大唐监狱如何消杀气值:uC/OS-II实验程序之二（消息邮箱）

uC/OS-II实验程序之二（消息邮箱）

消息邮箱是进程通讯中的重要工具，在本例中，使用一个POST任务来发送消息（一个字符，从A-Z），用一个PEND来接收消息。注意，在本例中发送任务是每个时钟周期都发送，而接收任务每3个时钟周期才接收一次。所以，一定会有某些字符不能接收到。

由于消息邮箱（长度为1的消息队列）是消息队列的特殊情况，所以在以后的消息队列程序中还将实验这种情况，看是否会有字符丢失。

/*
*********************************************************************************************************
*                                                uC/OS-II
*                                          The Real-Time Kernel
*
*                           (c) Copyright 2004, Yuan Fei, Hefei University of Technology
*                                           All Rights Reserved
*
*
*
* Filename     : test.c
* Programmer(s): yuan fei
* DESCRIPTION  : This file illustrate the usage of Message Mailbox.
*
*********************************************************************************************************
*/

#include "includes.h"
/*
*********************************************************************************************************
*                                                 TYPE
*********************************************************************************************************
*/

typedef  char                        MESSAGE;    /* 消息为单个字符                                          */

/*
*********************************************************************************************************
*                                               CONSTANTS
*********************************************************************************************************
*/

#define  TASK_STK_SIZE                 256       /* Size of each task's stacks (# of WORDs)            */
#define  N_TASKS                         2       /* Number of identical tasks                          */

/*
*********************************************************************************************************
*                                               VARIABLES
*********************************************************************************************************
*/

OS_STK        TaskStk[N_TASKS][TASK_STK_SIZE];        /* Tasks stacks                                  */
OS_STK        TaskStartStk[TASK_STK_SIZE];

OS_EVENT     *Mailbox;

                      
/*
*********************************************************************************************************
*                                           FUNCTION PROTOTYPES
*********************************************************************************************************
*/

        void  TaskStart(void *data);                  /* Function prototypes of Startup task           */
static  void  MboxPend(void *data);                   /* 等待字符的进程                                */
static  void  MboxPost(void *data);                   /* 发送字符的进程                                */

/*
*********************************************************************************************************
*                                                MAIN
*********************************************************************************************************
*/

void  main (void)
{
  
    PC_DispClrScr(DISP_FGND_WHITE + DISP_BGND_BLACK);      /* Clear the screen                         */
   
   
    OSInit();                                              /* Initialize uC/OS-II                      */

    PC_DOSSaveReturn();                                    /* Save environment to return to DOS        */
    PC_VectSet(uCOS, OSCtxSw);                             /* Install uC/OS-II's context switch vector */

   
    OSTaskCreate(TaskStart, (void *)0, &TaskStartStk[TASK_STK_SIZE - 1], 0);
    OSStart();                                             /* Start multitasking                       */
}

/*
*********************************************************************************************************
*                                              STARTUP TASK
*********************************************************************************************************
*/
void  TaskStart (void *pdata)
{
#if OS_CRITICAL_METHOD == 3                                /* Allocate storage for CPU status register */
    OS_CPU_SR  cpu_sr;
#endif
    INT16S     key;

    pdata = pdata;                                         /* Prevent compiler warning                 */

    OS_ENTER_CRITICAL();
    PC_VectSet(0x08, OSTickISR);                           /* Install uC/OS-II's clock tick ISR        */
    PC_SetTickRate(OS_TICKS_PER_SEC);                      /* Reprogram tick rate                      */
    OS_EXIT_CRITICAL();
   
    Mailbox = OSMboxCreate((void *) 0);

    OSTaskCreate(MboxPost, 0, &TaskStk[0][TASK_STK_SIZE - 1], 2);
    OSTaskCreate(MboxPend, 0, &TaskStk[1][TASK_STK_SIZE - 1], 3);

    for (;;) {
        if (PC_GetKey(&key) == TRUE) {                     /* See if key has been pressed              */
            if (key == 0x1B) {                             /* Yes, see if it's the ESCAPE key          */
                PC_DOSReturn();                            /* Return to DOS                            */
            }
        }

        OSTimeDlyHMSM(0, 0, 1, 0);                         /* Wait one second                          */
    }
}

static  void  MboxPost (void *pdata)
{  
    MESSAGE msg;
    
    for (msg = 'A'; msg <= 'Z'; msg++){
        OSMboxPost(Mailbox, &msg);
        OSTimeDly(1);
        if (msg == 'Z'){
            msg = 'A';
        }
    }
}

static  void  MboxPend (void *pdata)
{
    MESSAGE  msg;
    INT16U   i;
    INT8U    err;
   
    for (i = 0;; ++i){
        msg = *(MESSAGE*)OSMboxPend(Mailbox, 0, &err);

        PC_DispChar(i % 80, i / 80, msg, DISP_FGND_WHITE);
        OSTimeDly(3);        
        if (i > 2000){
            i = 0;
        }
    }
}