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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., 51 Franklin Street, Fifth Floor, Boston, MA
- * 02110-1301, USA.
- *
- * You can also choose to distribute this program under the terms of
- * the Unmodified Binary Distribution Licence (as given in the file
- * COPYING.UBDL), provided that you have satisfied its requirements.
- */
-
- /** @file
- *
- * Optimised string operations
- *
- */
-
- FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
-
- #include <string.h>
-
- /**
- * Copy memory area
- *
- * @v dest Destination address
- * @v src Source address
- * @v len Length
- * @ret dest Destination address
- */
- void * __attribute__ (( noinline )) __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%.
- */
- __asm__ __volatile__ ( "rep movsl"
- : "=&D" ( edi ), "=&S" ( esi ),
- "=&c" ( discard_ecx )
- : "0" ( edi ), "1" ( esi ), "2" ( len >> 2 )
- : "memory" );
- __asm__ __volatile__ ( "rep movsb"
- : "=&D" ( edi ), "=&S" ( esi ),
- "=&c" ( discard_ecx )
- : "0" ( edi ), "1" ( esi ), "2" ( len & 3 )
- : "memory" );
- return dest;
- }
-
- /**
- * Copy memory area backwards
- *
- * @v dest Destination address
- * @v src Source address
- * @v len Length
- * @ret dest Destination address
- */
- void * __attribute__ (( noinline )) __memcpy_reverse ( void *dest,
- const void *src,
- size_t len ) {
- void *edi = ( dest + len - 1 );
- const void *esi = ( src + len - 1 );
- int discard_ecx;
-
- /* Assume memmove() is not performance-critical, and perform a
- * bytewise copy for simplicity.
- */
- __asm__ __volatile__ ( "std\n\t"
- "rep movsb\n\t"
- "cld\n\t"
- : "=&D" ( edi ), "=&S" ( esi ),
- "=&c" ( discard_ecx )
- : "0" ( edi ), "1" ( esi ),
- "2" ( len )
- : "memory" );
- return dest;
- }
-
-
- /**
- * Copy (possibly overlapping) memory area
- *
- * @v dest Destination address
- * @v src Source address
- * @v len Length
- * @ret dest Destination address
- */
- void * __memmove ( void *dest, const void *src, size_t len ) {
-
- if ( dest <= src ) {
- return __memcpy ( dest, src, len );
- } else {
- return __memcpy_reverse ( dest, src, len );
- }
- }
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