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engines/icb/common/px_linkeddatafile.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_rcutypes.h"
+#include "engines/icb/common/px_string.h"
+#include "engines/icb/common/px_common.h"
+#include "engines/icb/common/px_clu_api.h"
+#include "engines/icb/common/px_linkeddatafile.h"
+
+namespace ICB {
+
+// get NUMBER given HASH (does the search) - hashs must be ordered for this binary search to succeed.
+uint32 LinkedDataObject::Fetch_item_number_by_hash(LinkedDataFile *file, const uint32 hash) {
+	int32 top, bottom;
+	int32 i;
+	uint32 current;
+
+	if (!FROM_LE_32(file->number_of_items))
+		return PX_LINKED_DATA_FILE_ERROR;
+
+	top = FROM_LE_32(file->number_of_items) - 1;
+	i = top >> 1;
+	bottom = 0;
+	for (;;) {
+		current = FROM_LE_32(file->list[i].name_hash_value);
+		if (hash == current)
+			return i;
+		else if (top == bottom)
+			return PX_LINKED_DATA_FILE_ERROR;
+		else if (hash > current) {
+			bottom = i + 1;
+			i = (top + bottom) >> 1;
+		} else {
+			top = i;
+			i = (top + bottom) >> 1;
+		}
+	}
+}
+
+} // End of namespace ICB