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authorJim Meyering <jim@meyering.net>2003-10-25 15:29:56 +0000
committerJim Meyering <jim@meyering.net>2003-10-25 15:29:56 +0000
commitbd67ac6ff2e2da0e77df949405406c6bca0e4903 (patch)
treebccd55e25fe59c95eaea73fdb6e920d7c0ed900c /lib/hash-pjw.c
parentfdb31735a27b7ee6f61a24d698ace9d98d166822 (diff)
downloadcoreutils-bd67ac6ff2e2da0e77df949405406c6bca0e4903.tar.xz
Update from gnulib.
Diffstat (limited to 'lib/hash-pjw.c')
-rw-r--r--lib/hash-pjw.c33
1 files changed, 15 insertions, 18 deletions
diff --git a/lib/hash-pjw.c b/lib/hash-pjw.c
index 0a14b3e7a..3328467e4 100644
--- a/lib/hash-pjw.c
+++ b/lib/hash-pjw.c
@@ -1,5 +1,5 @@
/* hash-pjw.c -- compute a hash value from a NUL-terminated string.
- Copyright 2001, 2003 Free Software Foundation, Inc.
+ Copyright (C) 2001, 2003 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
@@ -21,25 +21,22 @@
#include "hash-pjw.h"
+#include <limits.h>
+
+#define SIZE_BITS (sizeof (size_t) * CHAR_BIT)
+
/* A hash function for NUL-terminated char* strings using
- the method described in Aho, Sethi, & Ullman, p 436.
- Note that this hash function produces a lot of collisions when used
- with short strings with very varied bit patterns.
+ the method described by Bruno Haible.
See http://www.haible.de/bruno/hashfunc.html. */
-unsigned int
-hash_pjw (const void *x, unsigned int tablesize)
+size_t
+hash_pjw (const void *x, size_t 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);
+ const char *s;
+ size_t h = 0;
+
+ for (s = x; *s; s++)
+ h = *s + ((h << 9) | (h >> (SIZE_BITS - 9)));
+
+ return h % tablesize;
}