67 lines
2.1 KiB
C
67 lines
2.1 KiB
C
/****************************************************************************
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* libs/libc/math/lib_floor.c
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*
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* This file is a part of NuttX:
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*
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* Copyright (C) 2012 Gregory Nutt. All rights reserved.
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* Ported by: Darcy Gong
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*
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* It derives from the Rhombus OS math library by Nick Johnson which has
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* a compatibile, MIT-style license:
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*
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* Copyright (C) 2009-2011 Nick Johnson <nickbjohnson4224 at gmail.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <nuttx/compiler.h>
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#include <math.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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#ifdef CONFIG_HAVE_DOUBLE
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double floor(double x)
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{
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double modx;
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/* modf() will return the integer part of X. The return value of floor
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* differs for non-integer, negative values.
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*
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* x modf floor
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* ---- ----- -----
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* 2.0 2.0 2.0
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* 2.4 2.0 2.0
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* 2.9 2.0 2.0
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* -2.7 -2.0 -3.0
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* -2.0 -2.0 -2.0
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*/
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(void)modf(x, &modx);
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if (x < 0.0 && x < modx)
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{
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modx -= 1.0;
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}
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return modx;
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}
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#endif
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