Annotation of sys/lib/libkern/arch/alpha/byte_swap_4.S, Revision 1.1.1.1
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)
CVSweb