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author | Roland McGrath <roland@gnu.org> | 1995-02-18 01:27:10 +0000 |
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committer | Roland McGrath <roland@gnu.org> | 1995-02-18 01:27:10 +0000 |
commit | 28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch) | |
tree | 15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/alpha/strlen.c | |
download | glibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.zip glibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.tar.gz glibc-28f540f45bbacd939bfd07f213bcad2bf730b1bf.tar.bz2 |
initial import
Diffstat (limited to 'sysdeps/alpha/strlen.c')
-rw-r--r-- | sysdeps/alpha/strlen.c | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/sysdeps/alpha/strlen.c b/sysdeps/alpha/strlen.c new file mode 100644 index 0000000..d774447 --- /dev/null +++ b/sysdeps/alpha/strlen.c @@ -0,0 +1,54 @@ +/* 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 (;;) + { + int mask; + asm ("cmpbge %1, %2, %0" : "=r" (mask) : "r" (0), "r" (*longword_ptr++)); + if (mask) + { + /* Which of the bytes was the zero? */ + + const char *cp = (const char *) (longword_ptr - 1); + int i; + + for (i = 0; i < 6; i++) + if (cp[i] == 0) + return cp - str + i; + return cp - str + 7; + } + } +} |