Annotation of sys/lib/libkern/arch/alpha/byte_swap_4.S, Revision 1.1
1.1 ! nbrk 1: /* $OpenBSD: byte_swap_4.S,v 1.2 1996/10/31 00:43:15 niklas Exp $ */
! 2: /* $NetBSD: byte_swap_4.S,v 1.2 1996/10/17 04:26:22 cgd Exp $ */
! 3:
! 4: /*
! 5: * Copyright (c) 1996 Carnegie-Mellon University.
! 6: * All rights reserved.
! 7: *
! 8: * Author: Chris G. Demetriou
! 9: *
! 10: * Permission to use, copy, modify and distribute this software and
! 11: * its documentation is hereby granted, provided that both the copyright
! 12: * notice and this permission notice appear in all copies of the
! 13: * software, derivative works or modified versions, and any portions
! 14: * thereof, and that both notices appear in supporting documentation.
! 15: *
! 16: * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
! 17: * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
! 18: * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
! 19: *
! 20: * Carnegie Mellon requests users of this software to return to
! 21: *
! 22: * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
! 23: * School of Computer Science
! 24: * Carnegie Mellon University
! 25: * Pittsburgh PA 15213-3890
! 26: *
! 27: * any improvements or extensions that they make and grant Carnegie the
! 28: * rights to redistribute these changes.
! 29: */
! 30:
! 31: #include <machine/asm.h>
! 32:
! 33: #ifndef NAME
! 34: #define NAME byte_swap_4
! 35: #endif
! 36:
! 37: /*
! 38: * Byte-swap a 4-byte quantity. (Convert 0x01234567 to 0x67452301.)
! 39: *
! 40: * Argument is an unsigned 4-byte integer (u_int32_t).
! 41: */
! 42: LEAF(NAME, 1) /* a0 contains 0x01234567 */
! 43: extbl a0, 0, t0 /* t0 = 0x 67 */
! 44: extbl a0, 1, t1 /* t1 = 0x 45 */
! 45: extbl a0, 2, t2 /* t2 = 0x 23 */
! 46: extbl a0, 3, t3 /* t3 = 0x 01 */
! 47: sll t0, 24, t0 /* t0 = 0x67 */
! 48: sll t1, 16, t1 /* t1 = 0x 45 */
! 49: sll t2, 8, t2 /* t2 = 0x 23 */
! 50: or t3, t0, v0 /* v0 = 0x67 01 */
! 51: or t1, t2, t1 /* t1 = 0x 4523 */
! 52: or t1, v0, v0 /* v0 = 0x67452301 */
! 53: RET
! 54: END(NAME)
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