Fixed EMG data erroneously being converted from signed byte to unsign…

…ed integer.

myolib/src/main/java/eu/darken/myolib/processor/emg/EmgData.java

@@ -11,11 +11,11 @@
  * Class to hold EMG data from one of the Myo's 8 EMG sensors.
  */
 public class EmgData {
-    private final int[] mData;
+    private final byte[] mData;
     private final long mTimestamp;
     private final String mDeviceAddress;
 
-    public EmgData(String deviceAddress, long timestamp, int[] data) {
+    public EmgData(String deviceAddress, long timestamp, byte[] data) {
         mDeviceAddress = deviceAddress;
         mTimestamp = timestamp;
         mData = data;
@@ -26,18 +26,18 @@ public String getDeviceAddress() {
     }
 
     /**
-     * @return Array of int values ranging from 0 to 255.
-     * @see <a href="https://github.com/thalmiclabs/myo-bluetooth/blob/master/myohw.h">Myo protocol specification</a>
+     * @return Array of byte values ranging from -128 to 127.
+     * @see <a href="https://github.com/thalmiclabs/myo-bluetooth/blob/master/myohw.h#L371">Myo protocol specification</a>
      */
-    public int[] getData() {
+    public byte[] getData() {
         return mData;
     }
 
     @Override
     public String toString() {
         StringBuilder builder = new StringBuilder();
         for (int b : mData)
-            builder.append(String.format("%03d", b)).append(" ");
+            builder.append(String.format("%+04d", b)).append(" ");
         return builder.toString();
     }
 

myolib/src/main/java/eu/darken/myolib/processor/emg/EmgProcessor.java

@@ -25,14 +25,12 @@ public EmgProcessor() {
     }
 
     protected void doProcess(BaseDataPacket packet) {
-        int[] data1 = new int[8];
-        for (int i = 0; i < 8; i++)
-            data1[i] = packet.getData()[i] & 0xFF;
+        byte[] data1 = new byte[8];
+        System.arraycopy(packet.getData(), 0, data1, 0, 8);
         EmgData emgData1 = new EmgData(packet.getDeviceAddress(), packet.getTimeStamp(), data1);
 
-        int[] data2 = new int[8];
-        for (int i = 8; i < 16; i++)
-            data2[i - 8] = packet.getData()[i] & 0xFF;
+        byte[] data2 = new byte[8];
+        System.arraycopy(packet.getData(), 8, data2, 0, 8);
         EmgData emgData2 = new EmgData(packet.getDeviceAddress(), packet.getTimeStamp() + 5, data2);
 
         for (DataListener listener : getDataListeners()) {