diff options
Diffstat (limited to 'nuttx/libc/math/lib_frexp.c')
-rw-r--r-- | nuttx/libc/math/lib_frexp.c | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/nuttx/libc/math/lib_frexp.c b/nuttx/libc/math/lib_frexp.c new file mode 100644 index 000000000..b9576dfd4 --- /dev/null +++ b/nuttx/libc/math/lib_frexp.c @@ -0,0 +1,47 @@ +/************************************************************************ + * libc/math/lib_frexp.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 <nuttx/config.h> +#include <nuttx/compiler.h> + +#include <math.h> + +/************************************************************************ + * Public Functions + ************************************************************************/ + +#ifdef CONFIG_HAVE_DOUBLE +double frexp(double x, int *exponent) +{ + *exponent = (int)ceil(log2(x)); + return x / ldexp(1.0, *exponent); +} +#endif |