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authorJim Meyering <jim@meyering.net>2001-10-05 11:44:30 +0000
committerJim Meyering <jim@meyering.net>2001-10-05 11:44:30 +0000
commit0b9c7cac747d951c75aafd243f2a55d4a55a3eb6 (patch)
tree5f26369c1e37909c0e60a3cca8b368cf9abb532f /lib
parent32852d9825616c8a70dd6f2b44f3146e0ff60588 (diff)
downloadcoreutils-0b9c7cac747d951c75aafd243f2a55d4a55a3eb6.tar.xz
*** empty log message ***
Diffstat (limited to 'lib')
-rw-r--r--lib/hash-pjw.c42
-rw-r--r--lib/hash-pjw.h20
2 files changed, 62 insertions, 0 deletions
diff --git a/lib/hash-pjw.c b/lib/hash-pjw.c
new file mode 100644
index 000000000..141b08b51
--- /dev/null
+++ b/lib/hash-pjw.c
@@ -0,0 +1,42 @@
+/* hash-pjw.c -- compute a hash value from a NUL-terminated string.
+ Copyright 2001 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software Foundation,
+ Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+
+#if HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "hash-pjw.h"
+
+/* A hash function for NUL-terminated char* strings using
+ the method described in Aho, Sethi, & Ullman, p 436. */
+
+unsigned int
+hash_pjw (const void *x, unsigned int tablesize)
+{
+ const char *s = x;
+ unsigned int h = 0;
+ unsigned int g;
+
+ while (*s != 0)
+ {
+ h = (h << 4) + *s++;
+ if ((g = h & (unsigned int) 0xf0000000) != 0)
+ h = (h ^ (g >> 24)) ^ g;
+ }
+
+ return (h % tablesize);
+}
diff --git a/lib/hash-pjw.h b/lib/hash-pjw.h
new file mode 100644
index 000000000..efcda115a
--- /dev/null
+++ b/lib/hash-pjw.h
@@ -0,0 +1,20 @@
+/* hash-pjw.h -- declaration for a simple hash function
+ Copyright 2001 Free Software Foundation, Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; see the file COPYING.
+ If not, write to the Free Software Foundation,
+ 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+
+unsigned int
+hash_pjw (const void *x, unsigned int tablesize);