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-rw-r--r--arch/mips/math-emu/sp_sqrt.c117
1 files changed, 117 insertions, 0 deletions
diff --git a/arch/mips/math-emu/sp_sqrt.c b/arch/mips/math-emu/sp_sqrt.c
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index 000000000000..8a934b9f7eb8
--- /dev/null
+++ b/arch/mips/math-emu/sp_sqrt.c
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1/* IEEE754 floating point arithmetic
2 * single precision square root
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_sqrt(ieee754sp x)
31{
32 int ix, s, q, m, t, i;
33 unsigned int r;
34 COMPXSP;
35
36 /* take care of Inf and NaN */
37
38 EXPLODEXSP;
39 CLEARCX;
40 FLUSHXSP;
41
42 /* x == INF or NAN? */
43 switch (xc) {
44 case IEEE754_CLASS_QNAN:
45 /* sqrt(Nan) = Nan */
46 return ieee754sp_nanxcpt(x, "sqrt");
47 case IEEE754_CLASS_SNAN:
48 SETCX(IEEE754_INVALID_OPERATION);
49 return ieee754sp_nanxcpt(ieee754sp_indef(), "sqrt");
50 case IEEE754_CLASS_ZERO:
51 /* sqrt(0) = 0 */
52 return x;
53 case IEEE754_CLASS_INF:
54 if (xs) {
55 /* sqrt(-Inf) = Nan */
56 SETCX(IEEE754_INVALID_OPERATION);
57 return ieee754sp_nanxcpt(ieee754sp_indef(), "sqrt");
58 }
59 /* sqrt(+Inf) = Inf */
60 return x;
61 case IEEE754_CLASS_DNORM:
62 case IEEE754_CLASS_NORM:
63 if (xs) {
64 /* sqrt(-x) = Nan */
65 SETCX(IEEE754_INVALID_OPERATION);
66 return ieee754sp_nanxcpt(ieee754sp_indef(), "sqrt");
67 }
68 break;
69 }
70
71 ix = x.bits;
72
73 /* normalize x */
74 m = (ix >> 23);
75 if (m == 0) { /* subnormal x */
76 for (i = 0; (ix & 0x00800000) == 0; i++)
77 ix <<= 1;
78 m -= i - 1;
79 }
80 m -= 127; /* unbias exponent */
81 ix = (ix & 0x007fffff) | 0x00800000;
82 if (m & 1) /* odd m, double x to make it even */
83 ix += ix;
84 m >>= 1; /* m = [m/2] */
85
86 /* generate sqrt(x) bit by bit */
87 ix += ix;
88 q = s = 0; /* q = sqrt(x) */
89 r = 0x01000000; /* r = moving bit from right to left */
90
91 while (r != 0) {
92 t = s + r;
93 if (t <= ix) {
94 s = t + r;
95 ix -= t;
96 q += r;
97 }
98 ix += ix;
99 r >>= 1;
100 }
101
102 if (ix != 0) {
103 SETCX(IEEE754_INEXACT);
104 switch (ieee754_csr.rm) {
105 case IEEE754_RP:
106 q += 2;
107 break;
108 case IEEE754_RN:
109 q += (q & 1);
110 break;
111 }
112 }
113 ix = (q >> 1) + 0x3f000000;
114 ix += (m << 23);
115 x.bits = ix;
116 return x;
117}