Open SCSI Integrator's Manual for NonStop S-Series Servers

The Open SCSI I/O Process (IOP)
Open SCSI Integrator’s Manual for NonStop Servers—422988-002
4-3
Using the WRITEREAD[X] Procedures
nowait-depth
This parameter is optional. If nowait-depth is present and nonzero, it specifies
the number of nowait I/O operations that can be in progress for the file concurrently
with other processing. The Open SCSI IOP supports nowait I/O and a limit of 15
nowait I/O operations.
sync-depth
This parameter is optional. The Open SCSI IOP does not support the sync-ID
mechanism, so even if a nonzero value is assigned to sync-depth, the IOP treats
it as 0.
options
This parameter is not handled directly by the Open SCSI IOP.
seq-buffer-id
The Open SCSI IOP does not perform sequential block buffering.
seq-buffer-len
The Open SCSI IOP does not perform sequential block buffering.
primary-processhandle
The Open SCSI IOP does not directly support the primary-processhandle
parameter.
Using the WRITEREAD[X] Procedures
The Guardian WRITEREAD[X] procedures write data to a device from a buffer in the
application process, then wait for data to be transferred back (read) from the device. The
data from the read operation is returned in the same buffer as that used for the write
operation.
WRITEREAD is intended for use with 16-bit addresses, while WRITEREAD[X] is
intended for use with 32-bit extended addresses. Therefore, the data buffer for the
WRITEREAD[X] procedures can be in either the caller’s stack segment or any extended
data segment. For simplicity, in the remainder of this subsection, this procedure call is
referred to as WRITEREAD.
The syntax of the WRITEREAD procedure call is:
CALL WRITEREAD [x] (filenum !i
,buffer ! i,o
,write-count !i
,read-count !i
,[count-read] ! o
,[tag]); ! i