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strlcpy.S revision 1.2 
      1 /*	$NetBSD: strlcpy.S,v 1.2 2003/10/06 05:30:21 matt Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 2002 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Matthew Fredette.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *        This product includes software developed by the NetBSD
     21  *        Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 #include <machine/asm.h>
     40 
     41 #if defined(LIBC_SCCS) && !defined(lint)
     42         RCSID("$NetBSD: strlcpy.S,v 1.2 2003/10/06 05:30:21 matt Exp $")
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 /*
     46  * size_t strlcpy(char *dst, const char *src, size_t size);
     47  */
     48 LEAF_ENTRY(_strlcpy)
     49 	.weak strlcpy
     50 	strlcpy = _strlcpy
     51 
     52 	/* Always load the first byte of the source string. */
     53 	ldbs,ma		1(%arg1), %r1
     54 
     55 	/*
     56 	 * If our dst buffer is zero bytes, branch immediately
     57 	 * to the code that counts the (remaining) length
     58 	 * of the src string.
     59 	 */
     60 	comb,=		%r0, %arg2, $strlcpy_dst_done
     61 	copy		%arg1, %ret0
     62 
     63 	/*
     64 	 * If our dst buffer is one byte, branch immediately
     65 	 * to the code that NUL-terminates the dst buffer and
     66 	 * counts the (remaining) length of the src string.
     67 	 */
     68 	addib,=,n	-1, %arg2, $strlcpy_dst_full
     69 
     70 	/*
     71 	 * Loop copying bytes.  At the top of this loop,
     72 	 * %arg2 is always the number of bytes we can still
     73 	 * store, and %r1 holds the next byte to store.
     74 	 */
     75 $strlcpy_loop:
     76 	comb,=		%r0, %r1, $strlcpy_exit
     77 	stbs,ma		%r1, 1(%arg0)
     78 	addib,<>	-1, %arg2, $strlcpy_loop
     79 	ldbs,ma		1(%arg1), %r1
     80 
     81 $strlcpy_dst_full:
     82 	stbs,ma		%r0, 1(%arg0)
     83 
     84 $strlcpy_dst_done:
     85 	comb,<>,n	%r0, %r1, $strlcpy_dst_done
     86 	ldbs,ma		1(%arg1), %r1
     87 
     88 $strlcpy_exit:
     89 	bv		%r0(%rp)
     90 	sub		%arg1, %ret0, %ret0
     91 EXIT(strlcpy)
     92