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Annotation of sys/lib/libkern/arch/alpha/byte_swap_2.S, Revision 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)