#ifndef __MHz__
#define __MHz__

#include <machine/cpufunc.h>
#include <machine/clock.h>

int MHz = 1;
#define NOW (rdtsc()/MHz)

static int roundoff_MHz(int e)
{
	int possible[] = { 0, 25, 33, 50, 66, 75 };
	int x, y, z = 1000000;
	for (x = 0; ; x += 100) {
		for (y = 0; y < sizeof(possible)/sizeof(possible[0]); y++) {
			int p = x + possible[y], d = e - p;
			if (p == 0) continue;
			if (d < 0) d = -d;
			if (z > d) z = d, MHz = p;
			else {
				if (d * 100 > 15 * MHz)
					return -1;
				/* printf("CPU %d MHz\n", MHz); */
				return MHz;
			}
		}
	}
}

void determine_MHz()
{
	quad_t r1, r2;
	struct timeval t1, t2;
	int e;

	if (!tsc_is_broken && roundoff_MHz(tsc_freq/1000/1000) >= 0)
		return;

	MHz = 1;
	microtime(&t1); r1 = NOW;
	DELAY(1000000);
	microtime(&t2); r2 = NOW;

	e = (r2 - r1)/((t2.tv_sec-t1.tv_sec)*1000000 + t2.tv_usec-t1.tv_usec);
	if (roundoff_MHz(e) >= 0)
		return;

	panic("unable to determine CPU frequency!");
}

#endif