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edk2/MdePkg/Include/Library/MemoryAllocationLib.h
Michael Kubacki 7835e5802a MdePkg: Replace include guards with #pragma once 
Replace traditional `#ifndef`/`#define`/`#endif` include guards with
`#pragma` once.

`#pragma once` is a widely supported preprocessor directive that
prevents header files from being included multiple times. It is
supported by all toolchains used to build edk2: GCC, Clang/LLVM, and
MSVC.

Compared to macro-based include guards, `#pragma once`:

- Eliminates the risk of macro name collisions or copy/paste errors
  where two headers inadvertently use the same guard macro.
- Eliminate inconsistency in the way include guard macros are named
  (e.g., some files use `__FILE_H__`, others use `FILE_H_`, etc.).
- Reduces boilerplate (three lines replaced by one).
- Avoids polluting the macro namespace with guard symbols.
- Can improve build times as the preprocessor can skip re-opening the
  file entirely, rather than re-reading it to find the matching
  `#endif` ("multiple-include optimization").
  - Note that some compilers may already optimize traditional include
    guards, by recognzining the idiomatic pattern.

This change is made acknowledging that overall portability of the
code will technically be reduced, as `#pragma once` is not part of the
C/C++ standards.

However, this is considered acceptable given:

1. edk2 already defines a subset of supported compilers in
   BaseTools/Conf/tools_def.template, all of which have supported
   `#pragma once` for over two decades.
2. There have been concerns raised to the project about inconsistent
   include guard naming and potential macro collisions.

Approximate compiler support dates:

- MSVC: Supported since Visual C++ 4.2 (1996)
- GCC: Supported since 3.4 (2004)
  (http://gnu.ist.utl.pt/software/gcc/gcc-3.4/changes.html)
- Clang (LLVM based): Since initial release in 2007

Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
2026-02-23 21:01:28 +00:00

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/** @file
Provides services to allocate and free memory buffers of various memory types and alignments.
The Memory Allocation Library abstracts various common memory allocation operations. This library
allows code to be written in a phase-independent manner because the allocation of memory in PEI, DXE,
and SMM (for example) is done via a different mechanism. Using a common library interface makes it
much easier to port algorithms from phase to phase.
Copyright (c) 2006 - 2018, Intel Corporation. All rights reserved.<BR>
SPDX-License-Identifier: BSD-2-Clause-Patent
**/
#pragma once
/**
Allocates one or more 4KB pages of type EfiBootServicesData.
Allocates the number of 4KB pages of type EfiBootServicesData and returns a pointer to the
allocated buffer. The buffer returned is aligned on a 4KB boundary. If Pages is 0, then NULL
is returned. If there is not enough memory remaining to satisfy the request, then NULL is
returned.
@param Pages The number of 4 KB pages to allocate.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocatePages (
IN UINTN Pages
);
/**
Allocates one or more 4KB pages of type EfiRuntimeServicesData.
Allocates the number of 4KB pages of type EfiRuntimeServicesData and returns a pointer to the
allocated buffer. The buffer returned is aligned on a 4KB boundary. If Pages is 0, then NULL
is returned. If there is not enough memory remaining to satisfy the request, then NULL is
returned.
@param Pages The number of 4 KB pages to allocate.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateRuntimePages (
IN UINTN Pages
);
/**
Allocates one or more 4KB pages of type EfiReservedMemoryType.
Allocates the number of 4KB pages of type EfiReservedMemoryType and returns a pointer to the
allocated buffer. The buffer returned is aligned on a 4KB boundary. If Pages is 0, then NULL
is returned. If there is not enough memory remaining to satisfy the request, then NULL is
returned.
@param Pages The number of 4 KB pages to allocate.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateReservedPages (
IN UINTN Pages
);
/**
Frees one or more 4KB pages that were previously allocated with one of the page allocation
functions in the Memory Allocation Library.
Frees the number of 4KB pages specified by Pages from the buffer specified by Buffer. Buffer
must have been allocated on a previous call to the page allocation services of the Memory
Allocation Library. If it is not possible to free allocated pages, then this function will
perform no actions.
If Buffer was not allocated with a page allocation function in the Memory Allocation Library,
then ASSERT().
If Pages is zero, then ASSERT().
@param Buffer Pointer to the buffer of pages to free.
@param Pages The number of 4 KB pages to free.
**/
VOID
EFIAPI
FreePages (
IN VOID *Buffer,
IN UINTN Pages
);
/**
Allocates one or more 4KB pages of type EfiBootServicesData at a specified alignment.
Allocates the number of 4KB pages specified by Pages of type EfiBootServicesData with an
alignment specified by Alignment. The allocated buffer is returned. If Pages is 0, then NULL is
returned. If there is not enough memory at the specified alignment remaining to satisfy the
request, then NULL is returned.
If Alignment is not a power of two and Alignment is not zero, then ASSERT().
If Pages plus EFI_SIZE_TO_PAGES (Alignment) overflows, then ASSERT().
@param Pages The number of 4 KB pages to allocate.
@param Alignment The requested alignment of the allocation. Must be a power of two.
If Alignment is zero, then byte alignment is used.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateAlignedPages (
IN UINTN Pages,
IN UINTN Alignment
);
/**
Allocates one or more 4KB pages of type EfiRuntimeServicesData at a specified alignment.
Allocates the number of 4KB pages specified by Pages of type EfiRuntimeServicesData with an
alignment specified by Alignment. The allocated buffer is returned. If Pages is 0, then NULL is
returned. If there is not enough memory at the specified alignment remaining to satisfy the
request, then NULL is returned.
If Alignment is not a power of two and Alignment is not zero, then ASSERT().
If Pages plus EFI_SIZE_TO_PAGES (Alignment) overflows, then ASSERT().
@param Pages The number of 4 KB pages to allocate.
@param Alignment The requested alignment of the allocation. Must be a power of two.
If Alignment is zero, then byte alignment is used.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateAlignedRuntimePages (
IN UINTN Pages,
IN UINTN Alignment
);
/**
Allocates one or more 4KB pages of type EfiReservedMemoryType at a specified alignment.
Allocates the number of 4KB pages specified by Pages of type EfiReservedMemoryType with an
alignment specified by Alignment. The allocated buffer is returned. If Pages is 0, then NULL is
returned. If there is not enough memory at the specified alignment remaining to satisfy the
request, then NULL is returned.
If Alignment is not a power of two and Alignment is not zero, then ASSERT().
If Pages plus EFI_SIZE_TO_PAGES (Alignment) overflows, then ASSERT().
@param Pages The number of 4 KB pages to allocate.
@param Alignment The requested alignment of the allocation. Must be a power of two.
If Alignment is zero, then byte alignment is used.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateAlignedReservedPages (
IN UINTN Pages,
IN UINTN Alignment
);
/**
Frees one or more 4KB pages that were previously allocated with one of the aligned page
allocation functions in the Memory Allocation Library.
Frees the number of 4KB pages specified by Pages from the buffer specified by Buffer. Buffer
must have been allocated on a previous call to the aligned page allocation services of the Memory
Allocation Library. If it is not possible to free allocated pages, then this function will
perform no actions.
If Buffer was not allocated with an aligned page allocation function in the Memory Allocation
Library, then ASSERT().
If Pages is zero, then ASSERT().
@param Buffer Pointer to the buffer of pages to free.
@param Pages The number of 4 KB pages to free.
**/
VOID
EFIAPI
FreeAlignedPages (
IN VOID *Buffer,
IN UINTN Pages
);
/**
Allocates a buffer of type EfiBootServicesData.
Allocates the number bytes specified by AllocationSize of type EfiBootServicesData and returns a
pointer to the allocated buffer. If AllocationSize is 0, then a valid buffer of 0 size is
returned. If there is not enough memory remaining to satisfy the request, then NULL is returned.
@param AllocationSize The number of bytes to allocate.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocatePool (
IN UINTN AllocationSize
);
/**
Allocates a buffer of type EfiRuntimeServicesData.
Allocates the number bytes specified by AllocationSize of type EfiRuntimeServicesData and returns
a pointer to the allocated buffer. If AllocationSize is 0, then a valid buffer of 0 size is
returned. If there is not enough memory remaining to satisfy the request, then NULL is returned.
@param AllocationSize The number of bytes to allocate.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateRuntimePool (
IN UINTN AllocationSize
);
/**
Allocates a buffer of type EfiReservedMemoryType.
Allocates the number bytes specified by AllocationSize of type EfiReservedMemoryType and returns
a pointer to the allocated buffer. If AllocationSize is 0, then a valid buffer of 0 size is
returned. If there is not enough memory remaining to satisfy the request, then NULL is returned.
@param AllocationSize The number of bytes to allocate.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateReservedPool (
IN UINTN AllocationSize
);
/**
Allocates and zeros a buffer of type EfiBootServicesData.
Allocates the number bytes specified by AllocationSize of type EfiBootServicesData, clears the
buffer with zeros, and returns a pointer to the allocated buffer. If AllocationSize is 0, then a
valid buffer of 0 size is returned. If there is not enough memory remaining to satisfy the
request, then NULL is returned.
@param AllocationSize The number of bytes to allocate and zero.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateZeroPool (
IN UINTN AllocationSize
);
/**
Allocates and zeros a buffer of type EfiRuntimeServicesData.
Allocates the number bytes specified by AllocationSize of type EfiRuntimeServicesData, clears the
buffer with zeros, and returns a pointer to the allocated buffer. If AllocationSize is 0, then a
valid buffer of 0 size is returned. If there is not enough memory remaining to satisfy the
request, then NULL is returned.
@param AllocationSize The number of bytes to allocate and zero.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateRuntimeZeroPool (
IN UINTN AllocationSize
);
/**
Allocates and zeros a buffer of type EfiReservedMemoryType.
Allocates the number bytes specified by AllocationSize of type EfiReservedMemoryType, clears the
buffer with zeros, and returns a pointer to the allocated buffer. If AllocationSize is 0, then a
valid buffer of 0 size is returned. If there is not enough memory remaining to satisfy the
request, then NULL is returned.
@param AllocationSize The number of bytes to allocate and zero.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateReservedZeroPool (
IN UINTN AllocationSize
);
/**
Copies a buffer to an allocated buffer of type EfiBootServicesData.
Allocates the number bytes specified by AllocationSize of type EfiBootServicesData, copies
AllocationSize bytes from Buffer to the newly allocated buffer, and returns a pointer to the
allocated buffer. If AllocationSize is 0, then a valid buffer of 0 size is returned. If there
is not enough memory remaining to satisfy the request, then NULL is returned.
If Buffer is NULL, then ASSERT().
If AllocationSize is greater than (MAX_ADDRESS - Buffer + 1), then ASSERT().
@param AllocationSize The number of bytes to allocate and zero.
@param Buffer The buffer to copy to the allocated buffer.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateCopyPool (
IN UINTN AllocationSize,
IN CONST VOID *Buffer
);
/**
Copies a buffer to an allocated buffer of type EfiRuntimeServicesData.
Allocates the number bytes specified by AllocationSize of type EfiRuntimeServicesData, copies
AllocationSize bytes from Buffer to the newly allocated buffer, and returns a pointer to the
allocated buffer. If AllocationSize is 0, then a valid buffer of 0 size is returned. If there
is not enough memory remaining to satisfy the request, then NULL is returned.
If Buffer is NULL, then ASSERT().
If AllocationSize is greater than (MAX_ADDRESS - Buffer + 1), then ASSERT().
@param AllocationSize The number of bytes to allocate and zero.
@param Buffer The buffer to copy to the allocated buffer.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateRuntimeCopyPool (
IN UINTN AllocationSize,
IN CONST VOID *Buffer
);
/**
Copies a buffer to an allocated buffer of type EfiReservedMemoryType.
Allocates the number bytes specified by AllocationSize of type EfiReservedMemoryType, copies
AllocationSize bytes from Buffer to the newly allocated buffer, and returns a pointer to the
allocated buffer. If AllocationSize is 0, then a valid buffer of 0 size is returned. If there
is not enough memory remaining to satisfy the request, then NULL is returned.
If Buffer is NULL, then ASSERT().
If AllocationSize is greater than (MAX_ADDRESS - Buffer + 1), then ASSERT().
@param AllocationSize The number of bytes to allocate and zero.
@param Buffer The buffer to copy to the allocated buffer.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
AllocateReservedCopyPool (
IN UINTN AllocationSize,
IN CONST VOID *Buffer
);
/**
Reallocates a buffer of type EfiBootServicesData.
Allocates and zeros the number bytes specified by NewSize from memory of type
EfiBootServicesData. If OldBuffer is not NULL, then the smaller of OldSize and
NewSize bytes are copied from OldBuffer to the newly allocated buffer, and
OldBuffer is freed. A pointer to the newly allocated buffer is returned.
If NewSize is 0, then a valid buffer of 0 size is returned. If there is not
enough memory remaining to satisfy the request, then NULL is returned.
If the allocation of the new buffer is successful and the smaller of NewSize and OldSize
is greater than (MAX_ADDRESS - OldBuffer + 1), then ASSERT().
@param OldSize The size, in bytes, of OldBuffer.
@param NewSize The size, in bytes, of the buffer to reallocate.
@param OldBuffer The buffer to copy to the allocated buffer. This is an optional
parameter that may be NULL.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
ReallocatePool (
IN UINTN OldSize,
IN UINTN NewSize,
IN VOID *OldBuffer OPTIONAL
);
/**
Reallocates a buffer of type EfiRuntimeServicesData.
Allocates and zeros the number bytes specified by NewSize from memory of type
EfiRuntimeServicesData. If OldBuffer is not NULL, then the smaller of OldSize and
NewSize bytes are copied from OldBuffer to the newly allocated buffer, and
OldBuffer is freed. A pointer to the newly allocated buffer is returned.
If NewSize is 0, then a valid buffer of 0 size is returned. If there is not
enough memory remaining to satisfy the request, then NULL is returned.
If the allocation of the new buffer is successful and the smaller of NewSize and OldSize
is greater than (MAX_ADDRESS - OldBuffer + 1), then ASSERT().
@param OldSize The size, in bytes, of OldBuffer.
@param NewSize The size, in bytes, of the buffer to reallocate.
@param OldBuffer The buffer to copy to the allocated buffer. This is an optional
parameter that may be NULL.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
ReallocateRuntimePool (
IN UINTN OldSize,
IN UINTN NewSize,
IN VOID *OldBuffer OPTIONAL
);
/**
Reallocates a buffer of type EfiReservedMemoryType.
Allocates and zeros the number bytes specified by NewSize from memory of type
EfiReservedMemoryType. If OldBuffer is not NULL, then the smaller of OldSize and
NewSize bytes are copied from OldBuffer to the newly allocated buffer, and
OldBuffer is freed. A pointer to the newly allocated buffer is returned.
If NewSize is 0, then a valid buffer of 0 size is returned. If there is not
enough memory remaining to satisfy the request, then NULL is returned.
If the allocation of the new buffer is successful and the smaller of NewSize and OldSize
is greater than (MAX_ADDRESS - OldBuffer + 1), then ASSERT().
@param OldSize The size, in bytes, of OldBuffer.
@param NewSize The size, in bytes, of the buffer to reallocate.
@param OldBuffer The buffer to copy to the allocated buffer. This is an optional
parameter that may be NULL.
@return A pointer to the allocated buffer or NULL if allocation fails.
**/
VOID *
EFIAPI
ReallocateReservedPool (
IN UINTN OldSize,
IN UINTN NewSize,
IN VOID *OldBuffer OPTIONAL
);
/**
Frees a buffer that was previously allocated with one of the pool allocation functions in the
Memory Allocation Library.
Frees the buffer specified by Buffer. Buffer must have been allocated on a previous call to the
pool allocation services of the Memory Allocation Library. If it is not possible to free pool
resources, then this function will perform no actions.
If Buffer was not allocated with a pool allocation function in the Memory Allocation Library,
then ASSERT().
@param Buffer Pointer to the buffer to free.
**/
VOID
EFIAPI
FreePool (
IN VOID *Buffer
);
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