1 /* IEEE754 floating point arithmetic
2 * double precision: common utilities
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
8 * ########################################################################
10 * This program is free software; you can distribute it and/or modify it
11 * under the terms of the GNU General Public License (Version 2) as
12 * published by the Free Software Foundation.
14 * This program is distributed in the hope it will be useful, but WITHOUT
15 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
16 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
19 * You should have received a copy of the GNU General Public License along
20 * with this program; if not, write to the Free Software Foundation, Inc.,
21 * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
23 * ########################################################################
28 #include "ieee754dp.h"
30 ieee754dp ieee754dp_add(ieee754dp x, ieee754dp y)
43 switch (CLPAIR(xc, yc)) {
44 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
45 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
46 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
47 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
48 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
49 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
50 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
51 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
52 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
53 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
54 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
55 SETCX(IEEE754_INVALID_OPERATION);
56 return ieee754dp_nanxcpt(ieee754dp_indef(), "add", x, y);
58 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
59 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
60 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
61 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
64 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
65 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
66 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
67 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
68 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
75 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
78 SETCX(IEEE754_INVALID_OPERATION);
79 return ieee754dp_xcpt(ieee754dp_indef(), "add", x, y);
81 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
82 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
83 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
86 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
87 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
88 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
94 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
98 return ieee754dp_zero(ieee754_csr.rm ==
101 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
102 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
105 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
106 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
109 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
114 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
118 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
122 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
125 assert(xm & DP_HIDDEN_BIT);
126 assert(ym & DP_HIDDEN_BIT);
128 /* provide guard,round and stick bit space */
133 /* have to shift y fraction right to align
138 } else if (ye > xe) {
139 /* have to shift x fraction right to align
146 assert(xe <= DP_EMAX);
149 /* generate 28 bit result of adding two 27 bit numbers
150 * leaving result in xm,xs,xe
156 if (xm >> (DP_MBITS + 1 + 3)) { /* carry out */
171 return ieee754dp_zero(ieee754_csr.rm ==
174 /* normalize to rounding precision */
175 while ((xm >> (DP_MBITS + 3)) == 0) {
181 DPNORMRET2(xs, xe, xm, "add", x, y);