pTAL Reference Manual (H06.08+)

HP pTAL Reference Manual—523746-006
13-1
13 Hardware Indicators
Topics:
•
Managing Overflow Traps on page 13-1
•
Hardware Indicators After Assignments on page 13-3
•
Hardware Indicators in Conditional Expressions on page 13-8
•
Nesting Condition Code Tests on page 13-12
•
Using Hardware Indicators Across Procedures on page 13-14
Managing Overflow Traps
pTAL provides a “static T flag” with which you specify whether traps are enabled or
disabled at any point in your program. You manipulate the static T flag with:
Table 13-1. Hardware Indicators
Hardware
Indicator Representation Meaning
Overflow bit $OVERFLOW
Carry bit $CARRY
Condition code < or ‘<’ Less than
> or ‘>’ Greater than
= or ‘=’ Equal
<= or ‘<=’ Less than or equal
>= or ‘>=’ Greater than or equal
<> or ‘<>’ Not equal
In TNS architecture, a “hardware indicator” is one of three fields of the environment (ENV) register.
Directive or Attribute Scope Comment
OVERFLOW_TRAPS
Compilation unit OVERFLOW_TRAPS is the
default
[NO]OVERFLOW_TRAPS Procedure
Attribute
Procedure or
subprocedure
Overrides the
[NO]OVERFLOW_TRAPS
directive
[EN|DIS]ABLE_OVERFLOW_TRAPS
Block Attribute
Block Overrides both the
[NO]OVERFLOW_TRAPS
directive and the
[NO]OVERFLOW_TRAPS
procedure attribute