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      1 /*	$NetBSD: divsfm.c,v 1.5 2012/02/04 17:03:09 skrll Exp $	*/
      2 
      3 /*	$OpenBSD: divsfm.c,v 1.4 2001/03/29 03:58:17 mickey Exp $	*/
      4 
      5 /*
      6  * Copyright 1996 1995 by Open Software Foundation, Inc.
      7  *              All Rights Reserved
      8  *
      9  * Permission to use, copy, modify, and distribute this software and
     10  * its documentation for any purpose and without fee is hereby granted,
     11  * provided that the above copyright notice appears in all copies and
     12  * that both the copyright notice and this permission notice appear in
     13  * supporting documentation.
     14  *
     15  * OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
     16  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
     17  * FOR A PARTICULAR PURPOSE.
     18  *
     19  * IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
     20  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
     21  * LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
     22  * NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
     23  * WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
     24  *
     25  */
     26 /*
     27  * pmk1.1
     28  */
     29 /*
     30  * (c) Copyright 1986 HEWLETT-PACKARD COMPANY
     31  *
     32  * To anyone who acknowledges that this file is provided "AS IS"
     33  * without any express or implied warranty:
     34  *     permission to use, copy, modify, and distribute this file
     35  * for any purpose is hereby granted without fee, provided that
     36  * the above copyright notice and this notice appears in all
     37  * copies, and that the name of Hewlett-Packard Company not be
     38  * used in advertising or publicity pertaining to distribution
     39  * of the software without specific, written prior permission.
     40  * Hewlett-Packard Company makes no representations about the
     41  * suitability of this software for any purpose.
     42  */
     43 
     44 #include <sys/cdefs.h>
     45 __KERNEL_RCSID(0, "$NetBSD: divsfm.c,v 1.5 2012/02/04 17:03:09 skrll Exp $");
     46 
     47 #include "md.h"
     48 
     49 void
     50 divsfm(int opnd1, int opnd2, struct mdsfu_register *result)
     51 {
     52 	register int sign, op1_sign;
     53 
     54 	/* check divisor for zero */
     55 	if (opnd2 == 0) {
     56 		overflow = true;
     57 		return;
     58 	}
     59 
     60 	/* get sign of result */
     61 	sign = opnd1 ^ opnd2;
     62 
     63 	/* get absolute value of operands */
     64 	if (opnd1 < 0) {
     65 		opnd1 = -opnd1;
     66 		op1_sign = true;
     67 	}
     68 	else op1_sign = false;
     69 	if (opnd2 < 0) opnd2 = -opnd2;
     70 
     71 	/*
     72 	 * check for overflow
     73 	 *
     74 	 * if abs(opnd1) < 0, then opnd1 = -2**31
     75 	 * and abs(opnd1) >= abs(opnd2) always
     76 	 */
     77 	if (opnd1 >= opnd2 || opnd1 < 0) {
     78 		/* check for opnd2 = -2**31 */
     79 		if (opnd2 < 0 && opnd1 != opnd2) {
     80 			result_hi = 0;		/* remainder = 0 */
     81 			result_lo = opnd1 << 1;
     82 		}
     83 		else {
     84 			overflow = true;
     85 			return;
     86 		}
     87 	}
     88 	else {
     89 		/* do the divide */
     90 		divu(opnd1,0,opnd2,result);
     91 
     92 		/* return positive residue */
     93 		if (op1_sign && result_hi) {
     94 			result_hi = opnd2 - result_hi;
     95 			result_lo++;
     96 		}
     97 	}
     98 
     99 	/* check for overflow */
    100 	if (result_lo < 0) {
    101 		overflow = true;
    102 		return;
    103 	}
    104 	overflow = false;
    105 
    106 	/* return appropriately signed result */
    107 	if (sign<0) result_lo = -result_lo;
    108 	return;
    109 }
    110