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Diffstat (limited to 'nuttx/lib/math/lib_b16sin.c')
-rw-r--r-- | nuttx/lib/math/lib_b16sin.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/nuttx/lib/math/lib_b16sin.c b/nuttx/lib/math/lib_b16sin.c new file mode 100644 index 000000000..fc4b5e566 --- /dev/null +++ b/nuttx/lib/math/lib_b16sin.c @@ -0,0 +1,110 @@ +/**************************************************************************** + * 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; +} |