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#include "statsreport/common/highres_timer.h"

bool HighresTimer::perf_ratio_collected_ = false;
mach_timebase_info_data_t HighresTimer::perf_ratio_ = {0};

const uint64 NANOS_IN_MILLI = 1000000L;
const uint64 NANOS_IN_HALF_MILLI = 500000L;
const uint64 NANOS_IN_SECOND = 1000000000L;
const uint64 NANOS_IN_HALF_SECOND = 500000000L;

uint64 HighresTimer::GetElapsedMs() const {
  uint64 end_time = GetCurrentTicks();

  // Scale to ms and round to nearest ms - rounding is important
  // because otherwise the truncation error may accumulate e.g. in sums.
  //
  (void)GetTimerFrequency();
  return (static_cast<uint64>(end_time - start_ticks_) * perf_ratio_.numer +
          NANOS_IN_HALF_MILLI * perf_ratio_.denom) /
      (NANOS_IN_MILLI * perf_ratio_.denom);
}

uint64 HighresTimer::GetElapsedSec() const {
  uint64 end_time = GetCurrentTicks();

  // Scale to ms and round to nearest ms - rounding is important
  // because otherwise the truncation error may accumulate e.g. in sums.
  //
  (void)GetTimerFrequency();
  return (static_cast<uint64>(end_time - start_ticks_) * perf_ratio_.numer +
          NANOS_IN_HALF_SECOND * perf_ratio_.denom) /
      (NANOS_IN_SECOND * perf_ratio_.denom);
}

void HighresTimer::CollectPerfRatio() {
  mach_timebase_info(&perf_ratio_);
  perf_ratio_collected_ = true;
}