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1da177e4 LT |
1 | #ifndef _FIXP_ARITH_H |
2 | #define _FIXP_ARITH_H | |
3 | ||
559addc2 MCC |
4 | #include <linux/math64.h> |
5 | ||
1da177e4 | 6 | /* |
1da177e4 LT |
7 | * Simplistic fixed-point arithmetics. |
8 | * Hmm, I'm probably duplicating some code :( | |
9 | * | |
10 | * Copyright (c) 2002 Johann Deneux | |
11 | */ | |
12 | ||
13 | /* | |
14 | * This program is free software; you can redistribute it and/or modify | |
15 | * it under the terms of the GNU General Public License as published by | |
16 | * the Free Software Foundation; either version 2 of the License, or | |
17 | * (at your option) any later version. | |
18 | * | |
19 | * This program is distributed in the hope that it will be useful, | |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
22 | * GNU General Public License for more details. | |
23 | * | |
24 | * You should have received a copy of the GNU General Public License | |
25 | * along with this program; if not, write to the Free Software | |
26 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
27 | * | |
28 | * Should you need to contact me, the author, you can do so by | |
118e78d1 | 29 | * e-mail - mail your message to <johann.deneux@gmail.com> |
1da177e4 LT |
30 | */ |
31 | ||
32 | #include <linux/types.h> | |
33 | ||
559addc2 MCC |
34 | static const s32 sin_table[] = { |
35 | 0x00000000, 0x023be165, 0x04779632, 0x06b2f1d2, 0x08edc7b6, 0x0b27eb5c, | |
36 | 0x0d61304d, 0x0f996a26, 0x11d06c96, 0x14060b67, 0x163a1a7d, 0x186c6ddd, | |
37 | 0x1a9cd9ac, 0x1ccb3236, 0x1ef74bf2, 0x2120fb82, 0x234815ba, 0x256c6f9e, | |
38 | 0x278dde6e, 0x29ac379f, 0x2bc750e8, 0x2ddf003f, 0x2ff31bdd, 0x32037a44, | |
39 | 0x340ff241, 0x36185aee, 0x381c8bb5, 0x3a1c5c56, 0x3c17a4e7, 0x3e0e3ddb, | |
40 | 0x3fffffff, 0x41ecc483, 0x43d464fa, 0x45b6bb5d, 0x4793a20f, 0x496af3e1, | |
41 | 0x4b3c8c11, 0x4d084650, 0x4ecdfec6, 0x508d9210, 0x5246dd48, 0x53f9be04, | |
42 | 0x55a6125a, 0x574bb8e5, 0x58ea90c2, 0x5a827999, 0x5c135399, 0x5d9cff82, | |
43 | 0x5f1f5ea0, 0x609a52d1, 0x620dbe8a, 0x637984d3, 0x64dd894f, 0x6639b039, | |
44 | 0x678dde6d, 0x68d9f963, 0x6a1de735, 0x6b598ea1, 0x6c8cd70a, 0x6db7a879, | |
45 | 0x6ed9eba0, 0x6ff389de, 0x71046d3c, 0x720c8074, 0x730baeec, 0x7401e4bf, | |
46 | 0x74ef0ebb, 0x75d31a5f, 0x76adf5e5, 0x777f903b, 0x7847d908, 0x7906c0af, | |
47 | 0x79bc384c, 0x7a6831b8, 0x7b0a9f8c, 0x7ba3751c, 0x7c32a67c, 0x7cb82884, | |
48 | 0x7d33f0c8, 0x7da5f5a3, 0x7e0e2e31, 0x7e6c924f, 0x7ec11aa3, 0x7f0bc095, | |
49 | 0x7f4c7e52, 0x7f834ecf, 0x7fb02dc4, 0x7fd317b3, 0x7fec09e1, 0x7ffb025e, | |
50 | 0x7fffffff | |
51 | }; | |
1da177e4 | 52 | |
559addc2 MCC |
53 | /** |
54 | * __fixp_sin32() returns the sin of an angle in degrees | |
55 | * | |
56 | * @degrees: angle, in degrees, from 0 to 360. | |
57 | * | |
58 | * The returned value ranges from -0x7fffffff to +0x7fffffff. | |
59 | */ | |
60 | static inline s32 __fixp_sin32(int degrees) | |
61 | { | |
62 | s32 ret; | |
63 | bool negative = false; | |
1da177e4 | 64 | |
559addc2 MCC |
65 | if (degrees > 180) { |
66 | negative = true; | |
67 | degrees -= 180; | |
68 | } | |
69 | if (degrees > 90) | |
70 | degrees = 180 - degrees; | |
1da177e4 | 71 | |
559addc2 | 72 | ret = sin_table[degrees]; |
1da177e4 | 73 | |
559addc2 | 74 | return negative ? -ret : ret; |
1da177e4 LT |
75 | } |
76 | ||
559addc2 MCC |
77 | /** |
78 | * fixp_sin32() returns the sin of an angle in degrees | |
79 | * | |
80 | * @degrees: angle, in degrees. The angle can be positive or negative | |
81 | * | |
82 | * The returned value ranges from -0x7fffffff to +0x7fffffff. | |
83 | */ | |
84 | static inline s32 fixp_sin32(int degrees) | |
1da177e4 | 85 | { |
559addc2 MCC |
86 | degrees = (degrees % 360 + 360) % 360; |
87 | ||
88 | return __fixp_sin32(degrees); | |
1da177e4 LT |
89 | } |
90 | ||
559addc2 MCC |
91 | /* cos(x) = sin(x + 90 degrees) */ |
92 | #define fixp_cos32(v) fixp_sin32((v) + 90) | |
93 | ||
94 | /* | |
95 | * 16 bits variants | |
96 | * | |
97 | * The returned value ranges from -0x7fff to 0x7fff | |
98 | */ | |
99 | ||
100 | #define fixp_sin16(v) (fixp_sin32(v) >> 16) | |
101 | #define fixp_cos16(v) (fixp_cos32(v) >> 16) | |
102 | ||
103 | /** | |
104 | * fixp_sin32_rad() - calculates the sin of an angle in radians | |
105 | * | |
106 | * @radians: angle, in radians | |
107 | * @twopi: value to be used for 2*pi | |
108 | * | |
109 | * Provides a variant for the cases where just 360 | |
110 | * values is not enough. This function uses linear | |
111 | * interpolation to a wider range of values given by | |
112 | * twopi var. | |
113 | * | |
114 | * Experimental tests gave a maximum difference of | |
115 | * 0.000038 between the value calculated by sin() and | |
116 | * the one produced by this function, when twopi is | |
117 | * equal to 360000. That seems to be enough precision | |
118 | * for practical purposes. | |
119 | * | |
120 | * Please notice that two high numbers for twopi could cause | |
121 | * overflows, so the routine will not allow values of twopi | |
122 | * bigger than 1^18. | |
123 | */ | |
124 | static inline s32 fixp_sin32_rad(u32 radians, u32 twopi) | |
1da177e4 | 125 | { |
559addc2 MCC |
126 | int degrees; |
127 | s32 v1, v2, dx, dy; | |
128 | s64 tmp; | |
1da177e4 | 129 | |
559addc2 MCC |
130 | /* |
131 | * Avoid too large values for twopi, as we don't want overflows. | |
132 | */ | |
133 | BUG_ON(twopi > 1 << 18); | |
1da177e4 | 134 | |
559addc2 MCC |
135 | degrees = (radians * 360) / twopi; |
136 | tmp = radians - (degrees * twopi) / 360; | |
1da177e4 | 137 | |
559addc2 MCC |
138 | degrees = (degrees % 360 + 360) % 360; |
139 | v1 = __fixp_sin32(degrees); | |
1da177e4 | 140 | |
559addc2 | 141 | v2 = fixp_sin32(degrees + 1); |
1da177e4 | 142 | |
559addc2 MCC |
143 | dx = twopi / 360; |
144 | dy = v2 - v1; | |
145 | ||
146 | tmp *= dy; | |
147 | ||
148 | return v1 + div_s64(tmp, dx); | |
1da177e4 LT |
149 | } |
150 | ||
559addc2 MCC |
151 | /* cos(x) = sin(x + pi/2 radians) */ |
152 | ||
153 | #define fixp_cos32_rad(rad, twopi) \ | |
154 | fixp_sin32_rad(rad + twopi / 4, twopi) | |
155 | ||
1da177e4 | 156 | #endif |