xref: /titanic_50/usr/src/lib/libc/amd64/sys/gettimeofday.s (revision 1dd08564e4a3aafe66b00aee6f222b0885346fe8)
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#pragma ident	"%Z%%M%	%I%	%E% SMI"
28
29	.file	"%M%"
30
31#include "SYS.h"
32
33	ANSI_PRAGMA_WEAK(gettimeofday,function)
34
35/*
36 *  implements int gettimeofday(struct timeval *tp, void *tzp)
37 *
38 *	note that tzp is always ignored
39 */
40
41	ENTRY(gettimeofday)
42/*
43 *	use long long gethrestime()
44 */
45	pushq	%rdi		/* pointer to timeval */
46	SYSFASTTRAP(GETHRESTIME)
47/*
48 *	gethrestime trap returns seconds in %eax, nsecs in %edx
49 *	need to convert nsecs to usecs & store into area pointed
50 *	to by struct timeval * argument.
51 */
52	popq	%rcx		/* pointer to timeval */
53	jrcxz	1f		/* bail if we get a null pointer */
54	movq	%rax, (%rcx)	/* store seconds into timeval ptr	 */
55	movl	$274877907, %eax	/* divide by 1000 as impl. by gcc */
56	imull	%edx		/* See Hacker's Delight pg 162 */
57	sarl	$6, %edx	/* simplified by 0 <= nsec <= 1e9 */
58	movq	%rdx, 8(%rcx)	/* store usecs into timeval ptr + 8. */
591:
60	RETC			/* return 0 */
61	SET_SIZE(gettimeofday)
62
63