sysdeps/i386/strlen.c

   1 /* Determine the length of a string.  For Intel 80x86, x>=3.
   2    Copyright (C) 1991,1992,1993,1996,1997,2003 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4    Contributed by Torbjorn Granlund (tege@sics.se).
   5
   6    The GNU C Library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2.1 of the License, or (at your option) any later version.
  10
  11    The GNU C Library is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with the GNU C Library; if not, write to the Free
  18    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19    02111-1307 USA.  */
  20
  21 #include <string.h>
  22
  23 size_t
  24 strlen (const char *str)
  25 {
  26   int cnt;
  27
  28   asm("cld\n"                   /* Search forward.  */
  29       /* Some old versions of gas need `repne' instead of `repnz'.  */
  30       "repnz\n"                 /* Look for a zero byte.  */
  31       "scasb" /* %0, %1, %3 */ :
  32       "=c" (cnt) : "D" (str), "0" (-1), "a" (0));
  33
  34   return -2 - cnt;
  35 }
  36 libc_hidden_builtin_def (strlen)