How to use ReadFile API Read HID Device synchronous

[cedricvictor]

Dear all: I use ReadFile api to read HID device synchronous. My code show as below:

char preUsedSize = 0;
char curUsedSize = 0;

while(1)
{
opening_HANDLE = TestHid.ReturnHandle();
BOOL bGot = FALSE;
Data64_t aData64;
DWORD dwBytes = 0;

BOOL bSus = ::ReadFile(opening\_HANDLE, aData64.raw,    
                        sizeof(aData64), &dwBytes, NULL);
		
if( bSus )
{
    PTOUCH\_REPORT inputData = (PTOUCH\_REPORT)aData64.raw;
		
    curUsedSize = inputData->actualCnt;

    if(curUsedSize > preUsedSize)
{
        for(int i = 0; i<(curUsedSize - preUsedSize);i++)
        {		      
            Beep(0x7fff, 500);
    }					
   	}
preUsedSize = curUsedSize;
				
    bGot = TRUE;		
}
else
{
    CloseHandle(opening\_HANDLE);       
}

if(!bGot)
{				
 Sleep(500);
}

}

My question is how do I clean preUsedSize and curUsedSize to 0, If I did not get any data from my device(not get data failed)? The FALSE of bSus means I get data from HID device fail, not no data income. Thanks for your help, Victor.

[Richard Andrew x64]

Your question is not clear. It looks like you are asking how to set the variables preUsedSize and curUsedSize to zero. To that, the answer is:

preUsedSize = 0;
curUsedSize = 0;

The difficult we do right away... ...the impossible takes slightly longer.

[Heng Xiangzhong]

I can't understand your question well. Firstly, you read the file synchronous, so if no fails happens, it will be blocked here if no data income. I think so, happy to communicate with you !