Re: [8/13](resend)hidclass.sys: Add a processing thread for HID devices

[Aric Stewart]

> > -
> >
> > +static DWORD CALLBACK hid_device_thread(void *args)
> > +{
> > - DEVICE_OBJECT *device = (DEVICE_OBJECT*)args;
> > -
> > - IRP *irp;
> > - IO_STATUS_BLOCK irp_status;
> > - IO_STACK_LOCATION *irpsp;
> > - DWORD rc;
> > - HANDLE events[2];
> > - NTSTATUS ntrc;
> > -
> > - BASE_DEVICE_EXTENSION *ext = device->DeviceExtension;
> > - events[0] = CreateEventA(NULL, FALSE, FALSE, NULL);
> > - events[1] = ext->halt_event;
> > -
> > - if (ext->information.Polled)
> > - {
> > -
> >    while(1)
> > -
> >    {
> > -
> >        HID_XFER_PACKET *packet;
> > -
> >        ResetEvent(events[0]);
> > -
> > -
> >        packet = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(*packet) + ext->preparseData->caps.InputReportByteLength);
> > -
> >        packet->reportBufferLen = ext->preparseData->caps.InputReportByteLength;
> > -
> >        packet->reportBuffer = ((BYTE*)packet) + sizeof(*packet);
> > -
> >        packet->reportId = 0;
> > -
> > -
> >        irp = IoBuildDeviceIoControlRequest(IOCTL_HID_GET_INPUT_REPORT,
> > -
> >            device, NULL, 0, packet, sizeof(packet), TRUE, events[0],
> > -
> >            &irp_status);
> > -
> > -
> >        irpsp = IoGetNextIrpStackLocation(irp);
> > -
> >        irpsp->CompletionRoutine = read_Completion;
> > -
> >        irpsp->Control = SL_INVOKE_ON_SUCCESS | SL_INVOKE_ON_ERROR;
> > -
> > -
> >        ntrc = IoCallDriver(device, irp);
> > -
> > -
> >        if (ntrc == STATUS_PENDING)
> > -
> >            rc = WaitForMultipleObjects(2, events, FALSE, INFINITE);
> > -
> > -
> >        if (irp->IoStatus.u.Status == STATUS_SUCCESS)
> > -
> >        {
> > -
> >            RingBuffer_Write(ext->ring_buffer, packet);
>
> I'm not opposed to what you have here, but a get-buffer/commit-buffer
> model would avoid an allocation and a memcpy. Although this would
> complicate simultaneous writes, if that's a concern.

Part of the trickiness here is that the the packet gets 'consumed' by the IoCallDriver/IoCompleteRequest process. It needs to be a stack pointer. So I end up having to allocate it on the stack and then copy the result out of it.

-aric