/*
Copyright (c) 2021 - present 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
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

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,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#include "rdc_lib/RdcPerfTimer.h"

#include <x86intrin.h>

namespace amd {
namespace rdc {

static const uint64_t kNanosecondsPerSecond = 1000000000;

RdcPerfTimer::RdcPerfTimer(void) { freq_in_100mhz = MeasureTSCFreqHz(); }

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

int RdcPerfTimer::CreateTimer(void) {
  Timer* newTimer = new Timer;
  newTimer->_start = 0;
  newTimer->_clocks = 0;

  newTimer->_freq = kNanosecondsPerSecond;

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

int RdcPerfTimer::StartTimer(int index) {
  if (index >= static_cast<int>(_timers.size())) {
    Error("Cannot reset timer. Invalid handle.");
    return 1;
  }

// General Linux timing method
#ifndef _AMD
  struct timespec s;
  clock_gettime(CLOCK_MONOTONIC, &s);
  _timers[index]->_start = (uint64_t)s.tv_sec * kNanosecondsPerSecond + (uint64_t)s.tv_nsec;
#else

  // AMD timing method

  unsigned int unused;
  _timers[index]->_start = __rdtscp(&unused);

#endif

  return 0;
}

int RdcPerfTimer::StopTimer(int index) {
  uint64_t n = 0;

  if (index >= static_cast<int>(_timers.size())) {
    Error("Cannot reset timer. Invalid handle.");
    return 1;
  }

  // General Linux timing method
#ifndef _AMD
  struct timespec s;
  clock_gettime(CLOCK_MONOTONIC, &s);
  n = (uint64_t)s.tv_sec * kNanosecondsPerSecond + (uint64_t)s.tv_nsec;
#else
  // AMD Linux timing

  unsigned int unused;
  n = __rdtscp(&unused);
#endif

  n -= _timers[index]->_start;
  _timers[index]->_start = 0;

#ifndef _AMD
  _timers[index]->_clocks += n;
#else
  // convert to ms
  _timers[index]->_clocks += 1.0E-6 * 10 * n / freq_in_100mhz;
  cout << "_AMD is enabled!!!" << endl;
#endif

  return 0;
}

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

double RdcPerfTimer::ReadTimer(int index) {
  if (index >= static_cast<int>(_timers.size())) {
    Error("Cannot read timer. Invalid handle.");
    return 1;
  }

  double reading = static_cast<double>(_timers[index]->_clocks);

  reading = static_cast<double>(reading / _timers[index]->_freq);

  return reading;
}

void RdcPerfTimer::ResetTimer(int index) {
  // Check if index value is over the timer's size
  if (index >= static_cast<int>(_timers.size())) {
    Error("Invalid index value\n");
    exit(1);
  }

  _timers[index]->_clocks = 0.0;
  _timers[index]->_start = 0.0;
}

uint64_t RdcPerfTimer::CoarseTimestampUs() {
  struct timespec ts;
  clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
  return uint64_t(ts.tv_sec) * 1000000 + ts.tv_nsec / 1000;
}

uint64_t RdcPerfTimer::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;
}

}  // namespace rdc
}  // namespace amd