linux-vybrid_public/arch/arm64/lib/memmove.S

/*
 * Copyright (C) 2013 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include <linux/linkage.h>
#include <asm/assembler.h>

/*
 * Move a buffer from src to test (alignment handled by the hardware).
 * If dest <= src, call memcpy, otherwise copy in reverse order.
 *
 * Parameters:
 *	x0 - dest
 *	x1 - src
 *	x2 - n
 * Returns:
 *	x0 - dest
 */
ENTRY(memmove)
	cmp	x0, x1
	b.ls	memcpy
	add	x4, x0, x2
	add	x1, x1, x2
	subs	x2, x2, #8
	b.mi	2f
1:	ldr	x3, [x1, #-8]!
	subs	x2, x2, #8
	str	x3, [x4, #-8]!
	b.pl	1b
2:	adds	x2, x2, #4
	b.mi	3f
	ldr	w3, [x1, #-4]!
	sub	x2, x2, #4
	str	w3, [x4, #-4]!
3:	adds	x2, x2, #2
	b.mi	4f
	ldrh	w3, [x1, #-2]!
	sub	x2, x2, #2
	strh	w3, [x4, #-2]!
4:	adds	x2, x2, #1
	b.mi	5f
	ldrb	w3, [x1, #-1]
	strb	w3, [x4, #-1]
5:	ret
ENDPROC(memmove)