1/*
 2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
 3 *
 4 *   This program is free software; you can redistribute it and/or
 5 *   modify it under the terms of the GNU General Public License
 6 *   as published by the Free Software Foundation, version 2.
 7 *
 8 *   This program is distributed in the hope that it will be useful, but
 9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 *   NON INFRINGEMENT.  See the GNU General Public License for
12 *   more details.
13 */
14
15#include <linux/types.h>
16#include <linux/string.h>
17#include <linux/module.h>
18
19#undef strlen
20
21size_t strlen(const char *s)
22{
23	/* Get an aligned pointer. */
24	const uintptr_t s_int = (uintptr_t) s;
25	const uint32_t *p = (const uint32_t *)(s_int & -4);
26
27	/* Read the first word, but force bytes before the string to be nonzero.
28	 * This expression works because we know shift counts are taken mod 32.
29	 */
30	uint32_t v = *p | ((1 << (s_int << 3)) - 1);
31
32	uint32_t bits;
33	while ((bits = __insn_seqb(v, 0)) == 0)
34		v = *++p;
35
36	return ((const char *)p) + (__insn_ctz(bits) >> 3) - s;
37}
38EXPORT_SYMBOL(strlen);