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- /*
- * Copyright (C) 2007 Michael Brown <mbrown@fensystems.co.uk>.
- *
- * 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; either version 2 of the
- * License, or any later version.
- *
- * 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, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- */
-
- /** @file
- *
- * Optimised string operations
- *
- */
-
- #include <string.h>
-
- /**
- * Copy memory area
- *
- * @v dest Destination address
- * @v src Source address
- * @v len Length
- * @ret dest Destination address
- */
- __attribute__ (( regparm ( 3 ) )) void * __memcpy ( void *dest,
- const void *src,
- size_t len ) {
- void *edi = dest;
- const void *esi = src;
- int discard_ecx;
-
- /* We often do large dword-aligned and dword-length block
- * moves. Using movsl rather than movsb speeds these up by
- * around 32%.
- */
- if ( len >> 2 ) {
- __asm__ __volatile__ ( "rep movsl"
- : "=&D" ( edi ), "=&S" ( esi ),
- "=&c" ( discard_ecx )
- : "0" ( edi ), "1" ( esi ),
- "2" ( len >> 2 )
- : "memory" );
- }
- if ( len & 0x02 ) {
- __asm__ __volatile__ ( "movsw" : "=&D" ( edi ), "=&S" ( esi )
- : "0" ( edi ), "1" ( esi ) : "memory" );
- }
- if ( len & 0x01 ) {
- __asm__ __volatile__ ( "movsb" : "=&D" ( edi ), "=&S" ( esi )
- : "0" ( edi ), "1" ( esi ) : "memory" );
- }
- return dest;
- }
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