~ft/neindaw

57f49b5ea9632be13d0b695a2932fc7e6ed7ac0b — Sigrid Haflínudóttir a month ago 6668244
nanosec: cycles/nsec depending on what we have
1 files changed, 11 insertions(+), 27 deletions(-)

M util.c
M util.c => util.c +11 -27
@@ 1,5 1,6 @@
#include <u.h>
#include <libc.h>
#include <tos.h>

int usensec = 0;



@@ 58,49 59,32 @@ pathopen(char *path, char *fmt, ...)
 * nsec() is wallclock and can be adjusted by timesync
 * so need to use cycles() instead, but fall back to
 * nsec() in case we can't
 *
 * "fasthz" is how many ticks there are in a second
 * can be read from /dev/time
 *
 * perhaps using RDTSCP is even better
 */
uvlong
nanosec(void)
{
	static uvlong fasthz, xstart;
	uvlong x, div;
	int f, n, i;
	char tmp[128], *e;

	if (fasthz == ~0ULL)
	if(fasthz == ~0ULL)
		return nsec() - xstart;

	if (fasthz == 0) {
		fasthz = ~0ULL;
		xstart = nsec();
		if (usensec)
			return 0;
		if ((f = open("/dev/time", OREAD)) >= 0 && (n = read(f, tmp, sizeof(tmp)-1)) > 2) {
			tmp[n] = 0;
			e = tmp;
			for (i = 0; i < 3; i++)
				strtoll(e, &e, 10);
			if ((fasthz = strtoll(e, nil, 10)) < 1)
				fasthz = ~0ULL;
			else
				cycles(&xstart);
		}
		close(f);
		if (fasthz == ~0ULL) {
			fprint(2, "couldn't get fasthz, falling back to nsec()\n");
	if(fasthz == 0){
		if((fasthz = _tos->cyclefreq) == 0){
			fasthz = ~0ULL;
			xstart = nsec();
			fprint(2, "cyclefreq not available, falling back to nsec()\n");
			fprint(2, "you might want to disable aux/timesync\n");
			return 0;
		}else{
			cycles(&xstart);
		}
	}
	cycles(&x);
	x -= xstart;

	for (div = 1000000000ULL; x < 0x1999999999999999ULL && div > 1 ; div /= 10ULL, x *= 10ULL);
	/* this is ugly */
	for(div = 1000000000ULL; x < 0x1999999999999999ULL && div > 1 ; div /= 10ULL, x *= 10ULL);

	return x / (fasthz / div);
}