General
Application areas:: | Intertask communication; see "Intertask communication (ITC)"Communication; see "Communication (programs, users, system)" |
Macro type: | Type O; see "O-type macros" |
Macro description
Users participating in intertask communication (ITC) can delete the first message in their receive queue by means of the RELBF macro.
Users who want to analyze their receive queue may request the first message from a specified sender or the first message in the queue (FIFO). If they proceed according to the FIFO principle, they must delete the first message in the queue before accessing the next one. If the first message was not deleted implicitly when it was requested
(REVNT...REL=YES), it may be deleted explicitly by means of the RELBF macro.
A user who wants to delete the entire receive queue but does not yet want to terminate ITC participation (CLCOM) may keep issuing the RELBF macro in a loop until the return code indicates that the queue is empty.
Macro format and description of operands
RELBF |
Return information and error flags
R15:
+---------------+ | | | | | | | | | | | |a|a| +---------------+
A return code relating to the execution of the RELBF macro is transferred in the rightmost byte of register R15.
X'aa' | Meaning |
X' 00' | The first message in the receive queue has been deleted |
X' 04' | The receive queue was empty |
X' 08' | The task of the calling program is not an ITC participant |