cpucycles.c

#if defined(__i386__)

static __inline__ unsigned long long cpucycles(void)
{
    //printf("32 bit machine");
    unsigned long long int x;
    __asm__ volatile (".byte 0x0f, 0x31" : "=A" (x));
    return x;
}

#elif defined(__x86_64__)

static __inline__ unsigned long long cpucycles(void)
{
    //printf("64 bit machine");
    unsigned hi, lo;
    __asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
    return ( (unsigned long long)lo)|( ((unsigned long long)hi)<<32 );
}

#endif