freebsd-dev/lib/libc/arm/string/strncmp.S

/*      $NetBSD: strncmp.S,v 1.2 2003/04/05 23:08:52 bjh21 Exp $ */

/*
 * Copyright (c) 2002 ARM Ltd
 * All rights reserved.
 *
 * 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.
 * 3. The name of the company may not be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY ARM LTD ``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 ARM LTD 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>

__FBSDID("$FreeBSD$");

ENTRY(strncmp)
/* if (len == 0) return 0 */
	cmp	r2, #0
	moveq	r0, #0
	moveq	pc, lr

/* ip == last src address to compare */
	adds	ip, r0, r2
/* Use last possible address on overflow. */
	movcs	ip, #0
	sub	ip, ip, #1
1:
	ldrb	r2, [r0], #1
	ldrb	r3, [r1], #1
	cmp	ip, r0
	cmpcs	r2, #1
	cmpcs	r2, r3
	beq	1b
	sub	r0, r2, r3
	RET