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The cos table used at fixp-arith.h has only 8 bits of precision. That causes problems if it is reused on other drivers. As some media drivers require a higher precision sin/cos implementation, replace the current implementation by one that will provide 32 bits precision. The values generated by the new implementation matches the 32 bit precision of glibc's sin for an angle measured in integer degrees. It also provides support for fractional angles via linear interpolation. On experimental calculus, when used a table with a 0.001 degree angle, the maximum error for sin is 0.000038, which is likely good enough for practical purposes. There are some logic there that seems to be specific to the usage inside ff-memless.c. Move those logic to there, as they're not needed elsewhere. Cc: Hans de Goede <hdegoede@redhat.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com> Signed-off-by: Prashant Laddha <prladdha@cisco.com> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com> Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
157 lines
4.4 KiB
C
157 lines
4.4 KiB
C
#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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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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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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#endif
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