doc/porting/sync_v1.c

/* hello.c - Hello World demo */

/*
 * Copyright (c) 2012-2014 Wind River Systems, Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr.h>
#include <misc/printk.h>

/*
 * Microkernel version of hello world demo has two tasks that utilize
 * semaphores and sleeps to take turns printing a greeting message at
 * a controlled rate.
 */


/* specify delay between greetings (in ms); compute equivalent in ticks */

#define SLEEPTIME  500
#define SLEEPTICKS (SLEEPTIME * sys_clock_ticks_per_sec / 1000)

/*
 *
 * @param taskname    task identification string
 * @param mySem       task's own semaphore
 * @param otherSem    other task's semaphore
 *
 */
void helloLoop(const char *taskname, ksem_t mySem, ksem_t otherSem)
{
	while (1) {
		task_sem_take(mySem, TICKS_UNLIMITED);

		/* say "hello" */
		printk("%s: Hello World from %s!\n", taskname, CONFIG_ARCH);

		/* wait a while, then let other task have a turn */
		task_sleep(SLEEPTICKS);
		task_sem_give(otherSem);
	}
}

void taskA(void)
{
	/* taskA gives its own semaphore, allowing it to say hello right away */
	task_sem_give(TASKASEM);

	/* invoke routine that allows task to ping-pong hello messages with taskB */
	helloLoop(__func__, TASKASEM, TASKBSEM);
}

void taskB(void)
{
	/* invoke routine that allows task to ping-pong hello messages with taskA */
	helloLoop(__func__, TASKBSEM, TASKASEM);
}