1 /*
2 FUNCTION
3 <<lldiv>>---divide two long long integers
4
5 INDEX
6 lldiv
7
8 SYNOPSIS
9 #include <stdlib.h>
10 lldiv_t lldiv(long long <[n]>, long long <[d]>);
11
12 DESCRIPTION
13 Divide
14 @tex
15 $n/d$,
16 @end tex
17 @ifnottex
18 <[n]>/<[d]>,
19 @end ifnottex
20 returning quotient and remainder as two long long integers in a structure
21 <<lldiv_t>>.
22
23 RETURNS
24 The result is represented with the structure
25
26 . typedef struct
27 . {
28 . long long quot;
29 . long long rem;
30 . } lldiv_t;
31
32 where the <<quot>> field represents the quotient, and <<rem>> the
33 remainder. For nonzero <[d]>, if `<<<[r]> = ldiv(<[n]>,<[d]>);>>' then
34 <[n]> equals `<<<[r]>.rem + <[d]>*<[r]>.quot>>'.
35
36 To divide <<long>> rather than <<long long>> values, use the similar
37 function <<ldiv>>.
38
39 PORTABILITY
40 <<lldiv>> is ISO 9899 (C99) compatable.
41
42 No supporting OS subroutines are required.
43 */
44
45 /*-
46 * Copyright (c) 2001 Mike Barcroft <mike@FreeBSD.org>
47 * All rights reserved.
48 *
49 * Redistribution and use in source and binary forms, with or without
50 * modification, are permitted provided that the following conditions
51 * are met:
52 * 1. Redistributions of source code must retain the above copyright
53 * notice, this list of conditions and the following disclaimer.
54 * 2. Redistributions in binary form must reproduce the above copyright
55 * notice, this list of conditions and the following disclaimer in the
56 * documentation and/or other materials provided with the distribution.
57 *
58 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
59 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
60 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
61 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
62 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
63 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
64 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
65 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
66 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
67 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
68 * SUCH DAMAGE.
69 */
70
71 #include <stdlib.h>
72
73 /*
74 * The ANSI standard says that |r.quot| <= |n/d|, where
75 * n/d is to be computed in infinite precision. In other
76 * words, we should always truncate the quotient towards
77 * 0, never -infinity.
78 *
79 * Machine division and remainer may work either way when
80 * one or both of n or d is negative. If only one is
81 * negative and r.quot has been truncated towards -inf,
82 * r.rem will have the same sign as denom and the opposite
83 * sign of num; if both are negative and r.quot has been
84 * truncated towards -inf, r.rem will be positive (will
85 * have the opposite sign of num). These are considered
86 * `wrong'.
87 *
88 * If both are num and denom are positive, r will always
89 * be positive.
90 *
91 * This all boils down to:
92 * if num >= 0, but r.rem < 0, we got the wrong answer.
93 * In that case, to get the right answer, add 1 to r.quot and
94 * subtract denom from r.rem.
95 */
96 lldiv_t
lldiv(long long numer,long long denom)97 lldiv (long long numer, long long denom)
98 {
99 lldiv_t retval;
100
101 retval.quot = numer / denom;
102 retval.rem = numer % denom;
103 if (numer >= 0 && retval.rem < 0) {
104 retval.quot++;
105 retval.rem -= denom;
106 }
107 return (retval);
108 }
109
110
