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1 | /* Copyright (C) 1992 Free Software Foundation, Inc. |
2 | This file is part of the GNU C Library. | |
3 | ||
4 | The GNU C Library is free software; you can redistribute it and/or | |
5 | modify it under the terms of the GNU Library General Public License as | |
6 | published by the Free Software Foundation; either version 2 of the | |
7 | License, or (at your option) any later version. | |
8 | ||
9 | The GNU C Library is distributed in the hope that it will be useful, | |
10 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
12 | Library General Public License for more details. | |
13 | ||
14 | You should have received a copy of the GNU Library General Public | |
15 | License along with the GNU C Library; see the file COPYING.LIB. If | |
16 | not, write to the Free Software Foundation, Inc., 675 Mass Ave, | |
17 | Cambridge, MA 02139, USA. */ | |
18 | ||
19 | /* | |
20 | * Copyright (c) 1990 Regents of the University of California. | |
21 | * All rights reserved. | |
22 | * | |
23 | * This code is derived from software contributed to Berkeley by | |
24 | * Chris Torek. | |
25 | * | |
26 | * Redistribution and use in source and binary forms, with or without | |
27 | * modification, are permitted provided that the following conditions | |
28 | * are met: | |
29 | * 1. Redistributions of source code must retain the above copyright | |
30 | * notice, this list of conditions and the following disclaimer. | |
31 | * 2. Redistributions in binary form must reproduce the above copyright | |
32 | * notice, this list of conditions and the following disclaimer in the | |
33 | * documentation and/or other materials provided with the distribution. | |
34 | * 3. All advertising materials mentioning features or use of this software | |
35 | * must display the following acknowledgement: | |
36 | * This product includes software developed by the University of | |
37 | * California, Berkeley and its contributors. | |
38 | * 4. Neither the name of the University nor the names of its contributors | |
39 | * may be used to endorse or promote products derived from this software | |
40 | * without specific prior written permission. | |
41 | * | |
42 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
43 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
44 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
45 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
46 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
47 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
48 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
49 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
50 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
51 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
52 | * SUCH DAMAGE. | |
53 | */ | |
54 | ||
55 | #include <ansidecl.h> | |
56 | #include <stdlib.h> | |
57 | ||
58 | ||
59 | /* Return the `ldiv_t' representation of NUMER over DENOM. */ | |
60 | __CONSTVALUE | |
61 | ldiv_t | |
62 | DEFUN(ldiv, (numer, denom), long int numer AND long int denom) | |
63 | { | |
64 | ldiv_t result; | |
65 | ||
66 | result.quot = numer / denom; | |
67 | result.rem = numer % denom; | |
68 | ||
69 | /* The ANSI standard says that |QUOT| <= |NUMER / DENOM|, where | |
70 | NUMER / DENOM is to be computed in infinite precision. In | |
71 | other words, we should always truncate the quotient towards | |
72 | zero, never -infinity. Machine division and remainer may | |
73 | work either way when one or both of NUMER or DENOM is | |
74 | negative. If only one is negative and QUOT has been | |
75 | truncated towards -infinity, REM will have the same sign as | |
76 | DENOM and the opposite sign of NUMER; if both are negative | |
77 | and QUOT has been truncated towards -infinity, REM will be | |
78 | positive (will have the opposite sign of NUMER). These are | |
79 | considered `wrong'. If both are NUM and DENOM are positive, | |
80 | RESULT will always be positive. This all boils down to: if | |
81 | NUMER >= 0, but REM < 0, we got the wrong answer. In that | |
82 | case, to get the right answer, add 1 to QUOT and subtract | |
83 | DENOM from REM. */ | |
84 | ||
85 | if (numer >= 0 && result.rem < 0) | |
86 | { | |
87 | ++result.quot; | |
88 | result.rem -= denom; | |
89 | } | |
90 | ||
91 | return result; | |
92 | } |