/usr/share/calc/help/interrupt is in apcalc-common 2.12.4.4-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 | Interrupts
While a calculation is in progress, you can generate the SIGINT
signal, and the calculator will catch it. At appropriate points
within a calculation, the calculator will check that the signal
has been given, and will abort the calculation cleanly. If the
calculator is in the middle of a large calculation, it might be
a while before the interrupt has an effect.
You can generate the SIGINT signal multiple times if necessary,
and each time the calculator will abort the calculation at a more
risky place within the calculation. Each new interrupt prints a
message of the form:
[Abort level n]
where n ranges from 1 to 3. For n equal to 1, the calculator will
abort calculations at the next statement boundary specified by an
ABORT opcode as described below. For n equal to 2, the calculator
will abort calculations at the next opcode boundary. For n equal to 3,
the calculator will abort calculations at the next attempt to allocate
memory for the result of an integer arithmetic operation; this
level may be appropriate for stopping a builtin operation like
inversion of a large matrix.
If a final interrupt is given when n is 3, the calculator will
immediately abort the current calculation and longjmp back to the
top level command level. Doing this may result in corrupted data
structures and unpredictable future behavior, and so should only
be done as a last resort. You are advised to quit the calculator
after this has been done.
ABORT opcodes
If config("trace") & 2 is zero, ABORT opcodes are introduced at
various places in the opcodes for evaluation of command lines
and functions defined by "define ... { ... }" commands. In the
following, config("trace") has been set equal to 8 so that opcodes
are displayed when a function is defined. The function f(x)
evaluates x + (x - 1) + (x - 2) + ... until a zero term is
encountered. If f() is called with a negative or fractional x,
the calculation is never completed and to stop it, an interruption
(on many systems, by ctrl-C) will be necessary.
; config("trace", 8),
; define f(x) {local s; while (x) {s += x--} return s}
0: DEBUG line 2
2: PARAMADDR x
4: JUMPZ 19
6: DEBUG line 2
8: LOCALADDR s
10: DUPLICATE
11: PARAMADDR x
13: POSTDEC
14: POP
15: ADD
16: ASSIGNPOP
17: JUMP 2
19: DEBUG line 2
21: LOCALADDR s
23: RETURN
f(x) defined
(The line number following DEBUG refers to the line in the file
from which the definition is read.) If an attempt is made to
evaluate f(-1), the effect of the DEBUG at opcode 6 ensures that
a single SIGINT will stop the calculation at a start of
{s += x--} loop. In interactive mode, with ^C indicating
input of ctrl-C, the displayed output is as in:
; f(-1)
^C
[Abort level 1]
"f": line 2: Calculation aborted at statement boundary
The DEBUG opcodes are disabled by nonzero config("trace") & 2.
Changing config("trace") to achieve this, and defining g(x) with
the same definition as for f(x) gives:
; define g(x) {local s; while (x) {s += x--} return s}
0: PARAMADDR x
2: JUMPZ 15
4: LOCALADDR s
6: DUPLICATE
7: PARAMADDR x
9: POSTDEC
10: POP
11: ADD
12: ASSIGNPOP
13: JUMP 0
15: LOCALADDR s
17: RETURN
g(x) defined
If g(-1) is called, two interrupts are necessary, as in:
; g(-1)
^C
[Abort level 1]
^C
[Abort level 2]
"g": Calculation aborted in opcode
## Copyright (C) 1999-2006 David I. Bell, Landon Curt Noll and Ernest Bowen
##
## Calc is open software; you can redistribute it and/or modify it under
## the terms of the version 2.1 of the GNU Lesser General Public License
## as published by the Free Software Foundation.
##
## Calc is distributed in the hope that it will be useful, but WITHOUT
## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
## or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
## Public License for more details.
##
## A copy of version 2.1 of the GNU Lesser General Public License is
## distributed with calc under the filename COPYING-LGPL. You should have
## received a copy with calc; if not, write to Free Software Foundation, Inc.
## 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
##
## @(#) $Revision: 30.1 $
## @(#) $Id: interrupt,v 30.1 2007/03/16 11:10:42 chongo Exp $
## @(#) $Source: /usr/local/src/cmd/calc/help/RCS/interrupt,v $
##
## Under source code control: 1991/07/21 04:37:21
## File existed as early as: 1991
##
## chongo <was here> /\oo/\ http://www.isthe.com/chongo/
## Share and enjoy! :-) http://www.isthe.com/chongo/tech/comp/calc/
|