59 lines
1.6 KiB
C
59 lines
1.6 KiB
C
/*
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* Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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* 02110-1301, USA.
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*/
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/** @file
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*
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* Optimised string operations
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*
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*/
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FILE_LICENCE ( GPL2_OR_LATER );
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#include <string.h>
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/**
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* Copy memory area
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*
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* @v dest Destination address
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* @v src Source address
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* @v len Length
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* @ret dest Destination address
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*/
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void * __memcpy ( void *dest, const void *src, size_t len ) {
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void *edi = dest;
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const void *esi = src;
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int discard_ecx;
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/* We often do large dword-aligned and dword-length block
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* moves. Using movsl rather than movsb speeds these up by
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* around 32%.
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*/
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__asm__ __volatile__ ( "rep movsl"
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: "=&D" ( edi ), "=&S" ( esi ),
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"=&c" ( discard_ecx )
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: "0" ( edi ), "1" ( esi ), "2" ( len >> 2 )
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: "memory" );
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__asm__ __volatile__ ( "rep movsb"
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: "=&D" ( edi ), "=&S" ( esi ),
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"=&c" ( discard_ecx )
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: "0" ( edi ), "1" ( esi ), "2" ( len & 3 )
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: "memory" );
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return dest;
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}
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