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gerrit-public.fairphone.software / kernel / msm / 1a0e8a52ad56075663d8e120e2468fc96fb6fa6c / . / arch / mips / math-emu / dp_mul.c
blob: 48908a809c17f5839b6e4e0ead057da3cd36ac65 [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#include "ieee754dp.h"
29
30ieee754dp ieee754dp_mul(ieee754dp x, ieee754dp y)
31{
32 COMPXDP;
33 COMPYDP;
34
35 EXPLODEXDP;
36 EXPLODEYDP;
37
38 CLEARCX;
39
40 FLUSHXDP;
41 FLUSHYDP;
42
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(), "mul", x, y);
57
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):
62 return y;
63
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):
69 return x;
70
71
72 /* Infinity handling */
73
74 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
75 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
76 SETCX(IEEE754_INVALID_OPERATION);
77 return ieee754dp_xcpt(ieee754dp_indef(), "mul", x, y);
78
79 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
80 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
81 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
82 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
83 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
84 return ieee754dp_inf(xs ^ ys);
85
86 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
87 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
88 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
89 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
90 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
91 return ieee754dp_zero(xs ^ ys);
92
93
94 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
95 DPDNORMX;
96
97 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
98 DPDNORMY;
99 break;
100
101 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
102 DPDNORMX;
103 break;
104
105 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
106 break;
107 }
108 /* rm = xm * ym, re = xe+ye basicly */
109 assert(xm & DP_HIDDEN_BIT);
110 assert(ym & DP_HIDDEN_BIT);
111 {
112 int re = xe + ye;
113 int rs = xs ^ ys;
114 u64 rm;
115
116 /* shunt to top of word */
117 xm <<= 64 - (DP_MBITS + 1);
118 ym <<= 64 - (DP_MBITS + 1);
119
120 /* multiply 32bits xm,ym to give high 32bits rm with stickness
121 */
122
123 /* 32 * 32 => 64 */
Ralf Baechle21a151d2007-10-11 23:46:15 +0100[diff] [blame]124#define DPXMULT(x, y) ((u64)(x) * (u64)y)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]125
126 {
127 unsigned lxm = xm;
128 unsigned hxm = xm >> 32;
129 unsigned lym = ym;
130 unsigned hym = ym >> 32;
131 u64 lrm;
132 u64 hrm;
133
134 lrm = DPXMULT(lxm, lym);
135 hrm = DPXMULT(hxm, hym);
136
137 {
138 u64 t = DPXMULT(lxm, hym);
139 {
140 u64 at =
141 lrm + (t << 32);
142 hrm += at < lrm;
143 lrm = at;
144 }
145 hrm = hrm + (t >> 32);
146 }
147
148 {
149 u64 t = DPXMULT(hxm, lym);
150 {
151 u64 at =
152 lrm + (t << 32);
153 hrm += at < lrm;
154 lrm = at;
155 }
156 hrm = hrm + (t >> 32);
157 }
158 rm = hrm | (lrm != 0);
159 }
160
161 /*
162 * sticky shift down to normal rounding precision
163 */
164 if ((s64) rm < 0) {
165 rm =
166 (rm >> (64 - (DP_MBITS + 1 + 3))) |
167 ((rm << (DP_MBITS + 1 + 3)) != 0);
168 re++;
169 } else {
170 rm =
171 (rm >> (64 - (DP_MBITS + 1 + 3 + 1))) |
172 ((rm << (DP_MBITS + 1 + 3 + 1)) != 0);
173 }
174 assert(rm & (DP_HIDDEN_BIT << 3));
175 DPNORMRET2(rs, re, rm, "mul", x, y);
176 }
177}