Lucent Technologies USS-720 - Manual (Page 84)

7-26 Lucent Technologies Inc.
USS-720 Preliminary User Guide, Rev. 2
USB Device Driver February 1999
13
4 I/O Control Codes (continued)
4.17 IOCTL_READ_INTERRUPT_PIPE
IOCTL_READ_INTERRUPT_PIPE reports changes on the parallel port and buffer status when they occur. Details
regarding parameters and error codes follow.
4.17.1 Parameters
lpInBuffer—Points to an input buffer. Not used with this operation. Set to NULL.
nInBufferSize—Specifies the size (in bytes) of the buffer pointed to by lpInBuffer. Not used with this operation. Set
to zero.
lpOutBuffer—Points to an output buffer that will receive four status bytes reflecting changes in the parallel port and
buffer status as follows (see the
USS-720 USB-to-IEEE 1284 Bridge Preliminary Data Sheet, “Registers”):
nOutBufferSize—Specifies the size (in bytes) of the buffer pointed to by lpOutBuffer, which must be large enough to
contain 4 bytes.
lpBytesReturned—Points to a DWORD that receives the actual size (in bytes) of the data stored into lpOutBuffer.
4.17.2 Notes
None.
4.17.3 Error Codes
ERROR_INVALID_ALTERNATESETTING—The command is only supported in ALT_INTERFACE_2 (see
Section 4.9 of this document).
ERROR_NOT_ENOUGH_BUFFER—lpOutBuffer needs to be large enough to receive the status bytes.
STATUS_INSUFFICIENT_RESOURCES—Not enough memory to perform the request on this device instance.
Byte Description
0 Status.
1 Control.
2 Extended control.
3 USS-720 control.