/* SPDX-License-Identifier: GPL-2.0-or-later */ #ifndef _FIXP_ARITH_H #define _FIXP_ARITH_H #include <linux/bug.h> #include <linux/math64.h> /* * Simplistic fixed-point arithmetics. * Hmm, I'm probably duplicating some code :( * * Copyright (c) 2002 Johann Deneux */ /* * * Should you need to contact me, the author, you can do so by * e-mail - mail your message to <[email protected]> */ #include <linux/types.h> static const s32 sin_table[] = …; /** * __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) { … } /** * 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) { … } /* cos(x) = sin(x + 90 degrees) */ #define fixp_cos32(v) … /* * 16 bits variants * * The returned value ranges from -0x7fff to 0x7fff */ #define fixp_sin16(v) … #define fixp_cos16(v) … /** * 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) { … } /* cos(x) = sin(x + pi/2 radians) */ #define fixp_cos32_rad(rad, twopi) … /** * fixp_linear_interpolate() - interpolates a value from two known points * * @x0: x value of point 0 * @y0: y value of point 0 * @x1: x value of point 1 * @y1: y value of point 1 * @x: the linear interpolant */ static inline int fixp_linear_interpolate(int x0, int y0, int x1, int y1, int x) { … } #endif
Codebase Browser
linux