/*	$NetBSD: sync_fetch_and_sub_8.S,v 1.5.18.1 2021/08/11 17:05:42 martin Exp $	*/

/*-
 * Copyright (c) 2013 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Matt Thomas <matt@3am-software.com>
 *
 * 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 "atomic_op_asm.h"

#if defined(_ARM_ARCH_6)

ENTRY_NP(__sync_fetch_and_sub_8)
	push	{r4-r7}
	mov	ip, r0
#ifndef __ARM__EABI__
	mov	r3, r2
	mov	r2, r1
#endif
	DMB
1:	ldrexd	r0, r1, [ip]		/* load old value */
	subs	TLO, LO, NLO		/* calculate new value */
	sbcs	THI, HI, NHI		/* calculate new value */
	strexd	r6, r4, r5, [ip]	/* try to store */
	cmp	r6, #0			/*   succeed? */
	bne	1b			/*     no, try again */
	DMB
	pop	{r4-r7}
	RET				/* return old value */
END(__sync_fetch_and_sub_8)

CRT_ALIAS(__atomic_fetch_sub_8,__sync_fetch_and_sub_8)

#endif /* _ARM_ARCH_6 */