Re: ReadFille error caused by USB sniffer

Thanks for posting. Here's a rough example of the code, as you can see
it uses overlapped reads and WaitForSingleObject.

Thanks,

jh

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

int UsbHidDevice::Read(char * outBuf, int timeout)
{

    const int IDTechInputReportSize = 0x1fe; // This is a bit of a cheat,
but it is a constant
                                                // determined by examining
                                                // Capabilities.InputReportByteLength.
    DWORD bytesRead;
    DWORD Result;
    HANDLE hEventObject;
    OVERLAPPED HIDOverlapped;

    hEventObject = CreateEvent((LPSECURITY_ATTRIBUTES)NULL, FALSE, TRUE,
"");
    HIDOverlapped.hEvent = hEventObject;
    HIDOverlapped.Offset = 0;
    HIDOverlapped.OffsetHigh = 0;

    unsigned char inBuf[DTechInputReportSize+1];
    inBuf[0] = '\0';
    outBuf[0] = '\0';

    Result = ReadFile(m_usbHandle, inBuf, IDTechInputReportSize,
&bytesRead,
        (LPOVERLAPPED) &HIDOverlapped);
    Result = WaitForSingleObject(hEventObject, 1000);

    int i = 0;
    int j = 0;

    switch (Result) {
    case WAIT_OBJECT_0:
    {
        printf("\n\nWait_Object_0\n"); //####
        int getOLRResult = GetOverlappedResult(m_usbHandle, &HIDOverlapped,
&bytesRead, TRUE);
        if(!getOLRResult) {
            printf("\n!get\n");
            return 0;
        }
        else {
            for(i = 0; i < IDTechInputReportSize; i++) {
                outBuf[i] = 0;
            }

            i = 0;
            while(inBuf[i] != '%') {
                i++; //Throw all before the start sentinel.
            }

            while(i < IDTechInputReportSize)
            {
                switch(inBuf[i]) {
                case 0: case 0xd0: case '%': case '?': case 0x0d:
                    break;

                default:
                    outBuf[j] = inBuf[i];
                    j++;
                    break;
                }
                i++;
            }
        }
        outBuf[j] = '\0';
        break;
    }
    case WAIT_TIMEOUT:
        CancelIo(m_usbHandle);
        Sleep(1);
        printf(" TO "); //####
        break;

    default:
        CancelIo(m_usbHandle);
        printf("default"); //####
        break;
    }
    return strlen(outBuf);
}