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8d502ef682
Adds a function to interpolate against two points, this is carried arount as a helper function by tons of drivers. Signed-off-by: Craig Tatlor <ctatlor97@gmail.com> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> Link: https://lore.kernel.org/r/20201204025509.1075506-3-dmitry.baryshkov@linaro.org Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
164 lines
4.2 KiB
C
164 lines
4.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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#ifndef _FIXP_ARITH_H
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#define _FIXP_ARITH_H
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#include <linux/math64.h>
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/*
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* Simplistic fixed-point arithmetics.
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* Hmm, I'm probably duplicating some code :(
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*
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* Copyright (c) 2002 Johann Deneux
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*/
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/*
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*
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* Should you need to contact me, the author, you can do so by
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* e-mail - mail your message to <johann.deneux@gmail.com>
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*/
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#include <linux/types.h>
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static const s32 sin_table[] = {
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0x00000000, 0x023be165, 0x04779632, 0x06b2f1d2, 0x08edc7b6, 0x0b27eb5c,
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0x0d61304d, 0x0f996a26, 0x11d06c96, 0x14060b67, 0x163a1a7d, 0x186c6ddd,
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0x1a9cd9ac, 0x1ccb3236, 0x1ef74bf2, 0x2120fb82, 0x234815ba, 0x256c6f9e,
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0x278dde6e, 0x29ac379f, 0x2bc750e8, 0x2ddf003f, 0x2ff31bdd, 0x32037a44,
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0x340ff241, 0x36185aee, 0x381c8bb5, 0x3a1c5c56, 0x3c17a4e7, 0x3e0e3ddb,
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0x3fffffff, 0x41ecc483, 0x43d464fa, 0x45b6bb5d, 0x4793a20f, 0x496af3e1,
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0x4b3c8c11, 0x4d084650, 0x4ecdfec6, 0x508d9210, 0x5246dd48, 0x53f9be04,
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0x55a6125a, 0x574bb8e5, 0x58ea90c2, 0x5a827999, 0x5c135399, 0x5d9cff82,
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0x5f1f5ea0, 0x609a52d1, 0x620dbe8a, 0x637984d3, 0x64dd894f, 0x6639b039,
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0x678dde6d, 0x68d9f963, 0x6a1de735, 0x6b598ea1, 0x6c8cd70a, 0x6db7a879,
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0x6ed9eba0, 0x6ff389de, 0x71046d3c, 0x720c8074, 0x730baeec, 0x7401e4bf,
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0x74ef0ebb, 0x75d31a5f, 0x76adf5e5, 0x777f903b, 0x7847d908, 0x7906c0af,
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0x79bc384c, 0x7a6831b8, 0x7b0a9f8c, 0x7ba3751c, 0x7c32a67c, 0x7cb82884,
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0x7d33f0c8, 0x7da5f5a3, 0x7e0e2e31, 0x7e6c924f, 0x7ec11aa3, 0x7f0bc095,
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0x7f4c7e52, 0x7f834ecf, 0x7fb02dc4, 0x7fd317b3, 0x7fec09e1, 0x7ffb025e,
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0x7fffffff
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};
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/**
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* __fixp_sin32() returns the sin of an angle in degrees
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*
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* @degrees: angle, in degrees, from 0 to 360.
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*
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* The returned value ranges from -0x7fffffff to +0x7fffffff.
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*/
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static inline s32 __fixp_sin32(int degrees)
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{
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s32 ret;
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bool negative = false;
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if (degrees > 180) {
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negative = true;
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degrees -= 180;
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}
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if (degrees > 90)
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degrees = 180 - degrees;
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ret = sin_table[degrees];
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return negative ? -ret : ret;
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}
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/**
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* fixp_sin32() returns the sin of an angle in degrees
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*
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* @degrees: angle, in degrees. The angle can be positive or negative
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*
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* The returned value ranges from -0x7fffffff to +0x7fffffff.
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*/
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static inline s32 fixp_sin32(int degrees)
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{
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degrees = (degrees % 360 + 360) % 360;
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return __fixp_sin32(degrees);
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}
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/* cos(x) = sin(x + 90 degrees) */
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#define fixp_cos32(v) fixp_sin32((v) + 90)
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/*
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* 16 bits variants
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*
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* The returned value ranges from -0x7fff to 0x7fff
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*/
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#define fixp_sin16(v) (fixp_sin32(v) >> 16)
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#define fixp_cos16(v) (fixp_cos32(v) >> 16)
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/**
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* fixp_sin32_rad() - calculates the sin of an angle in radians
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*
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* @radians: angle, in radians
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* @twopi: value to be used for 2*pi
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*
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* Provides a variant for the cases where just 360
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* values is not enough. This function uses linear
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* interpolation to a wider range of values given by
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* twopi var.
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*
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* Experimental tests gave a maximum difference of
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* 0.000038 between the value calculated by sin() and
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* the one produced by this function, when twopi is
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* equal to 360000. That seems to be enough precision
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* for practical purposes.
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*
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* Please notice that two high numbers for twopi could cause
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* overflows, so the routine will not allow values of twopi
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* bigger than 1^18.
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*/
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static inline s32 fixp_sin32_rad(u32 radians, u32 twopi)
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{
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int degrees;
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s32 v1, v2, dx, dy;
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s64 tmp;
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/*
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* Avoid too large values for twopi, as we don't want overflows.
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*/
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BUG_ON(twopi > 1 << 18);
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degrees = (radians * 360) / twopi;
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tmp = radians - (degrees * twopi) / 360;
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degrees = (degrees % 360 + 360) % 360;
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v1 = __fixp_sin32(degrees);
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v2 = fixp_sin32(degrees + 1);
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dx = twopi / 360;
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dy = v2 - v1;
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tmp *= dy;
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return v1 + div_s64(tmp, dx);
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}
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/* cos(x) = sin(x + pi/2 radians) */
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#define fixp_cos32_rad(rad, twopi) \
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fixp_sin32_rad(rad + twopi / 4, twopi)
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/**
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* fixp_linear_interpolate() - interpolates a value from two known points
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*
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* @x0: x value of point 0
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* @y0: y value of point 0
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* @x1: x value of point 1
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* @y1: y value of point 1
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* @x: the linear interpolant
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*/
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static inline int fixp_linear_interpolate(int x0, int y0, int x1, int y1, int x)
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{
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if (y0 == y1 || x == x0)
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return y0;
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if (x1 == x0 || x == x1)
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return y1;
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return y0 + ((y1 - y0) * (x - x0) / (x1 - x0));
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}
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#endif
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