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+/* Implement simple hashing table with string based keys.
+   Copyright (C) 1994-2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Written by Ulrich Drepper <drepper@gnu.ai.mit.edu>, October 1994.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef hashval_t
+# define hashval_t unsigned long int
+#endif
+#include <limits.h>		/* For CHAR_BIT.  */
+
+hashval_t
+compute_hashval (const void *key, size_t keylen)
+{
+  size_t cnt;
+  hashval_t hval;
+
+  /* Compute the hash value for the given string.  The algorithm
+     is taken from [Aho,Sethi,Ullman], modified to reduce the number of
+     collisions for short strings with very varied bit patterns.
+     See http://www.clisp.org/haible/hashfunc.html.  */
+  cnt = 0;
+  hval = keylen;
+  while (cnt < keylen)
+    {
+      hval = (hval << 9) | (hval >> (sizeof hval * CHAR_BIT - 9));
+      hval += (hashval_t) ((const unsigned char *) key)[cnt++];
+    }
+  return hval != 0 ? hval : ~((hashval_t) 0);
+}