arch/tile/lib/strlen_64.c

   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
  20 size_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 }
  35 EXPORT_SYMBOL(strlen);