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/* $OpenBSD: frexp.c,v 1.10 2013/07/03 04:46:36 espie Exp $ */ |
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/*- |
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* Copyright (c) 2004 David Schultz <das@FreeBSD.ORG> |
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* All rights reserved. |
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* |
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* Redistribution and use in source and binary forms, with or without |
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* modification, are permitted provided that the following conditions |
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* are met: |
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* 1. Redistributions of source code must retain the above copyright |
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* notice, this list of conditions and the following disclaimer. |
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* 2. Redistributions in binary form must reproduce the above copyright |
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* notice, this list of conditions and the following disclaimer in the |
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* documentation and/or other materials provided with the distribution. |
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* |
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND |
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE |
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
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* SUCH DAMAGE. |
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* |
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* $FreeBSD: frexp.c,v 1.1 2004/07/18 21:23:39 das Exp $ |
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*/ |
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#include <sys/types.h> |
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#include <machine/ieee.h> |
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#include <float.h> |
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#include <math.h> |
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double |
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frexp(double v, int *ex) |
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{ |
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union { |
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double v; |
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struct ieee_double s; |
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} u; |
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u.v = v; |
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switch (u.s.dbl_exp) { |
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case 0: /* 0 or subnormal */ |
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if ((u.s.dbl_fracl | u.s.dbl_frach) == 0) { |
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*ex = 0; |
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} else { |
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/* |
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* The power of 2 is arbitrary, any value from 54 to |
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* 1024 will do. |
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*/ |
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u.v *= 0x1.0p514; |
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*ex = u.s.dbl_exp - (DBL_EXP_BIAS - 1 + 514); |
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u.s.dbl_exp = DBL_EXP_BIAS - 1; |
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} |
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break; |
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case DBL_EXP_INFNAN: /* Inf or NaN; value of *ex is unspecified */ |
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break; |
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default: /* normal */ |
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*ex = u.s.dbl_exp - (DBL_EXP_BIAS - 1); |
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u.s.dbl_exp = DBL_EXP_BIAS - 1; |
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break; |
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} |
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return (u.v); |
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} |
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#if LDBL_MANT_DIG == DBL_MANT_DIG |
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__strong_alias(frexpl, frexp); |
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#endif /* LDBL_MANT_DIG == DBL_MANT_DIG */ |