Statistics
| Branch: | Revision:

root / prex-0.9.0 / usr / lib / libc / stdlib / div.c @ 03e9c04a

History | View | Annotate | Download (2.71 KB)

1
/*
2
 * Copyright (c) 1990, 1993
3
 *        The Regents of the University of California.  All rights reserved.
4
 *
5
 * This code is derived from software contributed to Berkeley by
6
 * Chris Torek.
7
 *
8
 * Redistribution and use in source and binary forms, with or without
9
 * modification, are permitted provided that the following conditions
10
 * are met:
11
 * 1. Redistributions of source code must retain the above copyright
12
 *    notice, this list of conditions and the following disclaimer.
13
 * 2. Redistributions in binary form must reproduce the above copyright
14
 *    notice, this list of conditions and the following disclaimer in the
15
 *    documentation and/or other materials provided with the distribution.
16
 * 3. Neither the name of the University nor the names of its contributors
17
 *    may be used to endorse or promote products derived from this software
18
 *    without specific prior written permission.
19
 *
20
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30
 * SUCH DAMAGE.
31
 */
32

    
33
#include <stdlib.h>                /* div_t */
34

    
35
div_t
36
div(num, denom)
37
        int num, denom;
38
{
39
        div_t r;
40

    
41
        r.quot = num / denom;
42
        r.rem = num % denom;
43
        /*
44
         * The ANSI standard says that |r.quot| <= |n/d|, where
45
         * n/d is to be computed in infinite precision.  In other
46
         * words, we should always truncate the quotient towards
47
         * 0, never -infinity.
48
         *
49
         * Machine division and remainer may work either way when
50
         * one or both of n or d is negative.  If only one is
51
         * negative and r.quot has been truncated towards -inf,
52
         * r.rem will have the same sign as denom and the opposite
53
         * sign of num; if both are negative and r.quot has been
54
         * truncated towards -inf, r.rem will be positive (will
55
         * have the opposite sign of num).  These are considered
56
         * `wrong'.
57
         *
58
         * If both are num and denom are positive, r will always
59
         * be positive.
60
         *
61
         * This all boils down to:
62
         *        if num >= 0, but r.rem < 0, we got the wrong answer.
63
         * In that case, to get the right answer, add 1 to r.quot and
64
         * subtract denom from r.rem.
65
         */
66
        if (num >= 0 && r.rem < 0) {
67
                r.quot++;
68
                r.rem -= denom;
69
        }
70
        return (r);
71
}