/******************************************************************************
Copyright (c) 2018 Advanced Micro Devices, Inc. All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
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The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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THE SOFTWARE.
*******************************************************************************/

#include "util/perf_timer.h"

PerfTimer::PerfTimer() { freq_in_100mhz_ = MeasureTSCFreqHz(); }

PerfTimer::~PerfTimer() {
  while (!timers_.empty()) {
    Timer* temp = timers_.back();
    timers_.pop_back();
    delete temp;
  }
}

// New cretaed timer instantance index will be returned
int PerfTimer::CreateTimer() {
  Timer* newTimer = new Timer;
  newTimer->start = 0;
  newTimer->clocks = 0;

#ifdef _WIN32
  QueryPerformanceFrequency((LARGE_INTEGER*)&newTimer->freq);
#else
  newTimer->freq = (long long)1.0E3;
#endif

  /* Push back the address of new Timer instance created */
  timers_.push_back(newTimer);
  return (int)(timers_.size() - 1);
}

int PerfTimer::StartTimer(int index) {
  if (index >= (int)timers_.size()) {
    Error("Cannot reset timer. Invalid handle.");
    return FAILURE;
  }

#ifdef _WIN32
// General Windows timing method
#ifndef _AMD
  long long tmpStart;
  QueryPerformanceCounter((LARGE_INTEGER*)&(tmpStart));
  timers_[index]->start = (double)tmpStart;
#else
// AMD Windows timing method
#endif
#else
// General Linux timing method
#ifndef _AMD
  struct timeval s;
  gettimeofday(&s, 0);
  timers_[index]->start = s.tv_sec * 1.0E3 + ((double)(s.tv_usec / 1.0E3));
#else
  // AMD timing method
  unsigned int unused;
  timers_[index]->start = __rdtscp(&unused);
#endif
#endif

  return SUCCESS;
}


int PerfTimer::StopTimer(int index) {
  double n = 0;
  if (index >= (int)timers_.size()) {
    Error("Cannot reset timer. Invalid handle.");
    return FAILURE;
  }
#ifdef _WIN32
#ifndef _AMD
  long long n1;
  QueryPerformanceCounter((LARGE_INTEGER*)&(n1));
  n = (double)n1;
#else
// AMD Window Timing
#endif

#else
// General Linux timing method
#ifndef _AMD
  struct timeval s;
  gettimeofday(&s, 0);
  n = s.tv_sec * 1.0E3 + (double)(s.tv_usec / 1.0E3);
#else
  // AMD Linux timing
  unsigned int unused;
  n = __rdtscp(&unused);
#endif
#endif

  n -= timers_[index]->start;
  timers_[index]->start = 0;

#ifndef _AMD
  timers_[index]->clocks += n;
#else
  // timers_[index]->clocks += 10 * n / freq_in_100mhz_; // unit is ns
  timers_[index]->clocks += 1.0E-6 * 10 * n / freq_in_100mhz_;  // convert to ms
#endif

  return SUCCESS;
}

void PerfTimer::Error(std::string str) { std::cout << str << std::endl; }


double PerfTimer::ReadTimer(int index) {
  if (index >= (int)timers_.size()) {
    Error("Cannot read timer. Invalid handle.");
    return FAILURE;
  }

  double reading = double(timers_[index]->clocks);

  reading = double(reading / timers_[index]->freq);

  return reading;
}


uint64_t PerfTimer::CoarseTimestampUs() {
#ifdef _WIN32
  uint64_t freqHz, ticks;
  QueryPerformanceFrequency((LARGE_INTEGER*)&freqHz);
  QueryPerformanceCounter((LARGE_INTEGER*)&ticks);

  // Scale numerator and divisor until (ticks * 1000000) fits in uint64_t.
  while (ticks > (1ULL << 44)) {
    ticks /= 16;
    freqHz /= 16;
  }

  return (ticks * 1000000) / freqHz;
#else
  struct timespec ts;
  clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
  return uint64_t(ts.tv_sec) * 1000000 + ts.tv_nsec / 1000;
#endif
}

uint64_t PerfTimer::MeasureTSCFreqHz() {
  // Make a coarse interval measurement of TSC ticks for 1 gigacycles.
  unsigned int unused;
  uint64_t tscTicksEnd;

  uint64_t coarseBeginUs = CoarseTimestampUs();
  uint64_t tscTicksBegin = __rdtscp(&unused);
  do {
    tscTicksEnd = __rdtscp(&unused);
  } while (tscTicksEnd - tscTicksBegin < 1000000000);

  uint64_t coarseEndUs = CoarseTimestampUs();

  // Compute the TSC frequency and round to nearest 100MHz.
  uint64_t coarseIntervalNs = (coarseEndUs - coarseBeginUs) * 1000;
  uint64_t tscIntervalTicks = tscTicksEnd - tscTicksBegin;
  return (tscIntervalTicks * 10 + (coarseIntervalNs / 2)) / coarseIntervalNs;
}