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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 
     22 /*
     23  * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
     24  * Use is subject to license terms.
     25  */
     26 
     27 /*	Copyright (c) 1988 AT&T	*/
     28 /*	  All Rights Reserved	*/
     29 
     30 	.file	"gettimeofday.s"
     31 
     32 /*
     33  * C library -- gettimeofday
     34  * int gettimeofday (struct timeval *tp);
     35  */
     36 
     37 #include "SYS.h"
     38 
     39 	ANSI_PRAGMA_WEAK(gettimeofday,function)
     40 
     41 /*
     42  * The interface below calls the trap (0x27) to get the timestamp in
     43  * secs and nsecs. It than converts the nsecs value into usecs before
     44  * it returns.
     45  *
     46  * The algorithm used to perform the division by 1000 is based upon
     47  * algorithms for division based upon multiplication by invariant
     48  * integers.  Relevant sources for these algorithms are:
     49  *
     50  * Granlund, T.; Montgomery, P.L.: "Division by Invariant Integers using
     51  * Multiplication". SIGPLAN Notices, Vol. 29, June 1994, page 61.
     52  *
     53  * Magenheimer, D.J.; et al: "Integer Multiplication and Division on the HP
     54  * Precision Architecture". IEEE Transactions on Computers, Vol 37, No. 8,
     55  * August 1988, page 980.
     56  *
     57  * Steele G.; Warren H.: Hacker's Delight. 2002 Pearson Education, Ch 10
     58  *
     59  */
     60 
     61 	ENTRY(gettimeofday)
     62 	brz,pn	%o0, 1f
     63 	mov	%o0, %o5
     64 	SYSFASTTRAP(GETHRESTIME)
     65 	stn	%o0, [%o5]
     66 	sethi	%hi(0x10624DD3), %o2
     67 	or	%o2, %lo(0x10624DD3), %o2
     68 	mulx	%o1, %o2, %o2
     69 	srlx	%o2, 38, %o2
     70 	stn	%o2, [%o5 + CLONGSIZE]
     71 1:	RETC
     72 	SET_SIZE(gettimeofday)
     73