实例：信号量的使用 - 曲径通幽论坛

#include "includes.h"



#define TASK_STK_SIZE                 512

#define Task_Hold       0x01
#define Task_Post       0x00

OS_STK        DispCharMStk[TASK_STK_SIZE];        /*任务堆栈*/
OS_STK    DispCharYStk[TASK_STK_SIZE];
OS_STK    StartTaskStk[TASK_STK_SIZE];

   INT16S key;
   INT8U y1 = 0;
   INT8U y2 = 0;
   INT8U TaskID = 0;
   INT8U err;
   INT8U Flag;                                        /*信号量是否放开标志*/
   OS_EVENT *Fun_Sem;


void DispCharM(void *data);                  /*函数声明*/
void DispCharY(void *data);
void StartTask(void *data);
void Fun(INT8U *id);

void main (void)
{

PC_DispClrScr(DISP_FGND_WHITE + DISP_BGND_BLACK);      /*清屏*/

OSInit();                                              /* 初始化 uC/OS-II */

Fun_Sem = OSSemCreate(1);     /*建立只有一个资源的信号量*/

PC_DOSSaveReturn();                                    /*保存DOS的返回环境*/
PC_VectSet(uCOS, OSCtxSw);                             /*安装ucos的任务切换向量*/



OSTaskCreate(StartTask, (void *)0, &StartTaskStk[TASK_STK_SIZE - 1], 0);
OSStart();                                             /*多任务开始*/
}

void StartTask(void *pdata)
{
#if OS_CRITICAL_METHOD == 3

OS_CPU_SR cpu_sr;
#endif

pdata = pdata;                                         /*防止编译警告*/

OS_ENTER_CRITICAL();
PC_VectSet(0x08, OSTickISR);                           /*安装ucos的时钟向量*/
PC_SetTickRate(OS_TICKS_PER_SEC);                      /*设置时钟频率*/
OS_EXIT_CRITICAL();

OSStatInit();                                          /*初始化 uC/OS-II's 统计任务 */

OSTaskCreate(DispCharM,(void *)0, &DispCharMStk[TASK_STK_SIZE - 1], 2);

OSTaskCreate(DispCharY,(void *)0, &DispCharYStk[TASK_STK_SIZE - 1], 3); /*建立两个任务*/

for(;;)
{
if( Flag == Task_Hold)                    /*信号量是否被 hold 住*/
   {
   if( TaskID == 2 )                             /*是否被2#任务 hold 住*/
   {
    PC_DispStr(10,12,"Warning: DispCharM hold the semaphore for 15s",DISP_BGND_BLACK + DISP_FGND_WHITE);                        /* 显示警告信息:2#任务 hold 住信号量 15s*/
   }else if( TaskID == 3 )
   {
    PC_DispStr(10,12,"Warning: DispCharY hold the semaphore for 6s ",DISP_BGND_BLACK + DISP_FGND_WHITE);                         /* 显示警告信息:3#任务 hold 住信号量 6s*/
   }
   }else{
    PC_DispStr(10,12,"                                             ",DISP_BGND_BLACK + DISP_FGND_WHITE);
    }                                                         /*清除警告信息*/

if( PC_GetKey(&key) == TRUE )
{
   if( key == 0x1B )
   {
    PC_DOSReturn();
    }

}
     OSTimeDly(5);
  }

}
void DispCharM (void *pdata)
{
#if OS_CRITICAL_METHOD == 3
OS_CPU_SR cpu_sr;
#endif

pdata = pdata;

for (;;)
   {

    OSSemPend(Fun_Sem,0,&err);

    PC_DispStr(10,0,"DispCharM have got the semaphore",DISP_BGND_BLACK + DISP_FGND_WHITE);          /*显示已得到信号量*/


    PC_DispStr(10,8,"                                ",DISP_BGND_BLACK + DISP_FGND_WHITE);

    TaskID = OSPrioCur;       /*传送任务优先级号*/

    Fun(&TaskID);                  /*调用 Fun() 函数*/

    Flag = Task_Hold;

    OSTimeDlyHMSM(0,0,15,0);              /* hold 住信号量 15s */

    Flag = Task_Post;                               /*释放*/

    OSSemPost(Fun_Sem);

    if( PC_GetKey(&key) == TRUE )
{
   if( key == 0x1B )
   {
    PC_DOSReturn();
    }

}
     OSTimeDlyHMSM(0,0,2,0);

   }

}

void DispCharY(void *pdata)
{
#if OS_CRITICAL_METHOD == 3

OS_CPU_SR cpu_sr;
#endif

pdata = pdata;

for (;;)
   {
    OSSemPend(Fun_Sem,0,&err);

PC_DispStr(10,8,"DispCharY have got the semaphore",DISP_BGND_BLACK + DISP_FGND_WHITE);
PC_DispStr(10,0,"                                ",DISP_BGND_BLACK + DISP_FGND_WHITE);

    TaskID = OSPrioCur;

    Fun(&TaskID);

    Flag = Task_Hold;

    OSTimeDlyHMSM(0,0,6,0);

        Flag = Task_Post;
    OSSemPost(Fun_Sem);

if( PC_GetKey(&key) == TRUE )
{
   if( key == 0x1B )
   {
    PC_DOSReturn();
    }

}

   OSTimeDlyHMSM(0,0,1,0);
}
}

void Fun(INT8U *id)
{
  char *S_Fun = "# task is calling the Fun()";
  char s[50];

  sprintf(s, "%d", *id);
  strcat(s,S_Fun);
  if(*id == 2)
  {
PC_DispStr(10,1,s,DISP_BGND_BLACK + DISP_FGND_WHITE);
PC_DispStr(10,7,"                                ",DISP_BGND_BLACK + DISP_FGND_WHITE);
  }else if( *id == 3 ){
PC_DispStr(10,7,s,DISP_BGND_BLACK + DISP_FGND_WHITE);
PC_DispStr(10,1,"                                ",DISP_BGND_BLACK + DISP_FGND_WHITE);
  }

}