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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>
67 lines
2.1 KiB
C
67 lines
2.1 KiB
C
/** @file
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AML Resource Data Parser.
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Copyright (c) 2019 - 2020, Arm Limited. All rights reserved.<BR>
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SPDX-License-Identifier: BSD-2-Clause-Patent
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@par Glossary:
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- Rd or RD - Resource Data
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- Rds or RDS - Resource Data Small
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- Rdl or RDL - Resource Data Large
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**/
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#pragma once
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#include <AmlNodeDefines.h>
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#include <Stream/AmlStream.h>
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#include <ResourceData/AmlResourceData.h>
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/** Check whether the input stream is pointing to a valid list
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of resource data elements.
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The check is based on the size of resource data elements.
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This means that a buffer can pass this check with non-existing descriptor Ids
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that have a correct size.
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A list of resource data elements can contain one unique resource data
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element, without an end tag resource data. This is the case for
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a FieldList.
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@param [in] FStream Forward stream ideally pointing to a resource
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data element. The stream is not
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modified/progressing.
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The stream must not be at its end.
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@retval TRUE The buffer is holding a valid list of resource data elements.
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@retval FALSE Otherwise.
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**/
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BOOLEAN
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EFIAPI
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AmlRdIsResourceDataBuffer (
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IN CONST AML_STREAM *FStream
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);
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/** Parse a ResourceDataBuffer.
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For each resource data element, create a data node
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and add them to the variable list of arguments of the BufferNode.
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The input stream is expected to point to a valid list of resource data
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elements. A function is available to check it for the caller.
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@param [in] BufferNode Buffer node.
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@param [in] FStream Forward stream pointing to a resource data
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element.
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The stream must not be at its end.
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@retval EFI_SUCCESS The function completed successfully.
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@retval EFI_INVALID_PARAMETER Invalid parameter.
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@retval EFI_OUT_OF_RESOURCES Could not allocate memory.
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**/
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EFI_STATUS
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EFIAPI
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AmlParseResourceData (
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IN AML_OBJECT_NODE *BufferNode,
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IN AML_STREAM *FStream
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);
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