/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 * Common Development and Distribution License (the "License").

 * You may not use this file except in compliance with the License.

 *

 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

 * or http://www.opensolaris.org/os/licensing.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

 * If applicable, add the following below this CDDL HEADER, with the

 * fields enclosed by brackets "[]" replaced with your own identifying

 * information: Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 */

/*

 * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

/*

 * memcpy(s1, s2, len)

 *

 * Copy s2 to s1, always copy n bytes.

 * Note: this does not work for overlapped copies, bcopy() does

 *

 * Fast assembler language version of the following C-program for memcpy

 * which represents the `standard' for the C-library.

 *

 *	void * 

 *	memcpy(void *s, const void *s0, size_t n)

 *	{

 *		if (n != 0) {

 *	   	    char *s1 = s;

 *		    const char *s2 = s0;

 *		    do {

 *			*s1++ = *s2++;

 *		    } while (--n != 0);

 *		}

 *		return (s);

 *	}

 */

#include "SYS.h"

	ANSI_PRAGMA_WEAK(memcpy,function)

	ENTRY(memcpy)

	st	%o0, [%sp + 68]		! save des address for return val

	cmp	%o2, 17			! for small counts copy bytes

	bleu	.dbytecp

	andcc	%o1, 3, %o5		! is src word aligned

	bz	.aldst

	cmp	%o5, 2			! is src half-word aligned

	be	.s2algn

	cmp	%o5, 3			! src is byte aligned

.s1algn:ldub	[%o1], %o3		! move 1 or 3 bytes to align it

	inc	1, %o1

	stb	%o3, [%o0]		! move a byte to align src

	inc	1, %o0

	bne	.s2algn

	dec	%o2

	b	.ald			! now go align dest

	andcc	%o0, 3, %o5

.s2algn:lduh	[%o1], %o3		! know src is 2 byte alinged

	inc	2, %o1

	srl	%o3, 8, %o4

	stb	%o4, [%o0]		! have to do bytes,

	stb	%o3, [%o0 + 1]		! don't know dst alingment

	inc	2, %o0

	dec	2, %o2

.aldst:	andcc	%o0, 3, %o5		! align the destination address

.ald:	bz	.w4cp

	cmp	%o5, 2

	bz	.w2cp

	cmp	%o5, 3

.w3cp:	ld	[%o1], %o4

	inc	4, %o1

	srl	%o4, 24, %o5

	stb	%o5, [%o0]

	bne	.w1cp

	inc	%o0

	dec	1, %o2

	andn	%o2, 3, %o3		! o3 is aligned word count

	dec	4, %o3			! avoid reading beyond tail of src

	sub	%o1, %o0, %o1		! o1 gets the difference

1:	sll	%o4, 8, %g1		! save residual bytes

	ld	[%o1+%o0], %o4

	deccc	4, %o3

	srl	%o4, 24, %o5		! merge with residual

	or	%o5, %g1, %g1

	st	%g1, [%o0]

	bnz	1b

	inc	4, %o0

	sub	%o1, 3, %o1		! used one byte of last word read

	and	%o2, 3, %o2

	b	7f

	inc	4, %o2

.w1cp:	srl	%o4, 8, %o5

	sth	%o5, [%o0]

	inc	2, %o0

	dec	3, %o2

	andn	%o2, 3, %o3		! o3 is aligned word count

	dec	4, %o3			! avoid reading beyond tail of src

	sub	%o1, %o0, %o1		! o1 gets the difference

2:	sll	%o4, 24, %g1		! save residual bytes

	ld	[%o1+%o0], %o4

	deccc	4, %o3

	srl	%o4, 8, %o5		! merge with residual

	or	%o5, %g1, %g1

	st	%g1, [%o0]

	bnz	2b

	inc	4, %o0

	sub	%o1, 1, %o1		! used three bytes of last word read

	and	%o2, 3, %o2

	b	7f

	inc	4, %o2

.w2cp:	ld	[%o1], %o4

	inc	4, %o1

	srl	%o4, 16, %o5

	sth	%o5, [%o0]

	inc	2, %o0

	dec	2, %o2

	andn	%o2, 3, %o3		! o3 is aligned word count

	dec	4, %o3			! avoid reading beyond tail of src

	sub	%o1, %o0, %o1		! o1 gets the difference

3:	sll	%o4, 16, %g1		! save residual bytes

	ld	[%o1+%o0], %o4

	deccc	4, %o3

	srl	%o4, 16, %o5		! merge with residual

	or	%o5, %g1, %g1

	st	%g1, [%o0]

	bnz	3b

	inc	4, %o0

	sub	%o1, 2, %o1		! used two bytes of last word read

	and	%o2, 3, %o2

	b	7f

	inc	4, %o2

.w4cp:	andn	%o2, 3, %o3		! o3 is aligned word count

	sub	%o1, %o0, %o1		! o1 gets the difference

1:	ld	[%o1+%o0], %o4		! read from address

	deccc	4, %o3			! decrement count

	st	%o4, [%o0]		! write at destination address

	bgu	1b

	inc	4, %o0			! increment to address

	b	7f

	and	%o2, 3, %o2		! number of leftover bytes, if any

	!

	! differenced byte copy, works with any alignment

	!

.dbytecp:

	b	7f

	sub	%o1, %o0, %o1		! o1 gets the difference

4:	stb	%o4, [%o0]		! write to address

	inc	%o0			! inc to address

7:	deccc	%o2			! decrement count

	bgeu,a	4b			! loop till done

	ldub	[%o1+%o0], %o4		! read from address

	retl

	ld	[%sp + 68], %o0		! return s1, destination address

	SET_SIZE(memcpy)