libc/src/threads/linux/Futex.h

   1 //===-- Linux futex related definitions -------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #ifndef LLVM_LIBC_SRC_THREADS_LINUX_FUTEX_H
  10 #define LLVM_LIBC_SRC_THREADS_LINUX_FUTEX_H
  11
  12 #include "src/__support/macros/config.h"
  13 #include "src/__support/macros/properties/architectures.h" // Architecture macros
  14
  15 namespace LIBC_NAMESPACE_DECL {
  16
  17 #if (defined(LIBC_TARGET_ARCH_IS_AARCH64) ||                                   \
  18      defined(LIBC_TARGET_ARCH_IS_X86_64))
  19 // The futex data has to be exactly 4 bytes long. However, we use a uint type
  20 // here as we do not want to use `uint32_t` type to match the public definitions
  21 // of types which include a field for a futex word. With public definitions, we
  22 // cannot include <stdint.h> so we stick to the `unsigned int` type for x86_64
  23 // and aarch64
  24 using FutexWordType = unsigned int;
  25 static_assert(sizeof(FutexWordType) == 4,
  26               "Unexpected size of unsigned int type.");
  27 #else
  28 #error "Futex word base type not defined for the target architecture."
  29 #endif
  30
  31 } // namespace LIBC_NAMESPACE_DECL
  32
  33 #endif // LLVM_LIBC_SRC_THREADS_LINUX_FUTEX_H