timing.h

// Start of timing.h.

// The function get_wall_time() returns the wall time in microseconds
// (with an unspecified offset).

#ifdef _WIN32

#include <windows.h>

static int64_t get_wall_time(void) {
  LARGE_INTEGER time,freq;
  assert(QueryPerformanceFrequency(&freq));
  assert(QueryPerformanceCounter(&time));
  return ((double)time.QuadPart / freq.QuadPart) * 1000000;
}

#else
// Assuming POSIX

#include <time.h>
#include <sys/time.h>

static int64_t get_wall_time(void) {
  struct timeval time;
  assert(gettimeofday(&time,NULL) == 0);
  return time.tv_sec * 1000000 + time.tv_usec;
}

static int64_t get_wall_time_ns(void) {
  struct timespec time;
  assert(clock_gettime(CLOCK_REALTIME, &time) == 0);
  return time.tv_sec * 1000000000 + time.tv_nsec;
}


static inline uint64_t rdtsc() {
  unsigned int hi, lo;
  __asm__ __volatile__("rdtsc" : "=a"(lo), "=d"(hi));
  return  ((uint64_t) lo) | (((uint64_t) hi) << 32);
}

static inline void rdtsc_wait(uint64_t n) {
  const uint64_t start = rdtsc();
  while (rdtsc() < (start + n)) {
    __asm__("PAUSE");
  }
}
static inline void spin_for(uint64_t nb_cycles) {
  rdtsc_wait(nb_cycles);
}


#endif

// End of timing.h.