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      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