usr/src/lib/libc/i386/sys/gettimeofday.s

   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         .file   "gettimeofday.s"
  28
  29 #include "SYS.h"
  30
  31         ANSI_PRAGMA_WEAK(gettimeofday,function)
  32
  33 /
  34 /  implements int gettimeofday(struct timeval *tp, void *tzp)
  35 /
  36 /       note that tzp is always ignored
  37 /
  38
  39         ENTRY(gettimeofday)
  40 /
  41 /       use long long gethrestime()
  42 /
  43         SYSFASTTRAP(GETHRESTIME)
  44 /
  45 /       gethrestime trap returns seconds in %eax, nsecs in %edx
  46 /       need to convert nsecs to usecs & store into area pointed
  47 /       to by struct timeval * argument.
  48 /
  49         movl 4(%esp), %ecx      / put ptr to timeval in %ecx
  50         jecxz 1f                / bail if we get a null pointer
  51         movl %eax, (%ecx)       / store seconds into timeval ptr
  52         movl $274877907, %eax   / divide by 1000 as impl. by gcc
  53         imull %edx              / See Hacker's Delight pg 162
  54         sarl $6, %edx           / simplified by 0 <= nsec <= 1e9
  55         movl %edx, 4(%ecx)      / store usecs into timeval ptr + 4.
  56 1:
  57         RETC                    / return 0
  58         SET_SIZE(gettimeofday)
  59
  60