minix/common/lib/libc/arch/alpha/gen/byte_swap_4.S

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/* $NetBSD: byte_swap_4.S,v 1.3 2008/02/16 17:37:13 apb 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 <machine/asm.h>
/*
* Byte-swap a 4-byte quantity. (Convert 0x01234567 to 0x67452301.)
*
* Argument is an unsigned 4-byte integer (uint32_t).
*/
#if defined(_KERNEL) || defined(_STANDALONE)
#define BSWAP32 bswap32
#else /* defined(_KERNEL) || defined(_STANDALONE) */
#define BSWAP32 __bswap32
#endif /* defined(_KERNEL) || defined(_STANDALONE) */
LEAF(BSWAP32, 1) /* a0 contains 0x01234567 */
XLEAF(htonl, 1)
XLEAF(ntohl, 1)
insbl a0, 3, t0 /* t0 = 0x67 */
extbl a0, 1, t1 /* t1 = 0x 45 */
extbl a0, 2, t2 /* t2 = 0x 23 */
extbl a0, 3, t3 /* t3 = 0x 01 */
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(BSWAP32)