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etl/docs/utilities/memory.md
John Wellbelove 4a88884b39
Issue/add hugo support for documentation (#1449) 
* Add ranges

* Initial Hugo setup

* Work in progress

* Added selection for local or remote site

* Updated to 'light' theme

* Changed to using Hextra Hugo theme

* Changed to using Hextra Hugo theme

* Changed to Hextra Hugo theme

* Change to Hextra Hugo theme

* Updated Hugo setup.

* Updated Hugo setup.

# Conflicts:
#	docs/releases/_index.md

* Work in progress

* Added new fonts

Added new documentation

* Latest documentation updates

* Latest documentation updates

# Conflicts:
#	docs/containers/array.md
#	docs/containers/array_view.md
#	docs/containers/array_wrapper.md
#	docs/containers/bip_buffer_spsc_atomic.md
#	docs/containers/bitset.md
#	docs/containers/indirect_vector.md
#	docs/containers/vector.md
#	docs/getting-started/compilers.md

* Added bloom_filter markdown doc

* Added more documentation

Updated CSS for light and dark modes

* Fixed some menus

Added mode documentation files

* Updated CSS rules

Added badges to home page
Added uniqur_ptr + pool tutorial

* Fixed formatting on the home page markdown

Modified light amd dark code formatting

* Updated unique_ptr-with-pool

* Added container and shared message tutorials

* Updates to documentation

* Added const_multimap

* Updated source-formatting.md

* Added initial raw text files form Web site editor

* Innore coverage build directory

* Exported raw text documentation files from the web site editor

* Hugo updates

* Added Hugo intalation and markdown descriptions

* More addition to the documentation

* Added closure.md and updates to delegate.md

* Added format.md

* Added documentation for etl::delegate_observable, etl::function, Base64 codec

* Added io_port documentation

* Added basic_format_spec

* Added documentation for string_stream and string utilities.

* Added more documentation

Updated the documentation CSS

* Added documentation for clocks, day, duration

* Added more documentation for chrono classes

Updated callouts

* More chrono documentation

* Completed chrono documentation

* Maths functions documentation

* Completed maths documentation

* Completed maths documentation

* Completed maths documentation

* Completed maths documentation

* Added multiple documentation files

* Added iterator.md

* Added debug_count.md and versions.md

* Added debug_count.md and versions.md

* Added more documentation

* More documentation

* Added some design pattern documentation

Modified some of the layout files
Modified the About documentation

* Converted more documentation pages

Modified the site CSS

* Added more documentation

Moced some documentation files to new directories

* Added more documentation

Tweaks to CSS

* Added callback_timer_deferred_locked documentation

* Added callback_timer_locked documentation

* More documentation updates

* More documentation updates

* More documentation updates

* New documentation files.

Harmonised file name format

* New documentation files.

* Multiple document updates

* Multiple document updates

* Final conversion of web pages

* Updates before PR

* Updates before PR

* Updates before PR

# Conflicts:
#	docs/blog/_index.md

* Final pre PR updates

* Updates to message framework documentation

* Renamed directory

* Fix spelling

* Added author and date to blog files

Moved documentation files merged from development

* Fixed 'Description' typo

* Fix typos

# Conflicts:
#	docs/IO/io_port.md
#	docs/containers/sets/const-multiset.md
#	docs/containers/sets/const-set.md
#	docs/maths/correlation.md
#	docs/maths/gamma.md

* Renamed two files to lower case

* Minor renaming

* Added author and date

* Updated callout on bresenham_line.md

Added support for showing the ETL version on the documentation first page, by copying the version.txt file as a hugo asset.
Updated the Python 'update_release.py' to copy 'version.txt'

* Replace space in filename with hyphen.

Added more information to hugo-commands.md

* Replace space in filename with hyphen.

Added more information to hugo-commands.md

# Conflicts:
#	docs/getting-started/view-the-docs-locally/hugo-commands.md

* Added a link to pseudo_moving_average.md

* Updated title pages for groups

* Fixed missing 404 for non-existent pages

* Fixed coordinate variable names in the 'Calculating the intersection' example

---------

Co-authored-by: Roland Reichwein <Roland.Reichwein@bmw.de>
Co-authored-by: John Wellbelove <john.wellbelove@etlcpp.com>
Co-authored-by: John Wellbelove <john.wellbelove@etlcpp.co.uk>
2026-06-06 13:12:44 +01:00

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---
title: "memory"
---
## address_of
```cpp
template <typename T>
T* addressof(T& t)
```
**Description**
Returns the address of an object.
## default_delete
```cpp
template <typename T>
struct default_delete
```
---
```cpp
template <typename T>
struct default_delete<T[]>
```
## create_default_at
```cpp
template <typename T>
void create_default_at(T* p)
```
Creates a default value. For POD types this will be undefined.
---
```cpp
template <typename T, typename TCounter>
void create_default_at(T* p, TCounter count)
```
Creates a default value. For POD types this will be undefined.
The supplied counter will be incremented.
## create_value_at
```cpp
template <typename T>
void create_value_at(T* p)
```
Creates a default value by constructing the item with `T()`.
---
```cpp
template <typename T, typename TCounter>
void create_value_at(T* p, Tcounter count)
```
Creates a default value by constructing the item with `T()`.
The supplied a counter will be incremented.
## create_copy_at
```cpp
template <typename T>
void create_copy_at(T* p)
```
Creates a default value by constructing the item with `T(value)`.
---
```cpp
template <typename T, typename TCounter>
void create_copy_at(T* p, const T& value, Tcounter count)
```
Creates a default value by constructing the item with `T(value)`.
The supplied counter will be incremented.
## make_default_at
```cpp
template <typename T>
T& make_default_at(T* p)
```
Creates a default value. For POD types this will be undefined.
Returns a reference to the new object.
---
```cpp
template <typename T, typename TCounter>
T& make_default_at(T* p, Tcounter count)
```
**Description**
Creates a default value. For POD types this will be undefined.
Returns a reference to the new object.
The supplied counter will be incremented.
## make_value_at
```cpp
template <typename T>
T& make_value_at(T* p)
```
Creates a default value by constructing the item with `T()`.
Returns a reference to the new object.
---
```cpp
template <typename T, typename TCounter>
T& make_value_at(T* p, Tcounter count)
```
Creates a default value by constructing the item with `T()`.
Returns a reference to the new object.
## make_copy_at
Creates a default value by constructing the item with `T(value)`.
Returns a reference to the new object.
The second version is supplied a counter, which will be incremented.
```cpp
template <typename T>
T& make_copy_at(T* p)
```
---
```cpp
template <typename T, typename TCounter>
T& make_copy_at(T* p, const T& value, Tcounter count)
```
## destroy_at
```cpp
template <typename T>
void destroy_at(T* p)
```
Calls the destructor for non-pod types.
---
```cpp
template <typename T, typename TCounter>
void destroy_at(T* p, TCounter& count)
```
Calls the destructor for non-pod types.
The supplied counter will be decremented.
## destroy_n
```cpp
template <typename T, typename TSize >
void destroy_n(T* p, TSize n)
```
Calls the destructor for a range of non-pod types, starting at address `p`.
---
```cpp
template <typename T, typename TSize, typename TCounter>
void destroy_n(T* p, TSize n, TCounter& count)
```
Calls the destructor for a range of non-pod types, starting at address `p`.
The supplied counter will be decremented by the number of items destructed.
## destroy
```cpp
template <typename T>
void destroy(T* p, T* p_end)
```
Calls the destructor for a range of non-pod types, starting at address `p`.
---
```cpp
template <typename T, typename TCounter>
void destroy(T* p, T* p_end, TCounter& count)
```
Calls the destructor for a range of non-pod types, starting at address `p`.
The supplied counter will be decremented by the number of items destructed.
## create_copy
```cpp
template <typename T>
struct create_copy
```
Derive from this, passing the derived class as the template parameter.
Provides the following member functions that constructs a copy at the specified address.
---
```cpp
void create_copy_at(void* p);
```
---
```cpp
template <typename TCounter>
void create_copy_at(void* p, Tcounter& count);
```
---
```cpp
T& make_copy_at(void* p);
```
---
```cpp
template <typename TCounter>
T& make_copy_at(void* p, Tcounter& count);
```
### Example:
```cpp
class Test : public etl::create_copy<Test>
{
// Other members.
};
// Allocate memory large enough to contain a 'Test' object.
char buffer[sizeof(Test)];
Test test;
// Copy construct 'test' into the buffer memory.
Test& t = test.make_copy_at(buffer);
```
---
Create / Destroy objects
Functions that create or destroy objects in uninitialised memory.
Variations of the functions above that don't require an explicit `reinterpret_cast`.
```cpp
template <typename TObject>
TObject& construct_object_at(void* p, TObject&& object)
```
Construct the object at `p`.
In a debug build the pointer is checked for correct alignment.
An `etl::alignment_error` is asserted if incorrect.
From: `20.35.12`
---
```cpp
template <typename TObject, typename... TArgs>
TObject& construct_object_at(void* p, TArgs&&... args)
```
Construct the object at `p` from arguments.
In a debug build the pointer is checked for correct alignment.
An `etl::alignment_error` is asserted if incorrect.
From: `20.35.12`
---
```cpp
template <typename TObject>
TObject& get_object_at(void* p)
```
Get the object at `p`.
In a debug build the pointer is checked for correct alignment.
An `etl::alignment_error` is asserted if incorrect.
From: `20.35.12`
---
```cpp
template <typename TObject>
void destroy_object_at(void* p)
```
Destroy the object at `p`.
In a debug build the pointer is checked for correct alignment. An etl::alignment_error is asserted if incorrect.
From: `20.35.12`
## uninitialized_fill
Fills uninitialised memory with N values.
```cpp
template <typename TIterator, typename TSize, typename T>
TIterator uninitialized_fill_n(TIterator o_begin, TSize count, const T& value)
```
---
```cpp
template <typename TIterator, typename TSize, typename T, typename TCounter>
TIterator uninitialized_fill_n(TIterator o_begin, TSize count, const T& value, typename TCounter)
```
---
```cpp
template <typename TIterator, typename T>
TIterator uninitialized_fill(TIterator o_begin, TIterator o_end, const T& value)
```
---
```cpp
template <typename TIterator, typename TSize, typename T, typename TCounter>
TIterator uninitialized_fill_n(TIterator o_begin, TSize count, const T& value, typename TCounter)
```
Fills uninitialised memory range with a value.
## uninitialised_copy
```cpp
template <typename TInputIterator, typename TOutputIterator>
TIterator uninitialized_copy(TInputIterator i_begin, TInputIterator i_end, TOutputIterator o_begin)
```
```cpp
template <typename TInputIterator, typename TOutputIterator, typename TCounter>
TIterator uninitialized_copy(TInputIterator i_begin, TInputIterator i_end, TOutputIterator o_begin, typename TCounter)
```
Copies a range of objects to uninitialised memory.
## uninitialized_copy_n
```cpp
template <typename TInputIterator, typename TSize, typename TOutputIterator>
TIterator uninitialized_copy_n(TInputIterator i_begin, TSize count, TOutputIterator o_begin)
```
---
```cpp
template <typename TInputIterator, typename TSize, typename TOutputIterator, typename TCounter>
TIterator uninitialized_copy_n(TInputIterator i_begin, TSize count, TOutputIterator o_begin, typename TCounter)
```
Copies N objects to uninitialised memory.
## uninitialized_move
```cpp
template <typename TInputIterator, typename TOutputIterator>
TIterator uninitialized_move(TInputIterator i_begin, TInputIterator i_end, TOutputIterator o_begin)
```
```cpp
template <typename TInputIterator, typename TOutputIterator, typename TCounter>
TIterator uninitialized_move(TInputIterator i_begin, TInputIterator i_end, TOutputIterator o_begin, typename TCounter)
```
Moves a range of objects to uninitialised memory.
Note: If using C++03 then this function will call `etl::uninitialized_copy`
## uninitialized_copy_n
```cpp
template <typename TInputIterator, typename TSize, typename TOutputIterator>
TIterator uninitialized_move_n(TInputIterator i_begin, TSize count, TOutputIterator o_begin)
```
---
```cpp
template <typename TInputIterator, typename TSize, typename TOutputIterator, typename TCounter>
TIterator uninitialized_move_n(TInputIterator i_begin, TSize count, TOutputIterator o_begin, typename TCounter)
```
Moves N objects to uninitialised memory.
Note: If using C++03 then this function will call `etl::uninitialized_copy_n`
## uninitialized_default_construct
```cpp
template <typename TOutputIterator>
void uninitialized_default_construct(TOutputIterator o_begin, TOutputIterator o_end)
```
---
```cpp
template <typename TOutputIterator, typename TCounter>
void uninitialized_default_construct(TOutputIterator o_begin, TOutputIterator o_end, typename TCounter)
```
---
```cpp
template <typename TOutputIterator, typename TSize>
TOutputIterator uninitialized_default_construct_n(TOutputIterator o_begin, TSize n)
```
---
```cpp
template <typename TOutputIterator, typename TSize, typename TCounter>
TOutputIterator uninitialized_default_construct_n(TOutputIterator o_begin, TSize n, TCounter& count)
```
Creates default values. For POD types this will be undefined.
## uninitialized_value_construct
```cpp
template <typename TOutputIterator>
void uninitialized_value_construct(TOutputIterator o_begin, TOutputIterator o_end)
```
---
```cpp
template <typename TOutputIterator, typename TCounter>
void uninitialized_value_construct(TOutputIterator o_begin, TOutputIterator o_end, TCounter& count)
```
---
```cpp
template <typename TOutputIterator, typename TSize>
TOutputIterator uninitialized_value_construct_n(TOutputIterator o_begin, TSize n)
```
---
```cpp
template <typename TOutputIterator, typename TSize, typename TCounter>
TOutputIterator uninitialized_value_construct_n(TOutputIterator o_begin, TSize n, TCounter& count)
```
Creates values constructed with `T()`.
## unique_ptr
Like `std::unique_ptr`, `etl::unique_ptr` is a smart pointer that owns and manages another object through a pointer and disposes of that object when the `unique_ptr` goes out of scope.
https://en.cppreference.com/w/cpp/memory/unique_ptr
```cpp
template<typename T>
class unique_ptr
```
---
```cpp
template<typename T>
class unique_ptr<T[]>
```
## Memory clear
```cpp
void memory_clear(volatile char* p, size_t n)
```
---
```cpp
template <typename T>
void memory_clear(volatile T &object)
```
A low level function that clears an object's memory to zero.
## memory_clear_range
```cpp
template <typename T>
void memory_clear_range(volatile T* begin, size_t n)
```
---
```cpp
template <typename T>
void memory_clear_range(volatile T* begin, volatile T* end)
```
A low level function that clears a range to zero.
## memory_set
```cpp
void memory_set(volatile char* p, size_t n, char value)
```
```cpp
template <typename T>
void memory_set(volatile T &object, char value)
```
Low level functions that clear an object's memory to a value.
## memory_set_range
```cpp
template <typename T>
void memory_set_range(volatile T* begin, size_t n, char value)
```
---
```cpp
template <typename T>
void memory_set_range(volatile T* begin, volatile T* end, char value)
```
Low level functions that set a range to a value.
## wipe_on_destruct
A template class that will wipe the derived objects storage to zero on destruction.
Designed to eliminate sensitive data lurking around in memory after an object has been destructed.
```cpp
template <typename T>
struct wipe_on_destruct
```
`T` is the derived class whose storage must be wiped.
### Example
```cpp
struct UserData : public etl::wipe_on_destruct<UserData>
{
char secret_passcode[16];
char sensitive_user_name[16];
};
```
When an instance of `UserData` is destructed, the memory that it occupied will be set to zero.
## uninitialized_buffer
```cpp
template <size_t VObject_Size, size_t VN_Objects, size_t VAlignment>
class uninitialized_buffer
```
Creates an uninitialized memory buffer of `VN_Objects` each of `VObject_Size` with alignment `VAlignment`.
## uninitialized_buffer_of
```cpp
template <typename T, size_t VN_Objects>
class uninitialized_buffer_of
```
Creates an uninitialized memory buffer of `VN_Objects` each of type `T`.
## mem_copy
From: `20.26.0`
```cpp
template <typename TPointer>
TPointer mem_copy(const TPointer sb, const TPointer se, TPointer db) ETL_NOEXCEPT
```
Template wrapper for `memcpy`.
Copies all of the bytes in the source range to the destination range.
Type must be trivially copyable.
`sb` Pointer to source begin.
`se` Pointer to source end.
`db` Pointer to destination begin.
Returns a pointer to the destination.
---
```cpp
template <typename TPointer>
TPointer mem_copy(const TPointer sb, size_t n, TPointer db) ETL_NOEXCEPT
```
Template wrapper for `memcpy`.
Copies all of the bytes in the source range to the destination range.
Type must be trivially copyable.
`sb` Pointer to source begin.
`n` Source length.
`db` Pointer to destination begin.
Returns a pointer to the destination.
## mem_move
From: `20.26.0`
```cpp
template <typename TPointer>
TPointer mem_move(const TPointer sb, const TPointer se, TPointer db) ETL_NOEXCEPT
```
Template wrapper for `memmove`.
Moves all of the bytes in the source range to the destination range.
Type must be trivially copyable.
`sb` Pointer to source begin.
`se` Pointer to source end.
`db` Pointer to destination begin.
Returns a pointer to the destination.
---
```cpp
template <typename TPointer>
TPointer mem_move(const TPointer sb, size_t n, TPointer db) ETL_NOEXCEPT
```
Template wrapper for `memmove`.
Moves all of the bytes in the source range to the destination range.
Type must be trivially copyable.
`sb` Pointer to source begin.
`n` Source length.
`db` Pointer to destination begin.
Returns a pointer to the destination.
## mem_compare
From: `20.26.0`
```cpp
template <typename TPointer>
TPointer mem_compare(const TPointer sb, const TPointer se, TPointer db) ETL_NOEXCEPT
```
Template wrapper for `memcmp`.
Searches all of the bytes in the range for value.
Type must be trivially copyable.
`sb` Pointer to source begin.
`se` Pointer to source end.
`db` Pointer to destination begin.
Returns `<0`, `0`, `>0`. See documentation for `memcmp`.
---
```cpp
template <typename TPointer>
TPointer mem_compare(const TPointer sb, size_t n, TPointer db) ETL_NOEXCEPT
```
Template wrapper for `memcmp`.
Type must be trivially copyable.
`sb` Pointer to source begin.
`n` Source length.
`db` Pointer to destination begin.
Returns `<0`, `0`, `>0`. See documentation for `memcmp`.
## mem_set
From: `20.26.0`
```cpp
template <typename TPointer, typename T>
TPointer mem_set(const TPointer db, const TPointer de, T value) ETL_NOEXCEPT
```
Template wrapper for `memset`.
Sets all of the bytes in the range to `value`.
Type must be trivially copyable.
`db` Pointer to destination begin.
`de` Pointer to destination end.
`value` The value to write to the memory. This value is cast to `char`.
Returns a pointer to the destination.
---
```cpp
template <typename TPointer, typename T>
TPointer mem_set(const TPointer db, size_t n, T value) ETL_NOEXCEPT
```
Template wrapper for `memset`.
Sets all of the bytes in the range to `value`.
Type must be trivially copyable.
`db` Pointer to destination begin.
`n` Destination length.
`value` The value to write to the memory. This value is cast to `char`.
Returns a pointer to the destination.
## mem_char
From: `20.26.0`
```cpp
template <typename TPointer, typename T>
TPointer mem_char(const TPointer sb, const TPointer se, T value) ETL_NOEXCEPT
```
Template wrapper for `memchr`.
Searches all of the bytes in the range for `value`.
Type must be trivially copyable.
`db` Pointer to source begin.
`de` Pointer to source begin.
`value` The value to search for. This value is cast to `char`.
Returns a pointer to the character or se if not found.
---
```cpp
template <typename TPointer, typename T>
TPointer mem_char(const TPointer sb, size_t n, T value) ETL_NOEXCEPT
```
Template wrapper for `memchr`.
Searches all of the bytes in the range for `value`.
Type must be trivially copyable.
`db` Pointer to destination begin.
`n` Source length.
`value` The value to search for. This value is cast to `char`.
Returns a pointer to the character or `sb + n` if not found.
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