tsk2.c

psos调用实例

/* tsk2.c - Task #2 */

#include <psos.h>
#include <prepc.h>
#include <stdio.h>

#include "misc.h"
#include "appl.h"

/* wait_for_semaphore() - Wait until a semaphore exists */
ULONG
wait_for_semaphore(char name[4], int maxwait)
{
	ULONG	rc, smid;
	int	try = 0;

	do {
		/* See if the semaphore exists */
		if (0 == (rc = sm_ident(name, 0, &smid)))
			return(smid);	/* YES, SUCCESS! */
		/* No semaphore yet.  Wait a while and try again */
		tm_wkafter(10);
	} while (try++ < maxwait);	/* Try this many times */
	fail(rc, "wait_for_semaphore: timed out waiting for %s", name);
	/* The "successful" return is above, in case you missed it. */
}

void tsk2(ULONG me, ULONG him, ULONG l3, ULONG l4)
{
	ULONG	smid, rc;
	int	tally = 0;

	bprintf("\t\t\t%s Task begin\n", (char *) me);

	smid = wait_for_semaphore(SEM_NAM, 100);
	for (;;) {
		rc = sm_p(smid, SM_WAIT, 0);
		if ((rc == ERR_OBJDEL) || (rc == ERR_SKILLD))
			break;	/* Semaphore has been deleted.
				   Break loop and delete self. */
		else if (rc != 0)
			fail(rc, "%s sm_p(%08x) failed", me, smid);
		tally++;
		bprintf("\t\t\t%s awakened, tally is now %d\n",
		       (char *) me, tally);
	}

	bprintf("\t\t\t%s Task end\n", (char *) me);
	exit(0);
}