/*
 * make use of i386's Read TimeStamp Counter instruction
 */

#include <stdio.h>
#include <stdint.h>
#include <inttypes.h>

static inline uint64_t rdtsc(void)
{
  uint64_t tsc;
  __asm__ volatile(".byte 0x0f, 0x31" : "=A"(tsc));
  return tsc;
}

/*
 * read timestamp's low 32 bits
 */
static inline uint32_t rdtsc_lo(void)
{
  uint32_t tsc;
  __asm__ volatile(".byte 0x0f, 0x31" : "=a"(tsc) :: "%edx");
  return tsc;
}

int main(void)
{
  uint32_t ts[3] = {
    rdtsc_lo(),
    rdtsc_lo(),
    rdtsc_lo(),
  };
  uint8_t i = 0;
  for(i = 0; i < 3; i++)
    printf("%" PRIu32 " (+%" PRId32 ")\n",
      ts[i], i > 0 ? ts[i] - ts[i-1] : 0);
  return 0;
}