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Annotation of sys/arch/hppa/spmath/divsim.c, Revision 1.1.1.1

1.1       nbrk        1: /*     $OpenBSD: divsim.c,v 1.5 2002/05/07 22:19:30 mickey Exp $       */
                      2: /*
                      3:   (c) Copyright 1986 HEWLETT-PACKARD COMPANY
                      4:   To anyone who acknowledges that this file is provided "AS IS"
                      5:   without any express or implied warranty:
                      6:       permission to use, copy, modify, and distribute this file
                      7:   for any purpose is hereby granted without fee, provided that
                      8:   the above copyright notice and this notice appears in all
                      9:   copies, and that the name of Hewlett-Packard Company not be
                     10:   used in advertising or publicity pertaining to distribution
                     11:   of the software without specific, written prior permission.
                     12:   Hewlett-Packard Company makes no representations about the
                     13:   suitability of this software for any purpose.
                     14: */
                     15: /* @(#)divsim.c: Revision: 1.6.88.1 Date: 93/12/07 15:05:56 */
                     16:
                     17: #include "md.h"
                     18:
                     19: void
                     20: divsim(opnd1,opnd2,result)
                     21:        int opnd1, opnd2;
                     22:        struct mdsfu_register *result;
                     23: {
                     24:        int sign, op1_sign;
                     25:
                     26:        /* check divisor for zero */
                     27:        if (opnd2 == 0) {
                     28:                overflow = TRUE;
                     29:                return;
                     30:        }
                     31:
                     32:        /* get sign of result */
                     33:        sign = opnd1 ^ opnd2;
                     34:
                     35:        /* get absolute value of operands */
                     36:        if (opnd1 < 0) {
                     37:                opnd1 = -opnd1;
                     38:                op1_sign = TRUE;
                     39:        }
                     40:        else op1_sign = FALSE;
                     41:        if (opnd2 < 0) opnd2 = -opnd2;
                     42:
                     43:        /* check for opnd2 == -2**31 */
                     44:        if (opnd2 < 0) {
                     45:                if (opnd1 == opnd2) {
                     46:                        result_hi = 0;  /* remainder = 0 */
                     47:                        result_lo = 1;
                     48:                }
                     49:                else {
                     50:                        result_hi = opnd1;      /* remainder = opnd1 */
                     51:                        result_lo = 0;
                     52:                }
                     53:        }
                     54:        else {
                     55:                /* do the divide */
                     56:                divu(0,opnd1,opnd2,result);
                     57:
                     58:                /*
                     59:                 * check for overflow
                     60:                 *
                     61:                 * at this point, the only way we can get overflow
                     62:                 * is with opnd1 = -2**31 and opnd2 = -1
                     63:                 */
                     64:                if (sign>0 && result_lo<0) {
                     65:                        overflow = TRUE;
                     66:                        return;
                     67:                }
                     68:        }
                     69:        overflow = FALSE;
                     70:
                     71:        /* return positive residue */
                     72:        if (op1_sign && result_hi) {
                     73:                result_hi = opnd2 - result_hi;
                     74:                if (++result_lo < 0) {
                     75:                        overflow = TRUE;
                     76:                        return;
                     77:                }
                     78:        }
                     79:
                     80:        /* return appropriately signed result */
                     81:        if (sign<0) result_lo = -result_lo;
                     82:        return;
                     83: }