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gerrit-public.fairphone.software / kernel / msm / fcc234f888ba2365c44ba0507eb8a18eebf1f594 / . / arch / mips / math-emu / dp_add.c
blob: bcf73bb5c33a0de04c0f0c2ca1e4da9e978fb6e1 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]1/* IEEE754 floating point arithmetic
2 * double precision: common utilities
3 */
4/*
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
7 * http://www.algor.co.uk
8 *
9 * ########################################################################
10 *
11 * This program is free software; you can distribute it and/or modify it
12 * under the terms of the GNU General Public License (Version 2) as
13 * published by the Free Software Foundation.
14 *
15 * This program is distributed in the hope it will be useful, but WITHOUT
16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
17 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 * for more details.
19 *
20 * You should have received a copy of the GNU General Public License along
21 * with this program; if not, write to the Free Software Foundation, Inc.,
22 * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
23 *
24 * ########################################################################
25 *
26 */
27
28
29#include "ieee754dp.h"
30
31ieee754dp ieee754dp_add(ieee754dp x, ieee754dp y)
32{
33 COMPXDP;
34 COMPYDP;
35
36 EXPLODEXDP;
37 EXPLODEYDP;
38
39 CLEARCX;
40
41 FLUSHXDP;
42 FLUSHYDP;
43
44 switch (CLPAIR(xc, yc)) {
45 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
46 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
47 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
48 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
49 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
50 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
51 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
52 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
53 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
54 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
55 case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
56 SETCX(IEEE754_INVALID_OPERATION);
57 return ieee754dp_nanxcpt(ieee754dp_indef(), "add", x, y);
58
59 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
60 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
61 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
62 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
63 return y;
64
65 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
66 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
67 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
68 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
69 case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
70 return x;
71
72
73 /* Infinity handling
74 */
75
76 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
77 if (xs == ys)
78 return x;
79 SETCX(IEEE754_INVALID_OPERATION);
80 return ieee754dp_xcpt(ieee754dp_indef(), "add", x, y);
81
82 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
83 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
84 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
85 return y;
86
87 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
88 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
89 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
90 return x;
91
92 /* Zero handling
93 */
94
95 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
96 if (xs == ys)
97 return x;
98 else
99 return ieee754dp_zero(ieee754_csr.rm ==
100 IEEE754_RD);
101
102 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
103 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
104 return x;
105
106 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
107 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
108 return y;
109
110 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
111 DPDNORMX;
112
113 /* FALL THROUGH */
114
115 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
116 DPDNORMY;
117 break;
118
119 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
120 DPDNORMX;
121 break;
122
123 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
124 break;
125 }
126 assert(xm & DP_HIDDEN_BIT);
127 assert(ym & DP_HIDDEN_BIT);
128
129 /* provide guard,round and stick bit space */
130 xm <<= 3;
131 ym <<= 3;
132
133 if (xe > ye) {
134 /* have to shift y fraction right to align
135 */
136 int s = xe - ye;
137 ym = XDPSRS(ym, s);
138 ye += s;
139 } else if (ye > xe) {
140 /* have to shift x fraction right to align
141 */
142 int s = ye - xe;
143 xm = XDPSRS(xm, s);
144 xe += s;
145 }
146 assert(xe == ye);
147 assert(xe <= DP_EMAX);
148
149 if (xs == ys) {
150 /* generate 28 bit result of adding two 27 bit numbers
151 * leaving result in xm,xs,xe
152 */
153 xm = xm + ym;
154 xe = xe;
155 xs = xs;
156
157 if (xm >> (DP_MBITS + 1 + 3)) { /* carry out */
158 xm = XDPSRS1(xm);
159 xe++;
160 }
161 } else {
162 if (xm >= ym) {
163 xm = xm - ym;
164 xe = xe;
165 xs = xs;
166 } else {
167 xm = ym - xm;
168 xe = xe;
169 xs = ys;
170 }
171 if (xm == 0)
172 return ieee754dp_zero(ieee754_csr.rm ==
173 IEEE754_RD);
174
175 /* normalize to rounding precision */
176 while ((xm >> (DP_MBITS + 3)) == 0) {
177 xm <<= 1;
178 xe--;
179 }
180
181 }
182 DPNORMRET2(xs, xe, xm, "add", x, y);
183}