semaphore_sample.c

/* * Copyright (c) 2006-2018, RT-Thread Development Team * * SPDX-License-Identifier: Apache-2.0 * * Change Logs: * Date Author Notes * 2018-08-24 yangjie the first version *//* * 程序清单：信号量例程 * * 该例程创建了一个动态信号量，初始化两个线程，线程1在count每计数10次时， * 发送一个信号量，线程2在接收信号量后，对number进行加1操作 */#include <rtthread.h>#define THREAD_PRIORITY 25#define THREAD_TIMESLICE 5/* 指向信号量的指针 */static rt_sem_t dynamic_sem = RT_NULL;ALIGN(RT_ALIGN_SIZE)static char thread1_stack[1024];static struct rt_thread thread1;static void rt_thread1_entry(void *parameter){ static rt_uint8_t count = 0; while (1) { if (count <= 100) { count++; } else return; /* count每计数10次，就释放一次信号量 */ if (0 == (count % 10)) { rt_kprintf("thread1 release a dynamic semaphore.\n"); rt_sem_release(dynamic_sem); } }}ALIGN(RT_ALIGN_SIZE)static char thread2_stack[1024];static struct rt_thread thread2;static void rt_thread2_entry(void *parameter){ static rt_err_t result; static rt_uint8_t number = 0; while (1) { /* 永久方式等待信号量，获取到信号量，则执行number自加的操作 */ result = rt_sem_take(dynamic_sem, RT_WAITING_FOREVER); if (result != RT_EOK) { rt_kprintf("thread2 take a dynamic semaphore, failed.\n"); rt_sem_delete(dynamic_sem); return; } else { number++; rt_kprintf("thread2 take a dynamic semaphore. number = %d\n", number); } }}/* 信号量示例的初始化 */int semaphore_sample(){ /* 创建一个动态信号量，初始值是0 */ dynamic_sem = rt_sem_create("dsem", 0, RT_IPC_FLAG_FIFO); if (dynamic_sem == RT_NULL) { rt_kprintf("create dynamic semaphore failed.\n"); return -1; } else { rt_kprintf("create done. dynamic semaphore value = 0.\n"); } rt_thread_init(&thread1, "thread1", rt_thread1_entry, RT_NULL, &thread1_stack[0], sizeof(thread1_stack), THREAD_PRIORITY, THREAD_TIMESLICE); rt_thread_startup(&thread1); rt_thread_init(&thread2, "thread2", rt_thread2_entry, RT_NULL, &thread2_stack[0], sizeof(thread2_stack), THREAD_PRIORITY - 1, THREAD_TIMESLICE); rt_thread_startup(&thread2); return 0;}/* 导出到 msh 命令列表中 */MSH_CMD_EXPORT(semaphore_sample, semaphore sample);