Use range from evdev device for gamepad input

src/com/limelight/input/EvdevAbsolute.java

@@ -0,0 +1,55 @@
+package com.limelight.input;
+
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+
+/**
+ * Class that handles absolute input ranges from evdev device
+ * @author Iwan Timmer
+ */
+public class EvdevAbsolute {
+	
+	private final static int ABS_OFFSET = 0x40;
+	private final static int READ_ONLY = 2;
+	private final static char EVDEV_TYPE = 'E';
+	
+	private int avg;
+	private int range;
+	
+	public EvdevAbsolute(String filename, int axis) {
+		ByteBuffer buffer = ByteBuffer.allocate(6*4);
+		buffer.order(ByteOrder.nativeOrder());
+		byte[] data = buffer.array();
+		int request = getRequest(READ_ONLY, EVDEV_TYPE, ABS_OFFSET+axis, 6*4);
+		IO.ioctl(filename, data, request);
+		
+		buffer.getInt(); //Skip current value
+		int min = buffer.getInt();
+		int max = buffer.getInt();
+		avg = (min+max)/2;
+		range = max-avg;
+	}
+	
+	private int getRequest(int dir, int type, int nr, int size) {
+		return (dir << 30) | (size << 16) | (type << 8) | nr;
+	}
+	
+	/**
+	 * Convert input value to short range
+	 * @param value received input
+	 * @return input value as short
+	 */
+	public short getShort(int value) {
+		return (short) ((value-avg) * range / Short.MAX_VALUE);
+	}
+	
+	/**
+	 * Convert input value to byte range
+	 * @param value received input
+	 * @return input value as byte
+	 */
+	public byte getByte(int value) {
+		return (byte) ((value-avg) * range / Byte.MAX_VALUE);
+	}
+	
+}