【RTT新手求助】线程中的static变量和全局static变量区别

发布于 2021-04-09 16:36:58 浏览：1455 订阅该版

```c
/*
    现在first_init标志放在函数内部都不行了？放在全局就好了
    是因为内存占用太大了？不对呀，这个static又不占用栈空间？
    
    放在函数外，那么则通过串口发送demo_03命令，第二次进入的时候，first_init
    已经变为了1。
    但是如果放在函数内部，则第二次进入依然是0。理论上不应该呀，是不是内存溢出导致的？
    msh >free
    total memory: 4072
    used memory : 3128
    maximum allocated memory: 3128
*/

static uint8_t first_init = 0;

void demo_03(void)
{
    // static uint8_t first_init = 0;

if(first_init == 0)
    {
        first_init = 1;

rt_sem_init(&sem_lock,"sem_lock",1 ,RT_IPC_FLAG_FIFO);
        rt_sem_init(&sem_empty,"sem_empty",SEM_MAX,RT_IPC_FLAG_FIFO);
        rt_sem_init(&sem_full,"sem_full",0,RT_IPC_FLAG_FIFO);

rt_thread_init(&thread1,
                    "produce",
                    producer_thread,
                    NULL,
                    thread1_stack,
                    256,
                    1,
                    10);

rt_thread_init(&thread2,
                    "consum",
                    consumer_thread,
                    NULL,
                    thread2_stack,
                    256,
                    3,
                    10);
        
        rt_thread_startup(&thread1);
        rt_thread_startup(&thread2);
    }
    else
    {
        rt_kprintf("demo_03 is already started\n");
    }
}

MSH_CMD_EXPORT(demo_03, semaphore description)
```