1 /* 2 * Copyright 2008 Sun Microsystems, Inc. All rights reserved. 3 * Use is subject to license terms. 4 */ 5 6 /* 7 * Copyright (c) 1990, 1993 8 * The Regents of the University of California. All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * Chris Torek. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. All advertising materials mentioning features or use of this software 22 * must display the following acknowledgement: 23 * This product includes software developed by the University of 24 * California, Berkeley and its contributors. 25 * 4. Neither the name of the University nor the names of its contributors 26 * may be used to endorse or promote products derived from this software 27 * without specific prior written permission. 28 * 29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 39 * SUCH DAMAGE. 40 */ 41 42 #pragma ident "%Z%%M% %I% %E% SMI" 43 44 #include "lint.h" 45 #include <sys/types.h> 46 #include <stdlib.h> 47 48 div_t 49 div(num, denom) 50 int num, denom; 51 { 52 div_t r; 53 54 r.quot = num / denom; 55 r.rem = num % denom; 56 /* 57 * The ANSI standard says that |r.quot| <= |n/d|, where 58 * n/d is to be computed in infinite precision. In other 59 * words, we should always truncate the quotient towards 60 * 0, never -infinity. 61 * 62 * Machine division and remainer may work either way when 63 * one or both of n or d is negative. If only one is 64 * negative and r.quot has been truncated towards -inf, 65 * r.rem will have the same sign as denom and the opposite 66 * sign of num; if both are negative and r.quot has been 67 * truncated towards -inf, r.rem will be positive (will 68 * have the opposite sign of num). These are considered 69 * `wrong'. 70 * 71 * If both are num and denom are positive, r will always 72 * be positive. 73 * 74 * This all boils down to: 75 * if num >= 0, but r.rem < 0, we got the wrong answer. 76 * In that case, to get the right answer, add 1 to r.quot and 77 * subtract denom from r.rem. 78 */ 79 if (num >= 0 && r.rem < 0) { 80 r.quot++; 81 r.rem -= denom; 82 } 83 return (r); 84 } 85 86 ldiv_t 87 ldiv(num, denom) 88 long num, denom; 89 { 90 ldiv_t r; 91 92 /* see div() for comments */ 93 94 r.quot = num / denom; 95 r.rem = num % denom; 96 if (num >= 0 && r.rem < 0) { 97 r.quot++; 98 r.rem -= denom; 99 } 100 return (r); 101 } 102