text: /* main.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>
  
  /*
   * The hello world demo has two threads that utilize semaphores and sleeping
   * to take turns printing a greeting message at a controlled rate. The demo
   * shows both the static and dynamic approaches for spawning a thread; a real
   * world application would likely use the static approach for both threads.
   */
  
  
  /* size of stack area used by each thread */
  #define STACKSIZE 1024
  
  /* scheduling priority used by each thread */
  #define PRIORITY 7
  
  /* delay between greetings (in ms) */
  #define SLEEPTIME 500
  
  
  /*
   * @param my_name      thread identification string
   * @param my_sem       thread's own semaphore
   * @param other_sem    other thread's semaphore
   */
  void helloLoop(const char *my_name,
  	       struct k_sem *my_sem, struct k_sem *other_sem)
  {
  	while (1) {
  		/* take my semaphore */
  		k_sem_take(my_sem, K_FOREVER);
  
  		/* say "hello" */
  		printk("%s: Hello World from %s!\n", my_name, CONFIG_ARCH);
  
  		/* wait a while, then let other thread have a turn */
  		k_sleep(SLEEPTIME);
  		k_sem_give(other_sem);
  	}
  }
  
  /* define semaphores */
  
  K_SEM_DEFINE(threadA_sem, 1, 1);	/* starts off "available" */
  K_SEM_DEFINE(threadB_sem, 0, 1);	/* starts off "not available" */
  
  
  /* threadB is a dynamic thread that is spawned by threadA */
  
  void threadB(void *dummy1, void *dummy2, void *dummy3)
  {
  	/* invoke routine to ping-pong hello messages with threadA */
  	helloLoop(__func__, &threadB_sem, &threadA_sem);
  }
  
  char __noinit __stack threadB_stack_area[STACKSIZE];
  static struct k_thread threadB_data;
  
  /* threadA is a static thread that is spawned automatically */
  
  void threadA(void *dummy1, void *dummy2, void *dummy3)
  {
  	/* spawn threadB */
  	k_thread_create(&threadB_data, threadB_stack_area, STACKSIZE, threadB,
  			NULL, NULL, NULL, PRIORITY, 0, K_NO_WAIT);
  
  	/* invoke routine to ping-pong hello messages with threadB */
  	helloLoop(__func__, &threadA_sem, &threadB_sem);
  }
  
  K_THREAD_DEFINE(threadA_id, STACKSIZE, threadA, NULL, NULL, NULL,
  		PRIORITY, 0, K_NO_WAIT);
  