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/* $Id: frexp.cpp $ */
/** @file
* IPRT - No-CRT - frexp().
*/
/*
* Copyright (C) 2022 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#define IPRT_NO_CRT_FOR_3RD_PARTY
#include "internal/nocrt.h"
#include <iprt/nocrt/math.h>
#include <iprt/assertcompile.h>
#include <iprt/nocrt/limits.h>
/* Similar to the fxtract instruction. */
#undef frexp
double RT_NOCRT(frexp)(double rdValue, int *piExp)
{
RTFLOAT64U Value;
AssertCompile(sizeof(Value) == sizeof(rdValue));
Value.r = rdValue;
if (RTFLOAT64U_IS_NORMAL(&Value))
{
*piExp = (int)Value.s.uExponent - RTFLOAT64U_EXP_BIAS + 1;
Value.s.uExponent = RTFLOAT64U_EXP_BIAS - 1;
}
else if (RTFLOAT64U_IS_ZERO(&Value))
{
*piExp = 0;
return rdValue;
}
else if (RTFLOAT64U_IS_SUBNORMAL(&Value))
{
int iExp = -RTFLOAT64U_EXP_BIAS + 1;
uint64_t uFraction = Value.s64.uFraction;
while (!(uFraction & RT_BIT_64(RTFLOAT64U_FRACTION_BITS)))
{
iExp--;
uFraction <<= 1;
}
Value.s64.uFraction = uFraction;
Value.s64.uExponent = RTFLOAT64U_EXP_BIAS - 1;
*piExp = iExp + 1;
}
else
{
/* NaN, Inf */
*piExp = Value.s.fSign ? INT_MIN : INT_MAX;
return rdValue;
}
return Value.r;
}
RT_ALIAS_AND_EXPORT_NOCRT_SYMBOL(frexp);
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