1 /* IEEE754 floating point arithmetic
2 * single precision
3 */
4 /*
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
7 *
8 * ########################################################################
9 *
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.
13 *
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
17 * for more details.
18 *
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.
22 *
23 * ########################################################################
24 */
25
26
27 #include "ieee754sp.h"
28
ieee754sp_add(ieee754sp x,ieee754sp y)29 ieee754sp ieee754sp_add(ieee754sp x, ieee754sp y)
30 {
31 COMPXSP;
32 COMPYSP;
33
34 EXPLODEXSP;
35 EXPLODEYSP;
36
37 CLEARCX;
38
39 FLUSHXSP;
40 FLUSHYSP;
41
42 switch (CLPAIR(xc, yc)) {
43 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
44 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
45 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
46 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
47 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
48 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
49 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
50 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
51 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
52 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
53 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
54 SETCX(IEEE754_INVALID_OPERATION);
55 return ieee754sp_nanxcpt(ieee754sp_indef(), "add", x, y);
56
57 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
58 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
59 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
60 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
61 return y;
62
63 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
64 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
65 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
66 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
67 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
68 return x;
69
70
71 /* Infinity handling
72 */
73
74 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
75 if (xs == ys)
76 return x;
77 SETCX(IEEE754_INVALID_OPERATION);
78 return ieee754sp_xcpt(ieee754sp_indef(), "add", x, y);
79
80 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
81 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
82 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
83 return y;
84
85 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
86 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
87 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
88 return x;
89
90 /* Zero handling
91 */
92
93 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
94 if (xs == ys)
95 return x;
96 else
97 return ieee754sp_zero(ieee754_csr.rm ==
98 IEEE754_RD);
99
100 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
101 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
102 return x;
103
104 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
105 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
106 return y;
107
108 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
109 SPDNORMX;
110
111 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
112 SPDNORMY;
113 break;
114
115 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
116 SPDNORMX;
117 break;
118
119 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
120 break;
121 }
122 assert(xm & SP_HIDDEN_BIT);
123 assert(ym & SP_HIDDEN_BIT);
124
125 /* provide guard,round and stick bit space */
126 xm <<= 3;
127 ym <<= 3;
128
129 if (xe > ye) {
130 /* have to shift y fraction right to align
131 */
132 int s = xe - ye;
133 SPXSRSYn(s);
134 } else if (ye > xe) {
135 /* have to shift x fraction right to align
136 */
137 int s = ye - xe;
138 SPXSRSXn(s);
139 }
140 assert(xe == ye);
141 assert(xe <= SP_EMAX);
142
143 if (xs == ys) {
144 /* generate 28 bit result of adding two 27 bit numbers
145 * leaving result in xm,xs,xe
146 */
147 xm = xm + ym;
148 xe = xe;
149 xs = xs;
150
151 if (xm >> (SP_MBITS + 1 + 3)) { /* carry out */
152 SPXSRSX1();
153 }
154 } else {
155 if (xm >= ym) {
156 xm = xm - ym;
157 xe = xe;
158 xs = xs;
159 } else {
160 xm = ym - xm;
161 xe = xe;
162 xs = ys;
163 }
164 if (xm == 0)
165 return ieee754sp_zero(ieee754_csr.rm ==
166 IEEE754_RD);
167
168 /* normalize in extended single precision */
169 while ((xm >> (SP_MBITS + 3)) == 0) {
170 xm <<= 1;
171 xe--;
172 }
173
174 }
175 SPNORMRET2(xs, xe, xm, "add", x, y);
176 }
177