ConnectQueues

Declaration

virtual kern_return_t ConnectQueues(IOBufferMemoryDescriptor **ifmd, IOMemoryDescriptor **rxqmd, IOMemoryDescriptor **txqmd, IOMemoryDescriptor *in_rxqmd, IOMemoryDescriptor *in_txqmd, uint32_t in_rxqoffset, uint32_t in_txqoffset, uint8_t in_rxqlogsz, uint8_t in_txqlogsz);

Parameters

• ifmd:

  On return, a pointer to the memory buffer for storing interrupt-related data.

• rxqmd:

  On return, a pointer to the memory buffer for storing data received from the device.

• txqmd:

  On return, a pointer to the memory buffer for storing data ready to transmit to the device.

• in_rxqmd:

  An existing memory buffer to configure and return in the rxqmd parameter. Specify NULL if you want this method to create the memory buffer for you. If you specify your own buffer object, this method retains it.

• in_txqmd:

  An existing memory buffer to configure and return in the txqmd parameter. Specify NULL if you want this method to create the memory buffer for you. If you specify your own buffer object, this method retains it.

• in_rxqoffset:

  The offset, in bytes, to the beginning of the in_rxqmd buffer. The offset represents the location at which the system starts accessing the buffer data. Specify 0 to indicate the beginning of the memory buffer.

• in_txqoffset:

  The offset, in bytes, to the beginning of the in_txqmd buffer. The offset represents the location at which the system starts accessing the buffer data. Specify 0 to indicate the beginning of the memory buffer.

• in_rxqlogsz:

  The base-2 logarithmic size of the buffer in the in_rxqmd parameter. For example, specify 14 for a buffer that is 16 kilobytes (2^14 bytes) in size. If in_rxqmd is NULL, this method creates a 16 kilobyte buffer regardless of the value in this parameter.

• in_txqlogsz:

  The base-2 logarithmic size of the buffer in the in_txqmd parameter. For example, specify 14 for a buffer that is 16 kilobytes (2^14 bytes) in size. If in_txqmd is NULL, this method creates a 16 kilobyte buffer regardless of the value in this parameter.

Return Value

kIOReturnSuccess on success, or another value if an error occurs. See Error Codes.

Discussion

You do not need to call this method directly. At activation time, an IOUserUSBSerial object automatically creates memory buffers for managing data moving to and from the USB device. Calling this method after activation replaces the default queues with the new ones you provide.

If you want to provide the memory buffers yourself, specify those values in the in_rxqmd and in_txqmd parameters. When creating custom buffers, always make the size of your buffers a power of 2. If you specify NULL for in_rxqmd and in_txqmd, this method creates new buffers for you.

This method returns pointers to the buffers in the rxqmd and txqmd parameters. It also returns the system-created buffer for storing interrupt-related data in the ifmd parameter.

See Also

Configuring the Serial Data Queues

• DisconnectQueues