5.3多线程条件变量

多线程条件变量应用例子

















Input_manager.h

InputOpr 结构体添加

进程 ID ：pthread_t t_TreadID;

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

while (ptTmp)
{
if (0 == ptTmp->DeviceInit())
{
/* 创建子线程 */
pthread_create(&ptTmp->t_TreadID, NULL,
InputEventThreadFunction, ptTmp->GetInputEvent);
/* 最后一个参数是给 InputEventThreadFunction用的*/

iError = 0;
}
ptTmp = ptTmp->ptNext;
}
return iError;
}

/* 线程函数 */
static void* InputEventThreadFunction(void *pVoid)
{
T_InputEvent tInputEvent;

/* 定义函数指针 */
int (*GetInputEvent)(PT_InputEvent ptInputEvent);
/* 让这个函数指针指向 输入参数*/
GetInputEvent = (int (*)(PT_InputEvent))pVoid;

while(1)
{
if(0 == GetInputEvent(&tInputEvent))
{
/* 有数据变化，唤醒主进程，把tInputEvent的值传给一个全局变量 */
/* 访问临界资源前先获得互斥变量 */
pthread_mutex_lock(&g_tmutex);

/* 原子方法赋值 */
g_tInputEvent = tInputEvent;

/* 唤醒主线程 */
pthread_cond_signal(&g_tcondvar);

/* 释放互斥变量 */
pthread_mutex_unlock(&g_tmutex);

}
}

return NULL;

}

int GetInputEvent(PT_InputEvent ptInputEvent)
{
/* 休眠 */
pthread_mutex_lock(&g_tmutex);

/* 条件等待函数 */
pthread_cond_wait(&g_tcondvar, &g_tmutex);

/* 程序能够向下继续证明被唤醒啦 */
/* 被唤醒之后返回数据 */
*ptInputEvent = g_tInputEvent;
pthread_mutex_unlock(&g_tmutex);

return 0;
}

Makefile 添加线程库 –lpthread

LDFLAGS := -lm -lfreetype -lts –lpthread

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

其实就是两个输入方式都以循环方式等待有数据变化，然后唤醒主线程处理

改为滑动翻页

只需修改一个函数即可

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); /* 如果无数据则休眠 */

if(1 == iRet)
{
if ((tSamp.pressure > 0) && (bStart == 0))
{
tSampPressed = tSamp;
bStart = 1;
}

if (tSamp.pressure <= 0)
{
tSampReleased = tSamp;
//bStart = 0;
/* 处理数据 */
if(!bStart)
{
return -1;
}
else
{
iDelta = tSampReleased.x - tSampPressed.x;
ptInputEvent->tTime = tSampReleased.tv;
ptInputEvent->iType = INPUT_TYPE_TOUCHSCREEN;

if (iDelta > giXres/5)
{
/* 翻到上一页 */
ptInputEvent->iVal = INPUT_VALUE_UP;
}
else if (iDelta < 0 - giXres/5)
{
/* 翻到下一页 */
ptInputEvent->iVal = INPUT_VALUE_DOWN;
}
else
{
ptInputEvent->iVal = INPUT_VALUE_UNKNOWN;
}
return 0;
}
}
}
else
{
return -1;
}
}

return 0;
}