harvey/sys/src/libc/9sys/nsec.c

#include <u.h>
#include <libc.h>

static uvlong order = 0x0001020304050607ULL;

static void
be2vlong(vlong *to, uchar *f)
{
	uchar *t, *o;
	int i;

	t = (uchar*)to;
	o = (uchar*)&order;
	for(i = 0; i < sizeof order; i++)
		t[o[i]] = f[i];
}

vlong
nsec(void)
{
	static int fd = -1;
	uchar b[8];
	vlong t;
	int opened;

	opened = 0;
	if(fd < 0){
	reopen:
		if(opened++ || (fd = open("/dev/bintime", OREAD|OCEXEC)) < 0)
			return 0;
	}
	if(pread(fd, b, sizeof b, 0) != sizeof b){
		close(fd);
		fd = -1;
		goto reopen;
	}
	be2vlong(&t, b);
	return t;
}