1/*-
2 * Copyright (c) 2013 The NetBSD Foundation, Inc.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to The NetBSD Foundation
6 * by Matt Thomas of 3am Software Foundry.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
18 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
19 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
20 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
21 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
24 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
25 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
26 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
27 * POSSIBILITY OF SUCH DAMAGE.
28 */
29
30#include <machine/asm.h>
31
32RCSID("$NetBSD: strncat_naive.S,v 1.1 2013/01/23 05:44:52 matt Exp $")
33
34/* LINTSTUB: char *strncat(char *, const char *, size_t) */
35ENTRY(strncat)
36          teq       r2, #0                        /* count is 0? */
37          RETc(eq)                      /*   yes, just return dst */
38          mov       ip, r0                        /* need to preserve r0 */
391:        ldrb      r3, [ip], #1                  /* load next byte */
40          teq       r3, #0                        /* was it a NUL? */
41          bne       1b                            /*   no, get next byte */
42          sub       ip, ip, #1                    /* back up one to the NUL */
432:        subs      r2, r2, #1                    /* subtract 1 from the count */
44          blt       3f                            /*   <0? write terminating NUL */
45          ldrb      r3, [r1], #1                  /* load next byte from append */
46          strb      r3, [ip], #1                  /* store it */
47          teq       r3, #0                        /* was it a NUL? */
48          bne       2b                            /*   no, get next byte */
49          RET                                     /* return */
503:        mov       r3, #0                        /* load a NUL */
51          strb      r3, [ip]            /* store it */
52          RET                                     /* return */
53END(strncat)
54