/*-
 * Copyright (c) 2013 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matt Thomas of 3am Software Foundry.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <machine/asm.h>

RCSID("$NetBSD: strncat_naive.S,v 1.1 2013/01/23 05:44:52 matt Exp $")

/* LINTSTUB: char *strncat(char *, const char *, size_t) */
ENTRY(strncat)
        teq     r2, #0                  /* count is 0? */
        RETc(eq)                        /*   yes, just return dst */
        mov     ip, r0                  /* need to preserve r0 */
1:      ldrb    r3, [ip], #1            /* load next byte */
        teq     r3, #0                  /* was it a NUL? */
        bne     1b                      /*   no, get next byte */
        sub     ip, ip, #1              /* back up one to the NUL */
2:      subs    r2, r2, #1              /* subtract 1 from the count */
        blt     3f                      /*   <0? write terminating NUL */
        ldrb    r3, [r1], #1            /* load next byte from append */
        strb    r3, [ip], #1            /* store it */
        teq     r3, #0                  /* was it a NUL? */
        bne     2b                      /*   no, get next byte */
        RET                             /* return */
3:      mov     r3, #0                  /* load a NUL */
        strb    r3, [ip]                /* store it */
        RET                             /* return */
END(strncat)