px4-firmware/nuttx/lib/math/lib_b16sin.c

111 lines
3.5 KiB
C

/****************************************************************************
* lib/math/lib_b16sin.c
*
* Copyright (C) 2008, 2011 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* 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;
}