semaphor.c

UC/OS 在SparcLite 上的移植范例

/*
 * File:        semaphor.c
 *
 * uC/OS Real-time multitasking kernel for the MIPS processor.
 *
 * This program is an example of using semaphore to
 * implement task rendevous.
 *
 * Created by Marco Graziano ([e-mail]).
 *
 */

#include	"ucos.h" 	/* uC/OS interface */

/* allocate memory for tasks' stacks */
#define	STACKSIZE	2048
uint	Stack1[STACKSIZE];
uint	Stack2[STACKSIZE];

/* semaphores event control blocks */
OS_EVENT *Sem1;
OS_EVENT *Sem2;

/*
 * Task running at the highest priority. 
 */
void
Task1(void *i)
{
	uint	Reply;
	uint	Time;

	for (;;) {
		/* wait for the semaphore  */
		OSSemPend(Sem2, 100, &Reply);

		/* print task's id */
		/* putchar('1');  */
		Time = OSTimeGet();
		printf( "1 %d\n", Time );

		/* signal the semaphore */
		OSSemPost(Sem1);
	}
}

void
Task2(void *i)
{
	uint	Reply;
	uint	Time;

	for (;;) {
		/* wait for the semaphore */
		OSSemPend(Sem1, 100, &Reply);

		/* print task's id */
		/* putchar('2');  */
		Time = OSTimeGet();
		printf( "2 %d\n", Time );

		/* signal the semaphore */
		OSSemPost(Sem2);
	}
}

/*
 * Main function.
 */
int
main(int argc, char **argv)
{
	char	Id1 = '1';
	char	Id2 = '2';

	/* needed by uC/OS */
	OSInit();

	/* 
	 * create the semaphores
	 */
	Sem1 = OSSemCreate(1);
	Sem2 = OSSemCreate(1);

	/* 
	 * create the tasks in uC/OS and assign decreasing
	 * priority to them 
	 */
	OSTaskCreate(Task1, (void *)&Id1, (void *)&Stack1[STACKSIZE], 1);
	OSTaskCreate(Task2, (void *)&Id2, (void *)&Stack2[STACKSIZE], 2);

	CPUInit();
	/* start the os */
	OSStart();

	/* never reached */
} /* main */