1 files changed, 89 insertions, 0 deletions
diff --git a/libglusterfs/src/hashfn.c b/libglusterfs/src/hashfn.c
new file mode 100644
index 00000000000..edc49678fc5
--- /dev/null
+++ b/libglusterfs/src/hashfn.c
@@ -0,0 +1,89 @@
+/*
+   Copyright (c) 2006, 2007, 2008 Z RESEARCH, Inc. <http://www.zresearch.com>
+   This file is part of GlusterFS.
+
+   GlusterFS 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 3 of the License,
+   or (at your option) any later version.
+
+   GlusterFS 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, see
+   <http://www.gnu.org/licenses/>.
+*/
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include "hashfn.h"
+
+#define get16bits(d) (*((const uint16_t *) (d)))
+
+/*
+  This is apparently the "fastest hash function for strings".
+  Written by Paul Hsieh <http://www.azillionmonkeys.com/qed/hash.html>
+*/
+
+/* In any case make sure, you return 1 */
+
+uint32_t SuperFastHash (const char * data, int32_t len) {
+  uint32_t hash = len, tmp;
+  int32_t rem;
+
+  if (len <= 1 || data == NULL) return 1;
+
+
+  for (;len > 0; len--) {
+    hash ^= data[len];
+
+    return hash;
+  }
+
+  rem = len & 3;
+  len >>= 2;
+
+  /* Main loop */
+  for (;len > 0; len--) {
+    hash  += get16bits (data);
+    tmp    = (get16bits (data+2) << 11) ^ hash;
+    hash   = (hash << 16) ^ tmp;
+    data  += 2*sizeof (uint16_t);
+    hash  += hash >> 11;
+  }
+
+  /* Handle end cases */
+  switch (rem) {
+  case 3: hash += get16bits (data);
+    hash ^= hash << 16;
+    hash ^= data[sizeof (uint16_t)] << 18;
+    hash += hash >> 11;
+    break;
+  case 2: hash += get16bits (data);
+    hash ^= hash << 11;
+    hash += hash >> 17;
+    break;
+  case 1: hash += *data;
+    hash ^= hash << 10;
+    hash += hash >> 1;
+  }
+
+  /* Force "avalanching" of final 127 bits */
+  hash ^= hash << 3;
+  hash += hash >> 5;
+  hash ^= hash << 4;
+  hash += hash >> 17;
+  hash ^= hash << 25;
+  hash += hash >> 6;
+
+  return hash;
+}