Quelle fixp-arith.h Sprache: C

/* 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

quality95%

¤ Dauer der Verarbeitung: 0.4 Sekunden ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.