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BSD 4.3reno

/*
 * Copyright (c) 1983 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 "@(#)strncat.s	5.6 (Berkeley) 6/1/90"
#endif /* LIBC_SCCS and not lint */

/*
 * Concatenate string s2 on the end of s1
 * and return the base of s1.  The parameter
 * n is the maximum length of string s2 to
 * concatenate.
 *
 * char *
 * strncat(s1, s2, n)
 *	char *s1, *s2;
 *	int n;
 */
#include "DEFS.h"

ENTRY(strncat, R6)
	movl	12(ap),r6	# r6 = n
	bleq	done		# n <= 0
	movl	4(ap),r3	# r3 = s1
	movl	r3,r1
0:
	locc	$0,$65535,(r1)
	beql	0b
	movl	r1,r3		# r3 = index(s1, '\0');
	movl	8(ap),r1	# r1 = s2
1:
	movzwl	$65535,r2	# r2 = bytes in first chunk
	cmpl	r6,r2		# r2 = min(bytes in chunk, n);
	jgeq	2f
	movl	r6,r2
2:
	subl2	r2,r6		# update n
	locc	$0,r2,(r1)	# '\0' found?
	jneq	3f
	subl2	r2,r1		# back up pointer updated by locc
	movc3	r2,(r1),(r3)	# copy in next piece
	tstl	r6		# run out of space?
	jneq	1b
	clrb	(r3)		# force '\0' termination
	jbr	done
3:
	subl2	r0,r2		# r2 = number of bytes to move
	subl2	r2,r1		# back up pointer updated by locc
	incl	r2		# copy '\0' as well
	movc3	r2,(r1),(r3)	# copy in last piece
done:
	movl	4(ap),r0	# return s1
	ret

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