7.IPC之事件//依据RT-Thread内核编程的学习记录(非内核实现)

事件是什么，为什么需要事件？在RT-Thread中的IPC量已经包含了信号量，互斥量，邮箱，消息队列。事件作为IPC量的一种，它的和信号量和互斥锁类似，同样是为线程的运行增加限定条件。只不过事件的满足，拥有更加严格的条件。例如：同时满足1和2，满足1和2中的某一个，同时满足1，2，3，6中的条件或者满足其中某一个。

1.事件的创建

/*静态事件的创建*/

/*事件控制块*/

static struct rt_event static_event;

rt_event_init(&static_event,"name",type);

/*动态事件的创建*/

/*事件控制块*/
static rt_event_t dynamic_event = RT_NULL;

dynamic_event = rt_event_creat("name",type);

事件的创建，建议查看源码的创建例程。讲道理学到这里，应该很容易的开始学着查看ipc.c文件了

2.事件的发送

#define EVENT_FLAG3 (1 << 3)
#define EVENT_FLAG5 (1 << 5)

/*事件的发送，只有发送特定事件才能接受*/ 
rt_event_send(&event, EVENT_FLAG3);

/*
 * event structure
 */
struct rt_event
{
    struct rt_ipc_object parent;                        /**< inherit from ipc_object */

    rt_uint32_t          set;                           /**< event set */
};
typedef struct rt_event *rt_event_t;

这个位置set，rt_uint32_t有32位，每一位作为一个事件。所以传递得信息为EVENT_FLAG，这个数据是32位的具体某一位。

3.事件的接收

rt_uint32_t e;

RT_EOK == rt_event_recv(&static_event,                             //时间块
                        (EVENT_FLAG3 | EVENT_FLAG5),               //事件
                        RT_EVENT_FLAG_AND | RT_EVENT_FLAG_CLEAR,    //与，后面是复位作用
                        RT_WAITING_FOREVER,                         //一直等待
                        &e);                                        //e是 事件 的值


RT_EOK == rt_event_recv(&static_event, 
                        (EVENT_FLAG3 | EVENT_FLAG5),
                        RT_EVENT_FLAG_OR | RT_EVENT_FLAG_CLEAR,    //或
                        RT_WAITING_FOREVER, 
                        &e);

/*例程的打印信息，我也不知道怎么表示这个e是具体意思，只好把打印结果*/

thread2: send event3

thread1: OR recv event 0x8            //e

thread1: delay 1s to prepare the second event

thread2: send event5

thread2: send event3

thread2 leave.

thread1: AND recv event 0x28          //e

thread1 leave.

事件得接收时rt_event_rev()函数的具体使用方式，看了源代码看一眼就能清楚。

4.事件的例程

#include <rtthread.h>

#define THREAD_PRIORITY      9
#define THREAD_TIMESLICE     5

#define EVENT_FLAG3 (1 << 3)
#define EVENT_FLAG5 (1 << 5)

/* 事件控制块 */
static struct rt_event event;

ALIGN(RT_ALIGN_SIZE)
static char thread1_stack[1024];
static struct rt_thread thread1;

/* 线程1入口函数 */
static void thread1_recv_event(void *param)
{
    rt_uint32_t e;

    /* 第一次接收事件，事件3或事件5任意一个可以触发线程1，接收完后清除事件标志 */
    if (rt_event_recv(&event, (EVENT_FLAG3 | EVENT_FLAG5),
                      RT_EVENT_FLAG_OR | RT_EVENT_FLAG_CLEAR,
                      RT_WAITING_FOREVER, &e) == RT_EOK)
    {
        rt_kprintf("thread1: OR recv event 0x%x\n", e);
    }

    rt_kprintf("thread1: delay 1s to prepare the second event\n");
    rt_thread_mdelay(1000);

    /* 第二次接收事件，事件3和事件5均发生时才可以触发线程1，接收完后清除事件标志 */
    if (rt_event_recv(&event, (EVENT_FLAG3 | EVENT_FLAG5),
                      RT_EVENT_FLAG_AND | RT_EVENT_FLAG_CLEAR,
                      RT_WAITING_FOREVER, &e) == RT_EOK)
    {
        rt_kprintf("thread1: AND recv event 0x%x\n", e);
    }
    rt_kprintf("thread1 leave.\n");
}


ALIGN(RT_ALIGN_SIZE)
static char thread2_stack[1024];
static struct rt_thread thread2;

/* 线程2入口 */
static void thread2_send_event(void *param)
{
    rt_kprintf("thread2: send event3\n");
    rt_event_send(&event, EVENT_FLAG3);
    rt_thread_mdelay(200);

    rt_kprintf("thread2: send event5\n");
    rt_event_send(&event, EVENT_FLAG5);
    rt_thread_mdelay(200);

    rt_kprintf("thread2: send event3\n");
    rt_event_send(&event, EVENT_FLAG3);
    rt_kprintf("thread2 leave.\n");
}

int event_sample(void)
{
    rt_err_t result;

    /* 初始化事件对象 */
    result = rt_event_init(&event, "event", RT_IPC_FLAG_FIFO);
    if (result != RT_EOK)
    {
        rt_kprintf("init event failed.\n");
        return -1;
    }

    rt_thread_init(&thread1,
                   "thread1",
                   thread1_recv_event,
                   RT_NULL,
                   &thread1_stack[0],
                   sizeof(thread1_stack),
                   THREAD_PRIORITY - 1, THREAD_TIMESLICE);
    rt_thread_startup(&thread1);

    rt_thread_init(&thread2,
                   "thread2",
                   thread2_send_event,
                   RT_NULL,
                   &thread2_stack[0],
                   sizeof(thread2_stack),
                   THREAD_PRIORITY, THREAD_TIMESLICE);
    rt_thread_startup(&thread2);

    return 0;
}