1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
2 | #ifndef _FIXP_ARITH_H |
3 | #define _FIXP_ARITH_H |
4 | |
5 | #include <linux/bug.h> |
6 | #include <linux/math64.h> |
7 | |
8 | /* |
9 | * Simplistic fixed-point arithmetics. |
10 | * Hmm, I'm probably duplicating some code :( |
11 | * |
12 | * Copyright (c) 2002 Johann Deneux |
13 | */ |
14 | |
15 | /* |
16 | * |
17 | * Should you need to contact me, the author, you can do so by |
18 | * e-mail - mail your message to <johann.deneux@gmail.com> |
19 | */ |
20 | |
21 | #include <linux/types.h> |
22 | |
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 | }; |
41 | |
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; |
53 | |
54 | if (degrees > 180) { |
55 | negative = true; |
56 | degrees -= 180; |
57 | } |
58 | if (degrees > 90) |
59 | degrees = 180 - degrees; |
60 | |
61 | ret = sin_table[degrees]; |
62 | |
63 | return negative ? -ret : ret; |
64 | } |
65 | |
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) |
74 | { |
75 | degrees = (degrees % 360 + 360) % 360; |
76 | |
77 | return __fixp_sin32(degrees); |
78 | } |
79 | |
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) |
114 | { |
115 | int degrees; |
116 | s32 v1, v2, dx, dy; |
117 | s64 tmp; |
118 | |
119 | /* |
120 | * Avoid too large values for twopi, as we don't want overflows. |
121 | */ |
122 | BUG_ON(twopi > 1 << 18); |
123 | |
124 | degrees = (radians * 360) / twopi; |
125 | tmp = radians - (degrees * twopi) / 360; |
126 | |
127 | degrees = (degrees % 360 + 360) % 360; |
128 | v1 = __fixp_sin32(degrees); |
129 | |
130 | v2 = fixp_sin32(degrees: degrees + 1); |
131 | |
132 | dx = twopi / 360; |
133 | dy = v2 - v1; |
134 | |
135 | tmp *= dy; |
136 | |
137 | return v1 + div_s64(dividend: tmp, divisor: dx); |
138 | } |
139 | |
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 | |
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 | |
164 | #endif |
165 | |