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/* 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 <johann.deneux@gmail.com>
*/
#include <linux/types.h>
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
};
/**
* __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;
if (degrees > 180) {
negative = true;
degrees -= 180;
}
if (degrees > 90)
degrees = 180 - degrees;
ret = sin_table[degrees];
return negative ? -ret : ret;
}
/**
* 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)
{
degrees = (degrees % 360 + 360) % 360;
return __fixp_sin32(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 degrees;
s32 v1, v2, dx, dy;
s64 tmp;
/*
* Avoid too large values for twopi, as we don't want overflows.
*/
BUG_ON(twopi > 1 << 18);
degrees = (radians * 360) / twopi;
tmp = radians - (degrees * twopi) / 360;
degrees = (degrees % 360 + 360) % 360;
v1 = __fixp_sin32(degrees);
v2 = fixp_sin32(degrees + 1);
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)
/**
* 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)
{
if (y0 == y1 || x == x0)
return y0;
if (x1 == x0 || x == x1)
return y1;
return y0 + ((y1 - y0) * (x - x0) / (x1 - x0));
}
#endif
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