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review.evervolv.com / android_kernel_htc_msm8960 / 124b51c7a8a2b47f1c4739905a28ab3ea5f17faa / . / arch / mips / math-emu / sp_mul.c
blob: 3f070f82212f629479c3e1769079e9e1d14d375e [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.
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 "ieee754sp.h"
29
30ieee754sp ieee754sp_mul(ieee754sp x, ieee754sp y)
31{
32 COMPXSP;
33 COMPYSP;
34
35 EXPLODEXSP;
36 EXPLODEYSP;
37
38 CLEARCX;
39
40 FLUSHXSP;
41 FLUSHYSP;
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 ieee754sp_nanxcpt(ieee754sp_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 ieee754sp_xcpt(ieee754sp_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 ieee754sp_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 ieee754sp_zero(xs ^ ys);
92
93
94 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
95 SPDNORMX;
96
97 case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
98 SPDNORMY;
99 break;
100
101 case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
102 SPDNORMX;
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 & SP_HIDDEN_BIT);
110 assert(ym & SP_HIDDEN_BIT);
111
112 {
113 int re = xe + ye;
114 int rs = xs ^ ys;
115 unsigned rm;
116
117 /* shunt to top of word */
118 xm <<= 32 - (SP_MBITS + 1);
119 ym <<= 32 - (SP_MBITS + 1);
120
121 /* multiply 32bits xm,ym to give high 32bits rm with stickness
122 */
123 {
124 unsigned short lxm = xm & 0xffff;
125 unsigned short hxm = xm >> 16;
126 unsigned short lym = ym & 0xffff;
127 unsigned short hym = ym >> 16;
128 unsigned lrm;
129 unsigned hrm;
130
131 lrm = lxm * lym; /* 16 * 16 => 32 */
132 hrm = hxm * hym; /* 16 * 16 => 32 */
133
134 {
135 unsigned t = lxm * hym; /* 16 * 16 => 32 */
136 {
137 unsigned at = lrm + (t << 16);
138 hrm += at < lrm;
139 lrm = at;
140 }
141 hrm = hrm + (t >> 16);
142 }
143
144 {
145 unsigned t = hxm * lym; /* 16 * 16 => 32 */
146 {
147 unsigned at = lrm + (t << 16);
148 hrm += at < lrm;
149 lrm = at;
150 }
151 hrm = hrm + (t >> 16);
152 }
153 rm = hrm | (lrm != 0);
154 }
155
156 /*
157 * sticky shift down to normal rounding precision
158 */
159 if ((int) rm < 0) {
160 rm = (rm >> (32 - (SP_MBITS + 1 + 3))) |
161 ((rm << (SP_MBITS + 1 + 3)) != 0);
162 re++;
163 } else {
164 rm = (rm >> (32 - (SP_MBITS + 1 + 3 + 1))) |
165 ((rm << (SP_MBITS + 1 + 3 + 1)) != 0);
166 }
167 assert(rm & (SP_HIDDEN_BIT << 3));
168
169 SPNORMRET2(rs, re, rm, "mul", x, y);
170 }
171}