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/* Copyright (C) 1992 Free Software Foundation, Inc.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library 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. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <string.h>
/* Return the length of the null-terminated string STR. Scan for
the null terminator quickly by testing eight bytes at a time. */
size_t
strlen (const char *str)
{
const char *char_ptr;
const unsigned long int *longword_ptr;
/* Handle the first few characters by reading one character at a time.
Do this until STR is aligned on a 8-byte border. */
for (char_ptr = str; ((unsigned long int) char_ptr & 7) != 0; ++char_ptr)
if (*char_ptr == '\0')
return char_ptr - str;
longword_ptr = (unsigned long int *) char_ptr;
for (;;)
{
const unsigned long int longword = *longword_ptr++;
int mask;
/* Set bits in MASK if bytes in LONGWORD are zero. */
asm ("cmpbge $31, %1, %0" : "=r" (mask) : "r" (longword));
if (mask)
{
/* Which of the bytes was the zero? */
const char *cp = (const char *) (longword_ptr - 1);
int i;
for (i = 0; i < 8; i++)
if (cp[i] == 0)
return cp - str + i;
}
}
}
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