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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/alpha/strlen.c
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initial import
Diffstat (limited to 'sysdeps/alpha/strlen.c')
-rw-r--r--sysdeps/alpha/strlen.c54
1 files changed, 54 insertions, 0 deletions
diff --git a/sysdeps/alpha/strlen.c b/sysdeps/alpha/strlen.c
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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 (;;)
+ {
+ 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;
+ }
+ }
+}