54 lines
1.4 KiB
C
54 lines
1.4 KiB
C
/* Copyright (C) 1991, 1992 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If
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not, write to the Free Software Foundation, Inc., 675 Mass Ave,
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Cambridge, MA 02139, USA. */
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#include <ansidecl.h>
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#include <errno.h>
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#include <math.h>
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/* Break VALUE into a normalized fraction and an integral power of 2. */
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double
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DEFUN(frexp, (value, exp), double value AND int *exp)
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{
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#ifdef NAN
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if (__isinf (value))
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{
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errno = EDOM;
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*exp = 0;
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return __copysign (NAN, value);
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}
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#endif
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if (__isnan (value))
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{
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errno = EDOM;
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*exp = 0;
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return value;
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}
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if (value == 0)
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{
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*exp = 0;
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return value;
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}
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/* Add one to the exponent of the number,
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so we have one digit before the binary point. */
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*exp = (int) __logb (value) + 1;
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return ldexp (value, - *exp);
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}
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