| 1 | /* $Id: frexp.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */
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| 2 | /** @file
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| 3 | * IPRT - No-CRT - frexp().
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2022-2023 Oracle and/or its affiliates.
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| 8 | *
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| 9 | * This file is part of VirtualBox base platform packages, as
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| 10 | * available from https://www.virtualbox.org.
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| 11 | *
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| 12 | * This program is free software; you can redistribute it and/or
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| 13 | * modify it under the terms of the GNU General Public License
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| 14 | * as published by the Free Software Foundation, in version 3 of the
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| 15 | * License.
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| 16 | *
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| 17 | * This program is distributed in the hope that it will be useful, but
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| 18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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| 19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 20 | * General Public License for more details.
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| 21 | *
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| 22 | * You should have received a copy of the GNU General Public License
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| 23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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| 24 | *
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| 25 | * The contents of this file may alternatively be used under the terms
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| 26 | * of the Common Development and Distribution License Version 1.0
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| 27 | * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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| 28 | * in the VirtualBox distribution, in which case the provisions of the
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| 29 | * CDDL are applicable instead of those of the GPL.
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| 30 | *
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| 31 | * You may elect to license modified versions of this file under the
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| 32 | * terms and conditions of either the GPL or the CDDL or both.
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| 33 | *
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| 34 | * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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| 35 | */
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| 36 |
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| 37 |
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| 38 | /*********************************************************************************************************************************
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| 39 | * Header Files *
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| 40 | *********************************************************************************************************************************/
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| 41 | #define IPRT_NO_CRT_FOR_3RD_PARTY
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| 42 | #include "internal/nocrt.h"
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| 43 | #include <iprt/nocrt/math.h>
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| 44 | #include <iprt/assertcompile.h>
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| 45 | #include <iprt/nocrt/limits.h>
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| 46 |
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| 47 |
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| 48 | /* Similar to the fxtract instruction. */
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| 49 | #undef frexp
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| 50 | double RT_NOCRT(frexp)(double rdValue, int *piExp)
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| 51 | {
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| 52 | RTFLOAT64U Value;
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| 53 | AssertCompile(sizeof(Value) == sizeof(rdValue));
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| 54 | Value.r = rdValue;
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| 55 |
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| 56 | if (RTFLOAT64U_IS_NORMAL(&Value))
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| 57 | {
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| 58 | *piExp = (int)Value.s.uExponent - RTFLOAT64U_EXP_BIAS + 1;
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| 59 | Value.s.uExponent = RTFLOAT64U_EXP_BIAS - 1;
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| 60 | }
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| 61 | else if (RTFLOAT64U_IS_ZERO(&Value))
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| 62 | {
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| 63 | *piExp = 0;
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| 64 | return rdValue;
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| 65 | }
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| 66 | else if (RTFLOAT64U_IS_SUBNORMAL(&Value))
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| 67 | {
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| 68 | int iExp = -RTFLOAT64U_EXP_BIAS + 1;
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| 69 | uint64_t uFraction = Value.s64.uFraction;
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| 70 | while (!(uFraction & RT_BIT_64(RTFLOAT64U_FRACTION_BITS)))
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| 71 | {
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| 72 | iExp--;
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| 73 | uFraction <<= 1;
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| 74 | }
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| 75 | Value.s64.uFraction = uFraction;
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| 76 | Value.s64.uExponent = RTFLOAT64U_EXP_BIAS - 1;
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| 77 | *piExp = iExp + 1;
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| 78 | }
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| 79 | else
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| 80 | {
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| 81 | /* NaN, Inf */
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| 82 | *piExp = Value.s.fSign ? INT_MIN : INT_MAX;
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| 83 | return rdValue;
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| 84 | }
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| 85 | return Value.r;
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| 86 | }
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| 87 | RT_ALIAS_AND_EXPORT_NOCRT_SYMBOL(frexp);
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| 88 |
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