/*
   * 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);