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byte_swap_4.S revision 1.3 
      1 /*	$NetBSD: byte_swap_4.S,v 1.3 2009/12/14 00:39:00 matt Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1991, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Ralph Campbell.
      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  * 3. Neither the name of the University nor the names of its contributors
     19  *    may be used to endorse or promote products derived from this software
     20  *    without specific prior written permission.
     21  *
     22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     32  * SUCH DAMAGE.
     33  */
     34 
     35 #include <mips/asm.h>
     36 
     37 #if defined(LIBC_SCCS) && !defined(lint)
     38 #if 0
     39 	RCSID("from: @(#)htonl.s	8.1 (Berkeley) 6/4/93")
     40 #else
     41 	RCSID("$NetBSD: byte_swap_4.S,v 1.3 2009/12/14 00:39:00 matt Exp $")
     42 #endif
     43 #endif /* LIBC_SCCS and not lint */
     44 
     45 #undef _LOCORE
     46 #define _LOCORE		/* XXX not really, just assembly-code source */
     47 #include <machine/endian.h>
     48 
     49 #if defined(_KERNEL) || defined(_STANDALONE)
     50 #define	BSWAP32_NAME	bswap32
     51 #else
     52 #define	BSWAP32_NAME	__bswap32
     53 #endif
     54 
     55 NLEAF(BSWAP32_NAME)			# a0 = 0x11223344, return 0x44332211
     56 #if BYTE_ORDER == LITTLE_ENDIAN
     57 ALEAF(htonl)				# a0 = 0x11223344, return 0x44332211
     58 ALEAF(ntohl)
     59 #endif
     60 #if (__mips == 32 || __mips == 64) && __mips_isa_rev == 2
     61 	/*
     62 	 * If we are on MIPS32R2 or MIPS64R2 it's much easier
     63 	 */
     64 	wsbh	a0, a0			# word swap bytes within halfwords
     65 	rotr	v0, a0, 16		# rotate word 16bits
     66 	j	ra
     67 #else
     68 	srl	v1, a0, 24		# v1 = 0x00000011
     69 	sll	v0, a0, 24		# v0 = 0x44000000
     70 	or	v0, v0, v1
     71 	and	v1, a0, 0xff00
     72 	sll	v1, v1, 8		# v1 = 0x00330000
     73 	or	v0, v0, v1
     74 	srl	v1, a0, 8
     75 	and	v1, v1, 0xff00		# v1 = 0x00002200
     76 	or	v0, v0, v1
     77 	j	ra
     78 #endif
     79 END(BSWAP32_NAME)
     80 
     81 #if BYTE_ORDER == BIG_ENDIAN
     82 NLEAF(htonl)				# a0 = 0x11223344, return 0x44332211
     83 ALEAF(ntohl)
     84 	move	v0, a0
     85 	j	ra
     86 END(htonl)
     87 #endif
     88