/*      $NetBSD: divsim.c,v 1.5 2012/02/04 17:03:09 skrll Exp $ */

/*      $OpenBSD: divsim.c,v 1.4 2001/03/29 03:58:18 mickey Exp $       */

/*
* Copyright 1996 1995 by Open Software Foundation, Inc.
*              All Rights Reserved
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose and without fee is hereby granted,
* provided that the above copyright notice appears in all copies and
* that both the copyright notice and this permission notice appear in
* supporting documentation.
*
* OSF DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE.
*
* IN NO EVENT SHALL OSF BE LIABLE FOR ANY SPECIAL, INDIRECT, OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN ACTION OF CONTRACT,
* NEGLIGENCE, OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
/*
* pmk1.1
*/
/*
* (c) Copyright 1986 HEWLETT-PACKARD COMPANY
*
* To anyone who acknowledges that this file is provided "AS IS"
* without any express or implied warranty:
*     permission to use, copy, modify, and distribute this file
* for any purpose is hereby granted without fee, provided that
* the above copyright notice and this notice appears in all
* copies, and that the name of Hewlett-Packard Company not be
* used in advertising or publicity pertaining to distribution
* of the software without specific, written prior permission.
* Hewlett-Packard Company makes no representations about the
* suitability of this software for any purpose.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: divsim.c,v 1.5 2012/02/04 17:03:09 skrll Exp $");

#include "md.h"

void
divsim(int opnd1, int opnd2, struct mdsfu_register *result)
{
       int sign, op1_sign;

       /* check divisor for zero */
       if (opnd2 == 0) {
               overflow = true;
               return;
       }

       /* get sign of result */
       sign = opnd1 ^ opnd2;

       /* get absolute value of operands */
       if (opnd1 < 0) {
               opnd1 = -opnd1;
               op1_sign = true;
       }
       else op1_sign = false;
       if (opnd2 < 0) opnd2 = -opnd2;

       /* check for opnd2 == -2**31 */
       if (opnd2 < 0) {
               if (opnd1 == opnd2) {
                       result_hi = 0;  /* remainder = 0 */
                       result_lo = 1;
               }
               else {
                       result_hi = opnd1;      /* remainder = opnd1 */
                       result_lo = 0;
               }
       }
       else {
               /* do the divide */
               divu(0,opnd1,opnd2,result);

               /*
                * check for overflow
                *
                * at this point, the only way we can get overflow
                * is with opnd1 = -2**31 and opnd2 = -1
                */
               if (sign>0 && result_lo<0) {
                       overflow = true;
                       return;
               }
       }
       overflow = false;

       /* return positive residue */
       if (op1_sign && result_hi) {
               result_hi = opnd2 - result_hi;
               if (++result_lo < 0) {
                       overflow = true;
                       return;
               }
       }

       /* return appropriately signed result */
       if (sign<0) result_lo = -result_lo;
       return;
}