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1 | /* Copyright (C) 1992, 1997 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 not, | |
16 | write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, | |
17 | Boston, MA 02111-1307, USA. */ | |
28f540f4 | 18 | |
28f540f4 RM |
19 | #include <stdlib.h> |
20 | ||
21 | ||
22 | /* Return the `ldiv_t' representation of NUMER over DENOM. */ | |
28f540f4 | 23 | ldiv_t |
71a40c74 | 24 | ldiv (long int numer, long int denom) |
28f540f4 RM |
25 | { |
26 | ldiv_t result; | |
27 | ||
28 | result.quot = numer / denom; | |
29 | result.rem = numer % denom; | |
30 | ||
31 | /* The ANSI standard says that |QUOT| <= |NUMER / DENOM|, where | |
32 | NUMER / DENOM is to be computed in infinite precision. In | |
33 | other words, we should always truncate the quotient towards | |
34 | zero, never -infinity. Machine division and remainer may | |
35 | work either way when one or both of NUMER or DENOM is | |
36 | negative. If only one is negative and QUOT has been | |
37 | truncated towards -infinity, REM will have the same sign as | |
38 | DENOM and the opposite sign of NUMER; if both are negative | |
39 | and QUOT has been truncated towards -infinity, REM will be | |
40 | positive (will have the opposite sign of NUMER). These are | |
41 | considered `wrong'. If both are NUM and DENOM are positive, | |
42 | RESULT will always be positive. This all boils down to: if | |
43 | NUMER >= 0, but REM < 0, we got the wrong answer. In that | |
44 | case, to get the right answer, add 1 to QUOT and subtract | |
45 | DENOM from REM. */ | |
46 | ||
47 | if (numer >= 0 && result.rem < 0) | |
48 | { | |
49 | ++result.quot; | |
50 | result.rem -= denom; | |
51 | } | |
52 | ||
53 | return result; | |
54 | } |