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https://github.com/tianocore/edk2
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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>
47 lines
1.5 KiB
C
47 lines
1.5 KiB
C
/** @file
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Tpm2 device table generating Library
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Copyright (c) 2025, Arm Limited. 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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/** Build a SSDT table describing the TPM2 device.
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The table created by this function must be freed by FreeTpm2DeviceTable.
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@param [in] TpmDevInfo TPM2 Device info to describe in the SSDT table.
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@param [in] Name The Name to give to the Device.
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Must be a NULL-terminated ASL NameString
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e.g.: "DEV0", "DV15.DEV0", etc.
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@param [in] Uid UID for the TPM@ device.
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@param [out] Table If success, pointer to the created SSDT table.
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@retval EFI_SUCCESS Table generated successfully.
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@retval EFI_INVALID_PARAMETER A parameter is invalid.
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@retval EFI_NOT_FOUND Could not find information.
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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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BuildTpm2DeviceTable (
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IN CONST CM_ARCH_COMMON_TPM2_DEVICE_INFO *TpmDevInfo,
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IN CONST CHAR8 *Name,
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IN CONST UINT64 Uid,
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OUT EFI_ACPI_DESCRIPTION_HEADER **Table
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);
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/** Free an Tpm2 device table previously created by
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the BuildTpm2DeviceTable function.
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@param [in] Table Pointer to a Tpm2 Device table allocated by
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the BuildTpm2DeviceTable function.
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**/
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VOID
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EFIAPI
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FreeTpm2DeviceTable (
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IN EFI_ACPI_DESCRIPTION_HEADER *Table
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);
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