diff options
Diffstat (limited to 'include/linux/fixp-arith.h')
| -rw-r--r-- | include/linux/fixp-arith.h | 145 |
1 files changed, 107 insertions, 38 deletions
diff --git a/include/linux/fixp-arith.h b/include/linux/fixp-arith.h index 3089d7382325..d4686fe1cac7 100644 --- a/include/linux/fixp-arith.h +++ b/include/linux/fixp-arith.h @@ -1,6 +1,8 @@ #ifndef _FIXP_ARITH_H #define _FIXP_ARITH_H +#include <linux/math64.h> + /* * Simplistic fixed-point arithmetics. * Hmm, I'm probably duplicating some code :( @@ -29,59 +31,126 @@ #include <linux/types.h> -/* The type representing fixed-point values */ -typedef s16 fixp_t; +static const s32 sin_table[] = { + 0x00000000, 0x023be165, 0x04779632, 0x06b2f1d2, 0x08edc7b6, 0x0b27eb5c, + 0x0d61304d, 0x0f996a26, 0x11d06c96, 0x14060b67, 0x163a1a7d, 0x186c6ddd, + 0x1a9cd9ac, 0x1ccb3236, 0x1ef74bf2, 0x2120fb82, 0x234815ba, 0x256c6f9e, + 0x278dde6e, 0x29ac379f, 0x2bc750e8, 0x2ddf003f, 0x2ff31bdd, 0x32037a44, + 0x340ff241, 0x36185aee, 0x381c8bb5, 0x3a1c5c56, 0x3c17a4e7, 0x3e0e3ddb, + 0x3fffffff, 0x41ecc483, 0x43d464fa, 0x45b6bb5d, 0x4793a20f, 0x496af3e1, + 0x4b3c8c11, 0x4d084650, 0x4ecdfec6, 0x508d9210, 0x5246dd48, 0x53f9be04, + 0x55a6125a, 0x574bb8e5, 0x58ea90c2, 0x5a827999, 0x5c135399, 0x5d9cff82, + 0x5f1f5ea0, 0x609a52d1, 0x620dbe8a, 0x637984d3, 0x64dd894f, 0x6639b039, + 0x678dde6d, 0x68d9f963, 0x6a1de735, 0x6b598ea1, 0x6c8cd70a, 0x6db7a879, + 0x6ed9eba0, 0x6ff389de, 0x71046d3c, 0x720c8074, 0x730baeec, 0x7401e4bf, + 0x74ef0ebb, 0x75d31a5f, 0x76adf5e5, 0x777f903b, 0x7847d908, 0x7906c0af, + 0x79bc384c, 0x7a6831b8, 0x7b0a9f8c, 0x7ba3751c, 0x7c32a67c, 0x7cb82884, + 0x7d33f0c8, 0x7da5f5a3, 0x7e0e2e31, 0x7e6c924f, 0x7ec11aa3, 0x7f0bc095, + 0x7f4c7e52, 0x7f834ecf, 0x7fb02dc4, 0x7fd317b3, 0x7fec09e1, 0x7ffb025e, + 0x7fffffff +}; -#define FRAC_N 8 -#define FRAC_MASK ((1<<FRAC_N)-1) +/** + * __fixp_sin32() returns the sin of an angle in degrees + * + * @degrees: angle, in degrees, from 0 to 360. + * + * The returned value ranges from -0x7fffffff to +0x7fffffff. + */ +static inline s32 __fixp_sin32(int degrees) +{ + s32 ret; + bool negative = false; -/* Not to be used directly. Use fixp_{cos,sin} */ -static const fixp_t cos_table[46] = { - 0x0100, 0x00FF, 0x00FF, 0x00FE, 0x00FD, 0x00FC, 0x00FA, 0x00F8, - 0x00F6, 0x00F3, 0x00F0, 0x00ED, 0x00E9, 0x00E6, 0x00E2, 0x00DD, - 0x00D9, 0x00D4, 0x00CF, 0x00C9, 0x00C4, 0x00BE, 0x00B8, 0x00B1, - 0x00AB, 0x00A4, 0x009D, 0x0096, 0x008F, 0x0087, 0x0080, 0x0078, - 0x0070, 0x0068, 0x005F, 0x0057, 0x004F, 0x0046, 0x003D, 0x0035, - 0x002C, 0x0023, 0x001A, 0x0011, 0x0008, 0x0000 -}; + if (degrees > 180) { + negative = true; + degrees -= 180; + } + if (degrees > 90) + degrees = 180 - degrees; + ret = sin_table[degrees]; -/* a: 123 -> 123.0 */ -static inline fixp_t fixp_new(s16 a) -{ - return a<<FRAC_N; + return negative ? -ret : ret; } -/* a: 0xFFFF -> -1.0 - 0x8000 -> 1.0 - 0x0000 -> 0.0 -*/ -static inline fixp_t fixp_new16(s16 a) +/** + * fixp_sin32() returns the sin of an angle in degrees + * + * @degrees: angle, in degrees. The angle can be positive or negative + * + * The returned value ranges from -0x7fffffff to +0x7fffffff. + */ +static inline s32 fixp_sin32(int degrees) { - return ((s32)a)>>(16-FRAC_N); + degrees = (degrees % 360 + 360) % 360; + + return __fixp_sin32(degrees); } -static inline fixp_t fixp_cos(unsigned int degrees) +/* cos(x) = sin(x + 90 degrees) */ +#define fixp_cos32(v) fixp_sin32((v) + 90) + +/* + * 16 bits variants + * + * The returned value ranges from -0x7fff to 0x7fff + */ + +#define fixp_sin16(v) (fixp_sin32(v) >> 16) +#define fixp_cos16(v) (fixp_cos32(v) >> 16) + +/** + * fixp_sin32_rad() - calculates the sin of an angle in radians + * + * @radians: angle, in radians + * @twopi: value to be used for 2*pi + * + * Provides a variant for the cases where just 360 + * values is not enough. This function uses linear + * interpolation to a wider range of values given by + * twopi var. + * + * Experimental tests gave a maximum difference of + * 0.000038 between the value calculated by sin() and + * the one produced by this function, when twopi is + * equal to 360000. That seems to be enough precision + * for practical purposes. + * + * Please notice that two high numbers for twopi could cause + * overflows, so the routine will not allow values of twopi + * bigger than 1^18. + */ +static inline s32 fixp_sin32_rad(u32 radians, u32 twopi) { - int quadrant = (degrees / 90) & 3; - unsigned int i = degrees % 90; + int degrees; + s32 v1, v2, dx, dy; + s64 tmp; - if (quadrant == 1 || quadrant == 3) - i = 90 - i; + /* + * Avoid too large values for twopi, as we don't want overflows. + */ + BUG_ON(twopi > 1 << 18); - i >>= 1; + degrees = (radians * 360) / twopi; + tmp = radians - (degrees * twopi) / 360; - return (quadrant == 1 || quadrant == 2)? -cos_table[i] : cos_table[i]; -} + degrees = (degrees % 360 + 360) % 360; + v1 = __fixp_sin32(degrees); -static inline fixp_t fixp_sin(unsigned int degrees) -{ - return -fixp_cos(degrees + 90); -} + v2 = fixp_sin32(degrees + 1); -static inline fixp_t fixp_mult(fixp_t a, fixp_t b) -{ - return ((s32)(a*b))>>FRAC_N; + dx = twopi / 360; + dy = v2 - v1; + + tmp *= dy; + + return v1 + div_s64(tmp, dx); } +/* cos(x) = sin(x + pi/2 radians) */ + +#define fixp_cos32_rad(rad, twopi) \ + fixp_sin32_rad(rad + twopi / 4, twopi) + #endif |