MPE/iX Intrinsics Reference Manual (32650-90875)

640 Chapter10
Command Definitions (QUIT-ZSIZE)
XLIBTRAP
XLIBTRAP
NM and CM callable (differences noted below).
Enables or disables a user-written software library trap handling procedure.
Syntax
I*V I*
XLIBTRAP(
plabel,oldplabel );
NOTE Any user trap handler cannot perform a GOTO out of that procedure.
Performing an ESCAPE (Pascal) or completing the trap handling procedure
are the only valid ways to return. The state of the process and the program
results are not predictable after a non-local GOTO statement.
Parameters
plabel (NM) 32-bit signed integer by value (required)
(CM) 16-bit signed integer by value (required)
Passes the external-type label of the trap handling procedure. If the value
is 0, the trap handler is disabled.
oldplabel (NM) 32-bit signed integer by reference (required)
(CM) 16-bit signed integer by reference (required)
Returns the
plabel of the process's previous software library trap handler.
If no
plabel was previously configured, 0 is returned.
Operation Notes
When a program begins execution, the user-written software library trap handler is
disabled automatically. When enabled by the XLIBTRAP intrinsic, and subsequently
activated by an error, the user-written software library trap handler assumes control.
This trap handler can be enabled or disabled by calling the XLIBTRAP intrinsic.
Condition Codes
CCE (2) Request granted. Trap enabled.
CCG (0) Request granted. Trap disabled.
CCL (1) Request denied. An illegal
plabel was specified.
Related Information
Manual Trap Handling Programmer's Guide