123 lines
3.2 KiB
C
123 lines
3.2 KiB
C
/* $NetBSD: fpu_int.c,v 1.4 2001/02/18 20:05:58 chs Exp $ */
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/*
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* Copyright (c) 1995 Ken Nakata
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)fpu_int.c
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*/
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#include <sys/types.h>
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#include <machine/reg.h>
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#include "fpu_arith.h"
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#include "fpu_emulate.h"
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/* FINTRZ - always round to zero */
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struct fpn *
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fpu_intrz(fe)
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struct fpemu *fe;
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{
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register struct fpn *x = &fe->fe_f2;
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register int sh, clr, mask, i;
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/* special cases first */
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if (x->fp_class != FPC_NUM) {
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return x;
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}
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/* when |x| < 1.0 */
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if (x->fp_exp < 0) {
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x->fp_class = FPC_ZERO;
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x->fp_mant[0] = x->fp_mant[1] = x->fp_mant[2] = 0;
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return x;
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}
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/* real work */
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sh = FP_NMANT - 1 - x->fp_exp;
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if (sh <= 0) {
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return x;
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}
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clr = 2 - sh / 32;
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mask = (0xffffffff << (sh % 32));
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for (i = 2; i > clr; i--) {
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x->fp_mant[i] = 0;
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}
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x->fp_mant[i] &= mask;
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return x;
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}
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/* FINT */
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struct fpn *
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fpu_int(fe)
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struct fpemu *fe;
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{
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register struct fpn *x = &fe->fe_f2;
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register int rsh, lsh, wsh, i;
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/* special cases first */
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if (x->fp_class != FPC_NUM) {
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return x;
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}
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/* even if we have exponent == -1, we still have possiblity
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that the result >= 1.0 when mantissa ~= 1.0 and rounded up */
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if (x->fp_exp < -1) {
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x->fp_class = FPC_ZERO;
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x->fp_mant[0] = x->fp_mant[1] = x->fp_mant[2] = 0;
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return x;
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}
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/* real work */
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rsh = FP_NMANT - 1 - x->fp_exp;
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if (rsh - FP_NG <= 0) {
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return x;
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}
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fpu_shr(x, rsh - FP_NG); /* shift to the right */
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if (fpu_round(fe, x) == 1 /* rounded up */ &&
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x->fp_mant[2 - (FP_NMANT-rsh)/32] & (1 << ((FP_NMANT-rsh)%32))
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/* x >= 2.0 */) {
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rsh--; /* reduce shift count by 1 */
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x->fp_exp++; /* adjust exponent */
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}
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/* shift it back to the left */
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wsh = rsh / 32;
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lsh = rsh % 32;
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rsh = 32 - lsh;
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for (i = 0; i + wsh < 2; i++) {
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x->fp_mant[i] = (x->fp_mant[i+wsh] << lsh) | (x->fp_mant[i+wsh+1] >> rsh);
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}
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x->fp_mant[i++] = (x->fp_mant[i+wsh] << lsh);
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for (; i < 3; i++) {
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x->fp_mant[i] = 0;
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}
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return x;
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}
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