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author | px4dev <px4@purgatory.org> | 2013-01-14 21:01:58 -0800 |
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committer | px4dev <px4@purgatory.org> | 2013-01-14 21:01:58 -0800 |
commit | 854c6436b4e3b292fd04843795d0369dc8856783 (patch) | |
tree | 4d5602f5c70926d2dcd01294561ddd8df4378462 /nuttx/libc/math/lib_libsqrtapprox.c | |
parent | 6d138a845aabad31060bd00da0d20d177d3f4be4 (diff) | |
parent | c38ad4ded570eddadeeca3579d02dfc63dcc8a9d (diff) | |
download | px4-firmware-854c6436b4e3b292fd04843795d0369dc8856783.tar.gz px4-firmware-854c6436b4e3b292fd04843795d0369dc8856783.tar.bz2 px4-firmware-854c6436b4e3b292fd04843795d0369dc8856783.zip |
Pull NuttX up to the 6.24 release.
Merge branch 'nuttx-merge-5447'
Diffstat (limited to 'nuttx/libc/math/lib_libsqrtapprox.c')
-rw-r--r-- | nuttx/libc/math/lib_libsqrtapprox.c | 50 |
1 files changed, 50 insertions, 0 deletions
diff --git a/nuttx/libc/math/lib_libsqrtapprox.c b/nuttx/libc/math/lib_libsqrtapprox.c new file mode 100644 index 000000000..b6a9b0d54 --- /dev/null +++ b/nuttx/libc/math/lib_libsqrtapprox.c @@ -0,0 +1,50 @@ +/************************************************************************ + * libc/math/lib_libsqrtapprox.c + * + * This file is a part of NuttX: + * + * Copyright (C) 2012 Gregory Nutt. All rights reserved. + * Ported by: Darcy Gong + * + * It derives from the Rhombs OS math library by Nick Johnson which has + * a compatibile, MIT-style license: + * + * Copyright (C) 2009-2011 Nick Johnson <nickbjohnson4224 at gmail.com> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + * + ************************************************************************/ + +/************************************************************************ + * Included Files + ************************************************************************/ + +#include <stdint.h> +#include <math.h> + +/************************************************************************ + * Public Functions + ************************************************************************/ + +float lib_sqrtapprox(float x) +{ + int32_t i; + + /* Floats + bit manipulation = +inf fun! */ + + i = *((int32_t *) & x); + i = 0x1fc00000 + (i >> 1); + x = *((float *)&i); + + return x; +} |