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99 lines
3.5 KiB
C
99 lines
3.5 KiB
C
/**
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******************************************************************************
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* @addtogroup OpenPilot Math Utilities
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* @{
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* @addtogroup Sine and cosine methods that use a cached lookup table
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* @{
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*
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* @file sin_lookup.c
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
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* @brief Sine lookup table from flash with 1 degree resolution
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*
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* @see The GNU Public License (GPL) Version 3
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*
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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 3 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, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "math.h"
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#include "stdint.h"
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// This is a precomputed sin lookup table over 90 degrees that
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const float sin_table[] = {
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0.000000f,0.017452f,0.034899f,0.052336f,0.069756f,0.087156f,0.104528f,0.121869f,0.139173f,0.156434f,
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0.173648f,0.190809f,0.207912f,0.224951f,0.241922f,0.258819f,0.275637f,0.292372f,0.309017f,0.325568f,
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0.342020f,0.358368f,0.374607f,0.390731f,0.406737f,0.422618f,0.438371f,0.453990f,0.469472f,0.484810f,
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0.500000f,0.515038f,0.529919f,0.544639f,0.559193f,0.573576f,0.587785f,0.601815f,0.615661f,0.629320f,
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0.642788f,0.656059f,0.669131f,0.681998f,0.694658f,0.707107f,0.719340f,0.731354f,0.743145f,0.754710f,
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0.766044f,0.777146f,0.788011f,0.798636f,0.809017f,0.819152f,0.829038f,0.838671f,0.848048f,0.857167f,
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0.866025f,0.874620f,0.882948f,0.891007f,0.898794f,0.906308f,0.913545f,0.920505f,0.927184f,0.933580f,
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0.939693f,0.945519f,0.951057f,0.956305f,0.961262f,0.965926f,0.970296f,0.974370f,0.978148f,0.981627f,
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0.984808f,0.987688f,0.990268f,0.992546f,0.994522f,0.996195f,0.997564f,0.998630f,0.999391f,0.999848f
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};
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/**
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* Use the lookup table to return sine(angle) where angle is in radians
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* to save flash this cheats and uses trig functions to only save
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* 90 values
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* @param[in] angle Angle in degrees
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* @returns sin(angle)
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*/
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float sin_lookup_deg(float angle)
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{
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int i_ang = ((int32_t) angle) % 360;
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if(i_ang > 270) // for 270 to 360 deg
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return -sin_table[360 - i_ang];
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else if (i_ang > 180) // for 180 to 270 deg
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return -sin_table[i_ang - 180];
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else if (i_ang > 90) // for 90 to 170 deg
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return sin_table[180 - i_ang];
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else // for 0 to 90 deg
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return sin_table[i_ang];
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return 0;
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}
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/**
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* Get cos(angle) using the sine lookup table
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* @param[in] angle Angle in degrees
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* @returns cos(angle)
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*/
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float cos_lookup_deg(float angle)
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{
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return sin_lookup_deg(angle + 90);
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}
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/**
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* Use the lookup table to return sine(angle) where angle is in radians
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* @param[in] angle Angle in radians
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* @returns sin(angle)
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*/
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float sin_lookup_rad(float angle)
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{
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int degrees = angle * 180.0f / M_PI;
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return sin_lookup_deg(degrees);
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}
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/**
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* Use the lookup table to return sine(angle) where angle is in radians
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* @param[in] angle Angle in radians
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* @returns cos(angle)
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*/
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float cos_lookup_rad(float angle)
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{
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int degrees = angle * 180.0f / M_PI;
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return cos_lookup_deg(degrees);
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} |