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gerrit-public.fairphone.software / kernel / msm / b16fed0af8416ee0fe9af6c1977f7b05e7e7c9b2 / . / arch / mips / math-emu / sp_mul.c
blob: c06bb4022be5d742878f29159d5a7ee7e878f227 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]1/* IEEE754 floating point arithmetic
2 * single precision
3 */
4/*
5 * MIPS floating point support
6 * Copyright (C) 1994-2000 Algorithmics Ltd.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]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
29ieee754sp ieee754sp_mul(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(), "mul", 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 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
74 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
75 SETCX(IEEE754_INVALID_OPERATION);
76 return ieee754sp_xcpt(ieee754sp_indef(), "mul", x, y);
77
78 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
79 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
80 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
81 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
82 case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
83 return ieee754sp_inf(xs ^ ys);
84
85 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
86 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
87 case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
88 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
89 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
90 return ieee754sp_zero(xs ^ ys);
91
92
93 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
94 SPDNORMX;
95
96 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
97 SPDNORMY;
98 break;
99
100 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
101 SPDNORMX;
102 break;
103
104 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
105 break;
106 }
107 /* rm = xm * ym, re = xe+ye basicly */
108 assert(xm & SP_HIDDEN_BIT);
109 assert(ym & SP_HIDDEN_BIT);
110
111 {
112 int re = xe + ye;
113 int rs = xs ^ ys;
114 unsigned rm;
115
116 /* shunt to top of word */
117 xm <<= 32 - (SP_MBITS + 1);
118 ym <<= 32 - (SP_MBITS + 1);
119
120 /* multiply 32bits xm,ym to give high 32bits rm with stickness
121 */
122 {
123 unsigned short lxm = xm & 0xffff;
124 unsigned short hxm = xm >> 16;
125 unsigned short lym = ym & 0xffff;
126 unsigned short hym = ym >> 16;
127 unsigned lrm;
128 unsigned hrm;
129
130 lrm = lxm * lym; /* 16 * 16 => 32 */
131 hrm = hxm * hym; /* 16 * 16 => 32 */
132
133 {
134 unsigned t = lxm * hym; /* 16 * 16 => 32 */
135 {
136 unsigned at = lrm + (t << 16);
137 hrm += at < lrm;
138 lrm = at;
139 }
140 hrm = hrm + (t >> 16);
141 }
142
143 {
144 unsigned t = hxm * lym; /* 16 * 16 => 32 */
145 {
146 unsigned at = lrm + (t << 16);
147 hrm += at < lrm;
148 lrm = at;
149 }
150 hrm = hrm + (t >> 16);
151 }
152 rm = hrm | (lrm != 0);
153 }
154
155 /*
156 * sticky shift down to normal rounding precision
157 */
158 if ((int) rm < 0) {
159 rm = (rm >> (32 - (SP_MBITS + 1 + 3))) |
160 ((rm << (SP_MBITS + 1 + 3)) != 0);
161 re++;
162 } else {
163 rm = (rm >> (32 - (SP_MBITS + 1 + 3 + 1))) |
164 ((rm << (SP_MBITS + 1 + 3 + 1)) != 0);
165 }
166 assert(rm & (SP_HIDDEN_BIT << 3));
167
168 SPNORMRET2(rs, re, rm, "mul", x, y);
169 }
170}