1 #ifndef _FIXP_ARITH_H 2 #define _FIXP_ARITH_H 3 4 #include <linux/math64.h> 5 6 /* 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 29 * e-mail - mail your message to <johann.deneux@gmail.com> 30 */ 31 32 #include <linux/types.h> 33 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 }; 52 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 */ __fixp_sin32(int degrees)60 static inline s32 __fixp_sin32(int degrees) 61 { 62 s32 ret; 63 bool negative = false; 64 65 if (degrees > 180) { 66 negative = true; 67 degrees -= 180; 68 } 69 if (degrees > 90) 70 degrees = 180 - degrees; 71 72 ret = sin_table[degrees]; 73 74 return negative ? -ret : ret; 75 } 76 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 */ fixp_sin32(int degrees)84 static inline s32 fixp_sin32(int degrees) 85 { 86 degrees = (degrees % 360 + 360) % 360; 87 88 return __fixp_sin32(degrees); 89 } 90 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 */ fixp_sin32_rad(u32 radians,u32 twopi)124 static inline s32 fixp_sin32_rad(u32 radians, u32 twopi) 125 { 126 int degrees; 127 s32 v1, v2, dx, dy; 128 s64 tmp; 129 130 /* 131 * Avoid too large values for twopi, as we don't want overflows. 132 */ 133 BUG_ON(twopi > 1 << 18); 134 135 degrees = (radians * 360) / twopi; 136 tmp = radians - (degrees * twopi) / 360; 137 138 degrees = (degrees % 360 + 360) % 360; 139 v1 = __fixp_sin32(degrees); 140 141 v2 = fixp_sin32(degrees + 1); 142 143 dx = twopi / 360; 144 dy = v2 - v1; 145 146 tmp *= dy; 147 148 return v1 + div_s64(tmp, dx); 149 } 150 151 /* cos(x) = sin(x + pi/2 radians) */ 152 153 #define fixp_cos32_rad(rad, twopi) \ 154 fixp_sin32_rad(rad + twopi / 4, twopi) 155 156 #endif 157