213b954a90
- Add check in roundx() functions for infinite or NaN cases - Add block to avoid style warnings - Define long double constants and macros for infinity and nan - Correct return syntax to match NuttX style - Make c89 compliant - Fix definitions of INFINITY_L/NAN_L * include/nuttx/lib/math.h - match standard naming conventions - Rename isinf_l to isinfl - Rename isinf_f to isinff - Add finite() - Add finitel() - Add finitef() - Define isnanl and isnanf - Define isfinite() so that it uses the appropriate macro * libs/libc/math/lib_asinf.c libs/libc/math/lib_asinl.c libs/libc/math/lib_roundf.c libs/libc/math/lib_roundl.c libs/libc/math/lib_sqrtf.c libs/libc/math/lib_sqrtl.c - Use renamed macros - Use correct NAN_x or INFINIT_x macro on returns
87 lines
2.3 KiB
C
87 lines
2.3 KiB
C
/****************************************************************************
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* libs/libc/math/lib_sqrtf.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 compatible, 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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#include <errno.h>
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#include "libc.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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#ifndef CONFIG_LIBM_ARCH_SQRTF
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float sqrtf(float x)
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{
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float y;
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/* Filter out invalid/trivial inputs */
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if (x < 0.0F)
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{
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set_errno(EDOM);
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return NAN_F;
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}
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if (isnanf(x))
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{
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return NAN_F;
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}
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if (isinff(x))
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{
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return INFINITY_F;
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}
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if (x == 0.0F)
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{
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return 0.0F;
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}
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/* Guess square root (using bit manipulation) */
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y = lib_sqrtapprox(x);
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/* Perform three iterations of approximation. This number (3) is
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* definitely optimal
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*/
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y = 0.5F * (y + x / y);
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y = 0.5F * (y + x / y);
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y = 0.5F * (y + x / y);
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return y;
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}
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#endif
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