Accelerator Manual (G06.24+, H06.03+)

Accelerator Manual—527303-002
8-1
8 Future Guidelines
The following list provides guidelines for writing programs for future software platforms.
•
Do not use the contents, location, or size of the stack frame marker. The stack
frame marker is machine-dependent.
•
Do not use the contents of TNS machine-specific registers such as ENV, P, RP, L,
and S.
•
Do not depend upon results after an overflow being the same on all HP NonStop
systems.
•
Centralize TAL DEFINE macros that control overflow. Cover a simple area with the
following disable and enable defines:
DISABLE_OVERFLOW_TRAPS = CODE (RDE; ANRI %577; SETE) #;
ENABLE OVERFLOW_TRAPS = CODE (RDE; ANRI %737);
CODE (ORRI %200; SETE) #;
RESET_OVERFLOW_BIT = CODE (RDE; ANRI %737; SETE) #;
Do not jump into or out of this area; enter through the disable define and exit
through the enable define.
•
Use $OVERFLOW immediately after the arithmetic statement that might overflow.
•
Do not modify the ENV register saved in the stack frame marker.
•
Avoid process-to-process absolute addressing.
•
The size and alignment of system data structures and variables will change.
Future system variances are confined primarily to TAL programs. TAL programs
that do not contain any of the previously listed constructs should only be minimally
affected.
If you are writing privileged code, contact your HP analyst for additional
information.