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 | */ |

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 | */ |

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 | */ |

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 |