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