Function DELAY

freebsd/mips/mips/tick.c:196–226

* Wait for about n microseconds (at least!). */

 * Wait for about n microseconds (at least!).
 */
void
DELAY(int n)
{
	uint32_t cur, last, delta, usecs;

	TSENTER();
	/*
	 * This works by polling the timer and counting the number of
	 * microseconds that go by.
	 */
	last = mips_rd_count();
	delta = usecs = 0;

	while (n > usecs) {
		cur = mips_rd_count();

		/* Check to see if the timer has wrapped around. */
		if (cur < last)
			delta += cur + (0xffffffff - last) + 1;
		else
			delta += cur - last;

		last = cur;

		if (delta >= cycles_per_usec) {
			usecs += delta / cycles_per_usec;
			delta %= cycles_per_usec;
		}
	}
	TSEXIT();
}

static int
clock_start(struct eventtimer *et, sbintime_t first, sbintime_t period)