Use range from evdev device for gamepad input

build.xml

@@ -10,6 +10,7 @@
   <property name="libs.opus.dir" location="${basedir}/jni/nv_opus_dec/"/>
   <property name="libs.omx.dir" location="${basedir}/jni/nv_omx_dec/"/>
   <property name="libs.alsa.dir" location="${basedir}/jni/nv_alsa/"/>
+  <property name="libs.io.dir" location="${basedir}/jni/nv_io/"/>
   
   <property name="lib.dir" location="${basedir}/lib"/>
   <property name="build.dir" location="${basedir}/build"/>
@@ -40,6 +41,7 @@
 	  <exec executable="./build.sh" dir="${libs.omx.dir}"/>
 	  <exec executable="./build.sh" dir="${libs.opus.dir}"/>
 	  <exec executable="./build.sh" dir="${libs.alsa.dir}"/>
+	  <exec executable="./build.sh" dir="${libs.io.dir}"/>
   </target>
   
   <target name="compile-java" depends="init">
@@ -84,6 +86,7 @@
         <fileset dir="${libs.opus.dir}" includes="*.so"/>
         <fileset dir="${libs.omx.dir}" includes="*.so"/>
 		<fileset dir="${libs.alsa.dir}" includes="*.so"/>
+		<fileset dir="${libs.io.dir}" includes="*.so"/>
       </binlib>
     </one-jar>
   </target>

jni/nv_io/build.sh

@@ -0,0 +1,4 @@
+rm *.o libnv_io.so
+gcc -I $JAVA_HOME/include -I $JAVA_HOME/include/linux -fPIC -L. -c *.c
+gcc -shared -Wl,-soname,libnv_io.so -Wl,--no-undefined -o libnv_io.so *.o -L.
+rm *.o

jni/nv_io/nv_io_jni.c

@@ -0,0 +1,24 @@
+#include <fcntl.h>
+#include <jni.h>
+
+JNIEXPORT jboolean JNICALL
+Java_com_limelight_input_IO_ioctl(
+	JNIEnv *env, jobject this, // JNI parameters
+	jstring filename, jbyteArray buffer, jint request)
+{
+	const char* jni_filename = (*env)->GetStringUTFChars(env, filename, NULL);
+	unsigned char* jni_buffer = (*env)->GetByteArrayElements(env, buffer, NULL);
+
+	jboolean retval;
+	int fd;
+	if ((fd = open(jni_filename, O_RDONLY)) < 0) {
+		retval = 0;
+	} else {
+		ioctl(fd, request, jni_buffer);
+		close(fd);
+		retval = 1;
+	}
+
+	(*env)->ReleaseByteArrayElements(env, buffer, jni_buffer, 0);
+	return retval;
+}

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);
+	}
+	
+}

src/com/limelight/input/EvdevHandler.java

@@ -28,6 +28,8 @@ public class EvdevHandler implements Runnable {
 	private byte leftTrigger, rightTrigger;
 	private short leftStickX, leftStickY, rightStickX, rightStickY;
 	
+	private EvdevAbsolute absLX, absLY, absRX, absRY, absLT, absRT;
+	
 	private NvConnection conn;
 	private FileChannel deviceInput;
 	private ByteBuffer inputBuffer;
@@ -48,6 +50,13 @@ public class EvdevHandler implements Runnable {
 		inputBuffer = ByteBuffer.allocate(EvdevConstants.MAX_STRUCT_SIZE_BYTES);
 		inputBuffer.order(ByteOrder.nativeOrder());
 		
+		absLX = new EvdevAbsolute(device, mapping.abs_x);
+		absLY = new EvdevAbsolute(device, mapping.abs_y);
+		absRX = new EvdevAbsolute(device, mapping.abs_rx);
+		absRY = new EvdevAbsolute(device, mapping.abs_ry);
+		absLT = new EvdevAbsolute(device, mapping.abs_rudder);
+		absRT = new EvdevAbsolute(device, mapping.abs_throttle);
+		
 		translator = new KeyboardTranslator(conn);
 	}
 	
@@ -140,17 +149,17 @@ public class EvdevHandler implements Runnable {
 				conn.sendMouseMove((short) 0, (short) value);
 		} else if (type==EvdevConstants.EV_ABS) {
 			if (code==mapping.abs_x)
-				leftStickX = (short) value;
+				leftStickX = absLX.getShort(value);
 			else if (code==mapping.abs_y)
-				leftStickY = (short) value;
+				leftStickY = absLY.getShort(value);
 			else if (code==mapping.abs_rx)
-				rightStickX = (short) value;
+				rightStickX = absRX.getShort(value);
 			else if (code==mapping.abs_ry)
-				rightStickY = (short) value;
+				rightStickY = absRY.getShort(value);
 			else if (code==mapping.abs_throttle)
-				leftTrigger = (byte) value;
+				leftTrigger = absLT.getByte(value);
 			else if (code==mapping.abs_rudder)
-				rightTrigger = (byte) value;
+				rightTrigger = absRT.getByte(value);
 
 			conn.sendControllerInput(buttonFlags, leftTrigger, rightTrigger, leftStickX, leftStickY, rightStickX, rightStickY);
 		}

src/com/limelight/input/IO.java

@@ -0,0 +1,14 @@
+package com.limelight.input;
+
+/**
+ * IO bindings
+ * @author Iwan Timmer
+ */
+public class IO {
+	static {
+		System.loadLibrary("nv_io");
+	}
+	
+	public static native boolean ioctl(String filename, byte[] buffer, int request);
+	
+}