[deliverable/linux.git] / arch / tile / lib / strnlen_64.c

/*
 * Copyright 2013 Tilera Corporation. All Rights Reserved.
 *
 *   This program is free software; you can redistribute it and/or
 *   modify it under the terms of the GNU General Public License
 *   as published by the Free Software Foundation, version 2.
 *
 *   This program is distributed in the hope that it will be useful, but
 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 *   NON INFRINGEMENT.  See the GNU General Public License for
 *   more details.
 */

#include <linux/types.h>
#include <linux/string.h>
#include <linux/module.h>
#include "string-endian.h"

size_t strnlen(const char *s, size_t count)
{
	/* Get an aligned pointer. */
	const uintptr_t s_int = (uintptr_t) s;
	const uint64_t *p = (const uint64_t *)(s_int & -8);
	size_t bytes_read = sizeof(*p) - (s_int & (sizeof(*p) - 1));
	size_t len;
	uint64_t v, bits;

	/* Avoid page fault risk by not reading any bytes when count is 0. */
	if (count == 0)
		return 0;

	/* Read and MASK the first word. */
	v = *p | MASK(s_int);

	while ((bits = __insn_v1cmpeqi(v, 0)) == 0) {
		if (bytes_read >= count) {
			/* Read COUNT bytes and didn't find the terminator. */
			return count;
		}
		v = *++p;
		bytes_read += sizeof(v);
	}

	len = ((const char *) p) + (CFZ(bits) >> 3) - s;
	return (len < count ? len : count);
}
EXPORT_SYMBOL(strnlen);
Commit	Line	Data
5916700c KS	1	/*
	2	* Copyright 2013 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	#include "string-endian.h"
	19
	20	size_t strnlen(const char *s, size_t count)
	21	{
	22	/* Get an aligned pointer. */
	23	const uintptr_t s_int = (uintptr_t) s;
	24	const uint64_t p = (const uint64_t )(s_int & -8);
	25	size_t bytes_read = sizeof(p) - (s_int & (sizeof(p) - 1));
	26	size_t len;
	27	uint64_t v, bits;
	28
	29	/* Avoid page fault risk by not reading any bytes when count is 0. */
	30	if (count == 0)
	31	return 0;
	32
	33	/* Read and MASK the first word. */
	34	v = *p \| MASK(s_int);
	35
	36	while ((bits = __insn_v1cmpeqi(v, 0)) == 0) {
	37	if (bytes_read >= count) {
	38	/* Read COUNT bytes and didn't find the terminator. */
	39	return count;
	40	}
	41	v = *++p;
	42	bytes_read += sizeof(v);
	43	}
	44
	45	len = ((const char *) p) + (CFZ(bits) >> 3) - s;
	46	return (len < count ? len : count);
	47	}
	48	EXPORT_SYMBOL(strnlen);