mirror of
https://github.com/tianocore/edk2
synced 2026-08-27 00:23:19 -04:00
01f75b3927
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>
30 lines
859 B
C
30 lines
859 B
C
/** @file
|
|
Arm SCMI Info Library.
|
|
|
|
Copyright (c) 2022 - 2023, Arm Limited. All rights reserved.<BR>
|
|
|
|
SPDX-License-Identifier: BSD-2-Clause-Patent
|
|
**/
|
|
|
|
#pragma once
|
|
|
|
#include <ConfigurationManagerObject.h>
|
|
|
|
/** Populate a AML_CPC_INFO object based on SCMI information.
|
|
|
|
@param[in] DomainId Identifier for the performance domain.
|
|
@param[out] CpcInfo If success, this structure was populated from
|
|
information queried to the SCP.
|
|
|
|
@retval EFI_SUCCESS Success.
|
|
@retval EFI_DEVICE_ERROR Device error.
|
|
@retval EFI_INVALID_PARAMETER Invalid parameter.
|
|
@retval EFI_TIMEOUT Time out.
|
|
@retval EFI_UNSUPPORTED Unsupported.
|
|
**/
|
|
EFI_STATUS
|
|
EFIAPI
|
|
DynamicTablesScmiInfoGetFastChannel (
|
|
IN UINT32 DomainId,
|
|
OUT AML_CPC_INFO *CpcInfo
|
|
);
|