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      1 /*	$NetBSD: byte_swap_4.S,v 1.9 2020/12/11 09:02:33 dholland Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1997 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Neil A. Carson
      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 <machine/asm.h>
     33 
     34 #if defined(_KERNEL) || defined(_STANDALONE)
     35 #define	FUNC	_C_LABEL(bswap32)
     36 #else
     37 #define	FUNC	_C_LABEL(__bswap32)
     38 #endif
     39 ENTRY(FUNC)
     40 #ifdef _ARM_ARCH_6
     41 	rev	r0, r0
     42 #elif !defined(__thumb__)
     43 	eor	r1, r0, r0, ror #16	/* d.c.b.a -> db.ca.db.ca */
     44 	bic	r1, r1, #0x00FF0000	/* db.ca.db.ca -> db.0.db.ca */
     45 	mov	r0, r0, ror #8		/* d.c.b.a -> a.d.c.b */
     46 	eor	r0, r0, r1, lsr #8	/* a.d.c.b ^ 0.db.0.db -> a.b.c.d */
     47 #else
     48 	movs	r3, #16
     49 	lsls	r1, r0, #8		/* d.c.b.a -> c.b.a.0 */
     50 	lsrs	r0, r0, #8		/* d.c.b.a -> 0.d.c.b */
     51 	rors	r1, r3			/* c.b.a.0 -> a.0.c.b */
     52 	rors	r0, r3			/* 0.d.c.b -> c.b.0.d */
     53 	lsrs	r1, r1, #8		/* a.0.c.b -> 0.a.0.c */
     54 	lsls	r1, r1, #8		/* 0.a.0.c -> a.0.c.0 */
     55 	lsls	r0, r0, #8		/* c.b.0.d -> b.0.d.0 */
     56 	lsrs	r0, r0, #8		/* b.0.d.0 -> 0.b.0.d */
     57 	orrs	r0, r0, r1		/* a.0.c.0 | 0.b.0.d -> a.b.c.d */
     58 #endif
     59 	RET
     60 END(FUNC)
     61 
     62 #if BYTE_ORDER == LITTLE_ENDIAN
     63 STRONG_ALIAS(_C_LABEL(ntohl), FUNC)
     64 STRONG_ALIAS(_C_LABEL(htonl), FUNC)
     65 #endif
     66