/* $OpenBSD: byte_swap_4.S,v 1.3 1996/11/13 22:05:03 niklas Exp $ */ /* $NetBSD: byte_swap_4.S,v 1.2 1996/10/17 03:08:09 cgd Exp $ */ /* * Copyright (c) 1996 Carnegie-Mellon University. * All rights reserved. * * Author: Chris G. Demetriou * * Permission to use, copy, modify and distribute this software and * its documentation is hereby granted, provided that both the copyright * notice and this permission notice appear in all copies of the * software, derivative works or modified versions, and any portions * thereof, and that both notices appear in supporting documentation. * * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. * * Carnegie Mellon requests users of this software to return to * * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU * School of Computer Science * Carnegie Mellon University * Pittsburgh PA 15213-3890 * * any improvements or extensions that they make and grant Carnegie the * rights to redistribute these changes. */ #include #if defined(LIBC_SCCS) .text .asciz "$OpenBSD: byte_swap_4.S,v 1.3 1996/11/13 22:05:03 niklas Exp $" #endif #ifndef NAME #define NAME byte_swap_4 #endif /* * Byte-swap a 4-byte quantity. (Convert 0x01234567 to 0x67452301.) * * Argument is an unsigned 4-byte integer (u_int32_t). */ LEAF(NAME, 1) /* a0 contains 0x01234567 */ extbl a0, 0, t0 /* t0 = 0x 67 */ extbl a0, 1, t1 /* t1 = 0x 45 */ extbl a0, 2, t2 /* t2 = 0x 23 */ extbl a0, 3, t3 /* t3 = 0x 01 */ sll t0, 24, t0 /* t0 = 0x67 */ sll t1, 16, t1 /* t1 = 0x 45 */ sll t2, 8, t2 /* t2 = 0x 23 */ or t3, t0, v0 /* v0 = 0x67 01 */ or t1, t2, t1 /* t1 = 0x 4523 */ or t1, v0, v0 /* v0 = 0x67452301 */ RET END(NAME)