MPE/iX Intrinsics Reference Manual (32650-90905)

640 Chapter10
Command Definitions (QUIT-ZSIZE)
XCONTRAP
XCONTRAP
NM and CM callable (difference noted below).
Arms or disarms user-written subsystem break trap handling procedure.
Syntax
I*V I*
XCONTRAP(
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)
The plabel of the subsystem break trap handling procedure. It can be
either an NM or a CM plabel. If the value is 0, the subsystem break trap
handler is disarmed for the process.
Obtaining external plabels for the NM trap handling procedure depends
on the programming language. In Pascal/XL, for example, obtain the
plabel by using the waddress function. Supply the name of your subsystem
break trap handler as an argument to waddress.
1. Obtain the 16-bit external CM plabel of the CM subsystem break trap
handler. One way to do this is by using the LOADPROC intrinsic.
2. Pass this 16-bit plabel in the following 32-bit format:
(NM)
Bits Value/Meaning
31:1 Set to 1
30:1 Set to 0
29:1 Set to 1
16:13 Set to 0
0:16 16-bit external CM plabel
(CM)
Bits Value/Meaning