example1.c

ucos在ARM7系列cpu上的移值代码

/*
 * File:        example1.c
 *
 * uC/OS Real-time multitasking kernel for the ARM processor.
 *
 * Simple example of using multiple tasks and mailboxes.
 *
 * Created by Marco Graziano ([e-mail]).
 *
 */

#include	"ucos.h" 	/* uC/OS interface */
#include	"pid.h"		/* PID specific include */

extern	void PutByte(byte);	/* defined in pid.c */

/* allocate memory for tasks' stacks */
#define	STACKSIZE	64
uint	Stack1[STACKSIZE];
uint	Stack2[STACKSIZE];
uint	Stack3[STACKSIZE];

/* mailbox event control blocks */
OS_EVENT *Mbox1;
OS_EVENT *Mbox2;
OS_EVENT *Mbox3;

char	PassMsg[] = "Example 1";

/*
 * Task running at the lowest priority. 
 * Wait for a message in the first mailbox and post
 * a messages to the third mailbox.
 */
void
Task1(void *Id)
{
	char	*Msg;
	uint	err;

	for (;;) {
		/* wait for a message from the input mailbox */
		Msg = (char *)OSMboxPend(Mbox1, 0, &err);

		/* print task's id */
		PutByte(*(char *)Id); 

		/* post the input message to the output mailbox */
		OSMboxPost(Mbox2, Msg);
	}
}

void
Task2(void *Id)
{
	char	*Msg;
	uint	err;

	for (;;) {
		/* wait for a message from the input mailbox */
		Msg = (char *)OSMboxPend(Mbox2, 0, &err);

		/* print task's id */
		PutByte(*(char *)Id); 

		/* post the input message to the output mailbox */
		OSMboxPost(Mbox3, Msg);
	}
}


void
Task3(void *Id)
{
	char	*Msg;
	uint	err;

	for (;;) {
		/* wait for a message from the input mailbox */
		Msg = (char *)OSMboxPend(Mbox3, 0, &err);

		/* print task's id */
		PutByte(*(char *)Id);  

		/* post the input message to the output mailbox */
		OSMboxPost(Mbox1, Msg);
	}
}


/*
 * Main function.
 */
int
main(int argc, char **argv)
{
	char	Id1 = '1';
	char	Id2 = '2';
	char	Id3 = '3';

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

	/* 
	 * create the first mailbox in the pipeline with a message 
	 * in it to get the first task started.
	 */
	Mbox1 = OSMboxCreate(PassMsg); 

	/* create the remaining mailboxes empty */
	Mbox2 = OSMboxCreate((void *)0);
	Mbox3 = OSMboxCreate((void *)0);

	/* 
	 * create the tasks in uC/OS and assign increasing
	 * priorities to them so that Task3 at the end of
	 * the pipeline has the highest priority.
	 */
	OSTaskCreate(Task1, (void *)&Id1, (void *)&Stack1[STACKSIZE - 1], 3);
	OSTaskCreate(Task2, (void *)&Id2, (void *)&Stack2[STACKSIZE - 1], 2);
	OSTaskCreate(Task3, (void *)&Id3, (void *)&Stack3[STACKSIZE - 1], 1); 

	/* start the game */
	OSStart();

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