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/* $Id: memcmp.cpp $ */
/** @file
* IPRT - CRT Strings, memcmp().
*/
/*
* Copyright (C) 2006-2019 Oracle Corporation
*
* This file is part of VirtualBox Open Source Edition (OSE), as
* available from http://www.virtualbox.org. This file is free software;
* you can redistribute it and/or modify it under the terms of the GNU
* General Public License (GPL) as published by the Free Software
* Foundation, in version 2 as it comes in the "COPYING" file of the
* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
* VirtualBox OSE 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.
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#include <iprt/string.h>
#include <iprt/types.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 _MSC_VER
# if _MSC_VER >= 1400
__checkReturn int __cdecl memcmp(__in_bcount_opt(_Size) const void * pvDst, __in_bcount_opt(_Size) const void * pvSrc, __in size_t cb)
# else
int __cdecl memcmp(const void *pvDst, const void *pvSrc, size_t cb)
# endif
#else
int memcmp(const void *pvDst, const void *pvSrc, size_t cb)
#endif
{
register union
{
uint8_t const *pu8;
uint32_t const *pu32;
void const *pv;
} uDst, uSrc;
uDst.pv = pvDst;
uSrc.pv = pvSrc;
/* 32-bit word compare. */
register size_t c = cb >> 2;
while (c-- > 0)
{
/* ASSUMES int is at least 32-bit! */
register int32_t iDiff = *uDst.pu32++ - *uSrc.pu32++;
if (iDiff)
return iDiff;
}
/* Remaining byte moves. */
c = cb & 3;
while (c-- > 0)
{
register int8_t iDiff = *uDst.pu8++ - *uSrc.pu8++;
if (iDiff)
return iDiff;
}
return 0;
}
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