jbus/lib/Common.cpp

#ifndef _WIN32
#include <unistd.h>
#include <sys/time.h>
#if __APPLE__
#include <mach/mach_time.h>
#elif __linux__ || __FreeBSD__
#include <time.h>
#endif
#else
#ifndef WIN32_LEAN_AND_MEAN
#define WIN32_LEAN_AND_MEAN
#endif
#include <windows.h>
#include <WinSock2.h>
#endif

#include "jbus/Common.hpp"

namespace jbus {

#if __APPLE__
static u64 MachToDolphinNum;
static u64 MachToDolphinDenom;
#elif _WIN32
static LARGE_INTEGER PerfFrequency;
#endif

u64 GetGCTicks() {
#if __APPLE__
  return mach_absolute_time() * MachToDolphinNum / MachToDolphinDenom;
#elif __linux__ || __FreeBSD__
  struct timespec tp;
  clock_gettime(CLOCK_MONOTONIC, &tp);

  return u64((tp.tv_sec * 1000000000ull) + tp.tv_nsec) * GetGCTicksPerSec() / 1000000000ull;
#elif _WIN32
  LARGE_INTEGER perf;
  QueryPerformanceCounter(&perf);
  perf.QuadPart *= GetGCTicksPerSec();
  perf.QuadPart /= PerfFrequency.QuadPart;
  return perf.QuadPart;
#else
  return 0;
#endif
}

void WaitGCTicks(u64 ticks) {
#ifndef _WIN32
  struct timeval tv = {};
  tv.tv_sec = ticks / GetGCTicksPerSec();
  tv.tv_usec = (ticks % GetGCTicksPerSec()) * 1000000 / GetGCTicksPerSec();
  select(0, NULL, NULL, NULL, &tv);
#else
  if (ticks < GetGCTicksPerSec() / 60) {
    /* NT is useless for scheduling sub-millisecond intervals */
    u64 start = GetGCTicks();
    do {
      Sleep(0);
    } while (GetGCTicks() - start < ticks);
  } else {
    /* Use normal Sleep() for durations longer than ~16ms */
    Sleep(ticks * 1000 / GetGCTicksPerSec() + (ticks % GetGCTicksPerSec()) * 1000 / GetGCTicksPerSec());
  }
#endif
}

void Initialize() {
#if __APPLE__
  mach_timebase_info_data_t timebase;
  mach_timebase_info(&timebase);
  MachToDolphinNum = GetGCTicksPerSec() * timebase.numer;
  MachToDolphinDenom = 1000000000ull * timebase.denom;
#elif _WIN32
  WSADATA initData;
  WSAStartup(MAKEWORD(2, 2), &initData);
  QueryPerformanceFrequency(&PerfFrequency);
#endif
}

} // namespace jbus