/*
 * Copyright 2017-2019 Leonid Yuriev <leo@yuriev.ru>
 * and other libmdbx authors: please see AUTHORS file.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted only as authorized by the OpenLDAP
 * Public License.
 *
 * A copy of this license is available in the file LICENSE in the
 * top-level directory of the distribution or, alternatively, at
 * <http://www.OpenLDAP.org/license.html>.
 */

#include "test.h"

namespace chrono {

#define NSEC_PER_SEC 1000000000u
uint32_t ns2fractional(uint32_t ns) {
  assert(ns < NSEC_PER_SEC);
  /* LY: здесь и далее используется "длинное деление", которое
   * для ясности кода оставлено как есть (без ручной оптимизации). Так как
   * GCC, Clang и даже MSVC сами давно умеют конвертировать деление на
   * константу в быструю reciprocal-форму. */
  return ((uint64_t)ns << 32) / NSEC_PER_SEC;
}

uint32_t fractional2ns(uint32_t fractional) {
  return (fractional * (uint64_t)NSEC_PER_SEC) >> 32;
}

#define USEC_PER_SEC 1000000u
uint32_t us2fractional(uint32_t us) {
  assert(us < USEC_PER_SEC);
  return ((uint64_t)us << 32) / USEC_PER_SEC;
}

uint32_t fractional2us(uint32_t fractional) {
  return (fractional * (uint64_t)USEC_PER_SEC) >> 32;
}

#define MSEC_PER_SEC 1000u
uint32_t ms2fractional(uint32_t ms) {
  assert(ms < MSEC_PER_SEC);
  return ((uint64_t)ms << 32) / MSEC_PER_SEC;
}

uint32_t fractional2ms(uint32_t fractional) {
  return (fractional * (uint64_t)MSEC_PER_SEC) >> 32;
}

time from_ns(uint64_t ns) {
  time result;
  result.fixedpoint = ((ns / NSEC_PER_SEC) << 32) |
                      ns2fractional((uint32_t)(ns % NSEC_PER_SEC));
  return result;
}

time from_us(uint64_t us) {
  time result;
  result.fixedpoint = ((us / USEC_PER_SEC) << 32) |
                      us2fractional((uint32_t)(us % USEC_PER_SEC));
  return result;
}

time from_ms(uint64_t ms) {
  time result;
  result.fixedpoint = ((ms / MSEC_PER_SEC) << 32) |
                      ms2fractional((uint32_t)(ms % MSEC_PER_SEC));
  return result;
}

time now_realtime() {
#if defined(_WIN32) || defined(_WIN64) || defined(_WINDOWS)
  static void(WINAPI * query_time)(LPFILETIME);
  if (!query_time) {
    query_time = (void(WINAPI *)(LPFILETIME))GetProcAddress(
        GetModuleHandle(TEXT("kernel32.dll")),
        "GetSystemTimePreciseAsFileTime");
    if (!query_time)
      query_time = GetSystemTimeAsFileTime;
  }

  FILETIME filetime;
  query_time(&filetime);
  uint64_t ns100 =
      (uint64_t)filetime.dwHighDateTime << 32 | filetime.dwLowDateTime;
  return from_ns((ns100 - UINT64_C(116444736000000000)) * 100u);
#else
  struct timespec ts;
  if (unlikely(clock_gettime(CLOCK_REALTIME, &ts)))
    failure_perror("clock_gettime(CLOCK_REALTIME", errno);

  return from_timespec(ts);
#endif
}

time now_motonic() {
#if defined(_WIN32) || defined(_WIN64) || defined(_WINDOWS)
  static uint64_t reciprocal;
  static LARGE_INTEGER Frequency;
  if (reciprocal == 0) {
    if (!QueryPerformanceFrequency(&Frequency))
      failure_perror("QueryPerformanceFrequency()", GetLastError());
    reciprocal = (((UINT64_C(1) << 48) + Frequency.QuadPart / 2 + 1) /
                  Frequency.QuadPart);
    assert(reciprocal);
  }

  LARGE_INTEGER Counter;
  if (!QueryPerformanceCounter(&Counter))
    failure_perror("QueryPerformanceCounter()", GetLastError());

  time result;
  result.fixedpoint = (Counter.QuadPart / Frequency.QuadPart) << 32;
  uint64_t mod = Counter.QuadPart % Frequency.QuadPart;
  result.fixedpoint += (mod * reciprocal) >> 16;
  return result;
#else
  struct timespec ts;
  if (unlikely(clock_gettime(CLOCK_MONOTONIC, &ts)))
    failure_perror("clock_gettime(CLOCK_MONOTONIC)", errno);

  return from_timespec(ts);
#endif
}

} /* namespace chrono */