Annotation of sys/lib/libkern/arch/alpha/byte_swap_2.S, Revision 1.1.1.1
1.1 nbrk 1: /* $OpenBSD: byte_swap_2.S,v 1.2 1996/10/31 00:43:14 niklas Exp $ */
2: /* $NetBSD: byte_swap_2.S,v 1.2 1996/10/17 04:26:21 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_2
35: #endif
36:
37: /*
38: * Byte-swap a 2-byte quantity. (Convert 0x0123 to 0x2301.)
39: *
40: * Argument is an unsigned 2-byte integer (u_int16_t).
41: */
42: LEAF(NAME, 1) /* a0 contains 0x0123 */
43: extbl a0, 0, t0 /* t0 = 0x 23 */
44: extbl a0, 1, t1 /* t1 = 0x 01 */
45: sll t0, 8, t0 /* t1 = 0x23 */
46: or t0, t1, v0 /* v0 = 0x2301 */
47: RET
48: END(NAME)
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