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BSD 4.3reno

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that: (1) source distributions retain this entire copyright
 * notice and comment, and (2) distributions including binaries display
 * the following acknowledgement:  ``This product includes software
 * developed by the University of California, Berkeley and its contributors''
 * in the documentation or other materials provided with the distribution
 * and in all advertising materials mentioning features or use of this
 * software. Neither the name of the University nor the names of its
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
	.asciz "@(#)memmove.s	5.1 (Berkeley) 5/15/90"
#endif /* LIBC_SCCS and not lint */

/*
 * void *memmove(dst, src, size)
 * returns dst
 *
 * This optimises the usual case (count < 65536) at the expense
 * of some extra memory references and branches when count >= 65536.
 */

#include "DEFS.h"

ENTRY(memmove, 0)
	movzwl	$65535,r0	/* r0 = 64K (needed below) */
	movq	8(ap),r1	/* r1 = src, r2 = length */
	movl	4(ap),r3	/* r3 = dst */
	cmpl	r1,r3
	bgtru	1f		/* normal forward case */
	beql	2f		/* equal, nothing to do */
	addl2	r2,r1		/* overlaps iff src<dst but src+len>dst */
	cmpl	r1,r3
	bgtru	4f		/* overlapping, must move backwards */
	subl2	r2,r1

1:	/* move forward */
	cmpl	r2,r0
	bgtru	3f		/* stupid movc3 limitation */
	movc3	r2,(r1),(r3)	/* move it all */
2:
	movl	4(ap),r0	/* return original dst */
	ret
3:
	subl2	r0,12(ap)	/* adjust length by 64K */
	movc3	r0,(r1),(r3)	/* move 64K */
	movl	12(ap),r2
	decw	r0		/* from 0 to 65535 */
	brb	1b		/* retry */

4:	/* move backward */
	addl2	r2,r3
5:
	cmpl	r2,r0
	bgtru	6f		/* stupid movc3 limitation */
	subl2	r2,r1
	subl2	r2,r3
	movc3	r2,(r1),(r3)	/* move it all */
	movl	4(ap),r0	/* return original dst */
	ret
6:
	subl2	r0,12(ap)	/* adjust length by 64K */
	subl2	r0,r1
	subl2	r0,r3
	movc3	r0,(r1),(r3)	/* move 64K */
	movl	12(ap),r2
	decw	r0
	subl2	r0,r1
	subl2	r0,r3
	brb	5b

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