.
+
+```cpp
+ETL_CONSTEXPR14 uint16_t binary_interleave(uint8_t  first, uint8_t  second);
+ETL_CONSTEXPR14 uint32_t binary_interleave(uint16_t first, uint16_t second);
+ETL_CONSTEXPR14 uint64_t binary_interleave(uint32_t first, uint32_t second);
+```
+
+## Odd / Even
+Determines the odd or evenness of a value.
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR bool is_odd(T value)
+```
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR bool is_even(T value)
+```
+
+## Constants
+```cpp
+enum binary_constant
+```
+An enumeration of 256 constants from `b00000000` to `b11111111` (`0` to `255`)
+
+---
+
+```cpp
+enum bit_constant
+```
+An enumeration of 32 constants from `b0` to `b31` (`1` to `4294967296`)
+
+---
+
+```cpp
+template <size_t Position>
+struct bit
+```
+
+`value_type` The type of the value.  
+`value`      The value of the bit at `Position`.
+
+## Creating bit masks
+These classes and constexpr functions help create lsb and msb masks.
+
+```cpp
+template <typename T, size_t NBits>
+class lsb_mask;
+```
+Defines the member constant value as a binary value of NBits `1` shift to the LSB.  
+e.g. `lsb_mask<int8_t, 3>::value == 0b00000111`  
+From: `20.34.0`
+
+---
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR T make_lsb_mask(size_t nbits)
+```
+Returns a binary value of nbits `1` shift to the LSB.
+e.g. `make_lsb_mask<int8_t>(3) == 0b00000111`  
+From: `20.34.0`
+
+---
+
+```cpp
+template <typename T, size_t NBits>
+ETL_CONSTEXPR T make_lsb_mask()
+```
+**Description**  
+Returns a binary value of nbits `1` shift to the LSB.  
+e.g. `make_lsb_mask<int8_t, 3>() == 0b00000111`  
+From: `20.38.7`
+
+---
+
+```cpp
+template <typename T, size_t NBits>
+class msb_mask;
+```
+**Return**  
+A binary value of nbits `1` shift to the MSB.  
+e.g. `msb_mask<int8_t, 3>::value == 0b11100000`  
+From: `20.34.0`
+
+---
+
+```cpp
+template <typename T>
+ETL_CONSTEXPR T make_msb_mask(size_t nbits)
+```
+**Description**  
+Defines the member constant value as a binary value of NBits `1` shift to the MSB.  
+e.g. `make_msb_mask<int8_t>(3) == 0b11100000`  
+20.34.0
+
+---
+
+```cpp
+template <typename T, size_t NBits>
+ETL_CONSTEXPR T make_msb_mask()
+```
+**Description**  
+Defines the member constant value as a binary value of NBits `1` shift to the MSB.  
+e.g. `make_msb_mask<int8_t, 3>() == 0b11100000`  
+From: `20.38.7`  
+
+## Bit manipulation functors
+These functors are most useful where lambdas are not available.
+
+## binary_not
+```cpp
+template <typename T>
+struct binary_not : public etl::unary_function<T, T>;
+```
+From: `20.38.11`
+
+---
+
+```cpp
+ETL_CONSTEXPR
+binary_not()
+```
+**Description**  
+Default constructor.
+
+---
+
+```cpp
+ETL_CONSTEXPR
+ETL_NODISCARD
+T operator()(T value) const ETL_NOEXCEPT
+```
+**Return**  
+~value.
+
+## binary_and
+```cpp
+template <typename T>
+struct binary_and : public etl::unary_function<T, T>;
+```
+From: `20.38.11`  
+
+---
+
+```cpp
+ETL_CONSTEXPR
+explicit binary_and(T and_value)
+```
+**Description**  
+Constructor.  
+
+---
+
+```cpp
+ETL_CONSTEXPR
+ETL_NODISCARD
+T operator()(T value) const ETL_NOEXCEPT
+```
+**Return**  
+`value & and_value`.
+
+## binary_or
+```cpp
+template <typename T>
+struct binary_or : public etl::unary_function<T, T>;
+```
+From: `20.38.11`
+
+---
+
+```cpp
+ETL_CONSTEXPR
+explicit binary_or(T or_value)
+```
+**Description**  
+Constructor.
+
+---
+
+```cpp
+ETL_CONSTEXPR
+ETL_NODISCARD
+T operator()(T value) const ETL_NOEXCEPT
+```
+**Return**  
+`value | or_value`.
+
+## binary_xor
+```cpp
+template <typename T>
+struct binary_xor : public etl::unary_function<T, T>;
+```
+From: `20.38.11`
+
+---
+
+```cpp
+ETL_CONSTEXPR
+explicit binary_xor(T xor_value)
+```
+**Description**  
+Constructor.
+
+---
+
+```cpp
+ETL_CONSTEXPR
+ETL_NODISCARD
+T operator()(T value) const ETL_NOEXCEPT
+```
+**Return**  
+value ^ xor_value.

docs/binary/bit.md

@@ -0,0 +1,117 @@
+---
+title: "bit"
+---
+
+{{< callout type="info">}}
+  Header: `bit.h`  
+  Since: `TBC`  
+  Similar to: [STL bit header](https://en.cppreference.com/cpp/header/bit)
+{{< /callout >}}
+
+Utility functions for manipulating binary numbers.  
+A reverse engineered version of C++20's and C++23's `<bit>` header.
+
+## bit_cast
+```cpp
+template <typename TDestination, typename TSource>
+ETL_CONSTEXPR14 TDestination bit_cast(const TSource& source) ETL_NOEXCEPT
+```
+**Description**  
+Returns a value of type `TDestination` by reinterpreting the `TSource` object.
+
+## byteswap
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T byteswap(T n) ETL_NOEXCEPT
+```
+**Description**  
+Reverses the bytes in `n`.
+
+## has_single_bit
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 bool has_single_bit(T n) ETL_NOEXCEPT
+```
+**Description**  
+Checks if `n` is a power of two, or has one bit set.
+
+## bit_ceil
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T bit_ceil(T n)
+```
+**Description**  
+Calculates the smallest power of two, that is not smaller than `n`.
+
+## bit_floor
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T bit_floor(T n) ETL_NOEXCEPT
+```
+**Description**  
+Calculates the largest power of two that is not greater than `n`.
+
+## bit_width
+```cpp
+template <typename T>
+ETL_CONSTEXPR14 T bit_width(T n) ETL_NOEXCEPT
+```
+**Description**  
+If `n` is not `0`, calculates the number of bits needed to store it.  
+If `n` is `0`, then the result is `0`.
+
+## rotl
+```cpp
+template <typename T>
+ETL_NODISCARD ETL_CONSTEXPR14 T rotl(T value, int n) ETL_NOEXCEPT
+```
+**Description**  
+Computes a left circular shift of value by `n`.
+
+## rotr
+```cpp
+template <typename T>
+ETL_NODISCARD ETL_CONSTEXPR14 T rotr(T value, int n) ETL_NOEXCEPT
+```
+**Description**  
+Computes a right circular shift of value by `n`.
+
+## countl_zero
+```cpp
+template <typename T>
+ETL_NODISCARD ETL_CONSTEXPR14 int countl_zero(T value) ETL_NOEXCEPT
+```
+**Description**  
+Returns the number of consecutive `0` bits in `n`, starting from the most significant bit (left).
+
+## countl_one
+```cpp
+template <typename T>
+ETL_NODISCARD ETL_CONSTEXPR14 int countl_one(T value) ETL_NOEXCEPT
+```
+**Description**  
+Returns the number of consecutive `1` bits in `n`, starting from the most significant bit (left).
+
+## countr_zero
+```cpp
+template <typename T>
+ETL_NODISCARD ETL_CONSTEXPR14 int countr_zero(T value) ETL_NOEXCEPT
+```
+**Description**  
+Returns the number of consecutive `0` bits in `n`, starting from the least significant bit (right).
+
+## countr_one
+```cpp
+template <typename T>
+ETL_NODISCARD ETL_CONSTEXPR14 int countr_one(T value) ETL_NOEXCEPT
+```
+**Description**  
+Returns the number of consecutive `1` bits in `n`, starting from the least significant bit (right).
+
+## popcount
+```cpp
+template <typename T>
+ETL_NODISCARD ETL_CONSTEXPR14 int popcount(T value) ETL_NOEXCEPT
+```
+**Description**  
+Counts the number of `1` bits in an unsigned integer.

docs/binary/byte.md

@@ -0,0 +1,149 @@
+---
+title: "byte"
+---
+
+{{< callout type="info">}}
+  Header: `byte.h`  
+  From: `20.24.0`  
+  Similar to: [std::byte](https://en.cppreference.com/cpp/types/byte)
+{{< /callout >}}
+
+A type that implements the concept of byte
+
+**C++03** 
+Implemented as a class.  
+Cannot be cast using `static_cast`.  
+
+**C++11 or above**  
+Implemented as enum class.  
+All functions are `constexpr`.  
+
+## Constructors
+```cpp
+byte()
+```
+**Description**
+Constructs a default initialised byte.  
+C++03
+
+---
+
+```cpp
+template <typename T>
+explicit byte(T v)
+```
+Constructs a byte initialised to `v`.
+
+## Non-member functions
+```cpp
+template <typename TInteger>
+constexpr TInteger to_integer(etl::byte b) noexcept
+```
+**Description**  
+Converts to an integral type.  
+`constexpr` and `noexcept` for C++11 and above.
+
+---
+
+```cpp
+template <typename TInteger>
+constexpr etl::byte operator <<(etl::byte b, TInteger shift) noexcept
+```
+**Description**  
+Shifts the value of the byte to the left and returns the new byte.  
+`constexpr` and `noexcept` for C++11 and above.
+
+---
+
+```cpp
+template <typename TInteger>
+constexpr etl::byte operator >>(etl::byte b, TInteger shift) noexcept
+```
+**Description**  
+Shifts the value of the byte to the right and returns the new byte.  
+`constexpr` and `noexcept` for C++11 and above.
+
+---
+
+```cpp
+template <typename TInteger>
+constexpr etl::byte& operator <<=(etl::byte& b, TInteger shift) noexcept
+```
+**Description**  
+Shifts the value of the byte to the left and returns a reference to the byte.  
+`constexpr` and `noexcept` for C++11 and above.
+
+---
+
+```cpp
+template <typename TInteger>
+constexpr etl::byte& operator >>=(etl::byte& b, TInteger shift) noexcept
+```
+**Description**  
+Shifts the value of the byte to the right and returns a reference to the byte.  
+`constexpr` and `noexcept` for C++11 and above.
+
+---
+
+```cpp
+constexpr etl::byte operator |(etl::byte lhs, etl::byte rhs) noexcept
+```
+ORs the two bytes returns the new byte.  
+`constexpr` and `noexcept` for C++11 and above.
+
+---
+
+```cpp
+constexpr etl::byte operator &(etl::byte lhs, etl::byte rhs) noexcept
+```
+**Description**  
+ANDs the two bytes returns the new byte.  
+`constexpr` and `noexcept` for C++11 and above.
+
+---
+
+```cpp
+constexpr etl::byte operator ^(etl::byte lhs, etl::byte rhs) noexcept
+```
+**Description**  
+Exclusive ORs the two bytes returns the new byte.  
+`constexpr` and `noexcept` for C++11 and above.
+
+---
+
+```cpp
+constexpr etl::byte& operator |=(etl::byte& lhs, etl::byte rhs) noexcept
+```
+**Description**  
+ORs the two bytes returns and a reference to the first parameter.  
+`constexpr` for C++14 and above.  
+`noexcept` for C++11 and above.
+
+---
+
+```cpp
+constexpr etl::byte& operator &=(etl::byte& lhs, etl::byte rhs) noexcept
+```
+**Description**  
+ANDs the two bytes returns and a reference to the first parameter.  
+`constexpr` for C++14 and above.  
+`noexcept` for C++11 and above.
+
+---
+
+```cpp
+constexpr etl::byte& operator ^=(etl::byte& lhs, etl::byte rhs) noexcept
+```
+**Description**  
+Exclusive ORs the two bytes and returns a reference to the first parameter.  
+`constexpr` for C++14 and above.  
+`noexcept` for C++11 and above.
+
+---
+
+```cpp
+constexpr etl::byte operator ~(etl::byte b) noexcept
+```
+**Description**  
+Negates the value of the byte and returns the new value.  
+`constexpr` and `noexcept` for C++11 and above.

docs/binary/flags.md

@@ -0,0 +1,144 @@
+---
+title: "flags"
+---
+
+{{< callout type="info">}}
+  Header: `flags.h`  
+  Since: `TBC`  
+{{< /callout >}}
+
+Provides a wrapper around a set of binary flags.  
+Supports compile time and runtime variants  
+
+```cpp
+template <typename T, T MASK = etl::integral_limits<T>::max>
+class flags
+```
+`T` must be an unsigned integral type.  
+`MASK` is used to exclude unused or undefined bits from operations of the flags. By default, all bits are included.
+
+Most member functions may be chained.  
+```cpp
+bool isF5Set = flags.set(bitPattern, true).flip().test(F5);
+```
+
+## Constructor
+```cpp
+ETL_CONSTEXPR flags() ETL_NOEXCEPT
+```
+**Description**
+Constructs a flag set with all elements set to `0` (`false`).
+
+---
+
+```cpp
+ETL_CONSTEXPR flags(value_type pattern) ETL_NOEXCEPT
+```
+**Description**
+Constructs a flag set with elements set to pattern.
+
+---
+
+```cpp
+ETL_CONSTEXPR flags(const flags<T, MASK>& pattern) ETL_NOEXCEPT
+```
+**Description**
+Constructs a flag set with elements set to pattern.
+
+## Modifiers
+
+```cpp
+ETL_CONSTEXPR14 flags<T, MASK>& operator=(flags<T, MASK> other) ETL_NOEXCEPT
+```
+**Description**
+Assigns from another flags object.
+
+---
+
+```cpp
+ETL_CONSTEXPR14 flags<T, MASK>& operator=(value_type pattern) ETL_NOEXCEPT
+```
+**Description**
+Assigns from a bit pattern.
+
+---
+
+```cpp
+template <value_type pattern, bool value>
+ETL_CONSTEXPR14 flags<T, MASK>& set() ETL_NOEXCEPT
+```
+
+---
+
+```cpp
+template <value_type pattern>
+ETL_CONSTEXPR14 flags<T, MASK>& set(bool value) ETL_NOEXCEPT
+```
+
+---
+
+```cpp
+template <value_type pattern>
+ETL_CONSTEXPR14 flags<T, MASK>& set() ETL_NOEXCEPT
+```
+
+---
+
+```cpp
+ETL_CONSTEXPR14 flags<T, MASK>& set(value_type pattern) ETL_NOEXCEPT
+```
+
+---
+
+```cpp
+ETL_CONSTEXPR14 flags<T, MASK>& set(value_type pattern, bool value) ETL_NOEXCEPT
+```
+
+---
+
+```cpp
+ETL_CONSTEXPR14 flags<T, MASK>& clear() ETL_NOEXCEPT
+```
+____________________________________________________________________________________________________
+template <value_type pattern>
+ETL_CONSTEXPR14 flags<T, MASK>& reset() ETL_NOEXCEPT
+____________________________________________________________________________________________________
+ETL_CONSTEXPR14 flags<T, MASK>& reset(value_type pattern) ETL_NOEXCEPT
+____________________________________________________________________________________________________
+ETL_CONSTEXPR14 flags<T, MASK>& flip() ETL_NOEXCEPT
+____________________________________________________________________________________________________
+template <value_type pattern>
+ETL_CONSTEXPR14 flags<T, MASK>& flip() ETL_NOEXCEPT
+____________________________________________________________________________________________________
+ETL_CONSTEXPR14 flags<T, MASK>& flip(value_type pattern) ETL_NOEXCEPT
+____________________________________________________________________________________________________
+Access
+
+template <value_type pattern>
+ETL_CONSTEXPR bool test() const ETL_NOEXCEPT
+Test the bits for the compile time pattern.
+____________________________________________________________________________________________________
+ETL_CONSTEXPR bool test(value_type pattern) const ETL_NOEXCEPT
+Test the bits for the run time pattern.
+____________________________________________________________________________________________________
+ETL_CONSTEXPR value_type value() const ETL_NOEXCEPT
+ETL_CONSTEXPR operator value_type() const ETL_NOEXCEPT
+Returns the value of the flags as a value_type.
+____________________________________________________________________________________________________
+Operations
+
+____________________________________________________________________________________________________
+Non-member functions
+
+template <typename T, T MASK>
+void swap(flags<T, MASK>& lhs, flags<T, MASK>& rhs)
+Swaps two flags.
+
+template <typename T, T MASK>
+bool operator == (flags<T, MASK>& lhs, flags<T, MASK>& rhs)
+Checks equality of two flags.
+
+template <typename T, T MASK>
+bool operator != (flags<T, MASK>& lhs, flags<T, MASK>& rhs)
+Checks inequality of two flags.
+

docs/blog/_index.md

@@ -0,0 +1,15 @@
+---
+title: "Blog"
+weight: 3001
+---
+
+## Graphics
+
+[Determining line-line intersections]({{% relref "./graphics/determining-line-line-intersections.md" %}})  
+[Applications of dot and cross products]({{% relref "./graphics/applications-of-dot-and-cross-products.md" %}})  
+[Scanning an arbitrarily rotated rectangular region]({{% relref "./graphics/scanning-an-arbitrarily-rotated-rectangular-region.md" %}})  
+
+
+## Algorithms
+
+[Implementing a low cost moving average]({{% relref "implementing-a-low-cost-moving-average.md" %}})  

docs/blog/graphics/_index.md

@@ -0,0 +1,5 @@
+---
+title: "Graphics"
+weight: 1
+---
+

docs/blog/graphics/applications-of-dot-and-cross-products.md

@@ -0,0 +1,71 @@
+---
+title: "Applications of dot and cross products"
+weight: 5
+---
+
+**Author:** John Wellbelove  
+**Date:** 2019  
+
+## The problem
+Sometimes in graphical applications there is a need to know the relative position of a point with respect to a line from a reference point.  
+
+Where is the target in relation to the reference and its direction?  
+Dot and cross products can make this an easy task.  
+
+Let's start with a reminder of what dot and cross products are.  
+
+Take two vectors `x1,y1` and `x2,y2`  
+The dot product is `(x1 * x2) + (y1 * y2)` and the cross product is `(x1 * y2) - (x2 * y1)`.  
+
+Remember that the dot product is a scalar based on `cos(θ)` and the cross product is a scalar based on `sin(θ)`.  
+
+**Example**  
+
+![DotCross1](images/DotCross1.png)
+
+We have a reference object at `Xr,Yr` facing in the direction of the arrow.  
+
+The target is at point `Xt,Yt`  
+
+![DotCross3](images/DotCross3.png)
+
+A arbitrary point on the line from the reference in the specified direction is `Xw,Yw`  
+
+First, find the coordinates of the target and waypoint relative to the reference.  
+
+`dXw = Xw - Xr`  
+`dYw = Yw - Yr`  
+`dXt = Xt - Xr`  
+`dYt = Yt - Yr`  
+
+Now find the dot and cross products of these vectors.  
+
+`Dot   = (dXw * dXt) + (dYw * dYt)`  
+`Cross = (dXw * dYt) - (dXt * dYw)`  
+
+The absolute values of the dot and cross products is unimportant, we just need the *sign*.  
+
+`Dot > 0`, `Cross < 0` : The target is forward of the reference and to the right.  
+`Dot > 0`, `Cross > 0` : The target is forward of the reference and to the left.  
+`Dot < 0`, `Cross < 0` : The target is behind the reference and to the right.  
+`Dot < 0`, `Cross > 0` : The target is behind the reference and to the left.  
+
+*forward*, *behind*, *left*, and *right* are relative to the reference's direction.  
+This calculation will be valid for any direction.
+
+## Other uses
+This technique can also be used to determine if a point is within a closed convex hull.  
+
+![DotCross4](images/DotCross4.png)
+
+A closed convex hull defined by the lines `L1`, `L2`, `L3`, `L4`, and `L5`.  
+Point `P1` is inside the hull, point `P2` is outside.  
+For `P1`, the cross product for all of the lines will indicate that it is to the *right* and therefore, *must* be inside.  
+For `P2`, the cross product for `L1` will put it on the *left* hand side and therefore it *cannot* be inside the hull.  
+
+**Why does this work?**  
+The dot product of vectors `A` and `B` is `|A||B|cos(Ø)`  
+The cross product of vectors `A` and `B` is `|A||B|sin(Ø)`  
+Where `Ø` is the angle between the vectors `A` and `B`. Range `+-180°`
+
+Therefore the sign of the result indicates the quadrant that target occupies in the circle around the reference, relative to the reference's direction.  

docs/blog/graphics/determining-line-line-intersections.md

@@ -0,0 +1,115 @@
+---
+title: "Determining line-line intersections"
+weight: 2
+---
+
+**Author:** John Wellbelove  
+**Date:** 2019  
+
+It's quite common in graphics and image processing to want to know the intersection coordinates of two lines.  
+
+The common formula for a line is the familiar `y = Mx + C`.  
+
+But there is another that can be a lot easier to use when determining line to line intersections in a graphical environment.
+
+## The issues
+
+When using `y = Mx + C` you must be aware of the situations of when the line approaches 'vertical'.  
+In this case `M` tends towards infinity, which is not good in a programming environment.  
+
+The usual trick is to flip the coordinates when the slope is more than 1, and then flip back after the calculations have been made.
+This can be confusing to follow and result in errors.
+
+Also, to keep any accuracy, the calculations must normally be kept in the floating point domain, which is not ideal for performance, as the image will be in integral pixel coordinates.
+
+## The solution
+
+Change the definition of your lines to use the formula `Ax + By = C`.
+
+Ideally, your lines would already be in the form `Ax + By = C`, but this is not normally the case, but we *can* easily generate the parameters from two points.  
+Assume we have a line defined by `(x1, y1)` and `(x2, y2)`.  
+
+We can deduce `A`, `B`, and `C` thus:
+
+`A = y2 - y1`  
+`B = x1 - x2`  
+`C = Ax1`+ `By1`  
+
+---
+
+Another useful calculation is the *determinant*.  
+Given two lines `A1x + B1y = C1` and `A2x + B2y = C2`:  
+
+`determinant = A1 * B2 - A2 * B1`
+
+If `determinant` is zero, then the lines are parallel.  
+
+### Notes
+
+- If `A` and `B` are both non-zero.  
+  The equation represents a diagonal line.
+
+- If `A == 0`, `B != 0`.  
+  The line is the parallel to the x-axis.
+
+- If `A != 0`, `B == 0`.  
+  The line is the parallel to the y-axis.
+
+- If `C == 0`
+  The line passes through the origin.
+
+## Calculating the intersection
+
+The intersection point is calculated like this:  
+
+Given two lines described by the points `(x1, y1)`, `(x2, y2)`, and `(x3, y3)`, `(x4, y4)`.  
+
+![LineCross1](images/LineCross1.png)
+
+- Calculate the parameters `A`, `B`, and `C` for each.  
+  `A1x + B1y = C1` and `A2x + B2y = C2`  
+
+- Calculate the determinant.  
+  `determinant = A1 * B2 - A2 * B1`
+
+- If `determinant == 0` then the lines are parallel, and there is no intersection point.
+
+- Otherwise  
+  `x = (B2 * C1 - B1 * C2) / determinant`  
+  `y = (A1 * C2 - A2 * C1) / determinant`  
+
+## They don't need to physically intersect
+
+The intersection point can be found even if the line segments aren't actually long enough to intersect.  
+The calculation will effectively extend them to where they *would* intersect, if long enough.  
+
+This means you can find intersection points relative to a fixed reference line.
+
+![LineCross2](images/LineCross2.png)
+
+## Refection
+
+This describes reflecting a point across a reference line.  
+It uses the intersection method described above.
+
+In the example below, we want to reflect `P` in the line `Reference`, to give us `P'`.  
+
+![Reflection1](images/Reflection1.png)
+
+First, we need the reference line in the form `Ax + By = C`.  
+
+Next, we need to find the perpendicular from `Reference` through `P`.  
+Any line perpendicular to `Ax + By = C` takes the form `−Bx + Ay = D`.  
+To find `D`, just substitute the `x,y` coordinates from `P`.  
+
+Now we have the two lines in the form we require to find the intersection.
+
+Find `I`, which is the intersection of the reference line and the perpendicular to `P`.
+
+Compute `P'` by using the formula `P' = I + (I - P)`.  
+This calculates the vector from `P` to `I` and then adds it to `I` to move the same amount again.
+
+## Line to point distance
+
+The above technique can be used to find the distance of a point to a reference line.  
+This distance is merely the absolute length of the vector `I - P`.

docs/blog/graphics/dot-and-cross-products.md

@@ -0,0 +1,26 @@
+---
+title: "Dot and cross products"
+weight: 4
+---
+
+**Author:** John Wellbelove  
+**Date:** 2019  
+
+## Dot Product
+The dot product of two vectors is the sum of the products of the corresponding elements.  
+The dot product of vectors `(x1, y1)` and `(x2, y2)` is `x1 * x2 + y1 * y2`.  
+If `A` & `B` are vectors, the dot product is `|A||B|cos(θ)`, where `θ` is the angle between the `A` and `B`.  
+
+`|A|` is the length of the vector `A`.  
+`|B|` is the length of the vector `B`.  
+
+Therefore, we can calculate `cos(θ) = (A ⋅ B)/(|A||B|)`.  
+A dot product of `0` indicates two perpendicular lines, and the dot product is greatest when the lines are parallel.
+
+## Cross Product
+
+The cross product of vectors `(x1, y1)` and `(x2, y2)` is `x1 * y2 - y1 * x2`  
+If `A` & `B` are vectors, the cross product is `|A||B|sin(θ)`.  
+`|θ|` is the angle between the two vectors, but `θ` can be positive or negative.
+
+Therefore, we can calculate `sin(θ) = (A x B)/(|A||B|)`.  

docs/blog/graphics/scanning-an-arbitrarily-rotated-rectangular-region.md

@@ -0,0 +1,41 @@
+---
+title: "Scanning an arbitrarily rotated rectangular region"
+weight: 3
+---
+
+**Author:** John Wellbelove  
+**Date:** 2019  
+
+Quite often in image processing we need to scan a rectangular region in an image. The region is usually aligned to capture a specific feature in the image.  
+You may be presented with a skewed image, necessitating that the region should also be skewed.  
+
+![ScanRectangle1](images/ScanRectangle1.png)
+
+If it is not absolutely necessary to scan the region at the angle of skew, then the fastest way to interrogate the pixels is to scan the image horizontally.  
+
+
+
+As was shown in the previous post, the crossing points between two lines can be easily and efficiently determined.  
+By moving a reference line down across the region, the start and end x coordinates of each scan line can be found.  
+Only the y coordinate of the reference line is relevant, though it must have a length of at least 1 unit.  
+
+Of course, we must check every line in the rectangle, and every line in the rectangle may produce a crossing point.  
+The reference line shown below will identify points `P1`, `P2`, `P3` and `P4` as valid crossing points.  
+
+![ScanRectangle4](images/ScanRectangle4.png)
+
+The solution is to compare the crossing coordinates against the bounds of the enclosing rectangle. 
+
+![ScanRectangle5](images/ScanRectangle5.png)
+
+This would eliminate points `P1` and `P4`. 
+
+![ScanRectangle2](images/ScanRectangle2.png)
+
+This can be done for all scan lines in the bounded rectangle.
+
+![ScanRectangle6](images/ScanRectangle6.png)
+
+Vertical scans may be easily achieved by simply having a vertical reference line.  
+This technique can be applied to any convex hull.
+

docs/blog/implementing-a-low-cost-moving-average.md

@@ -0,0 +1,70 @@
+---
+title: "Implementing a moving average"
+weight: 10
+author: John Wellbelove
+---
+
+**Author:** John Wellbelove  
+**Date:** 2019  
+
+## Example
+Imagine we have accumulated 10 values and our window size is 10.  
+
+`[ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]`  
+
+The average of this sequence is `(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10) / 10 = 5.5`  
+
+We now add a new sample, `11` to the sequence. As the windows size is 10, we drop the first value.  
+`[ 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 ]`
+
+The average of this sequence is `(2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11) / 10 = 6.5`  
+Now, averaging over 10 samples each time is not that big an issue, but what if it's 1000 or 10,000? Then, the overhead, both in processing time and storage has started to become a little excessive.  
+In the case of 10,000 samples of 'double' we are looking at 10,000 additions + 1 division each time a sample is added and a likely storage requirement of 80,000 bytes!  
+
+So we have an algorithm that has processing and storage complexity of O(N).  
+
+## What other values give the same average?
+
+**So let's look at the problem again.**  
+
+There are many ways of getting the same average:  
+
+`[ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]` = Average of `5.5`  
+`[ 7, 7, 7, 7, 7, 4, 4, 4, 4, 4 ]` = Average of `5.5`
+
+---
+
+**But what about this?**  
+`[ 5.5, 5.5 , 5.5, 5.5, 5.5, 5.5, 5.5, 5.5, 5.5, 5.5 ]` = Average of `5.5`  
+
+An average of `5.5` can be got from 10 samples of `5.5`.  
+
+## So why store 10 samples? 
+
+We can simply simulate the original sum just by multiplying the current average by the number of samples.  
+The calculation of the average for adding a new sample becomes this:  
+`(Old_Average * Sample_Size) + New_Sample) / (Sample_Size + 1)`  
+
+Now we have 1 multiplication, 2 additions and 1 division.  
+
+Our algorithm now has a complexity of O(1).
+
+We can average over as large a sample size as we like and it will always take the same amount of time and use the same amount of storage. We can also change the sample size on-the-fly if we wish.  
+
+There is one downside in that the average will not exactly match the original version, as the actual oldest value is not being erased from the sum, but for the performance and storage advantages it may be a perfectly suitable solution.  
+
+You may find that you will need a slightly smaller sample size with the rolling mean to get similar results.  
+
+---
+
+**Note**  
+The multiplication may be elided by re-arranging the formula.
+
+`Old_Average + ((New_Sample - Old_Average) / (Sample_Size + 1))`  
+
+This may produce a *negative* interim value, which may be a problem if you are using scaled unsigned integral types for the average value.
+
+---
+
+The ETL has an implementation of this algorithm.  
+[pseudo_moving_average]({{% relref "../maths/pseudo_moving_average.md" %}})