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engines/icb/common/px_clu_api.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * Additional copyright for this file:
+ * Copyright (C) 1999-2000 Revolution Software Ltd.
+ * This code is based on source code created by Revolution Software,
+ * used with permission.
+ *
+ * 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 "engines/icb/common/px_common.h"
+
+#include "common/system.h"
+
+namespace ICB {
+
+const char *hashTable = "ABCDEFGHIJKLMNOPQRSTUVWXYZ012345";
+
+uint32 EngineHashString(const char *fn) {
+	if (fn == nullptr)
+		return 0;
+	char *f;
+	char c;
+	uint32 n;
+	n = 0;
+	f = const_cast<char *>(fn);
+	while ((c = *f) != 0) {
+		n = (n << 7) + (n << 1) + n + c; // n=128n+2n+n+c -> n=131n+c
+		                                 // n=131*n+c;                  // n=131n+c
+		f++;
+	}
+	return n;
+}
+
+// Take a filename, path whatever,
+// convert to hash value, then convert that hash value to
+// 7 character filename
+uint32 EngineHashFile(const char *fn, char *output) {
+	uint32 hash = EngineHashString(fn);
+	output[0] = hashTable[(hash >> 27) & 0x1F];
+	output[1] = hashTable[(hash >> 22) & 0x1F];
+	output[2] = hashTable[(hash >> 17) & 0x1F];
+	output[3] = hashTable[(hash >> 12) & 0x1F];
+	output[4] = hashTable[(hash >> 7) & 0x1F];
+	output[5] = hashTable[(hash >> 2) & 0x1F];
+	output[6] = hashTable[hash & 0x3];
+	output[7] = '\0';
+	return hash;
+}
+
+// Take a hash
+// convert that hash value to
+// 7 character filename
+uint32 EngineHashToFile(uint32 hash, char *output) {
+	output[0] = hashTable[(hash >> 27) & 0x1F];
+	output[1] = hashTable[(hash >> 22) & 0x1F];
+	output[2] = hashTable[(hash >> 17) & 0x1F];
+	output[3] = hashTable[(hash >> 12) & 0x1F];
+	output[4] = hashTable[(hash >> 7) & 0x1F];
+	output[5] = hashTable[(hash >> 2) & 0x1F];
+	output[6] = hashTable[hash & 0x3];
+	output[7] = '\0';
+	return hash;
+}
+
+} // End of namespace ICB