HP 3000 Manuals HP 3000 Manuals
XARITRAP
NM and CM callable (differences noted below).
Arms or disarms the user-written arithmetic trap handling procedure.
Syntax
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| |
| I*V I32V I32 I32 |
| XARITRAP(mask,plabel,oldmask,oldplabel);|
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NOTE By default, all traps except IEEE floating-point exceptions are
enabled, and the system trap handler is armed. Many floating-point
operations result in an inexact result. Most compiler libraries
doing floating-point operations result in an inexact trap if the
IEEE inexact result trap is enabled. Therefore, enable the IEEE
inexact result trap only if absolutely necessary.
Parameters
mask (NM) 32-bit signed integer by value (required)
(CM) 16-bit signed integer by value (required)
Determines which trap conditions, if enabled,
invoke the user-written software trap handler, and
which do not.
Value Meaning
1 Corresponding trap condition is armed
0 Corresponding trap condition is disarmed
The bits and their associated arithmetic errors
are:
(NM)
Bits Value/Meaning
31:1 3000 mode floating-point divide by zero
30:1 Integer divide by zero
29:1 3000 mode floating-point underflow
28:1 3000 mode floating-point overflow
27:1 Integer overflow
26:1 3000 mode double-precision overflow
25:1 3000 mode double-precision underflow
24:1 3000 mode double-precision divide by zero
23:1 Decimal overflow
22:1 Invalid ASCII digit
21:1 Invalid decimal digit
Table 4-29. (cont.)
Bits Value/Meaning
19:2 Reserved for the operating system
18:1 Decimal divide by zero
17:1 IEEE floating-point inexact result
16:1 IEEE floating-point underflow
15:1 IEEE floating-point overflow
14:1 IEEE floating-point divide by zero
13:1 IEEE floating-point invalid operation
12:1 Range errors
11:1 Software-detected NIL pointer reference
10:1 Software-detected misaligned result of pointer
arithmetic or error in conversion from long pointer to
short pointer
9:1 Unimplemented condition traps
8:1 Paragraph stack overflow
7:1 3000 mode packed decimal error
1:6 Reserved for the operating system
0:1 Assertion trap
(CM)
Bits Value/Meaning
15:1 3000 mode floating-point divide by zero
14:1 Integer divide by zero
13:1 3000 mode floating-point underflow
12:1 3000 mode floating-point overflow
11:1 Integer overflow
10:1 3000 mode double-precision overflow
9:1 3000 mode double-precision underflow
8:1 3000 mode double-precision divide by zero
7:1 Decimal overflow
6:1 Invalid ASCII digit
5:1 Invalid decimal digit
4:2 Reserved for the operating system
2:1 Decimal divide by zero
NOTE The following apply to the preceding trap conditions represented in
the mask:
* NM supports IEEE and 3000 mode formats. Both execute in NM,
but 3000 mode performs Hewlett-Packard 3000 type
manipulations. Since it is possible to use both formats
during program execution, there are separate bits in the
mask for enabling/disabling traps of these formats.
* Some error conditions specified here are not strictly
arithmetic traps (for example, range errors, nil pointers,
and paragraph stack overflow). However, many arithmetic
traps are caught by reserved instructions that raise
the conditional traps. For this reason, all are
enabled/disabled by XARITRAP.
* Some instructions that raise conditional traps are reserved
to indicate the above trap conditions. A nonreserved
instruction is one not generated by a compiler. If a
nonreserved instruction causes a conditional trap, it is
reported as an unimplemented condition trap. Only assembly
language programmers can generate such a trap.
plabel (NM) 32-bit signed integer by value (required)
(CM) 16-bit signed integer by value (required)
Passes the address of the trap handling procedure.
If the value is 0, the user-written arithmetic trap
handler is disabled.
oldmask (NM) 32-bit signed integer by reference (required)
(CM) 16-bit signed integer by reference (required)
Returns the value of the previous mask.
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
arithmetic trap handler. If no plabel was
previously configured, 0 is returned.
Operation Notes
This trap can be armed for any combination of events; at any given time,
there is only one user-written trap handler for all armed traps.
There is a difference between arming and enabling traps:
* Enabling a trap means that the occurrence of a trap condition is
not ignored.
* Arming a trap is required so that, on a trap condition, a
user-written routine is invoked and can take appropriate recovery
actions.
The following summarizes what can occur when an arithmetic trap condition
arises:
* If a trap is both enabled and armed, the user-written trap handler
is invoked whenever a trap condition occurs.
* If a trap is enabled but not armed, one of two situations applies:
* If a Pascal XL TRY statement is executed, control is passed
to the RECOVER block by doing an ESCAPE.
* If a Pascal XL TRY statement is executed, an error message
is output and the process aborts.
* If a trap is disabled, irrespective of whether it is armed, the
trap is ignored, and execution of the process continues without
any interruption.
Condition Codes
CCE (2) Request granted. The desired traps are now armed.
CCG (0) Request granted. All traps are now disarmed.
CCL (1) Not returned.
Related Information
Intrinsics None
Commands None
Manuals Trap Handling Programmer's Guide (32650-90026)