LXR linux/arch/tile/lib/strlen

   1/*
   2 * Copyright 2011 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
  20size_t strlen(const char *s)
  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
  26        /* Read and MASK the first word. */
  27        uint64_t v = *p | MASK(s_int);
  28
  29        uint64_t bits;
  30        while ((bits = __insn_v1cmpeqi(v, 0)) == 0)
  31                v = *++p;
  32
  33        return ((const char *)p) + (CFZ(bits) >> 3) - s;
  34}
  35EXPORT_SYMBOL(strlen);
  36