libc/src/time/gpu/clock.cpp

   1 //===-- GPU implementation of the clock function --------------------------===//
   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 #include "src/time/clock.h"
  10
  11 #include "src/__support/common.h"
  12 #include "src/__support/macros/config.h"
  13 #include "src/__support/time/gpu/time_utils.h"
  14
  15 namespace LIBC_NAMESPACE_DECL {
  16
  17 LLVM_LIBC_FUNCTION(clock_t, clock, ()) {
  18   if (!GPU_CLOCKS_PER_SEC)
  19     return clock_t(0);
  20
  21   uint64_t ticks = gpu::fixed_frequency_clock();
  22
  23   // We need to convert between the GPU's fixed frequency and whatever `time.h`
  24   // declares it to be. This is done so that dividing the result of this
  25   // function by 'CLOCKS_PER_SEC' yields the elapsed time.
  26   if (GPU_CLOCKS_PER_SEC > CLOCKS_PER_SEC)
  27     return clock_t(ticks / (GPU_CLOCKS_PER_SEC / CLOCKS_PER_SEC));
  28   return clock_t(ticks * (CLOCKS_PER_SEC / GPU_CLOCKS_PER_SEC));
  29 }
  30
  31 } // namespace LIBC_NAMESPACE_DECL