5.3多線程條件變數

多線程條件變數應用例子

Input_manager.h

InputOpr 結構體添加

進程 ID ：pthread_t t_TreadID;

int AllInputDevicesInit(void)
{
    PT_InputOpr ptTmp = g_ptInputOprHead;
    int iError = -1;

    while (ptTmp)
    {
        if (0 == ptTmp->DeviceInit())
        {
            /* 創建子線程 */
            pthread_create(&ptTmp->t_TreadID, NULL,
            InputEventThreadFunction, ptTmp->GetInputEvent);
            /* 最後一個參數是給 InputEventThreadFunction用的*/
            
            iError = 0;
        }
        ptTmp = ptTmp->ptNext;
    }
    return iError;
}

/* 線程函數 */
static void* InputEventThreadFunction(void *pVoid)
{
    T_InputEvent tInputEvent;
    
    /* 定義函數指針 */
    int (*GetInputEvent)(PT_InputEvent ptInputEvent);
    /* 讓這個函數指針指向 輸入參數*/
    GetInputEvent = (int (*)(PT_InputEvent))pVoid;
    
    while(1)
    {
        if(0 == GetInputEvent(&tInputEvent))
        {
            /* 有數據變化，喚醒主進程，把tInputEvent的值傳給一個全局變數 */
            /* 訪問臨界資源前先獲得互斥變數 */
            pthread_mutex_lock(&g_tmutex);

            /* 原子方法賦值 */
            g_tInputEvent = tInputEvent;

            /* 喚醒主線程 */
            pthread_cond_signal(&g_tcondvar);

            /* 釋放互斥變數 */
            pthread_mutex_unlock(&g_tmutex);
            
        }
    }

    return NULL;
    
}

int GetInputEvent(PT_InputEvent ptInputEvent)
{
    /* 休眠 */
    pthread_mutex_lock(&g_tmutex);
    
    /* 條件等待函數 */
    pthread_cond_wait(&g_tcondvar, &g_tmutex);
    
    /* 程式能夠向下繼續證明被喚醒啦 */
    /* 被喚醒之後返回數據 */
    *ptInputEvent = g_tInputEvent;
    pthread_mutex_unlock(&g_tmutex);

    return 0;    
}

Makefile 添加線程庫 –lpthread

LDFLAGS := -lm -lfreetype -lts –lpthread

g_tTSDev = ts_open(pcTSName, 0);  /* 以阻塞方式打開 */

其實就是兩個輸入方式都以迴圈方式等待有數據變化，然後喚醒主線程處理

改為滑動翻頁

只需修改一個函數即可

static int TouchScreenGetInputEvent(PT_InputEvent ptInputEvent)
{
    struct ts_sample tSamp;
    struct ts_sample tSampPressed;
    struct ts_sample tSampReleased;
    int iRet;
    int bStart = 0;
    int iDelta;

    static struct timeval tPreTime;


    while(1)
    {
        iRet = ts_read(g_tTSDev, &tSamp, 1); /* 如果無數據則休眠 */

        if(1 == iRet)
        {
            if ((tSamp.pressure > 0) && (bStart == 0))
                {
                    tSampPressed = tSamp;
                    bStart = 1;
                }
            
            if (tSamp.pressure <= 0)
            {
                tSampReleased = tSamp;
                //bStart = 0;
                /* 處理數據 */
                if(!bStart)
                {
                    return -1;
                }
                else
                {
                    iDelta = tSampReleased.x - tSampPressed.x;
                    ptInputEvent->tTime = tSampReleased.tv;
                    ptInputEvent->iType = INPUT_TYPE_TOUCHSCREEN;
                    
                    if (iDelta > giXres/5)
                    {
                        /* 翻到上一頁 */ 
                        ptInputEvent->iVal = INPUT_VALUE_UP;
                    }
                    else if (iDelta < 0 - giXres/5)
                    {
                        /* 翻到下一頁 */
                        ptInputEvent->iVal = INPUT_VALUE_DOWN;
                    }
                    else
                    {
                        ptInputEvent->iVal = INPUT_VALUE_UNKNOWN;
                    }
                    return 0;
                }
            }    
        }
        else
        {
            return -1;
        }
    }
    
    return 0;
}