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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>
48 lines
1.8 KiB
C
48 lines
1.8 KiB
C
/** @file
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The common variable volatile store routines shared by the DXE_RUNTIME variable
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module and the DXE_SMM variable module.
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Copyright (c) 2019, 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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#include "Variable.h"
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/**
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Copies any pending updates to runtime variable caches.
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@retval EFI_UNSUPPORTED The volatile store to be updated is not initialized properly.
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@retval EFI_SUCCESS The volatile store was updated successfully.
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**/
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EFI_STATUS
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FlushPendingRuntimeVariableCacheUpdates (
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VOID
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);
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/**
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Synchronizes the runtime variable caches with all pending updates outside runtime.
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Ensures all conditions are met to maintain coherency for runtime cache updates. This function will attempt
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to write the given update (and any other pending updates) if the ReadLock is available. Otherwise, the
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update is added as a pending update for the given variable store and it will be flushed to the runtime cache
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at the next opportunity the ReadLock is available.
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@param[in] VariableRuntimeCache Variable runtime cache structure for the runtime cache being synchronized.
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@param[in] Offset Offset in bytes to apply the update.
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@param[in] Length Length of data in bytes of the update.
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@retval EFI_SUCCESS The update was added as a pending update successfully. If the variable runtime
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cache ReadLock was available, the runtime cache was updated successfully.
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@retval EFI_UNSUPPORTED The volatile store to be updated is not initialized properly.
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**/
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EFI_STATUS
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SynchronizeRuntimeVariableCache (
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IN VARIABLE_RUNTIME_CACHE *VariableRuntimeCache,
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IN UINTN Offset,
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IN UINTN Length
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);
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