COMMON: Add string hashing algorithms

src/common/hash.h

@@ -0,0 +1,83 @@
+/* xoreos - A reimplementation of BioWare's Aurora engine
+ *
+ * xoreos is the legal property of its developers, whose names can be
+ * found in the AUTHORS file distributed with this source
+ * distribution.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ *
+ * The Infinity, Aurora, Odyssey and Eclipse engines, Copyright (c) BioWare corp.
+ * The Electron engine, Copyright (c) Obsidian Entertainment and BioWare corp.
+ */
+
+/** @file common/hash.h
+ *  Utility hash functions.
+ */
+
+#ifndef COMMON_HASH_H
+#define COMMON_HASH_H
+
+#include "common/types.h"
+#include "common/ustring.h"
+
+namespace Common {
+
+/** The algorithm used for hashing. */
+enum HashAlgo {
+	kHashNone  = -1, ///< No hashing at all.
+	kHashDJB2  =  0, ///< djb2 hash function by Daniel J. Bernstein.
+	kHashFNV64 =  1, ///< 64bit Fowler–Noll–Vo hash by Glenn Fowler, Landon Curt Noll and Phong Vo.
+	kHashMAX         ///< For range checks.
+};
+
+/** djb2 hash function by Daniel J. Bernstein. */
+static inline uint32 hashStringDJB2(const Common::UString &string) {
+	uint32 hash = 5381;
+
+	for (Common::UString::iterator it = string.begin(); it != string.end(); ++it)
+		hash = ((hash << 5) + hash) + *it;
+
+	return hash;
+}
+
+/** 64bit Fowler–Noll–Vo hash by Glenn Fowler, Landon Curt Noll and Phong Vo. */
+static inline uint64 hashStringFNV64(const Common::UString &string) {
+	uint64 hash = 0xCBF29CE484222325LL;
+
+	for (Common::UString::iterator it = string.begin(); it != string.end(); ++it)
+		hash = (hash * 1099511628211) ^ *it;
+
+	return hash;
+}
+
+static inline uint64 hashString(const Common::UString &string, HashAlgo algo) {
+	switch (algo) {
+		case kHashDJB2:
+			return hashStringDJB2(string);
+
+		case kHashFNV64:
+			return hashStringFNV64(string);
+
+		default:
+			break;
+	}
+
+	return 0;
+}
+
+} // End of namespace Common
+
+#endif // COMMON_HASH_H