Exchange/SNA Manual

WRITEREAD Procedure
Exchange/SNA System Procedure Calls
104700 Tandem Computers Incorporated 5–25
count-read
INT:ref:1
For a wait read operation, count-read returns the number of bytes in the record
received from the host (and now in buffer ).
For a nowait read operation, count-read is not used and can be omitted. The
size of the record received from the host is returned in the count-transferred
parameter of the call to AWAITIO that completes the read operation.
For a write operation, count-read is not used and can be omitted.
tag
INT(32):value
identifies individual nowait I/O operations when a single file can have two or
more nowait I/O operations outstanding at the same time. The value of tag is a
unique, arbitrary value that your program defines for each nowait I/O operation.
A subsequent call to AWAITIO that completes this I/O operation returns this
value to your program, identifying this I/O operation as the nowait I/O operation
that just completed.
If your program has no more than one outstanding nowait I/O operation against a
single file at one time, you can omit this parameter. In this case, the file number
returned by AWAITIO uniquely identifies the I/O operation that was completed.
If you opened the line server for wait I/O operations, omit this parameter.
Considerations The WRITEREAD procedure writes a record from your program to the specified
subdevice for transmission to the host or reads a record sent by the host to the
specified subdevice.
For write operations, the WRITEREAD procedure is functionally the same as the
WRITE procedure. For considerations regarding write operations, see the WRITE
procedure earlier in this section.
For read operations, the WRITEREAD procedure is functionally the same as the READ
procedure. For considerations regarding read operations, see the READ procedure
earlier in this section.
If you opened the Exchange/SNA line server for nowait I/O, you must call AWAITIO
to complete an I/O operation initiated by a call to WRITEREAD.