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

__inline__ unsigned long long int rdtsc()
{
	unsigned long long int x;
	__asm__ volatile (".byte 0x0f, 0x31" : "=A" (x));
	return x;
}

main ()
{
	struct timezone tz;
        struct timeval tvstart, tvstop;
        unsigned long long int cycles[2]; /* gotta be 64 bit */
	unsigned int microseconds; /* total time taken */
	
	bzero(&tz, sizeof(tz));

	/* get this function in cached memory */
	gettimeofday(&tvstart, &tz);
	cycles[0] = rdtsc();
	gettimeofday(&tvstart, &tz);

	/* we don't trust that this is any specific length of time */
	sleep(1);
	
	cycles[1] = rdtsc();
	gettimeofday(&tvstop, &tz);
	microseconds = ((tvstop.tv_sec-tvstart.tv_sec)*1000000) +
		(tvstop.tv_usec-tvstart.tv_usec);

	printf("%f MHz processor.\n",
		(float)(cycles[1]-cycles[0])/microseconds);
}