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/* $OpenBSD: frexp.c,v 1.2 2005/08/08 08:05:34 espie Exp $ */
/*-
* Copyright (c) 2004 David Schultz <das@FreeBSD.ORG>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* $FreeBSD: frexp.c,v 1.1 2004/07/18 21:23:39 das Exp $
*/
#include <sys/types.h>
#include <machine/ieee.h>
#include <math.h>
double
frexp(double v, int *ex)
{
union {
double v;
struct ieee_double s;
} u;
u.v = v;
switch (u.s.dbl_exp) {
case 0: /* 0 or subnormal */
if ((u.s.dbl_fracl | u.s.dbl_frach) == 0) {
*ex = 0;
} else {
/*
* The power of 2 is arbitrary, any value from 54 to
* 1024 will do.
*/
u.v *= 0x1.0p514;
*ex = u.s.dbl_exp - (DBL_EXP_BIAS - 1 + 514);
u.s.dbl_exp = DBL_EXP_BIAS - 1;
}
break;
case DBL_EXP_INFNAN: /* Inf or NaN; value of *ex is unspecified */
break;
default: /* normal */
*ex = u.s.dbl_exp - (DBL_EXP_BIAS - 1);
u.s.dbl_exp = DBL_EXP_BIAS - 1;
break;
}
return (u.v);
}
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