2022嵌入式8-3

• main.c
• 结果展示

#include
#include
#include

//定义一个条件变量
pthread_cond_t cond;

//互斥锁
pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

int flag = 0;

void *callBack1(void *arg)				
{
	while(1)
	{
		pthread_mutex_lock(&mutex);
		if(flag == 0)
		{
			printf("At");
			flag = 1;
		}
		else
			pthread_cond_wait(&cond, &mutex);
			
		pthread_cond_signal(&cond);
		pthread_mutex_unlock(&mutex);
	}
	pthread_exit(NULL);
}

void *callBack2(void *arg)				
{
	char temp;
	while(1)
	{
		pthread_mutex_lock(&mutex);
		if(flag == 1)
		{
			printf("Bt");
			flag = 2;
		}
		else
			pthread_cond_wait(&cond, &mutex);

		pthread_cond_signal(&cond);
		pthread_mutex_unlock(&mutex);
	}
	pthread_exit(NULL);
}

void *callBack3(void *arg)				
{
	while(1)
	{
		pthread_mutex_lock(&mutex);
		if(flag == 2)
		{
			printf("Ct");
			flag = 0;
		}
		else
			pthread_cond_wait(&cond, &mutex);

		pthread_cond_signal(&cond);
		pthread_mutex_unlock(&mutex);
	}
	pthread_exit(NULL);
}


int main(int argc, const char *argv[])
{
	//创建一个条件变量
	if(pthread_cond_init(&cond, NULL) != 0)
	{
		perror("pthread_cond_init");
		return -1;
	}
	//printf("创建条件变量成功n");
	
	//创建三个线程
	pthread_t tid1, tid2, tid3;
	if(pthread_create(&tid1, NULL, callBack1, NULL) != 0)
	{
		perror("pthread_create");
		return -1;
	}

	if(pthread_create(&tid2, NULL, callBack2, NULL) != 0)
	{
		perror("pthread_create");
		return -1;
	}

	if(pthread_create(&tid3, NULL, callBack3, NULL) != 0)
	{
		perror("pthread_create");
		return -1;
	}

	pthread_join(tid1, NULL);
	pthread_join(tid2, NULL);
	pthread_join(tid3, NULL);

	pthread_mutex_destroy(&mutex)
	return 0;
}