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Annotation of nono/fpe/fpu_int.c, revision 1.1.1.1

1.1       root        1: /*     $NetBSD: fpu_int.c,v 1.12 2013/03/19 09:17:17 isaki Exp $       */
                      2: 
                      3: /*
                      4:  * Copyright (c) 1995 Ken Nakata
                      5:  * All rights reserved.
                      6:  *
                      7:  * Redistribution and use in source and binary forms, with or without
                      8:  * modification, are permitted provided that the following conditions
                      9:  * are met:
                     10:  * 1. Redistributions of source code must retain the above copyright
                     11:  *    notice, this list of conditions and the following disclaimer.
                     12:  * 2. Redistributions in binary form must reproduce the above copyright
                     13:  *    notice, this list of conditions and the following disclaimer in the
                     14:  *    documentation and/or other materials provided with the distribution.
                     15:  *
                     16:  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
                     17:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     18:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     19:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
                     20:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     21:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     22:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     23:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     24:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     25:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     26:  * SUCH DAMAGE.
                     27:  *
                     28:  *     @(#)fpu_int.c
                     29:  */
                     30: 
                     31: #include "fpu_arith.h"
                     32: #include "fpu_emulate.h"
                     33: 
                     34: /* FINTRZ - always round to zero */
                     35: struct fpn *
                     36: fpu_intrz(struct fpemu *fe)
                     37: {
                     38:        struct fpn *x = &fe->fe_f2;
                     39:        int sh, clr, mask, i;
                     40:        uint32_t mant[3];
                     41: 
                     42:        /* special cases first */
                     43:        if (x->fp_class != FPC_NUM) {
                     44:                return x;
                     45:        }
                     46:        /* when |x| < 1.0 */
                     47:        if (x->fp_exp < 0) {
                     48:                x->fp_class = FPC_ZERO;
                     49:                x->fp_mant[0] = x->fp_mant[1] = x->fp_mant[2] = 0;
                     50:                fe->fe_fpsr |= FPSR_INEX2;
                     51:                return x;
                     52:        }
                     53: 
                     54:        /* real work */
                     55:        sh = FP_NMANT - 1 - x->fp_exp;
                     56:        if (sh <= 0) {
                     57:                return x;
                     58:        }
                     59: 
                     60:        clr = 2 - sh / 32;
                     61:        mask = (0xffffffff << (sh % 32));
                     62: 
                     63:        /* save */
                     64:        for (i = 0; i < 3; i++) {
                     65:                mant[i] = x->fp_mant[i];
                     66:        }
                     67: 
                     68:        for (i = 2; i > clr; i--) {
                     69:                x->fp_mant[i] = 0;
                     70:        }
                     71:        x->fp_mant[i] &= mask;
                     72: 
                     73:        /* check INEX2 */
                     74:        for (i = 0; i < 3; i++) {
                     75:                if (x->fp_mant[i] != mant[i]) {
                     76:                        fe->fe_fpsr |= FPSR_INEX2;
                     77:                }
                     78:        }
                     79: 
                     80:        return x;
                     81: }
                     82: 
                     83: /* FINT */
                     84: struct fpn *
                     85: fpu_int(struct fpemu *fe)
                     86: {
                     87:        struct fpn *x = &fe->fe_f2;
                     88:        int rsh;
                     89: 
                     90:        /* special cases first */
                     91:        if (x->fp_class != FPC_NUM) {
                     92:                return x;
                     93:        }
                     94: 
                     95:        rsh = FP_NMANT - 1 - x->fp_exp;
                     96:        if (rsh <= FP_NG) {
                     97:                return x;
                     98:        }
                     99: 
                    100:        /* shift to the right */
                    101:        x->fp_exp = 0;
                    102:        fpu_shr(x, rsh - FP_NG);
                    103: 
                    104:        /* round according to FPCR round mode */
                    105:        fpu_round(fe, x);
                    106: 
                    107:        /* shift it back to the left */
                    108:        x->fp_exp = FP_NMANT - 1;
                    109:        fpu_norm(x);
                    110: 
                    111:        return x;
                    112: }

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