BluetoothUtils.java

package com.arduinoandroid.arduinopulserate.Bluetooth;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

/**
 * Created by stefanbuttigieg on 12/09/14.
 */

public class BluetoothUtils {

    // Filtering by custom UUID is broken in Android 4.3 and 4.4, see:
    //   http://stackoverflow.com/questions/18019161/startlescan-with-128-bit-uuids-doesnt-work-on-native-android-ble-implementation?noredirect=1#comment27879874_18019161
    // This is a workaround function from the SO thread to manually parse advertisement data.
    public static List<UUID> parseUUIDs(final byte[] advertisedData) {
        List<UUID> uuids = new ArrayList<UUID>();

        int offset = 0;
        while (offset < (advertisedData.length - 2)) {
            int len = advertisedData[offset++];
            if (len == 0)
                break;

            int type = advertisedData[offset++];
            switch (type) {
                case 0x02: // Partial list of 16-bit UUIDs
                case 0x03: // Complete list of 16-bit UUIDs
                    while (len > 1) {
                        int uuid16 = advertisedData[offset++];
                        uuid16 += (advertisedData[offset++] << 8);
                        len -= 2;
                        uuids.add(UUID.fromString(String.format("%08x-0000-1000-8000-00805f9b34fb", uuid16)));
                    }
                    break;
                case 0x06:// Partial list of 128-bit UUIDs
                case 0x07:// Complete list of 128-bit UUIDs
                    // Loop through the advertised 128-bit UUID's.
                    while (len >= 16) {
                        try {
                            // Wrap the advertised bits and order them.
                            ByteBuffer buffer = ByteBuffer.wrap(advertisedData, offset++, 16).order(ByteOrder.LITTLE_ENDIAN);
                            long mostSignificantBit = buffer.getLong();
                            long leastSignificantBit = buffer.getLong();
                            uuids.add(new UUID(leastSignificantBit,
                                    mostSignificantBit));
                        } catch (IndexOutOfBoundsException e) {
                            // Defensive programming.
                            //Log.e(LOG_TAG, e.toString());
                            continue;
                        } finally {
                            // Move the offset to read the next uuid.
                            offset += 15;
                            len -= 16;
                        }
                    }
                    break;
                default:
                    offset += (len - 1);
                    break;
            }
        }
        return uuids;
    }
}