Guardian Procedure Calls Reference Manual (G06.25+)

Guardian Procedure Calls (R)
Guardian Procedure Calls Reference Manual—522629-013
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READUPDATE[X] Procedures
READUPDATE[X] Procedures
Summary
Syntax for C Programmers
Syntax for TAL Programmers
Parameters
Condition Code Settings
Considerations
Disk File Considerations
Interprocess Communication Considerations
Considerations for READUPDATEX Only
Errors for READUPDATEX Only
Related Programming Manuals
Summary
The READUPDATE[X] procedures read data from a disk or process file in anticipation
of a subsequent write to the file. READUPDATE is intended for use with 16-bit
addresses, while READUPDATEX is intended for use with 32-bit extended addresses.
Therefore, the data buffer for READUPDATEX can be either in the caller’s stack
segment or any extended data segment.
•
Disk files
READUPDATE[X] is used for random processing. Data is read from the file at the
position of the current-record pointer. A call to this procedure typically follows a
corresponding call to POSITION or KEYPOSITION. The values of the current- and
next-record pointers do not change with the call to READUPDATE[X].
•
Queue Files
READUPDATE[X] is not supported on queue files. An attempt to use
READUPDATE[X] will be rejected with error 2.
•
Interprocess communication
READUPDATE[X] reads a message from the $RECEIVE file that is answered in a
later call to REPLY[X]. Each message read by READUPDATE[X] must be replied
to in a corresponding call to REPLY[X].