Home | History | Annotate | Line # | Download | only in fpe
fpu_int.c revision 1.5.6.3
      1  1.5.6.3    skrll /*	$NetBSD: fpu_int.c,v 1.5.6.3 2004/09/21 13:17:35 skrll Exp $	*/
      2      1.1   briggs 
      3      1.1   briggs /*
      4      1.1   briggs  * Copyright (c) 1995 Ken Nakata
      5      1.1   briggs  * All rights reserved.
      6      1.1   briggs  *
      7      1.1   briggs  * Redistribution and use in source and binary forms, with or without
      8      1.1   briggs  * modification, are permitted provided that the following conditions
      9      1.1   briggs  * are met:
     10      1.1   briggs  * 1. Redistributions of source code must retain the above copyright
     11      1.1   briggs  *    notice, this list of conditions and the following disclaimer.
     12      1.1   briggs  * 2. Redistributions in binary form must reproduce the above copyright
     13      1.1   briggs  *    notice, this list of conditions and the following disclaimer in the
     14      1.1   briggs  *    documentation and/or other materials provided with the distribution.
     15      1.1   briggs  *
     16      1.1   briggs  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     17      1.1   briggs  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     18      1.1   briggs  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     19      1.1   briggs  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     20      1.1   briggs  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     21      1.1   briggs  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     22      1.1   briggs  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     23      1.1   briggs  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     24      1.1   briggs  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     25      1.1   briggs  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     26      1.1   briggs  * SUCH DAMAGE.
     27      1.1   briggs  *
     28      1.1   briggs  *	@(#)fpu_int.c
     29      1.1   briggs  */
     30      1.1   briggs 
     31  1.5.6.1    skrll #include <sys/cdefs.h>
     32  1.5.6.3    skrll __KERNEL_RCSID(0, "$NetBSD: fpu_int.c,v 1.5.6.3 2004/09/21 13:17:35 skrll Exp $");
     33  1.5.6.1    skrll 
     34      1.1   briggs #include <sys/types.h>
     35      1.1   briggs 
     36      1.1   briggs #include <machine/reg.h>
     37      1.1   briggs 
     38      1.1   briggs #include "fpu_arith.h"
     39      1.1   briggs #include "fpu_emulate.h"
     40      1.1   briggs 
     41      1.1   briggs /* FINTRZ - always round to zero */
     42      1.1   briggs struct fpn *
     43      1.1   briggs fpu_intrz(fe)
     44      1.1   briggs      struct fpemu *fe;
     45      1.1   briggs {
     46      1.1   briggs   register struct fpn *x = &fe->fe_f2;
     47      1.1   briggs   register int sh, clr, mask, i;
     48      1.1   briggs 
     49      1.1   briggs   /* special cases first */
     50      1.1   briggs   if (x->fp_class != FPC_NUM) {
     51      1.1   briggs     return x;
     52      1.1   briggs   }
     53      1.1   briggs   /* when |x| < 1.0 */
     54      1.1   briggs   if (x->fp_exp < 0) {
     55      1.1   briggs     x->fp_class = FPC_ZERO;
     56      1.2   briggs     x->fp_mant[0] = x->fp_mant[1] = x->fp_mant[2] = 0;
     57      1.1   briggs     return x;
     58      1.1   briggs   }
     59      1.1   briggs 
     60      1.1   briggs   /* real work */
     61      1.1   briggs   sh = FP_NMANT - 1 - x->fp_exp;
     62      1.1   briggs   if (sh <= 0) {
     63      1.1   briggs     return x;
     64      1.1   briggs   }
     65      1.1   briggs 
     66      1.3       is   clr = 2 - sh / 32;
     67      1.1   briggs   mask = (0xffffffff << (sh % 32));
     68      1.1   briggs 
     69      1.2   briggs   for (i = 2; i > clr; i--) {
     70      1.1   briggs     x->fp_mant[i] = 0;
     71      1.1   briggs   }
     72      1.1   briggs   x->fp_mant[i] &= mask;
     73      1.1   briggs 
     74      1.1   briggs   return x;
     75      1.1   briggs }
     76      1.1   briggs 
     77      1.1   briggs /* FINT */
     78      1.1   briggs struct fpn *
     79      1.1   briggs fpu_int(fe)
     80      1.1   briggs      struct fpemu *fe;
     81      1.1   briggs {
     82      1.1   briggs   register struct fpn *x = &fe->fe_f2;
     83      1.1   briggs   register int rsh, lsh, wsh, i;
     84      1.1   briggs 
     85      1.1   briggs   /* special cases first */
     86      1.1   briggs   if (x->fp_class != FPC_NUM) {
     87      1.1   briggs     return x;
     88      1.1   briggs   }
     89      1.1   briggs   /* even if we have exponent == -1, we still have possiblity
     90      1.1   briggs      that the result >= 1.0 when mantissa ~= 1.0 and rounded up */
     91      1.1   briggs   if (x->fp_exp < -1) {
     92      1.1   briggs     x->fp_class = FPC_ZERO;
     93      1.2   briggs     x->fp_mant[0] = x->fp_mant[1] = x->fp_mant[2] = 0;
     94      1.1   briggs     return x;
     95      1.1   briggs   }
     96      1.1   briggs 
     97      1.1   briggs   /* real work */
     98      1.1   briggs   rsh = FP_NMANT - 1 - x->fp_exp;
     99      1.1   briggs   if (rsh - FP_NG <= 0) {
    100      1.1   briggs     return x;
    101      1.1   briggs   }
    102      1.1   briggs 
    103      1.1   briggs   fpu_shr(x, rsh - FP_NG);	/* shift to the right */
    104      1.1   briggs 
    105      1.4      chs   if (fpu_round(fe, x) == 1 /* rounded up */ &&
    106      1.2   briggs       x->fp_mant[2 - (FP_NMANT-rsh)/32] & (1 << ((FP_NMANT-rsh)%32))
    107      1.1   briggs       /* x >= 2.0 */) {
    108      1.1   briggs     rsh--;			/* reduce shift count by 1 */
    109      1.1   briggs     x->fp_exp++;		/* adjust exponent */
    110      1.1   briggs   }
    111      1.1   briggs 
    112      1.1   briggs   /* shift it back to the left */
    113      1.1   briggs   wsh = rsh / 32;
    114      1.1   briggs   lsh = rsh % 32;
    115      1.1   briggs   rsh = 32 - lsh;
    116      1.2   briggs   for (i = 0; i + wsh < 2; i++) {
    117      1.1   briggs     x->fp_mant[i] = (x->fp_mant[i+wsh] << lsh) | (x->fp_mant[i+wsh+1] >> rsh);
    118      1.1   briggs   }
    119      1.5  thorpej   x->fp_mant[i] = (x->fp_mant[i+wsh] << lsh);
    120      1.5  thorpej   i++;
    121      1.2   briggs   for (; i < 3; i++) {
    122      1.1   briggs     x->fp_mant[i] = 0;
    123      1.1   briggs   }
    124      1.1   briggs 
    125      1.1   briggs   return x;
    126      1.1   briggs }
    127