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author | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2008-11-29 01:19:35 +0000 |
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committer | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2008-11-29 01:19:35 +0000 |
commit | 94ade9753269d0a0ba330a4bdb3ec1e5cffe99ac (patch) | |
tree | 66ad16e0cfe1c142988ac63b0596485a94ea0fcc /nuttx/lib | |
parent | 62f15df2d7d7ad3a3bc4a93fbb6e94644f1e0f3f (diff) | |
download | px4-nuttx-94ade9753269d0a0ba330a4bdb3ec1e5cffe99ac.tar.gz px4-nuttx-94ade9753269d0a0ba330a4bdb3ec1e5cffe99ac.tar.bz2 px4-nuttx-94ade9753269d0a0ba330a4bdb3ec1e5cffe99ac.zip |
Add fixed precision sin() and cos()
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@1342 42af7a65-404d-4744-a932-0658087f49c3
Diffstat (limited to 'nuttx/lib')
-rw-r--r-- | nuttx/lib/Makefile | 2 | ||||
-rw-r--r-- | nuttx/lib/lib_b16cos.c | 64 | ||||
-rw-r--r-- | nuttx/lib/lib_b16sin.c | 110 | ||||
-rw-r--r-- | nuttx/lib/lib_fixedmath.c | 47 |
4 files changed, 222 insertions, 1 deletions
diff --git a/nuttx/lib/Makefile b/nuttx/lib/Makefile index c58b2dbcb..47c410309 100644 --- a/nuttx/lib/Makefile +++ b/nuttx/lib/Makefile @@ -71,7 +71,7 @@ endif STDLIB_SRCS = lib_rand.c -MATH_SRCS = lib_rint.c lib_fixedmath.c +MATH_SRCS = lib_rint.c lib_fixedmath.c lib_b16sin.c lib_b16cos.c UNISTD_SRCS = lib_getopt.c ifneq ($(CONFIG_NFILE_DESCRIPTORS),0) diff --git a/nuttx/lib/lib_b16cos.c b/nuttx/lib/lib_b16cos.c new file mode 100644 index 000000000..93f5ee2f6 --- /dev/null +++ b/nuttx/lib/lib_b16cos.c @@ -0,0 +1,64 @@ +/**************************************************************************** + * lib/lib_b16cos.c + * + * Copyright (C) 2007, 2008 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 + ****************************************************************************/ + +/**************************************************************************** + * Global Functions + ****************************************************************************/ + +/**************************************************************************** + * Name: b16cos + ****************************************************************************/ + +b16_t b16cos(b16_t rad) +{ + /* Compute cosine: sin(rad + PI/2) = cos(rad) */ + + rad += b16HALFPI; + if (rad > b16PI) + { + rad -= b16TWOPI; + } + return b16sin(rad); +} diff --git a/nuttx/lib/lib_b16sin.c b/nuttx/lib/lib_b16sin.c new file mode 100644 index 000000000..7e2bcac56 --- /dev/null +++ b/nuttx/lib/lib_b16sin.c @@ -0,0 +1,110 @@ +/**************************************************************************** + * lib/lib_b16sin.c + * + * Copyright (C) 2008 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; +} diff --git a/nuttx/lib/lib_fixedmath.c b/nuttx/lib/lib_fixedmath.c index 0b09653c5..e5f7ce3a4 100644 --- a/nuttx/lib/lib_fixedmath.c +++ b/nuttx/lib/lib_fixedmath.c @@ -165,6 +165,53 @@ ub16_t ub16mulub16(ub16_t m1, ub16_t m2) * Name: b16divb16 **************************************************************************/ +b16_t b16sqr(b16_t a) +{ + b16_t sq; + + /* The result is always positive. Just take the absolute value */ + + if (a < 0) + { + a = -a; + } + + /* Overflow occurred if the result is negative */ + + sq = (bt_t)ub16sqr(a); + if (sq < 0) + { + sq = b16MAX; + } + return sq; +} + +/**************************************************************************** + * Name: b16divb16 + **************************************************************************/ + +ub16_t ub16sqr(ub16_t a) +{ + /* Let: + * + * m = mi*2**16 + mf (b16) + * + * Then: + * + * m*m = (mi*mi)*2**32 + 2*(m1*m2)*2**16 + mf*mf (b32) + * = (mi*mi)*2**16 + 2*(mi*mf) + mf*mf*2**-16 (b16) + */ + + uint32 mi = ((uint32)m1 >> 16); + uint32 mf = ((uint32)m1 & 0x0000ffff); + + return (mi*mi << 16) + (mi*mf << 1) (((mf*mf) + b16HALF) >> 16); +} + +/**************************************************************************** + * Name: b16divb16 + **************************************************************************/ + b16_t b16divb16(b16_t num, b16_t denom) { boolean negate; |