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strlcpy.S revision 1.1 
      1 /*	$NetBSD: strlcpy.S,v 1.1 2002/06/06 20:31:22 fredette 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 1.1 2002/06/06 20:31:22 fredette 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 
     50 	/* Always load the first byte of the source string. */
     51 	ldbs,ma		1(%arg1), %r1
     52 
     53 	/*
     54 	 * If our dst buffer is zero bytes, branch immediately
     55 	 * to the code that counts the (remaining) length
     56 	 * of the src string.
     57 	 */
     58 	comb,=		%r0, %arg2, $strlcpy_dst_done
     59 	copy		%arg1, %ret0
     60 
     61 	/*
     62 	 * If our dst buffer is one byte, branch immediately
     63 	 * to the code that NUL-terminates the dst buffer and
     64 	 * counts the (remaining) length of the src string.
     65 	 */
     66 	addib,=,n	-1, %arg2, $strlcpy_dst_full
     67 
     68 	/*
     69 	 * Loop copying bytes.  At the top of this loop,
     70 	 * %arg2 is always the number of bytes we can still
     71 	 * store, and %r1 holds the next byte to store.
     72 	 */
     73 $strlcpy_loop
     74 	comb,=		%r0, %r1, $strlcpy_exit
     75 	stbs,ma		%r1, 1(%arg0)
     76 	addib,<>	-1, %arg2, $strlcpy_loop
     77 	ldbs,ma		1(%arg1), %r1
     78 
     79 $strlcpy_dst_full
     80 	stbs,ma		%r0, 1(%arg0)
     81 
     82 $strlcpy_dst_done
     83 	comb,<>,n	%r0, %r1, $stlcpy_dst_done
     84 	ldbs,ma		1(%arg1), %r1
     85 
     86 $strlcpy_exit
     87 	bv		%r0(%rp)
     88 	sub		%arg1, %ret0, %ret0
     89 EXIT(strlcpy)
     90