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/* $OpenBSD: frexp.c,v 1.5 2003/06/02 20:18:32 millert Exp $ */
/*
* Copyright (c) 1992, 1993
* The Regents of the University of California. All rights reserved.
*
* This software was developed by the Computer Systems Engineering group
* at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
* contributed to Berkeley.
*
* 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.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char rcsid[] = "$OpenBSD: frexp.c,v 1.5 2003/06/02 20:18:32 millert Exp $";
#endif /* LIBC_SCCS and not lint */
#include <sys/types.h>
#include <machine/ieee.h>
/*
* Split the given value into a fraction in the range [0.5, 1.0) and
* an exponent, such that frac * (2^exp) == value. If value is 0,
* return 0.
*/
double
frexp(value, eptr)
double value;
int *eptr;
{
union {
double v;
struct ieee_double s;
} u;
if (value) {
/*
* Fractions in [0.5..1.0) have an exponent of 2^-1.
* Leave Inf and NaN alone, however.
* WHAT ABOUT DENORMS?
*/
u.v = value;
if (u.s.dbl_exp != DBL_EXP_INFNAN) {
*eptr = u.s.dbl_exp - (DBL_EXP_BIAS - 1);
u.s.dbl_exp = DBL_EXP_BIAS - 1;
}
return (u.v);
} else {
*eptr = 0;
return ((double)0);
}
}
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