1394ddk程序分析疑难点

DDK中的IsochAttachBuffers(
    HWND                        hWnd,
    PSTR                        szDeviceName,
    PISOCH_ATTACH_BUFFERS       isochAttachBuffers,
    BOOL                        bAutoAlloc,
    BOOL                        bAutoFill
    )
{
    HANDLE      hDevice;

    PISOCH_ATTACH_BUFFERS           pIsochAttachBuffers;

    PRING3_ISOCH_DESCRIPTOR         pR3TempDescriptor;
    RING3_ISOCH_DESCRIPTOR          R3_IsochDescriptor;
    OVERLAPPED                      overLapped;
    
    ULONG                           ulBufferSize;
    DWORD                           dwBytesRet;
    DWORD                           dwRet;
    
    ULONG                           i, n;

    hDevice = OpenDevice(hWnd, szDeviceName, TRUE);

    if (hDevice != INVALID_HANDLE_VALUE) {

        R3_IsochDescriptor = isochAttachBuffers->R3_IsochDescriptor[0];
    
        // they are always required to give me at least one filled in ring3 isoch descriptor.
        // this way if they set the bAutoAlloc flag, i have a template on what to set up.
        // basically, i\'ll auto allocate however many descriptors they want, base on the first one.
        // if they want something more, then they are required to allocate all of the descriptors themselves

        //
        // if the bAutoAlloc flag is set, that means that we allocate according to
        // the first descriptor. we assume there\'s only one configured descriptor
        //
        if (bAutoAlloc) {

            // lets calculate the buffer size
            ulBufferSize = sizeof(ISOCH_ATTACH_BUFFERS) +
                (isochAttachBuffers->R3_IsochDescriptor[0].ulLength*isochAttachBuffers->nNumberOfDescriptors) +
                (sizeof(RING3_ISOCH_DESCRIPTOR)*(isochAttachBuffers->nNumberOfDescriptors-1));

           TRACE(TL_TRACE, (hWnd, \"size of ISOCH_ATTACH_BUFFERS = %d\\r\\n\", sizeof(ISOCH_ATTACH_BUFFERS)));
  TRACE(TL_TRACE, (hWnd, \"size of CYCLE_TIME = %d\\r\\n\", sizeof(CYCLE_TIME)));
           TRACE(TL_TRACE, (hWnd, \"size of  HANDLE = %d\\r\\n\", sizeof( HANDLE)));
           TRACE(TL_TRACE, (hWnd, \"size of ulBufferSize = %d\\r\\n\", ulBufferSize));
pIsochAttachBuffers = (PISOCH_ATTACH_BUFFERS)LocalAlloc(LPTR, ulBufferSize);
            if (!pIsochAttachBuffers) {
                
                dwRet = GetLastError();
                TRACE(TL_ERROR, (hWnd, \"Could not allocate pIsochAttachBuffers\\r\\n\"));
                goto Exit_IsochAttachBuffers;
            }
    
            ZeroMemory(pIsochAttachBuffers, ulBufferSize);

            *pIsochAttachBuffers = *isochAttachBuffers;

         //
            // now we need to setup each descriptor
            //
            pR3TempDescriptor = &pIsochAttachBuffers->R3_IsochDescriptor[0];

            for (i=0; i < isochAttachBuffers->nNumberOfDescriptors; i++) {

            *pR3TempDescriptor = R3_IsochDescriptor;

           TRACE(TL_TRACE, (hWnd, \"(ULONG_PTR)pR3TempDescriptor = %d\\r\\n\", (ULONG_PTR)pR3TempDescriptor));
TRACE(TL_TRACE, (hWnd, \"pR3TempDescriptor->ulLength= %d\\r\\n\", pR3TempDescriptor->ulLength));
pR3TempDescriptor =
                (PRING3_ISOCH_DESCRIPTOR)((ULONG_PTR)pR3TempDescriptor +
                                              pR3TempDescriptor->ulLength +
                                              sizeof(RING3_ISOCH_DESCRIPTOR));
TRACE(TL_TRACE, (hWnd, \"pR3TempDescriptor = %d\\r\\n\", pR3TempDescriptor));
          
           TRACE(TL_TRACE, (hWnd, \"sizeof(RING3_ISOCH_DESCRIPTOR= %d\\r\\n\", sizeof(RING3_ISOCH_DESCRIPTOR)));
          
}
        }
        else {

            // we have already received an allocated buffer, let\'s just map it into
            // our attach struct and pass it down.
            pIsochAttachBuffers = isochAttachBuffers;
            ulBufferSize = pIsochAttachBuffers->ulBufferSize;
        }

        TRACE(TL_TRACE, (hWnd, \"pIsochAttachBuffers = %d\\r\\n\", pIsochAttachBuffers));
if (pIsochAttachBuffers) {

            overLapped.hEvent = CreateEvent( NULL, TRUE, FALSE, NULL );

            // reset our event, in case we\'ll be doing another attach
            ResetEvent(overLapped.hEvent);

          
 
if (bAutoFill) {

                // get the point to the first descriptor
                pR3TempDescriptor = &pIsochAttachBuffers->R3_IsochDescriptor[0];

                for (i=0; i < pIsochAttachBuffers->nNumberOfDescriptors;  i++) {

                    // if we\'re listening, fill it with 0\'s
                    // if we\'re talking, fill it incrementally
                   TRACE(TL_TRACE, (hWnd, \"size of isochAttachBuffers->R3_IsochDescriptor.fulFlags= %d\\r\\n\", isochAttachBuffers->R3_IsochDescriptor[0].fulFlags));
if (isochAttachBuffers->R3_IsochDescriptor.fulFlags & RESOURCE_USED_IN_LISTENING) {
                      
                        FillMemory(&pR3TempDescriptor->Data, pR3TempDescriptor->ulLength, 0);
                     TRACE(TL_TRACE, (hWnd, \"pR3TempDescriptor->Data = %d\\r\\n\", *pR3TempDescriptor->Data));
                    }
                    else {

                        if (pR3TempDescriptor->fulFlags == DESCRIPTOR_HEADER_SCATTER_GATHER) {


                        }
                
                       else {

                            for (n=0; n < (pR3TempDescriptor->ulLength/sizeof(ULONG)); n++) {

                                CopyMemory((ULONG *)&pR3TempDescriptor->Data+n, (ULONG *)&n, sizeof(ULONG));

                         //TRACE(TL_TRACE, (hWnd, \"(ULONG )&pR3TempDescriptor->Data = %d\\r\\n\", *pR3TempDescriptor->Data+n));

}
                        }
                    }

                    pR3TempDescriptor = (PRING3_ISOCH_DESCRIPTOR)((ULONG_PTR)pR3TempDescriptor +
                                    pR3TempDescriptor->ulLength + sizeof(RING3_ISOCH_DESCRIPTOR));

                }
            }
        
       }
        TRACE(TL_TRACE, (hWnd, \"pIsochAttachBuffers = %d\\r\\n\", pIsochAttachBuffers->R3_IsochDescriptor[0].ulLength));
   //&pIsochAttachBuffers->R3_IsochDescriptor[0]=pR3TempDescriptor;
        DeviceIoControl( hDevice,
                         IOCTL_ISOCH_ATTACH_BUFFERS,
                         pIsochAttachBuffers,
                         ulBufferSize,
                         pIsochAttachBuffers,
                         ulBufferSize,
                         &dwBytesRet,
                         &overLapped);

        dwRet = GetLastError();

        if ((dwRet != ERROR_SUCCESS) && (dwRet != ERROR_IO_PENDING)) {

            TRACE(TL_ERROR, (hWnd, \"IsochAttachBuffers Failed = %d\\r\\n\", dwRet));
        }
        else {

            // we got a pending, so we need to wait...
            if (dwRet == ERROR_IO_PENDING) {

                if (!GetOverlappedResult(hDevice, &overLapped, &dwBytesRet, TRUE)) {

                    // getoverlappedresult failed, lets find out why...
                    dwRet = GetLastError();
                    TRACE(TL_ERROR, (hWnd, \"IsochAttachBuffers1: GetOverlappedResult Failed! dwRet = %d\\r\\n\", dwRet));

                }
            }
        }
        
        // free up resources
        CloseHandle(hDevice);
    }
    else {

        dwRet = GetLastError();
        TRACE(TL_ERROR, (hWnd, \"Error = 0x%x\\r\\n\", dwRet));        
    }

Exit_IsochAttachBuffers:
    
    TRACE(TL_TRACE, (hWnd, \"pIsochDescriptor = 0x%x\\r\\n\", pIsochAttachBuffers->pIsochDescriptor));
    TRACE(TL_TRACE, (hWnd, \"Exit IsochAttachBuffers\\r\\n\"));
    return(dwRet);
} // IsochAttachBuffers
这个函数中的pR3TempDescriptor跟pIsochAttachBuffers好像没有关系，有谁研究过？