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byte_swap_4.S revision 1.4.26.1 
      1 /*	$NetBSD: byte_swap_4.S,v 1.4.26.1 2013/02/25 00:23:55 tls 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 _ENTRY(_C_LABEL(bswap32))
     36 #else
     37 _ENTRY(_C_LABEL(__bswap32))
     38 #endif
     39 #if BYTE_ORDER == LITTLE_ENDIAN
     40 _ENTRY(_C_LABEL(ntohl))
     41 _ENTRY(_C_LABEL(htonl))
     42 #endif
     43 _PROF_PROLOGUE
     44 #ifdef _ARM_ARCH_6
     45 	rev	r0, r0
     46 #else
     47 	eor	r1, r0, r0, ror #16	/* 4.3.2.1 -> 42.31.42.31 */
     48 	bic	r1, r1, #0x00FF0000	/* 42.31.42.31 -> 42.0.42.31 */
     49 	mov	r0, r0, ror #8		/* 4.3.2.1 -> 1.4.3.2 */
     50 	eor	r0, r0, r1, lsr #8	/* 1.4.3.2 ^ 0.42.0.42 -> 1.2.3.4 */
     51 #endif
     52 	RET
     53