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WdfUsbTargetPipeFormatRequestForUrb method

[Applies to KMDF only]

The WdfUsbTargetPipeFormatRequestForUrb method builds an USB request for a specified USB pipe, using request parameters that a specified URB describes, but it does not send the request.

Syntax


NTSTATUS WdfUsbTargetPipeFormatRequestForUrb(
  [in]           WDFUSBPIPE        Pipe,
  [in]           WDFREQUEST        Request,
  [in]           WDFMEMORY         UrbMemory,
  [in, optional] PWDFMEMORY_OFFSET UrbMemoryOffset
);

Parameters

Pipe [in]

A handle to a framework pipe object that was obtained by calling WdfUsbInterfaceGetConfiguredPipe.

Request [in]

A handle to a framework request object. For more information, see the following Remarks section.

UrbMemory [in]

A handle to a framework memory object that contains a URB structure.

If the driver previously called WdfUsbTargetDeviceCreateWithParameters to create UsbDevice, the driver must use WdfUsbTargetDeviceCreateUrb or WdfUsbTargetDeviceCreateIsochUrb to create the URB contained in this memory object.

UrbMemoryOffset [in, optional]

A pointer to a caller-allocated WDFMEMORY_OFFSET structure that supplies optional byte offset and length values. The framework uses these values to determine the beginning address of the URB within the memory that UrbMemory specifies. If this pointer is NULL, the URB is located at the beginning of the UrbMemory memory.

Return value

WdfUsbTargetPipeFormatRequestForUrb returns the I/O target's completion status value if the operation succeeds. Otherwise, this method can return one of the following values:

Return codeDescription
STATUS_INVALID_PARAMETER

An invalid parameter was detected.

STATUS_INSUFFICIENT_RESOURCES

Insufficient memory was available.

STATUS_INTEGER_OVERFLOW

The offset that the UsbMemoryOffset parameter specified was invalid.

STATUS_REQUEST_NOT_ACCEPTED

The I/O request packet (IRP) that the Request parameter represents does not provide enough IO_STACK_LOCATION structures to allow the driver to forward the request.

 

This method also might return other NTSTATUS values.

A bug check occurs if the driver supplies an invalid object handle.

Remarks

Use WdfUsbTargetPipeFormatRequestForUrb, followed by WdfRequestSend, to send a USB request either synchronously or asynchronously. Alternatively, use the WdfUsbTargetPipeSendUrbSynchronously method to send a request synchronously.

The framework does not examine the USB request. If the request changes the state of the USB pipe, the framework will not be aware of the change.

You can forward an I/O request that your driver received in an I/O queue, or you can create and send a new request.

To forward an I/O request that your driver received in an I/O queue, specify the received request's handle for the WdfUsbTargetPipeFormatRequestForUrb method's Request parameter.

To create a new I/O request, call WdfRequestCreate to preallocate a request object. Supply the request handle for the WdfUsbTargetPipeFormatRequestForUrb method's Request parameter. You can reuse the request object by calling WdfRequestReuse, so your driver's EvtDriverDeviceAdd callback function can preallocate request objects for a device.

After calling WdfUsbTargetPipeFormatRequestForUrb to format an I/O request, the driver must call WdfRequestSend to send the request (either synchronously or asynchronously) to an I/O target.

Multiple calls to WdfUsbTargetPipeFormatRequestForUrb that use the same request do not cause additional resource allocations. Therefore, to reduce the chance that WdfRequestCreate will return STATUS_INSUFFICIENT_RESOURCES, your driver's EvtDriverDeviceAdd callback function can call WdfRequestCreate to preallocate one or more request objects for a device. The driver can subsequently reuse (call WdfRequestReuse), reformat (call WdfUsbTargetPipeFormatRequestForUrb), and resend (call WdfRequestSend) each request object without risking a STATUS_INSUFFICIENT_RESOURCES return value from a later call to WdfRequestCreate. All subsequent calls to WdfUsbTargetPipeFormatRequestForUrb for the reused request object will return STATUS_SUCCESS, if parameter values do not change. (If the driver does not call the same request-formatting method each time, additional resources might be allocated.)

For information about obtaining status information after an I/O request completes, see Obtaining Completion Information.

For more information about the WdfUsbTargetPipeFormatRequestForUrb method and USB I/O targets, see USB I/O Targets.

Examples

The following code example creates a memory object that represents a URB. Then, the example initializes the URB, formats a USB request that contains the URB, registers a CompletionRoutine callback function, and sends the request.


URB  urb;
PURB  pUrb = NULL;
WDFMEMORY  urbMemory
NTSTATUS status;

status = WdfMemoryCreate(
                         WDF_NO_OBJECT_ATTRIBUTES,
                         NonPagedPool,
                         0,
                         sizeof(struct _URB_GET_CURRENT_FRAME_NUMBER),
                         &urbMemory,
                         NULL
                         );
if (!NT_SUCCESS(status)){
    return status;
}

pUrb = WdfMemoryGetBuffer(
                          urbMemory,
                          NULL
                          );

pUrb->UrbHeader.Length = (USHORT) sizeof(struct _URB_GET_CURRENT_FRAME_NUMBER);
pUrb->UrbHeader.Function = URB_FUNCTION_GET_CURRENT_FRAME_NUMBER;
pUrb->UrbGetCurrentFrameNumber.FrameNumber = 0; 

status = WdfUsbTargetPipeFormatRequestForUrb(
                                             pipe,
                                             Request,
                                             urbMemory,
                                             NULL
                                             );
if (!NT_SUCCESS(status)) {
    goto Exit;
}
WdfRequestSetCompletionRoutine(
                               Request,
                               UrbCompletionRoutine,
                               pipe
                               );
if (WdfRequestSend(
                   Request,
                   WdfUsbTargetPipeGetIoTarget(pipe),
                   WDF_NO_SEND_OPTIONS
                   ) == FALSE) {
    status = WdfRequestGetStatus(Request);
    goto Exit;
}
Exit:
if (!NT_SUCCESS(status)) {
    WdfRequestCompleteWithInformation(
                                      Request,
                                      status,
                                      0
                                      );
}
return;

Requirements

Target platform

Universal

Minimum KMDF version

1.0

Header

Wdfusb.h (include Wdfusb.h)

Library

Wdf01000.sys (see Framework Library Versioning.)

IRQL

<=DISPATCH_LEVEL

DDI compliance rules

DriverCreate, KmdfIrql, KmdfIrql2, RequestFormattedValid, RequestSendAndForgetNoFormatting, RequestSendAndForgetNoFormatting2, UsbKmdfIrql, UsbKmdfIrql2

See also

WDFMEMORY_OFFSET
WdfRequestCompleteWithInformation
WdfMemoryCreate
WdfMemoryGetBuffer
WdfRequestSend
WdfRequestSetCompletionRoutine
WdfUsbInterfaceGetConfiguredPipe

 

 

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