请教高手 ezusb.sys 驱动实时处理如何写呢。给我的源码给点意见吧

高手们好：
  我的应用程序如下：
 
 ULONG ulLength = 8*1024*1024;
 unsigned char *tempbuffer=(unsigned char *)malloc(ulLength);
bResult = DeviceIoControl (hDevice， ioctl_val,
&bulkControl,
sizeof (BULK_TRANSFER_CONTROL),
tempbuffer,
ulLength ,//length
(unsigned long *)&nBytes,
NULL);
  驱动里的程序如下：
 NTSTATUS
Ezusb_Read_Write(
   IN  PDEVICE_OBJECT fdo,
   IN  PIRP Irp
   )
{
   PDEVICE_EXTENSION          pdx = fdo->DeviceExtension;
   NTSTATUS                   ntStatus;
   PIO_STACK_LOCATION         irp＝StackIoGetCurrentIrpStackLocation (Irp);
   PBULK_TRANSFER_CONTROL     bulkControl =
                              (PBULK_TRANSFER_CONTROL)Irp->AssociatedIrp.SystemBuffer;
   int i;
   ULONG                      bufferLength =
                              irpStack->Parameters.DeviceIoControl.OutputBufferLength;
  
   PURB                       urb = NULL;
   ULONG                      urbSize = 0;
   ULONG                      transferFlags = 0;
   ULONG Length = MmGetMdlByteCount(Irp->MdlAddress); //addin
   PUSBD_INTERFACE_INFORMATION interfaceInfo = NULL;
   BYTE* pMdlAddress = MmGetSystemAddressForMdlSafe(Irp->MdlAddress, NormalPagePriority);//addin
   ULONG singleTransferLength = 64*1024;//addin
   PUSBD_PIPE_INFORMATION     pipeInfo = NULL;
   USBD_PIPE_HANDLE           pipeHandle = NULL;
  
  
    Ezusb_KdPrint((\"OutputBufferLength==%d\\n\"),irpStack->Parameters.DeviceIoControl.OutputBufferLength);
    Ezusb_KdPrint((\"enter Ezusb_Read_Write()\\n\"));
    Ezusb_KdPrint((\"bulkControl->pipeNum=%d\\n\",bulkControl->pipeNum));
    Ezusb_KdPrint((\"Length=%d\\n\",Length));
   //
   // verify that the selected pipe is valid, and get a handle to it. If anything
   // is wrong, return an error
   //
   interfaceInfo = pdx->Interface;

   if (!interfaceInfo)
   {
      Ezusb_KdPrint((\"Ezusb_Read_Write() no interface info - Exiting\\n\"));
      return STATUS_UNSUCCESSFUL;
   }
   Ezusb_KdPrint((\"interfaceInfo->NumberOfPipes=%d\\n\",interfaceInfo->NumberOfPipes));
   if (bulkControl->pipeNum > interfaceInfo->NumberOfPipes)
   {
      Ezusb_KdPrint((\"pipeNum  Ezusb_Read_Write() invalid pipe - Exiting\\n\"));
      return STATUS_INVALID_PARAMETER;
   }

   pipeInfo = &(interfaceInfo->Pipes[bulkControl->pipeNum]);

   if (!((pipeInfo->PipeType == UsbdPipeTypeBulk) ||
         (pipeInfo->PipeType == UsbdPipeTypeInterrupt)))
   {
      Ezusb_KdPrint((\" PipeType Ezusb_Read_Write() invalid pipe - Exiting\\n\"));
      return STATUS_INVALID_PARAMETER;
   }

   pipeHandle = pipeInfo->PipeHandle;

   if (!pipeHandle)
   {
      Ezusb_KdPrint((\"pipeHandle Ezusb_Read_Write() invalid pipe - Exiting\\n\"));
      return STATUS_UNSUCCESSFUL;
   }
  
     Ezusb_KdPrint((\"pipe\'s MaximumTransferSize==%d\\n\"),pipeInfo->MaximumTransferSize);
   if (bufferLength > pipeInfo->MaximumTransferSize)
   {
      Ezusb_KdPrint((\"Ezusb_Read_Write() invalid transfer size - Exiting\\n\"));
      return STATUS_INVALID_PARAMETER;
   }
  
   //
   // allocate and fill in the Usb request (URB)
  // RtlCopyMemory
   //
   urbSize = sizeof(struct _URB_BULK_OR_INTERRUPT_TRANSFER);

   urb = ExAllocatePool(NonPagedPool,urbSize);

   if (!urb)
   {
      Ezusb_KdPrint((\"Ezusb_Read_Write() unable to alloc URB - Exiting\\n\"));
      return STATUS_NO_MEMORY;
   }
  
  
  // PVOID ioBuffer = Irp->AssociatedIrp.SystemBuffer;
    
    Ezusb_KdPrint((\"Irp->MdlAddress bufferLength==%d\\n\"),bufferLength);
   transferFlags = USBD_SHORT_TRANSFER_OK;
      //  transferFlags = USBD_TRANSFER_DIRECTION_IN;
   //
   // get direction info from the endpoint address
   //
  
  for(  i=0; i< 128; i++)
  {
   if (USB_ENDPOINT_DIRECTION_IN(pipeInfo->EndpointAddress))
      transferFlags |= USBD_TRANSFER_DIRECTION_IN;

   UsbBuildInterruptOrBulkTransferRequest(urb,        //ptr to urb
                        (USHORT) urbSize,             //size of urb
  pipeHandle,                   //usbd pipe handle
  NULL,                          //TransferBuffer
  Irp->MdlAddress,              //mdl
  singleTransferLength,//bufferLength,                 //bufferlength
  transferFlags,                //flags
  NULL);                        //link

   //
   // Call the USB Stack.
   //
ntStatus = Ezusb_CallUSBD(fdo, urb);
  
   //
   // If the transfer was successful, report the length of the transfer to the
   // caller by setting IoStatus.Information
   //
   if (NT_SUCCESS(ntStatus))
   {
      Irp->IoStatus.Information = urb->UrbBulkOrInterruptTransfer.TransferBufferLength;
      Ezusb_KdPrint((\"Successfully transfered 0x%x bytes\\n\",Irp->IoStatus.Information));
   }
    
//然后用UsbBuildInterruptOrBulkTransferRequest（）循环读取数据放到ioBuffer中，每次成功返回后都拷贝数据如下：
     RtlCopyMemory((pMdlAddress + i*singleTransferLength), bulkControl, singleTransferLength);
   }
   //
   // free the URB
   //
   ExFreePool(urb);

   return ntStatus;
}
我是依葫芦画瓢，拿别人的程序改的。我想实现的功能是在应用中开大缓存，把地址传给驱动，然驱动不断循环从设备那读取我要的数据，后拷贝到我的应用缓存中去。这样行吗。
  我在调试中发现outputbufferlength的值不是我传来的值，甚至是负数。驱动在if (bufferLength > pipeInfo->MaximumTransferSize)这里就退出了。所以下面的我就无法调。我想也会有很多错的。清高手们看看。。

有哪位高手指导啊。