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58de02af29
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>
50 lines
1.4 KiB
C
50 lines
1.4 KiB
C
/** @file
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DpcLib.h.
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Copyright (c) 2007 - 2018, 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 <Protocol/Dpc.h>
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/**
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Add a Deferred Procedure Call to the end of the DPC queue.
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@param[in] DpcTpl The EFI_TPL that the DPC should invoke.
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@param[in] DpcProcedure The pointer to the DPC's function.
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@param[in] DpcContext The pointer to the DPC's context. Passed to DpcProcedure
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when DpcProcedure is invoked.
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@retval EFI_SUCCESS The DPC was queued.
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@retval EFI_INVALID_PARAMETER DpcTpl is not a valid EFI_TPL.
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@retval EFI_INVALID_PARAMETER DpcProcedure is NULL.
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@retval EFI_OUT_OF_RESOURCES There are not enough resources available to
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add the DPC to the queue.
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**/
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EFI_STATUS
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EFIAPI
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QueueDpc (
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IN EFI_TPL DpcTpl,
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IN EFI_DPC_PROCEDURE DpcProcedure,
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IN VOID *DpcContext OPTIONAL
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);
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/**
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Dispatch the queue of DPCs. All DPCs that have been queued with a DpcTpl
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value greater than or equal to the current TPL are invoked in the order that
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they were queued. DPCs with higher DpcTpl values are invoked before DPCs with
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lower DpcTpl values.
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@retval EFI_SUCCESS One or more DPCs were invoked.
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@retval EFI_NOT_FOUND No DPCs were invoked.
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**/
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EFI_STATUS
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EFIAPI
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DispatchDpc (
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VOID
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);
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