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WINUSB_ISOCH_READ structure

[This documentation is preliminary and is subject to change.]

The WINUSB_ISOCH_READ structure is used in an IOCTL_WINUSB_READ_ISOCH_PIPE request that reads data from an isochronous OUT endpoint.

Syntax


typedef struct _WINUSB_ISOCH_READ {
  UCHAR                       InterfaceIndex;
  UCHAR                       PipeID;
  ULONG                       BufferLength;
  PVOID                       Buffer;
  BOOLEAN                     StartAsap;
  BOOLEAN                     ContinueStream;
  ULONG                       StartFrame;
  ULONG                       NumberOfPackets;
  PUSBD_ISO_PACKET_DESCRIPTOR IsoPacketDescriptors[1];
} WINUSB_ISOCH_READ, *PWINUSB_ISOCH_READ;

Members

InterfaceIndex

Device-defined number of the USB interface that has the isochronous endpoint from which the request receives data.

PipeID

Derived from Bit 3...0 of the bEndpointAddress field in the endpoint descriptor.

BufferLength

Length in bytes of the buffer pointed to by Buffer.

Buffer

Pointer to the buffer that holds the data received from the endpoint.

StartAsap

If TRUE, the USB driver stack sends the transfer (resulting from the request) in the next appropriate frame. For the first time that the driver stack sends the isochronous packets as soon as it can. The USB driver stack tracks the next frame to use for subsequent requests. If there is a delay in sending a subsequent transfer, the driver stack considers some or all packets to be late and does not transfer those packets.

If FALSE, you must specify the StartFrame value.

ContinueStream

If TRUE, the USB driver stack fails the request if Winusb.sys cannot schedule a transfer in order to continue with the request without dropping one or more frames.

StartFrame

A frame number in which the first isochronous packet is sent.

NumberOfPackets

Number of isochronous packets that hold the entire buffer.

IsoPacketDescriptors

An array of USBD_ISO_PACKET_DESCRIPTOR that describes the details of each isochronous packet in the transfer. NumberOfPackets specifies the number of elements in the array.

Requirements

Header

Winusbio.h (include Winusbio.h)

See also

IOCTL_WINUSB_READ_ISOCH_PIPE
USBD_ISO_PACKET_DESCRIPTOR

 

 

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Build date: 6/19/2013

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