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https://github.com/tianocore/edk2
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de527ff606
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>
44 lines
1.3 KiB
C
44 lines
1.3 KiB
C
/** @file
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Deal with devices that just exist in memory space.
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To follow the EFI driver model you need a root handle to start with. An
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EFI driver will have a driver binding protocol (Supported, Start, Stop)
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that is used to layer on top of a handle via a gBS->ConnectController.
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The first handle has to just be in the system to make that work. For
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PCI it is a PCI Root Bridge IO protocol that provides the root.
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On an embedded system with MMIO device we need a handle to just
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show up. That handle will have this protocol and a device path
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protocol on it.
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For an ethernet device the device path must contain a MAC address device path
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node.
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Copyright (c) 2008 - 2009, Apple Inc. 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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//
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// Protocol GUID
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//
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// BF4B9D10-13EC-43dd-8880-E90B718F27DE
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#define EMBEDDED_DEVICE_PROTOCOL_GUID \
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{ 0xbf4b9d10, 0x13ec, 0x43dd, { 0x88, 0x80, 0xe9, 0xb, 0x71, 0x8f, 0x27, 0xde } }
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typedef struct {
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UINT16 VendorId;
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UINT16 DeviceId;
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UINT16 RevisionId;
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UINT16 SubsystemId;
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UINT16 SubsystemVendorId;
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UINT8 ClassCode[3];
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UINT8 HeaderSize;
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UINTN BaseAddress;
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} EMBEDDED_DEVICE_PROTOCOL;
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extern EFI_GUID gEmbeddedDeviceGuid;
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