stm32F103-RT-Thread–信号量(semaphare)

信号量(semaphare)

主要是量这个字, 表示这个信号有一定的量, 可以是0,也可是10,也可以是任意数字, 但是当他为0的时候就表示不可以使用了, 当为非零的时候可以使用,每使用一次即-1,释放的时候+1,为0就等待释放.

static int count = 0;

static rt_sem_t sem = RT_NULL;                          // semaphore control block
static rt_thread_t sem_1_thread = RT_NULL;              // semaphore thread_1 control block
static rt_thread_t sem_2_thread = RT_NULL;              // semaphore thread_2 control block
static rt_thread_t sem_3_thread = RT_NULL;              // semaphore thread_2 control block

static void sem_thread_1_entry(void *parmaeter);
static void sem_thread_2_entry(void *parmaeter);
static void sem_thread_3_entry(void *parmaeter);

int main(void){

    /* 这里的main简化了 */
    sem = rt_sem_create("sem_count_per10_++", 0,RT_IPC_FLAG_FIFO);
    
    sem_1_thread = rt_thread_create("sem_1_thread", sem_thread_1_entry, RT_NULL, 512, 3, 20);
    rt_thread_startup(sem_1_thread);
    
    
    sem_2_thread = rt_thread_create("sem_2_thread", sem_thread_2_entry, RT_NULL, 512, 2, 20);
    rt_thread_startup(sem_2_thread);
    
    
    sem_3_thread = rt_thread_create("sem_3_thread", sem_thread_3_entry,RT_NULL, 512, 2, 20);
    rt_thread_startup(sem_3_thread);
    
}


static void sem_thread_1_entry(void *parameter){
    while (1)   
    {
        if (count <= 100)
        {
            count++;
        }
        else
            return;

        if (0 == count % 10)
        {
            rt_kprintf("thread_1 is release the semaphore %d\n",count);
            rt_sem_release(sem);    // release the semaphore
        }
        
    }
    
}

/*this thread is to get the semphore and do +1*/
static void sem_thread_2_entry(void *parameter){

    while (1)
    {
        rt_err_t result = RT_NULL;
        result = rt_sem_take(sem,RT_WAITING_FOREVER);
        
        if(result==RT_EOK){
            count++;
            rt_kprintf("thread_[2] if take the semaphore and after ++ is: [%d]\n",count);
        }
        else{
            rt_kprintf("[2]take the semaphore is failed!!!!!\n");
            rt_sem_delete(sem);
            return;
        }
    }   
}


static void sem_thread_3_entry(void *parameter){

    while (1)
    {
        rt_err_t result = RT_NULL;
        result = rt_sem_take(sem,RT_WAITING_FOREVER);
        
        if(result==RT_EOK){
            count++;
            rt_kprintf("thread_[3] if take the semaphore and after ++ is: [%d]\n",count);
        }
        else{
            rt_kprintf("[3]take the semaphore is failed!!!!!\n");
            rt_sem_delete(sem);
            return;
        }
    }   
}