| 1 | /* $Id: memcmp.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */
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| 2 | /** @file
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| 3 | * IPRT - CRT Strings, memcmp().
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2006-2023 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 | #include "internal/iprt.h"
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| 42 | #include <iprt/string.h>
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| 43 |
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| 44 |
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| 45 | /**
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| 46 | * Copies a memory.
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| 47 | *
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| 48 | * @returns 0 if pvDst and pvSrc are equal
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| 49 | * @returns <0 if pvDst is 'smaller' than pvSrc.
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| 50 | * @returns >0 if pvDst is 'larger' than pvSrc.
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| 51 | *
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| 52 | * @param pvDst Pointer to the target block.
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| 53 | * @param pvSrc Pointer to the source block.
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| 54 | * @param cb The size of the block.
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| 55 | */
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| 56 | #ifdef IPRT_NO_CRT
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| 57 | # undef memcmp
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| 58 | int RT_NOCRT(memcmp)(const void *pvDst, const void *pvSrc, size_t cb)
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| 59 | #elif RT_MSC_PREREQ(RT_MSC_VER_VS2005)
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| 60 | __checkReturn int __cdecl
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| 61 | memcmp(__in_bcount_opt(_Size) const void *pvDst, __in_bcount_opt(_Size) const void *pvSrc, __in size_t cb)
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| 62 | #else
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| 63 | int memcmp(const void *pvDst, const void *pvSrc, size_t cb)
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| 64 | #endif
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| 65 | {
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| 66 | union
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| 67 | {
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| 68 | uint8_t const *pu8;
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| 69 | uint32_t const *pu32;
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| 70 | void const *pv;
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| 71 | } uDst, uSrc;
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| 72 | uDst.pv = pvDst;
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| 73 | uSrc.pv = pvSrc;
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| 74 |
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| 75 | /* 32-bit word compare. */
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| 76 | size_t c = cb >> 2;
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| 77 | while (c-- > 0)
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| 78 | {
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| 79 | /* ASSUMES int is at least 32-bit! */
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| 80 | int32_t iDiff = *uDst.pu32++ - *uSrc.pu32++;
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| 81 | if (iDiff)
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| 82 | return iDiff;
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| 83 | }
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| 84 |
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| 85 | /* Remaining byte moves. */
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| 86 | c = cb & 3;
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| 87 | while (c-- > 0)
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| 88 | {
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| 89 | int8_t iDiff = *uDst.pu8++ - *uSrc.pu8++;
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| 90 | if (iDiff)
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| 91 | return iDiff;
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| 92 | }
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| 93 |
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| 94 | return 0;
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| 95 | }
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| 96 | RT_ALIAS_AND_EXPORT_NOCRT_SYMBOL(memcmp);
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| 97 |
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