forked from Archive/PX4-Autopilot
111 lines
3.5 KiB
C
111 lines
3.5 KiB
C
|
/****************************************************************************
|
||
|
|
* lib/math/lib_b16sin.c
|
||
|
|
*
|
||
|
|
* Copyright (C) 2008, 2011 Gregory Nutt. All rights reserved.
|
||
|
|
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
|
||
|
|
*
|
||
|
|
* Redistribution and use in source and binary forms, with or without
|
||
|
|
* modification, are permitted provided that the following conditions
|
||
|
|
* are met:
|
||
|
|
*
|
||
|
|
* 1. Redistributions of source code must retain the above copyright
|
||
|
|
* notice, this list of conditions and the following disclaimer.
|
||
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
||
|
|
* notice, this list of conditions and the following disclaimer in
|
||
|
|
* the documentation and/or other materials provided with the
|
||
|
|
* distribution.
|
||
|
|
* 3. Neither the name NuttX nor the names of its contributors may be
|
||
|
|
* used to endorse or promote products derived from this software
|
||
|
|
* without specific prior written permission.
|
||
|
|
*
|
||
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
||
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
||
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
|
||
|
|
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
|
||
|
|
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
|
||
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
|
||
|
|
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
|
||
|
|
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
|
||
|
|
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
||
|
|
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
|
||
|
|
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
||
|
|
* POSSIBILITY OF SUCH DAMAGE.
|
||
|
|
*
|
||
|
|
****************************************************************************/
|
||
|
|
|
||
|
|
/****************************************************************************
|
||
|
|
* Included Files
|
||
|
|
****************************************************************************/
|
||
|
|
|
||
|
|
#include <fixedmath.h>
|
||
|
|
|
||
|
|
/****************************************************************************
|
||
|
|
* Pre-processor Definitions
|
||
|
|
****************************************************************************/
|
||
|
|
|
||
|
|
#define b16_P225 0x0000399a
|
||
|
|
#define b16_P405284735 0x000067c1
|
||
|
|
#define b16_1P27323954 0x000145f3
|
||
|
|
|
||
|
|
/****************************************************************************
|
||
|
|
* Global Functions
|
||
|
|
****************************************************************************/
|
||
|
|
|
||
|
|
/****************************************************************************
|
||
|
|
* Name: b16sin
|
||
|
|
* Ref: http://lab.polygonal.de/2007/07/18/fast-and-accurate-sinecosine-approximation/
|
||
|
|
****************************************************************************/
|
||
|
|
|
||
|
|
b16_t b16sin(b16_t rad)
|
||
|
|
{
|
||
|
|
b16_t tmp1;
|
||
|
|
b16_t tmp2;
|
||
|
|
b16_t tmp3;
|
||
|
|
|
||
|
|
/* Force angle into the good range */
|
||
|
|
|
||
|
|
if (rad < -b16PI)
|
||
|
|
{
|
||
|
|
rad += b16TWOPI;
|
||
|
|
}
|
||
|
|
else if (rad > b16PI)
|
||
|
|
{
|
||
|
|
rad -= b16TWOPI;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* tmp1 = 1.27323954 * rad
|
||
|
|
* tmp2 = .405284735 * rad * rad
|
||
|
|
*/
|
||
|
|
|
||
|
|
|
||
|
|
tmp1 = b16mulb16(b16_1P27323954, rad);
|
||
|
|
tmp2 = b16mulb16(b16_P405284735, b16sqr(rad));
|
||
|
|
|
||
|
|
if (rad < 0)
|
||
|
|
{
|
||
|
|
/* tmp3 = 1.27323954 * rad + .405284735 * rad * rad */
|
||
|
|
|
||
|
|
tmp3 = tmp1 + tmp2;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
/* tmp3 = 1.27323954 * rad - 0.405284735 * rad * rad */
|
||
|
|
|
||
|
|
tmp3 = tmp1 - tmp2;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* tmp1 = tmp3*tmp3 */
|
||
|
|
|
||
|
|
tmp1 = b16sqr(tmp3);
|
||
|
|
if (tmp3 < 0)
|
||
|
|
{
|
||
|
|
/* tmp1 = tmp3 * -tmp3 */
|
||
|
|
|
||
|
|
tmp1 = -tmp1;
|
||
|
|
}
|
||
|
|
|
||
|
|
/* Return sin = .225 * (tmp3 * (+/-tmp3) - tmp3) + tmp3 */
|
||
|
|
|
||
|
|
return b16mulb16(b16_P225, (tmp1 - tmp3)) + tmp3;
|
||
|
|
}
|