mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-29 16:21:07 +00:00
5fa2588651
of the byte that was zero, so we return a valid number. Mon Apr 17 12:02:49 1995 Brendan Kehoe (brendan@zen.org) * sysdeps/alpha/strlen.c (strlen): Fix cmpbge insn, and returning of the byte that was zero, so we return a valid number. * sysdeps/unix/bsd/ultrix4/mips/sysdep.h: New file defining
56 lines
1.7 KiB
C
56 lines
1.7 KiB
C
/* 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;
|
|
}
|
|
}
|
|
}
|