diff options
Diffstat (limited to 'contrib/syslinux-4.02/gpxe/src/arch/x86/core/x86_string.c')
-rw-r--r-- | contrib/syslinux-4.02/gpxe/src/arch/x86/core/x86_string.c | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/contrib/syslinux-4.02/gpxe/src/arch/x86/core/x86_string.c b/contrib/syslinux-4.02/gpxe/src/arch/x86/core/x86_string.c new file mode 100644 index 0000000..5838eba --- /dev/null +++ b/contrib/syslinux-4.02/gpxe/src/arch/x86/core/x86_string.c @@ -0,0 +1,63 @@ +/* + * 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 + * + */ + +FILE_LICENCE ( GPL2_OR_LATER ); + +#include <string.h> + +/** + * Copy memory area + * + * @v dest Destination address + * @v src Source address + * @v len Length + * @ret dest Destination address + */ +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; +} |