55 lines
1.7 KiB
ArmAsm
55 lines
1.7 KiB
ArmAsm
/* $FreeBSD$ */
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/* $NetBSD: byte_swap_4.S,v 1.2 1996/10/17 03:08:09 cgd Exp $ */
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/*
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* Copyright (c) 1996 Carnegie-Mellon University.
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* All rights reserved.
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*
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* Author: Chris G. Demetriou
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*
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* Permission to use, copy, modify and distribute this software and
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* its documentation is hereby granted, provided that both the copyright
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* notice and this permission notice appear in all copies of the
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* software, derivative works or modified versions, and any portions
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* thereof, and that both notices appear in supporting documentation.
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*
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* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
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* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
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* FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
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*
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* Carnegie Mellon requests users of this software to return to
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*
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* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
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* School of Computer Science
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* Carnegie Mellon University
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* Pittsburgh PA 15213-3890
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*
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* any improvements or extensions that they make and grant Carnegie the
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* rights to redistribute these changes.
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*/
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#include <machine/asm.h>
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#ifndef NAME
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#define NAME byte_swap_4
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#endif
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/*
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* Byte-swap a 4-byte quantity. (Convert 0x01234567 to 0x67452301.)
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*
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* Argument is an unsigned 4-byte integer (u_int32_t).
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*/
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LEAF(NAME, 1) /* a0 contains 0x01234567 */
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extbl a0, 0, t0 /* t0 = 0x 67 */
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extbl a0, 1, t1 /* t1 = 0x 45 */
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extbl a0, 2, t2 /* t2 = 0x 23 */
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extbl a0, 3, t3 /* t3 = 0x 01 */
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sll t0, 24, t0 /* t0 = 0x67 */
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sll t1, 16, t1 /* t1 = 0x 45 */
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sll t2, 8, t2 /* t2 = 0x 23 */
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or t3, t0, v0 /* v0 = 0x67 01 */
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or t1, t2, t1 /* t1 = 0x 4523 */
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or t1, v0, v0 /* v0 = 0x67452301 */
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RET
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END(NAME)
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