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1a59d1b8 | 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
1da177e4 LT |
2 | #ifndef _FIXP_ARITH_H |
3 | #define _FIXP_ARITH_H | |
4 | ||
5e7a0af7 | 5 | #include <linux/bug.h> |
559addc2 MCC |
6 | #include <linux/math64.h> |
7 | ||
1da177e4 | 8 | /* |
1da177e4 LT |
9 | * Simplistic fixed-point arithmetics. |
10 | * Hmm, I'm probably duplicating some code :( | |
11 | * | |
12 | * Copyright (c) 2002 Johann Deneux | |
13 | */ | |
14 | ||
15 | /* | |
1da177e4 LT |
16 | * |
17 | * Should you need to contact me, the author, you can do so by | |
118e78d1 | 18 | * e-mail - mail your message to <johann.deneux@gmail.com> |
1da177e4 LT |
19 | */ |
20 | ||
21 | #include <linux/types.h> | |
22 | ||
559addc2 MCC |
23 | static const s32 sin_table[] = { |
24 | 0x00000000, 0x023be165, 0x04779632, 0x06b2f1d2, 0x08edc7b6, 0x0b27eb5c, | |
25 | 0x0d61304d, 0x0f996a26, 0x11d06c96, 0x14060b67, 0x163a1a7d, 0x186c6ddd, | |
26 | 0x1a9cd9ac, 0x1ccb3236, 0x1ef74bf2, 0x2120fb82, 0x234815ba, 0x256c6f9e, | |
27 | 0x278dde6e, 0x29ac379f, 0x2bc750e8, 0x2ddf003f, 0x2ff31bdd, 0x32037a44, | |
28 | 0x340ff241, 0x36185aee, 0x381c8bb5, 0x3a1c5c56, 0x3c17a4e7, 0x3e0e3ddb, | |
29 | 0x3fffffff, 0x41ecc483, 0x43d464fa, 0x45b6bb5d, 0x4793a20f, 0x496af3e1, | |
30 | 0x4b3c8c11, 0x4d084650, 0x4ecdfec6, 0x508d9210, 0x5246dd48, 0x53f9be04, | |
31 | 0x55a6125a, 0x574bb8e5, 0x58ea90c2, 0x5a827999, 0x5c135399, 0x5d9cff82, | |
32 | 0x5f1f5ea0, 0x609a52d1, 0x620dbe8a, 0x637984d3, 0x64dd894f, 0x6639b039, | |
33 | 0x678dde6d, 0x68d9f963, 0x6a1de735, 0x6b598ea1, 0x6c8cd70a, 0x6db7a879, | |
34 | 0x6ed9eba0, 0x6ff389de, 0x71046d3c, 0x720c8074, 0x730baeec, 0x7401e4bf, | |
35 | 0x74ef0ebb, 0x75d31a5f, 0x76adf5e5, 0x777f903b, 0x7847d908, 0x7906c0af, | |
36 | 0x79bc384c, 0x7a6831b8, 0x7b0a9f8c, 0x7ba3751c, 0x7c32a67c, 0x7cb82884, | |
37 | 0x7d33f0c8, 0x7da5f5a3, 0x7e0e2e31, 0x7e6c924f, 0x7ec11aa3, 0x7f0bc095, | |
38 | 0x7f4c7e52, 0x7f834ecf, 0x7fb02dc4, 0x7fd317b3, 0x7fec09e1, 0x7ffb025e, | |
39 | 0x7fffffff | |
40 | }; | |
1da177e4 | 41 | |
559addc2 MCC |
42 | /** |
43 | * __fixp_sin32() returns the sin of an angle in degrees | |
44 | * | |
45 | * @degrees: angle, in degrees, from 0 to 360. | |
46 | * | |
47 | * The returned value ranges from -0x7fffffff to +0x7fffffff. | |
48 | */ | |
49 | static inline s32 __fixp_sin32(int degrees) | |
50 | { | |
51 | s32 ret; | |
52 | bool negative = false; | |
1da177e4 | 53 | |
559addc2 MCC |
54 | if (degrees > 180) { |
55 | negative = true; | |
56 | degrees -= 180; | |
57 | } | |
58 | if (degrees > 90) | |
59 | degrees = 180 - degrees; | |
1da177e4 | 60 | |
559addc2 | 61 | ret = sin_table[degrees]; |
1da177e4 | 62 | |
559addc2 | 63 | return negative ? -ret : ret; |
1da177e4 LT |
64 | } |
65 | ||
559addc2 MCC |
66 | /** |
67 | * fixp_sin32() returns the sin of an angle in degrees | |
68 | * | |
69 | * @degrees: angle, in degrees. The angle can be positive or negative | |
70 | * | |
71 | * The returned value ranges from -0x7fffffff to +0x7fffffff. | |
72 | */ | |
73 | static inline s32 fixp_sin32(int degrees) | |
1da177e4 | 74 | { |
559addc2 MCC |
75 | degrees = (degrees % 360 + 360) % 360; |
76 | ||
77 | return __fixp_sin32(degrees); | |
1da177e4 LT |
78 | } |
79 | ||
559addc2 MCC |
80 | /* cos(x) = sin(x + 90 degrees) */ |
81 | #define fixp_cos32(v) fixp_sin32((v) + 90) | |
82 | ||
83 | /* | |
84 | * 16 bits variants | |
85 | * | |
86 | * The returned value ranges from -0x7fff to 0x7fff | |
87 | */ | |
88 | ||
89 | #define fixp_sin16(v) (fixp_sin32(v) >> 16) | |
90 | #define fixp_cos16(v) (fixp_cos32(v) >> 16) | |
91 | ||
92 | /** | |
93 | * fixp_sin32_rad() - calculates the sin of an angle in radians | |
94 | * | |
95 | * @radians: angle, in radians | |
96 | * @twopi: value to be used for 2*pi | |
97 | * | |
98 | * Provides a variant for the cases where just 360 | |
99 | * values is not enough. This function uses linear | |
100 | * interpolation to a wider range of values given by | |
101 | * twopi var. | |
102 | * | |
103 | * Experimental tests gave a maximum difference of | |
104 | * 0.000038 between the value calculated by sin() and | |
105 | * the one produced by this function, when twopi is | |
106 | * equal to 360000. That seems to be enough precision | |
107 | * for practical purposes. | |
108 | * | |
109 | * Please notice that two high numbers for twopi could cause | |
110 | * overflows, so the routine will not allow values of twopi | |
111 | * bigger than 1^18. | |
112 | */ | |
113 | static inline s32 fixp_sin32_rad(u32 radians, u32 twopi) | |
1da177e4 | 114 | { |
559addc2 MCC |
115 | int degrees; |
116 | s32 v1, v2, dx, dy; | |
117 | s64 tmp; | |
1da177e4 | 118 | |
559addc2 MCC |
119 | /* |
120 | * Avoid too large values for twopi, as we don't want overflows. | |
121 | */ | |
122 | BUG_ON(twopi > 1 << 18); | |
1da177e4 | 123 | |
559addc2 MCC |
124 | degrees = (radians * 360) / twopi; |
125 | tmp = radians - (degrees * twopi) / 360; | |
1da177e4 | 126 | |
559addc2 MCC |
127 | degrees = (degrees % 360 + 360) % 360; |
128 | v1 = __fixp_sin32(degrees); | |
1da177e4 | 129 | |
559addc2 | 130 | v2 = fixp_sin32(degrees + 1); |
1da177e4 | 131 | |
559addc2 MCC |
132 | dx = twopi / 360; |
133 | dy = v2 - v1; | |
134 | ||
135 | tmp *= dy; | |
136 | ||
137 | return v1 + div_s64(tmp, dx); | |
1da177e4 LT |
138 | } |
139 | ||
559addc2 MCC |
140 | /* cos(x) = sin(x + pi/2 radians) */ |
141 | ||
142 | #define fixp_cos32_rad(rad, twopi) \ | |
143 | fixp_sin32_rad(rad + twopi / 4, twopi) | |
144 | ||
8d502ef6 CT |
145 | /** |
146 | * fixp_linear_interpolate() - interpolates a value from two known points | |
147 | * | |
148 | * @x0: x value of point 0 | |
149 | * @y0: y value of point 0 | |
150 | * @x1: x value of point 1 | |
151 | * @y1: y value of point 1 | |
152 | * @x: the linear interpolant | |
153 | */ | |
154 | static inline int fixp_linear_interpolate(int x0, int y0, int x1, int y1, int x) | |
155 | { | |
156 | if (y0 == y1 || x == x0) | |
157 | return y0; | |
158 | if (x1 == x0 || x == x1) | |
159 | return y1; | |
160 | ||
161 | return y0 + ((y1 - y0) * (x - x0) / (x1 - x0)); | |
162 | } | |
163 | ||
1da177e4 | 164 | #endif |