VxWorks中的消息队列实现

本示例主要介绍了在VxWorks中使用消息队列进行进程间通信的实现方式。使用msgQSend和msgQReceive函数可以分别发送和接收消息，并且可以设置如何处理阻塞和非阻塞状态。此外，示例代码还展示了如何使用semGive和semTake函数来实现信号量同步。

#include <vxWorks.h>
#include <msgQLib.h>
#include <semLib.h>
#include <stdio.h>

#define MAX_MSG_SIZE 100

MsgQId msgQId; //消息队列ID
SEM_ID semId; //信号量ID

void task1(void)
{
    char msg[MAX_MSG_SIZE] = "Hello, VxWorks!";
    while (1) {
        semTake(semId, WAIT_FOREVER); //等待信号量
        if (msgQSend(msgQId, msg, strlen(msg) + 1, NO_WAIT, MSG_PRI_NORMAL) == ERROR) {
            printf("Error sending message.\n");
        }    
    }
}

void task2(void)
{
    char msg[MAX_MSG_SIZE];
    int nBytesReceived;
    while (1) {
        nBytesReceived = msgQReceive(msgQId, msg, MAX_MSG_SIZE, WAIT_FOREVER);
        if (nBytesReceived == ERROR) {
            printf("Error receiving message.\n");
        } else {
            printf("Received message: %s\n", msg);
            semGive(semId); //释放信号量
        }    
    }
}

int main(void)
{
    msgQId = msgQCreate(10, MAX_MSG_SIZE, MSG_Q_FIFO); //创建消息队列

    semId = semBCreate(SEM_Q_PRIORITY, SEM_EMPTY); //创建空信号量

    taskSpawn("t1", 90, 0, 10000, (FUNCPTR)task1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
    taskSpawn("t2", 90, 0, 10000, (FUNCPTR)task2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0);

    while (1)
        taskDelay(sysClkRateGet() * 10); //延时等待

    return 0;
}

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