xref: /illumos-gate/usr/src/lib/libc/amd64/gen/wslen.S (revision 55fea89d)
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	"wslen.s"
28
29/*
30 * Wide character wcslen() implementation
31 *
32 * size_t
33 * wcslen(const wchar_t *s)
34 *{
35 *	const wchar_t *s0 = s + 1;
36 *	while (*s++)
37 *		;
38 *	return (s - s0);
39 *}
40 */
41
42#include <sys/asm_linkage.h>
43
44	ANSI_PRAGMA_WEAK(wcslen,function)
45	ANSI_PRAGMA_WEAK(wslen,function)
46
47	ENTRY(wcslen)		/* (wchar_t *) */
48	xorl	%eax,%eax
49
50	.align	8
51.loop:
52	cmpl	$0,(%rdi)
53	je	.out0
54	cmpl	$0,4(%rdi)
55	je	.out1
56	cmpl	$0,8(%rdi)
57	je	.out2
58	cmpl	$0,12(%rdi)
59	je	.out3
60	addq	$4,%rax
61	addq	$16,%rdi
62	jmp	.loop
63
64	.align	4
65.out1:
66	incq	%rax
67.out0:
68	ret
69
70	.align	4
71.out2:
72	addq	$2,%rax
73	ret
74
75	.align	4
76.out3:
77	addq	$3, %rax
78	ret
79	SET_SIZE(wcslen)
80
81	ENTRY(wslen)
82	jmp	wcslen		/ tail call into wcslen
83	SET_SIZE(wslen)
84