diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /arch/mips/math-emu/sp_sqrt.c |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'arch/mips/math-emu/sp_sqrt.c')
-rw-r--r-- | arch/mips/math-emu/sp_sqrt.c | 117 |
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 new file mode 100644 index 000000000000..8a934b9f7eb8 --- /dev/null +++ b/arch/mips/math-emu/sp_sqrt.c | |||
@@ -0,0 +1,117 @@ | |||
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 | |||
30 | ieee754sp 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 | } | ||