New hmap and hmapx hash table implementations.

[pspp-builds.git] / src / libpspp / hash-functions.c

diff --git a/src/libpspp/hash-functions.c b/src/libpspp/hash-functions.c
new file mode 100644 (file)
index 0000000..2318777
--- /dev/null
+++ b/src/libpspp/hash-functions.c
@@ -0,0 +1,90 @@
+/* PSPP - a program for statistical analysis.
+   Copyright (C) 1997-9, 2000, 2008 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 3 of the License, 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, see <http://www.gnu.org/licenses/>. */
+
+#include <config.h>
+#include <libpspp/hash-functions.h>
+#include <assert.h>
+#include <ctype.h>
+#include <math.h>
+
+/* Fowler-Noll-Vo hash constants, for 32-bit word sizes. */
+#define FNV_32_PRIME 16777619u
+#define FNV_32_BASIS 2166136261u
+
+/* Fowler-Noll-Vo 32-bit hash, for bytes. */
+unsigned
+hsh_hash_bytes (const void *buf_, size_t size)
+{
+  const unsigned char *buf = (const unsigned char *) buf_;
+  unsigned hash;
+
+  assert (buf != NULL);
+
+  hash = FNV_32_BASIS;
+  while (size-- > 0)
+    hash = (hash * FNV_32_PRIME) ^ *buf++;
+
+  return hash;
+}
+
+/* Fowler-Noll-Vo 32-bit hash, for strings. */
+unsigned
+hsh_hash_string (const char *s_)
+{
+  const unsigned char *s = (const unsigned char *) s_;
+  unsigned hash;
+
+  assert (s != NULL);
+
+  hash = FNV_32_BASIS;
+  while (*s != '\0')
+    hash = (hash * FNV_32_PRIME) ^ *s++;
+
+  return hash;
+}
+
+/* Fowler-Noll-Vo 32-bit hash, for case-insensitive strings. */
+unsigned
+hsh_hash_case_string (const char *s_)
+{
+  const unsigned char *s = (const unsigned char *) s_;
+  unsigned hash;
+
+  assert (s != NULL);
+
+  hash = FNV_32_BASIS;
+  while (*s != '\0')
+    hash = (hash * FNV_32_PRIME) ^ toupper (*s++);
+
+  return hash;
+}
+
+/* Hash for ints. */
+unsigned
+hsh_hash_int (int i)
+{
+  return hsh_hash_bytes (&i, sizeof i);
+}
+
+/* Hash for double. */
+unsigned
+hsh_hash_double (double d)
+{
+  if (!isnan (d))
+    return hsh_hash_bytes (&d, sizeof d);
+  else
+    return 0;
+}