/*-
 * 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: strlen_naive.S,v 1.9 2022/12/03 11:30:24 skrll Exp $")

#ifdef STRNLEN
/* LINTSTUB: size_t strnlen(const char *, size_t) */
ENTRY(strnlen)
        adds    r3, r0, #1      /* start of src + NUL */
#ifdef __thumb__
        adds    r2, r0, r1      /* &src[maxlen] */
        mov     ip, r2
#else
        adds    ip, r0, r1      /* &src[maxlen] */
#endif
1:      cmp     r0, ip          /* is this the end of string? */
        beq     2f              /*   yes it is */
#ifdef __thumb__
        ldrb    r2, [r0]        /* read a byte */
        adds    r0, r0, #1      /* advance to next byte */
#else
        ldrb    r2, [r0], #1    /* read a byte */
#endif
        cmp     r2, #0          /* is it a NUL? */
        bne     1b              /*   no, get next byte */
        subs    r0, r0, r3      /* get difference between start and end */
        RET                     /* return */
2:      mov     r0, r1          /* get maxlen */
        RET                     /* return */
END(strnlen)
#else /* STRNLEN */
/* LINTSTUB: size_t strlen(const char *) */
ENTRY(strlen)
        adds    r3, r0, #1      /* start of src + NUL */
1:
#ifdef __thumb__
        ldrb    r2, [r0]        /* read a byte */
        adds    r0, r0, #1
#else
        ldrb    r2, [r0], #1    /* read a byte */
#endif
        cmp     r2, #0          /* is it a NUL? */
        bne     1b              /*   no, get next byte */
        subs    r0, r0, r3      /* return difference between start and end */
        RET
END(strlen)
#endif /* !STRNLEN */