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https://github.com/tianocore/edk2
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7a934d0bef
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>
43 lines
1.1 KiB
C
43 lines
1.1 KiB
C
/** @file
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The library to print all the HOBs.
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Copyright (c) 2024, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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**/
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#pragma once
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/**
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HOB Print Handler to print HOB information.
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@param[in] HobStart A pointer to the HOB of type EFI_HOB_TYPE_GUID_EXTENSION.
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@param[in] HobLength The length in bytes of the HOB of type EFI_HOB_TYPE_GUID_EXTENSION.
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@retval EFI_SUCCESS If it completed successfully.
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@retval EFI_UNSUPPORTED If the HOB type is not supported.
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**/
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typedef
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EFI_STATUS
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(*HOB_PRINT_HANDLER)(
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IN VOID *Hob,
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IN UINT16 HobLength
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);
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/**
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Print all HOBs info from the HOB list.
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If the input PrintHandler is not NULL, the PrintHandler will be processed first.
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If PrintHandler returns EFI_SUCCESS, default HOB info print logic in PrintHobList
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will be skipped.
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@param[in] HobStart A pointer to the HOB list.
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@param[in] PrintHandler A custom handler to print HOB info.
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**/
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VOID
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EFIAPI
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PrintHobList (
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IN CONST VOID *HobStart,
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IN HOB_PRINT_HANDLER PrintHandler OPTIONAL
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);
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