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7835e5802a
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>
33 lines
1.1 KiB
C
33 lines
1.1 KiB
C
/** @file
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Present the boot mode values in PI.
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Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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@par Revision Reference:
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PI Version 1.2.1A
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**/
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#pragma once
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///
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/// EFI boot mode
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///
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typedef UINT32 EFI_BOOT_MODE;
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//
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// 0x21 - 0xf..f are reserved.
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//
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#define BOOT_WITH_FULL_CONFIGURATION 0x00
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#define BOOT_WITH_MINIMAL_CONFIGURATION 0x01
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#define BOOT_ASSUMING_NO_CONFIGURATION_CHANGES 0x02
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#define BOOT_WITH_FULL_CONFIGURATION_PLUS_DIAGNOSTICS 0x03
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#define BOOT_WITH_DEFAULT_SETTINGS 0x04
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#define BOOT_ON_S4_RESUME 0x05
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#define BOOT_ON_S5_RESUME 0x06
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#define BOOT_WITH_MFG_MODE_SETTINGS 0x07
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#define BOOT_ON_S2_RESUME 0x10
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#define BOOT_ON_S3_RESUME 0x11
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#define BOOT_ON_FLASH_UPDATE 0x12
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#define BOOT_IN_RECOVERY_MODE 0x20
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