libc/src/__support/time/linux/clock_conversion.h

   1 //===--- clock conversion linux implementation ------------------*- 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___SUPPORT_TIME_LINUX_CLOCK_CONVERSION_H
  10 #define LLVM_LIBC_SRC___SUPPORT_TIME_LINUX_CLOCK_CONVERSION_H
  11
  12 #include "src/__support/macros/config.h"
  13 #include "src/__support/time/linux/clock_gettime.h"
  14 #include "src/__support/time/units.h"
  15
  16 namespace LIBC_NAMESPACE_DECL {
  17 namespace internal {
  18
  19 LIBC_INLINE timespec convert_clock(timespec input, clockid_t from,
  20                                    clockid_t to) {
  21   using namespace time_units;
  22   timespec from_time;
  23   timespec to_time;
  24   timespec output;
  25   internal::clock_gettime(from, &from_time);
  26   internal::clock_gettime(to, &to_time);
  27   output.tv_sec = input.tv_sec - from_time.tv_sec + to_time.tv_sec;
  28   output.tv_nsec = input.tv_nsec - from_time.tv_nsec + to_time.tv_nsec;
  29
  30   if (output.tv_nsec > 1_s_ns) {
  31     output.tv_sec++;
  32     output.tv_nsec -= 1_s_ns;
  33   } else if (output.tv_nsec < 0) {
  34     output.tv_sec--;
  35     output.tv_nsec += 1_s_ns;
  36   }
  37   return output;
  38 }
  39
  40 } // namespace internal
  41 } // namespace LIBC_NAMESPACE_DECL
  42
  43 #endif // LLVM_LIBC_SRC___SUPPORT_TIME_LINUX_CLOCK_CONVERSION_H