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/* $Id: memcmp.cpp $ */
/** @file
* IPRT - CRT Strings, memcmp().
*/
/*
* Copyright (C) 2006-2023 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 *
*********************************************************************************************************************************/
#include "internal/iprt.h"
#include <iprt/string.h>
/**
* Copies a memory.
*
* @returns 0 if pvDst and pvSrc are equal
* @returns <0 if pvDst is 'smaller' than pvSrc.
* @returns >0 if pvDst is 'larger' than pvSrc.
*
* @param pvDst Pointer to the target block.
* @param pvSrc Pointer to the source block.
* @param cb The size of the block.
*/
#ifdef IPRT_NO_CRT
# undef memcmp
int RT_NOCRT(memcmp)(const void *pvDst, const void *pvSrc, size_t cb)
#elif RT_MSC_PREREQ(RT_MSC_VER_VS2005)
__checkReturn int __cdecl
memcmp(__in_bcount_opt(_Size) const void *pvDst, __in_bcount_opt(_Size) const void *pvSrc, __in size_t cb)
#else
int memcmp(const void *pvDst, const void *pvSrc, size_t cb)
#endif
{
union
{
uint8_t const *pu8;
uint32_t const *pu32;
void const *pv;
} uDst, uSrc;
uDst.pv = pvDst;
uSrc.pv = pvSrc;
/* 32-bit word compare. */
size_t c = cb >> 2;
while (c-- > 0)
{
/* ASSUMES int is at least 32-bit! */
int32_t iDiff = *uDst.pu32++ - *uSrc.pu32++;
if (iDiff)
return iDiff;
}
/* Remaining byte moves. */
c = cb & 3;
while (c-- > 0)
{
int8_t iDiff = *uDst.pu8++ - *uSrc.pu8++;
if (iDiff)
return iDiff;
}
return 0;
}
RT_ALIAS_AND_EXPORT_NOCRT_SYMBOL(memcmp);
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