add: [imp] byte & ut

include/libimp/byte.h

@@ -0,0 +1,169 @@
+/**
+ * @file libimp/byte.h
+ * @author mutouyun (orz@orzz.org)
+ * @brief Define the byte type
+ * @date 2022-11-12
+ */
+#pragma once
+
+#include <type_traits>
+#include <cstdint>
+#include <cstddef>  // std::byte (since C++17)
+
+#include "fmt/format.h"
+
+#include "libimp/def.h"
+#include "libimp/detect_plat.h"
+
+#if defined(LIBIMP_CPP_17) && defined(__cpp_lib_byte)
+#define LIBIMP_CPP_LIB_BYTE_
+#endif // __cpp_lib_byte
+
+LIBIMP_NAMESPACE_BEG_
+
+class byte;
+
+namespace detail {
+
+template <typename T>
+using is_integral = 
+  typename std::enable_if<std::is_integral<T>::value>::type;
+
+template <typename T>
+using is_not_byte = 
+  typename std::enable_if<!std::is_same<
+  typename std::remove_cv<T>::type, byte>::value>::type;
+
+} // namespace detail
+
+/**
+ * @brief A distinct type that implements the concept of byte as specified in the C++ language definition.
+ * @see https://en.cppreference.com/w/cpp/types/byte
+ */
+class byte {
+  std::uint8_t bits_;
+
+public:
+  constexpr byte() noexcept
+    : byte(0) {}
+  
+  template <typename T, typename = detail::is_integral<T>>
+  constexpr byte(T v) noexcept
+    : bits_(static_cast<std::uint8_t>(v)) {}
+
+#ifdef LIBIMP_CPP_LIB_BYTE_
+  constexpr byte(std::byte b) noexcept
+    : byte(std::to_integer<std::uint8_t>(b)) {}
+#endif // LIBIMP_CPP_LIB_BYTE_
+
+  template <typename T, typename = detail::is_integral<T>>
+  explicit constexpr operator T() const noexcept {
+    return static_cast<T>(bits_);
+  }
+
+#ifdef LIBIMP_CPP_LIB_BYTE_
+  explicit constexpr operator std::byte() const noexcept {
+    /// @brief C++17 relaxed enum class initialization rules.
+    /// @see https://en.cppreference.com/w/cpp/language/enum#enum_relaxed_init_cpp17
+    return std::byte{bits_};
+  }
+#endif // LIBIMP_CPP_LIB_BYTE_
+
+  friend bool operator==(byte const &lhs, byte const &rhs) noexcept {
+    return lhs.bits_ == rhs.bits_;
+  }
+
+  friend bool operator!=(byte const &lhs, byte const &rhs) noexcept {
+    return !(lhs == rhs);
+  }
+};
+
+/**
+ * @brief Non-member functions.
+ */
+
+template <typename T, typename = detail::is_integral<T>>
+constexpr T to_integer(byte b) noexcept {
+  return T(b);
+}
+
+/// @brief std::operator<<, operator>>
+
+template <typename T, typename = detail::is_integral<T>>
+constexpr byte operator<<(byte b, T shift) noexcept {
+  return byte(to_integer<unsigned>(b) << shift);
+}
+
+template <typename T, typename = detail::is_integral<T>>
+constexpr byte operator>>(byte b, T shift) noexcept {
+  return byte(to_integer<unsigned>(b) >> shift);
+}
+
+/// @brief std::operator<<=, operator>>=
+
+template <typename T, typename = detail::is_integral<T>>
+constexpr byte &operator<<=(byte &b, T shift) noexcept {
+  return b = b << shift;
+}
+
+template <typename T, typename = detail::is_integral<T>>
+constexpr byte &operator>>=(byte &b, T shift) noexcept {
+  return b = b >> shift;
+}
+
+/// @brief std::operator|, operator&, operator^, operator~
+
+constexpr byte operator|(byte l, byte r) noexcept { return byte(to_integer<unsigned>(l) | to_integer<unsigned>(r)); }
+constexpr byte operator&(byte l, byte r) noexcept { return byte(to_integer<unsigned>(l) & to_integer<unsigned>(r)); }
+constexpr byte operator^(byte l, byte r) noexcept { return byte(to_integer<unsigned>(l) ^ to_integer<unsigned>(r)); }
+constexpr byte operator~(byte b)         noexcept { return byte(~to_integer<unsigned>(b)); }
+
+/// @brief std::operator|=, operator&=, operator^=
+
+constexpr byte &operator|=(byte &l, byte r) noexcept { return l = l | r; }
+constexpr byte &operator&=(byte &l, byte r) noexcept { return l = l & r; }
+constexpr byte &operator^=(byte &l, byte r) noexcept { return l = l ^ r; }
+
+/// @brief Cast pointer to byte*.
+
+template <typename T, typename = detail::is_not_byte<T>>
+byte *byte_cast(T *p) noexcept {
+  return reinterpret_cast<byte *>(p);
+}
+
+template <typename T, typename = detail::is_not_byte<T>>
+byte const *byte_cast(T const *p) noexcept {
+  return reinterpret_cast<byte const *>(p);
+}
+
+/// @brief Cast byte* to a pointer of another type.
+
+template <typename T, typename = detail::is_not_byte<T>>
+T *byte_cast(byte *p) noexcept {
+  if (reinterpret_cast<std::size_t>(p) % alignof(T) != 0) {
+    return nullptr;
+  }
+  return reinterpret_cast<T *>(p);
+}
+
+template <typename T, typename U = typename std::add_const<T>::type, 
+          typename = detail::is_not_byte<T>>
+U *byte_cast(byte const *p) noexcept {
+  if (reinterpret_cast<std::size_t>(p) % alignof(T) != 0) {
+    return nullptr;
+  }
+  return reinterpret_cast<U *>(p);
+}
+
+LIBIMP_NAMESPACE_END_
+
+template <>
+struct fmt::formatter<::LIBIMP_::byte> {
+  constexpr auto parse(format_parse_context& ctx) const {
+    return ctx.end();
+  }
+  template <typename FormatContext>
+  auto format(::LIBIMP_::byte b, FormatContext &ctx) {
+    return format_to(ctx.out(), "{:#04x}", static_cast<std::uint8_t>(b));
+  }
+};

include/libimp/span.h

@@ -16,12 +16,17 @@
 #include <algorithm>
 #include <cstdint>
 #include <initializer_list>
-#ifdef LIBIMP_CPP_20
-#include <span>
-#endif // LIBIMP_CPP_20
+
+#include "fmt/format.h"
 
 #include "libimp/def.h"
 #include "libimp/detect_plat.h"
+#include "libimp/byte.h"
+
+#if defined(LIBIMP_CPP_20) && defined(__cpp_lib_span)
+#include <span>
+#define LIBIMP_CPP_LIB_SPAN_
+#endif // __cpp_lib_span
 
 LIBIMP_NAMESPACE_BEG_
 namespace detail {
@@ -138,13 +143,13 @@ public:
     : ptr_   (s.data())
     , extent_(s.size()) {}
 
-#if defined(LIBIMP_CPP_20) || defined(__cpp_lib_span)
+#ifdef LIBIMP_CPP_LIB_SPAN_
   template <typename U, std::size_t E,
             typename = detail::is_array_convertible<U, T>>
   constexpr span(std::span<U, E> const &s) noexcept
     : ptr_   (s.data())
     , extent_(s.size()) {}
-#endif // LIBIMP_CPP_20
+#endif // LIBIMP_CPP_LIB_SPAN_
 
   constexpr size_type size() const noexcept {
     return extent_;
@@ -221,9 +226,9 @@ bool operator==(span<T> a, span<U> b) noexcept {
 /// @see https://en.cppreference.com/w/cpp/container/span/as_bytes
 
 template <typename T, 
-          typename Byte = typename std::conditional<std::is_const<T>::value, std::uint8_t const, std::uint8_t>::type>
+          typename Byte = typename std::conditional<std::is_const<T>::value, byte const, byte>::type>
 auto as_bytes(span<T> s) noexcept -> span<Byte> {
-  return {reinterpret_cast<Byte *>(s.data()), s.size_bytes()};
+  return {byte_cast(s.data()), s.size_bytes()};
 }
 
 /// @brief Constructs an object of type T and wraps it in a span.
@@ -274,3 +279,21 @@ inline auto make_span(std::string const &str) noexcept -> span<char const> {
 }
 
 LIBIMP_NAMESPACE_END_
+
+template <typename T>
+struct fmt::formatter<::LIBIMP_::span<T>> {
+  constexpr auto parse(format_parse_context& ctx) const {
+    return ctx.end();
+  }
+  template <typename FormatContext>
+  auto format(::LIBIMP_::span<T> s, FormatContext &ctx) {
+    if (s.empty()) {
+      return format_to(ctx.out(), "");
+    }
+    auto appender = format_to(ctx.out(), "{}", s[0]);
+    for (std::size_t i = 1; i < s.size(); ++i) {
+      appender = format_to(appender, " {}", s[i]);
+    }
+    return appender;
+  }
+};

test/CMakeLists.txt

@@ -13,8 +13,12 @@ include_directories(
   ${LIBIPC_PROJECT_DIR}/src
   ${LIBIPC_PROJECT_DIR}/test)
 
-file(GLOB SRC_FILES  ${LIBIPC_PROJECT_DIR}/test/*.cpp)
-file(GLOB HEAD_FILES ${LIBIPC_PROJECT_DIR}/test/*.h)
+file(GLOB SRC_FILES
+  ${LIBIPC_PROJECT_DIR}/test/imp/*.cpp
+  ${LIBIPC_PROJECT_DIR}/test/*.cpp)
+
+file(GLOB HEAD_FILES
+  ${LIBIPC_PROJECT_DIR}/test/*.h)
 
 add_executable(${PROJECT_NAME} ${SRC_FILES} ${HEAD_FILES})
 

test/imp/test_imp_byte.cpp

@@ -0,0 +1,65 @@
+
+#include "gtest/gtest.h"
+
+#include "libimp/byte.h"
+#include "libimp/span.h"
+
+TEST(byte, construct) {
+  {
+    imp::byte b;
+    EXPECT_EQ(int(b), 0);
+  }
+  {
+    imp::byte b {123};
+    EXPECT_EQ(int(b), 123);
+  }
+  {
+    imp::byte b {65535};
+    EXPECT_EQ(int(b), 255);
+    EXPECT_EQ(std::int8_t(b), -1);
+  }
+  {
+    imp::byte b {65536};
+    EXPECT_EQ(int(b), 0);
+  }
+}
+
+TEST(byte, compare) {
+  {
+    imp::byte b1, b2;
+    EXPECT_EQ(b1, b2);
+  }
+  {
+    imp::byte b1, b2(321);
+    EXPECT_NE(b1, b2);
+  }
+}
+
+TEST(byte, fmt) {
+  {
+    imp::byte b1, b2(31);
+    EXPECT_EQ(fmt::format("{}", b1), "0x00");
+    EXPECT_EQ(fmt::format("{}", b2), "0x1f");
+  }
+  {
+    imp::byte bs[] {31, 32, 33, 34, 35, 36, 37, 38};
+    EXPECT_EQ(fmt::format("{}", imp::make_span(bs)), 
+              "0x1f 0x20 0x21 0x22 0x23 0x24 0x25 0x26");
+  }
+}
+
+TEST(byte, byte_cast) {
+  int a = 654321;
+  int *pa = &a;
+
+  // int * => byte *
+  imp::byte *pb = imp::byte_cast(pa);
+  EXPECT_EQ((std::size_t)pb, (std::size_t)pa);
+
+  // byte * => int32_t *
+  std::int32_t *pc = imp::byte_cast<std::int32_t>(pb);
+  EXPECT_EQ(*pc, a);
+
+  // byte alignment check
+  EXPECT_EQ(imp::byte_cast<int>(pb + 1), nullptr);
+}

test/imp/test_imp_span.cpp

@@ -41,7 +41,7 @@ TEST(span, span) {
     test_proc(imp::make_span({6, 7, 8, 9}), sp.last(4));
     test_proc(imp::make_span({3, 4, 5, 6}), sp.subspan(3, 4));
     test_proc(imp::make_span({3, 4, 5, 6, 7, 8, 9}), sp.subspan(3));
-    test_proc(imp::make_span((char *)sp.data(), sp.size_bytes()), imp::as_bytes(sp));
+    test_proc(imp::make_span((imp::byte *)sp.data(), sp.size_bytes()), imp::as_bytes(sp));
   }
   {
     std::string buf = "0123456789";
@@ -53,4 +53,9 @@ TEST(span, span) {
     test_proc(imp::make_span("3456", 4), sp.subspan(3, 4));
     test_proc(imp::make_span("3456789", 7), sp.subspan(3));
   }
+}
+
+TEST(span, fmt) {
+  EXPECT_EQ(fmt::format("{}", imp::span<int>{}), "");
+  EXPECT_EQ(fmt::format("{}", imp::make_span({1, 3, 2, 4, 5, 6, 7})), "1 3 2 4 5 6 7");
 }