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/*
 * Sleep -- suspent execution for interval
 * See that alarms previously
 * and intermediately set are properly handled.
 */

#include "signal.h"

extern	int	func();		/* Allow pause to return */

sleep(sec)
register unsigned sec;
{
	register unsigned osec;
	int (*ofunc)();

	for (;;) {
		ofunc = signal(SIGALRM, func);
		osec = alarm(sec);
		if (sec == 0) {
			break;
		} else if (osec == 0) {		/* No current alarm */
			func(0);
			break;
		} else if (osec < sec) {	/* Current alarm precedes us */
			alarm(osec);
			func(0);
			(*ofunc)();
			sec -= osec;
			continue;
		} else if (osec == sec) {	/* Contemporaneous */
			func(0);
			(*ofunc)();
			sec -= osec;
			continue;
		} else if (osec > sec) {	/* Current alarm follows us */
			osec -= sec;
			func(0);
			break;
		}
	}
	signal(SIGALRM, ofunc);
	alarm(osec);
}

/*
 * Called to wait for SIGALRM,
 * and to catch SIGALRM thus waking up the pause half.
 */
static
func(n)
int n;
{
	static int done;

	if (n == 0) {
		done = 0;
		do pause(); while (done == 0);
	} else {
		++done;
	}
}

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