/* The following contains adapted code from the kernel, thus is Licensed under the GPLv2
 */
#include <stdio.h>

#define HZ 1000

#define NSEC_PER_SEC 1000000000LL

#define PMTMR_TICKS_PER_SEC	3579545

#define CLOCK_TICK_RATE		1193182

#define LATCH  ((CLOCK_TICK_RATE + HZ/2) / HZ)	/* For divider */
#define CLOCK_TICK_OVERFLOW	(LATCH * HZ - CLOCK_TICK_RATE)
#define SH_DIV(NOM,DEN,LSH) (   (((NOM) / (DEN)) << (LSH))              \
                             + ((((NOM) % (DEN)) << (LSH)) + (DEN) / 2) / (DEN))
#define ACTHZ (SH_DIV (CLOCK_TICK_RATE, LATCH, 8))
#define NSEC_PER_JIFFY	((unsigned long)((((unsigned long long)NSEC_PER_SEC)<<8)/ACTHZ))


#define CLOCK_TICK_ADJUST 0
#define XCLOCK_TICK_ADJUST	(((long long)CLOCK_TICK_OVERFLOW * NSEC_PER_SEC) / \
					(long long)CLOCK_TICK_RATE)


unsigned long hz2mult(unsigned long hz, unsigned long shift)
{
        unsigned long long tmp = NSEC_PER_SEC << shift;
        return (tmp + hz/2)/hz;
}



void calculate_values(char* name, unsigned long mult, unsigned long shift, unsigned long ntp_hz)
{
	unsigned long long tmp;
	unsigned long long length_nsec = (NSEC_PER_SEC + CLOCK_TICK_ADJUST);
	unsigned long long interval_length = length_nsec/ntp_hz;
	long long error;

//	printf("\n%s\n==========\n", name);
	printf("%s	", name);
	tmp = interval_length;
	tmp <<= shift;
	tmp += mult/2;
	tmp /= mult;
	if(tmp == 0) {
		printf("dived to zero!\n");
		tmp = 1;
	}
	
	
	
//	printf("%llu cycles per %llu ns\n", tmp, interval_length);
//	printf("%llu ns per cycle\n", (1*mult)>>shift);
//	printf("%llu ns per interval\n", (tmp*mult)>>shift);


	error = ((interval_length*ntp_hz) << shift) - ((tmp*ntp_hz*mult));
	error >>= shift;
	
	printf("%lld ppb error\n",error);

}


void main(void)
{
	unsigned long shift, mult;
	
	printf("HZ=%ld CLOCK_TICK_ADJUST=%ld\n", HZ, CLOCK_TICK_ADJUST);

	/* jiffies */
	calculate_values("jiffies     ", NSEC_PER_JIFFY  << 8, 8, HZ);
	calculate_values("jiffies NOHZ", NSEC_PER_JIFFY  << 8, 8, 2);
	
	/* pit */
	calculate_values("pit     ", hz2mult(CLOCK_TICK_RATE,20), 20, HZ);
	calculate_values("pit NOHZ", hz2mult(CLOCK_TICK_RATE,20), 20, 2);

	/* acpi_pm */
	calculate_values("acpi_pm     ", hz2mult(PMTMR_TICKS_PER_SEC,22), 22, HZ);
	calculate_values("acpi_pm NOHZ", hz2mult(PMTMR_TICKS_PER_SEC,22), 22, 2);
	
	printf("\n");
}