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atomic_dec_64.S revision 1.2 
      1 /* $NetBSD: atomic_dec_64.S,v 1.2 2020/08/12 12:59:57 skrll Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2014 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Matt Thomas of 3am Software Foundry.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     29  * POSSIBILITY OF SUCH DAMAGE.
     30  */
     31 
     32 #include "atomic_op_asm.h"
     33 
     34 ENTRY_NP(_atomic_dec_64)
     35 1:	ldxr	x2, [x0]		/* load old value (return value) */
     36 	sub	x2, x2, #1		/* calculate new value */
     37 	stxr	w3, x2, [x0]		/* try to store */
     38 	cbnz	w3, 2f			/*   succeed? no, try again? */
     39 	ret				/* return new value */
     40 2:	b	1b
     41 END(_atomic_dec_64)
     42 
     43 ATOMIC_OP_ALIAS(atomic_dec_64,_atomic_dec_64)
     44 ATOMIC_OP_ALIAS(atomic_dec_ptr,_atomic_dec_64)
     45 ATOMIC_OP_ALIAS(atomic_dec_ulong,_atomic_dec_64)
     46 STRONG_ALIAS(_atomic_dec_ptr,_atomic_dec_64)
     47 STRONG_ALIAS(_atomic_dec_ulong,_atomic_dec_64)
     48 
     49 ENTRY_NP(_atomic_dec_64_nv)
     50 	mov	x4, x0			/* need r0 for return value */
     51 1:	ldxr	x0, [x4]		/* load old value */
     52 	sub	x0, x0, #1		/* calculate new value (return value) */
     53 	stxr	w3, x0, [x4]		/* try to store */
     54 	cbnz	w3, 2f			/*   succeed? no, try again? */
     55 	ret				/* return new value */
     56 2:	b	1b
     57 END(_atomic_dec_64_nv)
     58 
     59 ATOMIC_OP_ALIAS(atomic_dec_64_nv,_atomic_dec_64_nv)
     60 ATOMIC_OP_ALIAS(atomic_dec_ptr_nv,_atomic_dec_64_nv)
     61 ATOMIC_OP_ALIAS(atomic_dec_ulong_nv,_atomic_dec_64_nv)
     62 STRONG_ALIAS(_atomic_dec_ptr_nv,_atomic_dec_64_nv)
     63 STRONG_ALIAS(_atomic_dec_ulong_nv,_atomic_dec_64_nv)
     64