HP 3000 Manuals HP 3000 Manuals
Handling Software System Traps
Information relating to the system trap is passed to the system trap
handling routine through its four parameters:
trapcode 32-bit signed integer passed by value
A constant value that is useful when the same
trap handler is used to handle different types
of system traps.
intrinsicnum 32-bit signed integer passed by value
A unique intrinsic identifier (ID).
See Appendix C for a complete list of intrinsic
numbers.
intrinsicerr 32-bit signed integer passed by value
A number that identifies the error detected by
the intrinsic. If the error is greater than
20, the error is specific to a given intrinsic.
Otherwise, the number identifies a general
intrinsic error.
parmnum 32-bit signed integer passed by value
A number that identifies the error-causing
parameter that was passed to the intrinsic. If
the error is not caused by a parameter, then
zero is passed as the parmnum value.
NOTE An NM system trap handling routine differs from a CM system trap
handler in its calling sequence [refer to the Introduction to MPE
XL for MPE V Programmers (30367-90005)] and the method by which the
trap routine obtains error information. However, you need supply
only the version for the mode in which you invoke intrinsics.
You do not need to modify existing CM applications that use a
system trap handler in order to run them on MPE XL. Likewise, new
NM applications need not specify a CM version of their NM trap
handling routine. Only those doing mixed-mode programming, who
invoke intrinsics in both modes, need to specify and arm trap
handling routines in both modes in order to capture all possible
system traps.
CAUTION A user-defined trap handling procedure cannot perform a goto out
of that procedure. The state of the process and the program
results are not predictable after a non-local goto. Performing
an ESCAPE (HP Pascal/XL) or completing the trap handling
procedure are the only valid ways to return.