1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * Chris Torek.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 *    notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 *    notice, this list of conditions and the following disclaimer in the
17 *    documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 *    may be used to endorse or promote products derived from this software
20 *    without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 */
34
35#if defined(LIBC_SCCS) && !defined(lint)
36static char sccsid[] = "@(#)div.c	8.1 (Berkeley) 6/4/93";
37#endif /* LIBC_SCCS and not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD$");
40
41#include <stdlib.h>		/* div_t */
42
43div_t
44div(num, denom)
45	int num, denom;
46{
47	div_t r;
48
49	r.quot = num / denom;
50	r.rem = num % denom;
51#if !defined(__STDC_VERSION__) || (__STDC_VERSION__ < 199901L)
52	/*
53	 * The ANSI standard says that |r.quot| <= |n/d|, where
54	 * n/d is to be computed in infinite precision.  In other
55	 * words, we should always truncate the quotient towards
56	 * 0, never -infinity.
57	 *
58	 * Machine division and remainer may work either way when
59	 * one or both of n or d is negative.  If only one is
60	 * negative and r.quot has been truncated towards -inf,
61	 * r.rem will have the same sign as denom and the opposite
62	 * sign of num; if both are negative and r.quot has been
63	 * truncated towards -inf, r.rem will be positive (will
64	 * have the opposite sign of num).  These are considered
65	 * `wrong'.
66	 *
67	 * If both are num and denom are positive, r will always
68	 * be positive.
69	 *
70	 * This all boils down to:
71	 *	if num >= 0, but r.rem < 0, we got the wrong answer.
72	 * In that case, to get the right answer, add 1 to r.quot and
73	 * subtract denom from r.rem.
74	 */
75	if (num >= 0 && r.rem < 0) {
76		r.quot++;
77		r.rem -= denom;
78	}
79#endif
80	return (r);
81}
82