124 lines
3.3 KiB
C
124 lines
3.3 KiB
C
/* $NetBSD: fpu_int.c,v 1.5 2002/05/30 20:56:26 thorpej Exp $ */
|
|
|
|
/*
|
|
* Copyright (c) 1995 Ken Nakata
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
|
|
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
|
|
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
* SUCH DAMAGE.
|
|
*
|
|
* @(#)fpu_int.c
|
|
*/
|
|
|
|
#include <sys/types.h>
|
|
|
|
#include <machine/reg.h>
|
|
|
|
#include "fpu_arith.h"
|
|
#include "fpu_emulate.h"
|
|
|
|
/* FINTRZ - always round to zero */
|
|
struct fpn *
|
|
fpu_intrz(fe)
|
|
struct fpemu *fe;
|
|
{
|
|
register struct fpn *x = &fe->fe_f2;
|
|
register int sh, clr, mask, i;
|
|
|
|
/* special cases first */
|
|
if (x->fp_class != FPC_NUM) {
|
|
return x;
|
|
}
|
|
/* when |x| < 1.0 */
|
|
if (x->fp_exp < 0) {
|
|
x->fp_class = FPC_ZERO;
|
|
x->fp_mant[0] = x->fp_mant[1] = x->fp_mant[2] = 0;
|
|
return x;
|
|
}
|
|
|
|
/* real work */
|
|
sh = FP_NMANT - 1 - x->fp_exp;
|
|
if (sh <= 0) {
|
|
return x;
|
|
}
|
|
|
|
clr = 2 - sh / 32;
|
|
mask = (0xffffffff << (sh % 32));
|
|
|
|
for (i = 2; i > clr; i--) {
|
|
x->fp_mant[i] = 0;
|
|
}
|
|
x->fp_mant[i] &= mask;
|
|
|
|
return x;
|
|
}
|
|
|
|
/* FINT */
|
|
struct fpn *
|
|
fpu_int(fe)
|
|
struct fpemu *fe;
|
|
{
|
|
register struct fpn *x = &fe->fe_f2;
|
|
register int rsh, lsh, wsh, i;
|
|
|
|
/* special cases first */
|
|
if (x->fp_class != FPC_NUM) {
|
|
return x;
|
|
}
|
|
/* even if we have exponent == -1, we still have possiblity
|
|
that the result >= 1.0 when mantissa ~= 1.0 and rounded up */
|
|
if (x->fp_exp < -1) {
|
|
x->fp_class = FPC_ZERO;
|
|
x->fp_mant[0] = x->fp_mant[1] = x->fp_mant[2] = 0;
|
|
return x;
|
|
}
|
|
|
|
/* real work */
|
|
rsh = FP_NMANT - 1 - x->fp_exp;
|
|
if (rsh - FP_NG <= 0) {
|
|
return x;
|
|
}
|
|
|
|
fpu_shr(x, rsh - FP_NG); /* shift to the right */
|
|
|
|
if (fpu_round(fe, x) == 1 /* rounded up */ &&
|
|
x->fp_mant[2 - (FP_NMANT-rsh)/32] & (1 << ((FP_NMANT-rsh)%32))
|
|
/* x >= 2.0 */) {
|
|
rsh--; /* reduce shift count by 1 */
|
|
x->fp_exp++; /* adjust exponent */
|
|
}
|
|
|
|
/* shift it back to the left */
|
|
wsh = rsh / 32;
|
|
lsh = rsh % 32;
|
|
rsh = 32 - lsh;
|
|
for (i = 0; i + wsh < 2; i++) {
|
|
x->fp_mant[i] = (x->fp_mant[i+wsh] << lsh) | (x->fp_mant[i+wsh+1] >> rsh);
|
|
}
|
|
x->fp_mant[i] = (x->fp_mant[i+wsh] << lsh);
|
|
i++;
|
|
for (; i < 3; i++) {
|
|
x->fp_mant[i] = 0;
|
|
}
|
|
|
|
return x;
|
|
}
|