xnu-4903.270.47.tar.gz

[apple/xnu.git] / osfmk / x86_64 / bcopy.s

/*
 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * @OSF_COPYRIGHT@
 */
/*
 * Mach Operating System
 * Copyright (c) 1991,1990 Carnegie Mellon University
 * All Rights Reserved.
 * 
 * Permission to use, copy, modify and distribute this software and its
 * documentation is hereby granted, provided that both the copyright
 * notice and this permission notice appear in all copies of the
 * software, derivative works or modified versions, and any portions
 * thereof, and that both notices appear in supporting documentation.
 * 
 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
 * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
 * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
 * 
 * Carnegie Mellon requests users of this software to return to
 * 
 *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
 *  School of Computer Science
 *  Carnegie Mellon University
 *  Pittsburgh PA 15213-3890
 * 
 * any improvements or extensions that they make and grant Carnegie Mellon
 * the rights to redistribute these changes.
 */
/*
 */

#include <i386/asm.h>

/* void *memcpy((void *) to, (const void *) from, (size_t) bcount) */
/*			rdi,	 	     rsi,	      rdx   */
/*
 * Note: memcpy does not support overlapping copies
 */
ENTRY(memcpy)
	movq	%rdi, %rax			/* return destination */
	movq	%rdx,%rcx
	cld					/* copy forwards */
	rep
	movsb
	ret

/* void bcopy((const char *) from, (char *) to, (unsigned int) count) */
/*			      rdi, 	   rsi,			 rdx  */

ENTRY(bcopy_no_overwrite)
	xchgq	%rsi,%rdi
	jmp	EXT(memcpy)

/*
 * bcopy(src, dst, cnt)
 *       rdi, rsi, rdx
 *  ws@tools.de     (Wolfgang Solfrank, TooLs GmbH) +49-228-985800
 */
ENTRY(bcopy)
	xchgq	%rsi,%rdi
	movq	%rdx,%rcx

	movq	%rdi,%rax
	subq	%rsi,%rax
	cmpq	%rcx,%rax			/* overlapping && src < dst? */
	jb	1f

	cld					/* nope, copy forwards */
	rep
	movsb
	ret

	/* ALIGN_TEXT */
1:
	addq	%rcx,%rdi			/* copy backwards */
	addq	%rcx,%rsi
	decq	%rdi
	decq	%rsi
	andq	$7,%rcx				/* any fractional bytes? */
	std
	rep
	movsb
	movq	%rdx,%rcx			/* copy remainder by 32-bit words */
	shrq	$3,%rcx
	subq	$7,%rsi
	subq	$7,%rdi
	rep
	movsq
	cld
	ret