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engines/icb/keyboard.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 "engines/icb/keyboard.h"
+
+namespace ICB {
+
+#define MAX_KEY_BUFFER 32
+
+uint8 keyBacklog = 0;           // The number of key presses waiting to be processed.
+uint8 keyPointer = 0;           // Index of the next key to read from the buffer.
+char keyBuffer[MAX_KEY_BUFFER]; // The keyboard buffer
+
+void WriteKey(char key) {
+	if (keyBacklog < MAX_KEY_BUFFER) {
+		keyBuffer[(keyPointer + keyBacklog) % MAX_KEY_BUFFER] = key;
+		keyBacklog += 1;
+	}
+}
+
+void Clear_key_buffer() {
+	// clear all the backlog - we need this when we start using other methods (direct input) for reading keys
+
+	keyBacklog = 0;
+	keyPointer = 0;
+}
+
+bool KeyWaiting() {
+	if (keyBacklog)
+		return (true);
+	else
+		return (false);
+}
+
+int32 ReadKey(char *key) {
+	if (!keyBacklog)
+		return (0);
+
+	if (key == nullptr)
+		return 0;
+
+	*key = keyBuffer[keyPointer++];
+	if (keyPointer == MAX_KEY_BUFFER)
+		keyPointer = 0;
+
+	keyBacklog -= 1;
+
+	return (1);
+}
+
+} // End of namespace ICB