server/location/GpsLocationProvider.java

/*
 * Copyright (C) 2008 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.server.location;

import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.location.Criteria;
import android.location.IGpsStatusListener;
import android.location.IGpsStatusProvider;
import android.location.ILocationManager;
import android.location.INetInitiatedListener;
import android.location.Location;
import android.location.LocationManager;
import android.location.LocationProvider;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;
import android.net.SntpClient;
import android.os.Binder;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.os.Looper;
import android.os.Message;
import android.os.PowerManager;
import android.os.Process;
import android.os.RemoteException;
import android.os.ServiceManager;
import android.os.SystemClock;
import android.provider.Settings;
import android.util.Log;
import android.util.SparseIntArray;

import com.android.internal.app.IBatteryStats;
import com.android.internal.telephony.Phone;
import com.android.internal.location.GpsNetInitiatedHandler;
import com.android.internal.location.GpsNetInitiatedHandler.GpsNiNotification;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.StringBufferInputStream;
import java.net.InetAddress;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Date;
import java.util.Properties;
import java.util.Map.Entry;
import java.util.concurrent.CountDownLatch;

/**
 * A GPS implementation of LocationProvider used by LocationManager.
 *
 * {@hide}
 */
public class GpsLocationProvider implements LocationProviderInterface {

    private static final String TAG = "GpsLocationProvider";

    private static final boolean DEBUG = false;
    private static final boolean VERBOSE = false;

    // these need to match GpsPositionMode enum in gps.h
    private static final int GPS_POSITION_MODE_STANDALONE = 0;
    private static final int GPS_POSITION_MODE_MS_BASED = 1;
    private static final int GPS_POSITION_MODE_MS_ASSISTED = 2;

    // these need to match GpsPositionRecurrence enum in gps.h
    private static final int GPS_POSITION_RECURRENCE_PERIODIC = 0;
    private static final int GPS_POSITION_RECURRENCE_SINGLE = 1;

    // these need to match GpsStatusValue defines in gps.h
    private static final int GPS_STATUS_NONE = 0;
    private static final int GPS_STATUS_SESSION_BEGIN = 1;
    private static final int GPS_STATUS_SESSION_END = 2;
    private static final int GPS_STATUS_ENGINE_ON = 3;
    private static final int GPS_STATUS_ENGINE_OFF = 4;

    // these need to match GpsApgsStatusValue defines in gps.h
    /** AGPS status event values. */
    private static final int GPS_REQUEST_AGPS_DATA_CONN = 1;
    private static final int GPS_RELEASE_AGPS_DATA_CONN = 2;
    private static final int GPS_AGPS_DATA_CONNECTED = 3;
    private static final int GPS_AGPS_DATA_CONN_DONE = 4;
    private static final int GPS_AGPS_DATA_CONN_FAILED = 5;

    // these need to match GpsLocationFlags enum in gps.h
    private static final int LOCATION_INVALID = 0;
    private static final int LOCATION_HAS_LAT_LONG = 1;
    private static final int LOCATION_HAS_ALTITUDE = 2;
    private static final int LOCATION_HAS_SPEED = 4;
    private static final int LOCATION_HAS_BEARING = 8;
    private static final int LOCATION_HAS_ACCURACY = 16;

// IMPORTANT - the GPS_DELETE_* symbols here must match constants in gps.h
    private static final int GPS_DELETE_EPHEMERIS = 0x0001;
    private static final int GPS_DELETE_ALMANAC = 0x0002;
    private static final int GPS_DELETE_POSITION = 0x0004;
    private static final int GPS_DELETE_TIME = 0x0008;
    private static final int GPS_DELETE_IONO = 0x0010;
    private static final int GPS_DELETE_UTC = 0x0020;
    private static final int GPS_DELETE_HEALTH = 0x0040;
    private static final int GPS_DELETE_SVDIR = 0x0080;
    private static final int GPS_DELETE_SVSTEER = 0x0100;
    private static final int GPS_DELETE_SADATA = 0x0200;
    private static final int GPS_DELETE_RTI = 0x0400;
    private static final int GPS_DELETE_CELLDB_INFO = 0x8000;
    private static final int GPS_DELETE_ALL = 0xFFFF;

    // The GPS_CAPABILITY_* flags must match the values in gps.h
    private static final int GPS_CAPABILITY_SCHEDULING = 0x0000001;
    private static final int GPS_CAPABILITY_MSB = 0x0000002;
    private static final int GPS_CAPABILITY_MSA = 0x0000004;
    private static final int GPS_CAPABILITY_SINGLE_SHOT = 0x0000008;


    // these need to match AGpsType enum in gps.h
    private static final int AGPS_TYPE_SUPL = 1;
    private static final int AGPS_TYPE_C2K = 2;

    // for mAGpsDataConnectionState
    private static final int AGPS_DATA_CONNECTION_CLOSED = 0;
    private static final int AGPS_DATA_CONNECTION_OPENING = 1;
    private static final int AGPS_DATA_CONNECTION_OPEN = 2;

    // Handler messages
    private static final int CHECK_LOCATION = 1;
    private static final int ENABLE = 2;
    private static final int ENABLE_TRACKING = 3;
    private static final int UPDATE_NETWORK_STATE = 4;
    private static final int INJECT_NTP_TIME = 5;
    private static final int DOWNLOAD_XTRA_DATA = 6;
    private static final int UPDATE_LOCATION = 7;
    private static final int ADD_LISTENER = 8;
    private static final int REMOVE_LISTENER = 9;
    private static final int REQUEST_SINGLE_SHOT = 10;

    private static final String PROPERTIES_FILE = "/etc/gps.conf";

    private int mLocationFlags = LOCATION_INVALID;

    // current status
    private int mStatus = LocationProvider.TEMPORARILY_UNAVAILABLE;

    // time for last status update
    private long mStatusUpdateTime = SystemClock.elapsedRealtime();

    // turn off GPS fix icon if we haven't received a fix in 10 seconds
    private static final long RECENT_FIX_TIMEOUT = 10 * 1000;

    // stop trying if we do not receive a fix within 60 seconds
    private static final int NO_FIX_TIMEOUT = 60 * 1000;

    // true if we are enabled
    private volatile boolean mEnabled;

    // true if we have network connectivity
    private boolean mNetworkAvailable;

    // flags to trigger NTP or XTRA data download when network becomes available
    // initialized to true so we do NTP and XTRA when the network comes up after booting
    private boolean mInjectNtpTimePending = true;
    private boolean mDownloadXtraDataPending = true;

    // true if GPS is navigating
    private boolean mNavigating;

    // true if GPS engine is on
    private boolean mEngineOn;

    // requested frequency of fixes, in milliseconds
    private int mFixInterval = 1000;

    // true if we started navigation
    private boolean mStarted;

    // true if single shot request is in progress
    private boolean mSingleShot;

    // capabilities of the GPS engine
    private int mEngineCapabilities;

    // for calculating time to first fix
    private long mFixRequestTime = 0;
    // time to first fix for most recent session
    private int mTTFF = 0;
    // time we received our last fix
    private long mLastFixTime;

    private int mPositionMode;

    // properties loaded from PROPERTIES_FILE
    private Properties mProperties;
    private String mNtpServer;
    private String mSuplServerHost;
    private int mSuplServerPort;
    private String mC2KServerHost;
    private int mC2KServerPort;

    private final Context mContext;
    private final ILocationManager mLocationManager;
    private Location mLocation = new Location(LocationManager.GPS_PROVIDER);
    private Bundle mLocationExtras = new Bundle();
    private ArrayList<Listener> mListeners = new ArrayList<Listener>();

    // GpsLocationProvider's handler thread
    private final Thread mThread;
    // Handler for processing events in mThread.
    private Handler mHandler;
    // Used to signal when our main thread has initialized everything
    private final CountDownLatch mInitializedLatch = new CountDownLatch(1);
    // Thread for receiving events from the native code
    private Thread mEventThread;

    private String mAGpsApn;
    private int mAGpsDataConnectionState;
    private final ConnectivityManager mConnMgr;
    private final GpsNetInitiatedHandler mNIHandler;

    // Wakelocks
    private final static String WAKELOCK_KEY = "GpsLocationProvider";
    private final PowerManager.WakeLock mWakeLock;
    // bitfield of pending messages to our Handler
    // used only for messages that cannot have multiple instances queued
    private int mPendingMessageBits;
    // separate counter for ADD_LISTENER and REMOVE_LISTENER messages,
    // which might have multiple instances queued
    private int mPendingListenerMessages;

    // Alarms
    private final static String ALARM_WAKEUP = "com.android.internal.location.ALARM_WAKEUP";
    private final static String ALARM_TIMEOUT = "com.android.internal.location.ALARM_TIMEOUT";
    private final AlarmManager mAlarmManager;
    private final PendingIntent mWakeupIntent;
    private final PendingIntent mTimeoutIntent;

    private final IBatteryStats mBatteryStats;
    private final SparseIntArray mClientUids = new SparseIntArray();

    // how often to request NTP time, in milliseconds
    // current setting 4 hours
    private static final long NTP_INTERVAL = 4*60*60*1000;
    // how long to wait if we have a network error in NTP or XTRA downloading
    // current setting - 5 minutes
    private static final long RETRY_INTERVAL = 5*60*1000;

    // to avoid injecting bad NTP time, we reject any time fixes that differ from system time
    // by more than 5 minutes.
    private static final long MAX_NTP_SYSTEM_TIME_OFFSET = 5*60*1000;

    private final IGpsStatusProvider mGpsStatusProvider = new IGpsStatusProvider.Stub() {
        public void addGpsStatusListener(IGpsStatusListener listener) throws RemoteException {
            if (listener == null) {
                throw new NullPointerException("listener is null in addGpsStatusListener");
            }

            synchronized(mListeners) {
                IBinder binder = listener.asBinder();
                int size = mListeners.size();
                for (int i = 0; i < size; i++) {
                    Listener test = mListeners.get(i);
                    if (binder.equals(test.mListener.asBinder())) {
                        // listener already added
                        return;
                    }
                }

                Listener l = new Listener(listener);
                binder.linkToDeath(l, 0);
                mListeners.add(l);
            }
        }

        public void removeGpsStatusListener(IGpsStatusListener listener) {
            if (listener == null) {
                throw new NullPointerException("listener is null in addGpsStatusListener");
            }

            synchronized(mListeners) {
                IBinder binder = listener.asBinder();
                Listener l = null;
                int size = mListeners.size();
                for (int i = 0; i < size && l == null; i++) {
                    Listener test = mListeners.get(i);
                    if (binder.equals(test.mListener.asBinder())) {
                        l = test;
                    }
                }

                if (l != null) {
                    mListeners.remove(l);
                    binder.unlinkToDeath(l, 0);
                }
            }
        }
    };

    public IGpsStatusProvider getGpsStatusProvider() {
        return mGpsStatusProvider;
    }

    private final BroadcastReceiver mBroadcastReciever = new BroadcastReceiver() {
        @Override public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();

            if (action.equals(ALARM_WAKEUP)) {
                if (DEBUG) Log.d(TAG, "ALARM_WAKEUP");
                startNavigating(false);
            } else if (action.equals(ALARM_TIMEOUT)) {
                if (DEBUG) Log.d(TAG, "ALARM_TIMEOUT");
                hibernate();
            }
        }
    };

    public static boolean isSupported() {
        return native_is_supported();
    }

    public GpsLocationProvider(Context context, ILocationManager locationManager) {
        mContext = context;
        mLocationManager = locationManager;
        mNIHandler = new GpsNetInitiatedHandler(context);

        mLocation.setExtras(mLocationExtras);

        // Create a wake lock
        PowerManager powerManager = (PowerManager) mContext.getSystemService(Context.POWER_SERVICE);
        mWakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, WAKELOCK_KEY);
        mWakeLock.setReferenceCounted(false);

        mAlarmManager = (AlarmManager)mContext.getSystemService(Context.ALARM_SERVICE);
        mWakeupIntent = PendingIntent.getBroadcast(mContext, 0, new Intent(ALARM_WAKEUP), 0);
        mTimeoutIntent = PendingIntent.getBroadcast(mContext, 0, new Intent(ALARM_TIMEOUT), 0);

        mConnMgr = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);

        // Battery statistics service to be notified when GPS turns on or off
        mBatteryStats = IBatteryStats.Stub.asInterface(ServiceManager.getService("batteryinfo"));

        mProperties = new Properties();
        try {
            File file = new File(PROPERTIES_FILE);
            FileInputStream stream = new FileInputStream(file);
            mProperties.load(stream);
            stream.close();
            mNtpServer = mProperties.getProperty("NTP_SERVER", null);

            mSuplServerHost = mProperties.getProperty("SUPL_HOST");
            String portString = mProperties.getProperty("SUPL_PORT");
            if (mSuplServerHost != null && portString != null) {
                try {
                    mSuplServerPort = Integer.parseInt(portString);
                } catch (NumberFormatException e) {
                    Log.e(TAG, "unable to parse SUPL_PORT: " + portString);
                }
            }

            mC2KServerHost = mProperties.getProperty("C2K_HOST");
            portString = mProperties.getProperty("C2K_PORT");
            if (mC2KServerHost != null && portString != null) {
                try {
                    mC2KServerPort = Integer.parseInt(portString);
                } catch (NumberFormatException e) {
                    Log.e(TAG, "unable to parse C2K_PORT: " + portString);
                }
            }
        } catch (IOException e) {
            Log.w(TAG, "Could not open GPS configuration file " + PROPERTIES_FILE);
        }

        // wait until we are fully initialized before returning
        mThread = new GpsLocationProviderThread();
        mThread.start();
        while (true) {
            try {
                mInitializedLatch.await();
                break;
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
            }
        }
    }

    private void initialize() {
        // register our receiver on our thread rather than the main thread
        IntentFilter intentFilter = new IntentFilter();
        intentFilter.addAction(ALARM_WAKEUP);
        intentFilter.addAction(ALARM_TIMEOUT);
        mContext.registerReceiver(mBroadcastReciever, intentFilter);
    }

    /**
     * Returns the name of this provider.
     */
    public String getName() {
        return LocationManager.GPS_PROVIDER;
    }

    /**
     * Returns true if the provider requires access to a
     * data network (e.g., the Internet), false otherwise.
     */
    public boolean requiresNetwork() {
        return true;
    }

    public void updateNetworkState(int state, NetworkInfo info) {
        sendMessage(UPDATE_NETWORK_STATE, state, info);
    }

    private void handleUpdateNetworkState(int state, NetworkInfo info) {
        mNetworkAvailable = (state == LocationProvider.AVAILABLE);

        if (DEBUG) {
            Log.d(TAG, "updateNetworkState " + (mNetworkAvailable ? "available" : "unavailable")
                + " info: " + info);
        }

        if (info != null && info.getType() == ConnectivityManager.TYPE_MOBILE_SUPL
                && mAGpsDataConnectionState == AGPS_DATA_CONNECTION_OPENING) {
            String apnName = info.getExtraInfo();
            if (mNetworkAvailable && apnName != null && apnName.length() > 0) {
                mAGpsApn = apnName;
                if (DEBUG) Log.d(TAG, "call native_agps_data_conn_open");
                native_agps_data_conn_open(apnName);
                mAGpsDataConnectionState = AGPS_DATA_CONNECTION_OPEN;
            } else {
                if (DEBUG) Log.d(TAG, "call native_agps_data_conn_failed");
                mAGpsApn = null;
                mAGpsDataConnectionState = AGPS_DATA_CONNECTION_CLOSED;
                native_agps_data_conn_failed();
            }
        }

        if (mNetworkAvailable) {
            if (mInjectNtpTimePending) {
                sendMessage(INJECT_NTP_TIME, 0, null);
            }
            if (mDownloadXtraDataPending) {
                sendMessage(DOWNLOAD_XTRA_DATA, 0, null);
            }
        }
    }

    private void handleInjectNtpTime() {
        if (!mNetworkAvailable) {
            // try again when network is up
            mInjectNtpTimePending = true;
            return;
        }
        mInjectNtpTimePending = false;

        SntpClient client = new SntpClient();
        long delay;

        if (client.requestTime(mNtpServer, 10000)) {
            long time = client.getNtpTime();
            long timeReference = client.getNtpTimeReference();
            int certainty = (int)(client.getRoundTripTime()/2);
            long now = System.currentTimeMillis();

            Log.d(TAG, "NTP server returned: "
                    + time + " (" + new Date(time)
                    + ") reference: " + timeReference
                    + " certainty: " + certainty
                    + " system time offset: " + (time - now));

            native_inject_time(time, timeReference, certainty);
            delay = NTP_INTERVAL;
        } else {
            if (DEBUG) Log.d(TAG, "requestTime failed");
            delay = RETRY_INTERVAL;
        }

        // send delayed message for next NTP injection
        // since this is delayed and not urgent we do not hold a wake lock here
        mHandler.removeMessages(INJECT_NTP_TIME);
        mHandler.sendMessageDelayed(Message.obtain(mHandler, INJECT_NTP_TIME), delay);
    }

    private void handleDownloadXtraData() {
        if (!mDownloadXtraDataPending) {
            // try again when network is up
            mDownloadXtraDataPending = true;
            return;
        }
        mDownloadXtraDataPending = false;


        GpsXtraDownloader xtraDownloader = new GpsXtraDownloader(mContext, mProperties);
        byte[] data = xtraDownloader.downloadXtraData();
        if (data != null) {
            if (DEBUG) {
                Log.d(TAG, "calling native_inject_xtra_data");
            }
            native_inject_xtra_data(data, data.length);
        } else {
            // try again later
            // since this is delayed and not urgent we do not hold a wake lock here
            mHandler.removeMessages(DOWNLOAD_XTRA_DATA);
            mHandler.sendMessageDelayed(Message.obtain(mHandler, DOWNLOAD_XTRA_DATA), RETRY_INTERVAL);
        }
    }

    /**
     * This is called to inform us when another location provider returns a location.
     * Someday we might use this for network location injection to aid the GPS
     */
    public void updateLocation(Location location) {
        sendMessage(UPDATE_LOCATION, 0, location);
    }

    private void handleUpdateLocation(Location location) {
        if (location.hasAccuracy()) {
            native_inject_location(location.getLatitude(), location.getLongitude(),
                    location.getAccuracy());
        }
    }

    /**
     * Returns true if the provider requires access to a
     * satellite-based positioning system (e.g., GPS), false
     * otherwise.
     */
    public boolean requiresSatellite() {
        return true;
    }

    /**
     * Returns true if the provider requires access to an appropriate
     * cellular network (e.g., to make use of cell tower IDs), false
     * otherwise.
     */
    public boolean requiresCell() {
        return false;
    }

    /**
     * Returns true if the use of this provider may result in a
     * monetary charge to the user, false if use is free.  It is up to
     * each provider to give accurate information.
     */
    public boolean hasMonetaryCost() {
        return false;
    }

    /**
     * Returns true if the provider is able to provide altitude
     * information, false otherwise.  A provider that reports altitude
     * under most circumstances but may occassionally not report it
     * should return true.
     */
    public boolean supportsAltitude() {
        return true;
    }

    /**
     * Returns true if the provider is able to provide speed
     * information, false otherwise.  A provider that reports speed
     * under most circumstances but may occassionally not report it
     * should return true.
     */
    public boolean supportsSpeed() {
        return true;
    }

    /**
     * Returns true if the provider is able to provide bearing
     * information, false otherwise.  A provider that reports bearing
     * under most circumstances but may occassionally not report it
     * should return true.
     */
    public boolean supportsBearing() {
        return true;
    }

    /**
     * Returns the power requirement for this provider.
     *
     * @return the power requirement for this provider, as one of the
     * constants Criteria.POWER_REQUIREMENT_*.
     */
    public int getPowerRequirement() {
        return Criteria.POWER_HIGH;
    }

    /**
     * Returns true if this provider meets the given criteria,
     * false otherwise.
     */
    public boolean meetsCriteria(Criteria criteria) {
        return (criteria.getPowerRequirement() != Criteria.POWER_LOW);
    }

    /**
     * Returns the horizontal accuracy of this provider
     *
     * @return the accuracy of location from this provider, as one
     * of the constants Criteria.ACCURACY_*.
     */
    public int getAccuracy() {
        return Criteria.ACCURACY_FINE;
    }

    /**
     * Enables this provider.  When enabled, calls to getStatus()
     * must be handled.  Hardware may be started up
     * when the provider is enabled.
     */
    public void enable() {
        synchronized (mHandler) {
            sendMessage(ENABLE, 1, null);
        }
    }

    private void handleEnable() {
        if (DEBUG) Log.d(TAG, "handleEnable");
        if (mEnabled) return;
        mEnabled = native_init();

        if (mEnabled) {
            if (mSuplServerHost != null) {
                native_set_agps_server(AGPS_TYPE_SUPL, mSuplServerHost, mSuplServerPort);
            }
            if (mC2KServerHost != null) {
                native_set_agps_server(AGPS_TYPE_C2K, mC2KServerHost, mC2KServerPort);
            }

            // run event listener thread while we are enabled
            mEventThread = new GpsEventThread();
            mEventThread.start();
        } else {
            Log.w(TAG, "Failed to enable location provider");
        }
    }

    /**
     * Disables this provider.  When disabled, calls to getStatus()
     * need not be handled.  Hardware may be shut
     * down while the provider is disabled.
     */
    public void disable() {
        synchronized (mHandler) {
            sendMessage(ENABLE, 0, null);
        }
    }

    private void handleDisable() {
        if (DEBUG) Log.d(TAG, "handleDisable");
        if (!mEnabled) return;

        mEnabled = false;
        stopNavigating();
        native_disable();

        // make sure our event thread exits
        if (mEventThread != null) {
            try {
                mEventThread.join();
            } catch (InterruptedException e) {
                Log.w(TAG, "InterruptedException when joining mEventThread");
            }
            mEventThread = null;
        }

        // do this before releasing wakelock
        native_cleanup();

        // The GpsEventThread does not wait for the GPS to shutdown
        // so we need to report the GPS_STATUS_ENGINE_OFF event here
        if (mNavigating) {
            reportStatus(GPS_STATUS_SESSION_END);
        }
        if (mEngineOn) {
            reportStatus(GPS_STATUS_ENGINE_OFF);
        }
    }

    public boolean isEnabled() {
        return mEnabled;
    }

    public int getStatus(Bundle extras) {
        if (extras != null) {
            extras.putInt("satellites", mSvCount);
        }
        return mStatus;
    }

    private void updateStatus(int status, int svCount) {
        if (status != mStatus || svCount != mSvCount) {
            mStatus = status;
            mSvCount = svCount;
            mLocationExtras.putInt("satellites", svCount);
            mStatusUpdateTime = SystemClock.elapsedRealtime();
        }
    }

    public long getStatusUpdateTime() {
        return mStatusUpdateTime;
    }

    public void enableLocationTracking(boolean enable) {
        // FIXME - should set a flag here to avoid race conditions with single shot request
        synchronized (mHandler) {
            sendMessage(ENABLE_TRACKING, (enable ? 1 : 0), null);
        }
    }

    private void handleEnableLocationTracking(boolean enable) {
        if (enable) {
            mTTFF = 0;
            mLastFixTime = 0;
            startNavigating(false);
        } else {
            if (!hasCapability(GPS_CAPABILITY_SCHEDULING)) {
                mAlarmManager.cancel(mWakeupIntent);
                mAlarmManager.cancel(mTimeoutIntent);
            }
            stopNavigating();
        }
    }

    public boolean requestSingleShotFix() {
        if (mStarted) {
            // cannot do single shot if already navigating
            return false;
        }
        synchronized (mHandler) {
            mHandler.removeMessages(REQUEST_SINGLE_SHOT);
            Message m = Message.obtain(mHandler, REQUEST_SINGLE_SHOT);
            mHandler.sendMessage(m);
        }
        return true;
    }

    private void handleRequestSingleShot() {
        mTTFF = 0;
        mLastFixTime = 0;
        startNavigating(true);
    }

    public void setMinTime(long minTime) {
        if (DEBUG) Log.d(TAG, "setMinTime " + minTime);

        if (minTime >= 0) {
            mFixInterval = (int)minTime;

            if (mStarted && hasCapability(GPS_CAPABILITY_SCHEDULING)) {
                if (!native_set_position_mode(mPositionMode, GPS_POSITION_RECURRENCE_PERIODIC,
                        mFixInterval, 0, 0)) {
                    Log.e(TAG, "set_position_mode failed in setMinTime()");
                }
            }
        }
    }

    public String getInternalState() {
        return native_get_internal_state();
    }

    private final class Listener implements IBinder.DeathRecipient {
        final IGpsStatusListener mListener;

        int mSensors = 0;

        Listener(IGpsStatusListener listener) {
            mListener = listener;
        }

        public void binderDied() {
            if (DEBUG) Log.d(TAG, "GPS status listener died");

            synchronized(mListeners) {
                mListeners.remove(this);
            }
            if (mListener != null) {
                mListener.asBinder().unlinkToDeath(this, 0);
            }
        }
    }

    public void addListener(int uid) {
        synchronized (mWakeLock) {
            mPendingListenerMessages++;
           mWakeLock.acquire();
            Message m = Message.obtain(mHandler, ADD_LISTENER);
            m.arg1 = uid;
            mHandler.sendMessage(m);
        }
    }

    private void handleAddListener(int uid) {
        synchronized(mListeners) {
            if (mClientUids.indexOfKey(uid) >= 0) {
                // Shouldn't be here -- already have this uid.
                Log.w(TAG, "Duplicate add listener for uid " + uid);
                return;
            }
            mClientUids.put(uid, 0);
            if (mNavigating) {
                try {
                    mBatteryStats.noteStartGps(uid);
                } catch (RemoteException e) {
                    Log.w(TAG, "RemoteException in addListener");
                }
            }
        }
    }

    public void removeListener(int uid) {
        synchronized (mWakeLock) {
            mPendingListenerMessages++;
            mWakeLock.acquire();
            Message m = Message.obtain(mHandler, REMOVE_LISTENER);
            m.arg1 = uid;
            mHandler.sendMessage(m);
        }
    }

    private void handleRemoveListener(int uid) {
        synchronized(mListeners) {
            if (mClientUids.indexOfKey(uid) < 0) {
                // Shouldn't be here -- don't have this uid.
                Log.w(TAG, "Unneeded remove listener for uid " + uid);
                return;
            }
            mClientUids.delete(uid);
            if (mNavigating) {
                try {
                    mBatteryStats.noteStopGps(uid);
                } catch (RemoteException e) {
                    Log.w(TAG, "RemoteException in removeListener");
                }
            }
        }
    }

    public boolean sendExtraCommand(String command, Bundle extras) {

        long identity = Binder.clearCallingIdentity();
        boolean result = false;

        if ("delete_aiding_data".equals(command)) {
            result = deleteAidingData(extras);
        } else if ("force_time_injection".equals(command)) {
            sendMessage(INJECT_NTP_TIME, 0, null);
            result = true;
        } else if ("force_xtra_injection".equals(command)) {
            if (native_supports_xtra()) {
                xtraDownloadRequest();
                result = true;
            }
        } else {
            Log.w(TAG, "sendExtraCommand: unknown command " + command);
        }

        Binder.restoreCallingIdentity(identity);
        return result;
    }

    private boolean deleteAidingData(Bundle extras) {
        int flags;

        if (extras == null) {
            flags = GPS_DELETE_ALL;
        } else {
            flags = 0;
            if (extras.getBoolean("ephemeris")) flags |= GPS_DELETE_EPHEMERIS;
            if (extras.getBoolean("almanac")) flags |= GPS_DELETE_ALMANAC;
            if (extras.getBoolean("position")) flags |= GPS_DELETE_POSITION;
            if (extras.getBoolean("time")) flags |= GPS_DELETE_TIME;
            if (extras.getBoolean("iono")) flags |= GPS_DELETE_IONO;
            if (extras.getBoolean("utc")) flags |= GPS_DELETE_UTC;
            if (extras.getBoolean("health")) flags |= GPS_DELETE_HEALTH;
            if (extras.getBoolean("svdir")) flags |= GPS_DELETE_SVDIR;
            if (extras.getBoolean("svsteer")) flags |= GPS_DELETE_SVSTEER;
            if (extras.getBoolean("sadata")) flags |= GPS_DELETE_SADATA;
            if (extras.getBoolean("rti")) flags |= GPS_DELETE_RTI;
            if (extras.getBoolean("celldb-info")) flags |= GPS_DELETE_CELLDB_INFO;
            if (extras.getBoolean("all")) flags |= GPS_DELETE_ALL;
        }

        if (flags != 0) {
            native_delete_aiding_data(flags);
            return true;
        }

        return false;
    }

    private void startNavigating(boolean singleShot) {
        if (!mStarted) {
            if (DEBUG) Log.d(TAG, "startNavigating");
            mStarted = true;
            mSingleShot = singleShot;
            mPositionMode = GPS_POSITION_MODE_STANDALONE;

             if (Settings.Secure.getInt(mContext.getContentResolver(),
                    Settings.Secure.ASSISTED_GPS_ENABLED, 1) != 0) {
                if (singleShot && hasCapability(GPS_CAPABILITY_MSA)) {
                    mPositionMode = GPS_POSITION_MODE_MS_ASSISTED;
                } else if (hasCapability(GPS_CAPABILITY_MSA)) {
                    mPositionMode = GPS_POSITION_MODE_MS_BASED;
                }
            }

            int interval = (hasCapability(GPS_CAPABILITY_SCHEDULING) ? mFixInterval : 1000);
            if (!native_set_position_mode(mPositionMode, GPS_POSITION_RECURRENCE_PERIODIC,
                    interval, 0, 0)) {
                mStarted = false;
                Log.e(TAG, "set_position_mode failed in startNavigating()");
                return;
            }
            if (!native_start()) {
                mStarted = false;
                Log.e(TAG, "native_start failed in startNavigating()");
                return;
            }

            // reset SV count to zero
            updateStatus(LocationProvider.TEMPORARILY_UNAVAILABLE, 0);
            mFixRequestTime = System.currentTimeMillis();
            if (!hasCapability(GPS_CAPABILITY_SCHEDULING)) {
                // set timer to give up if we do not receive a fix within NO_FIX_TIMEOUT
                // and our fix interval is not short
                if (mFixInterval >= NO_FIX_TIMEOUT) {
                    mAlarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP,
                            SystemClock.elapsedRealtime() + NO_FIX_TIMEOUT, mTimeoutIntent);
                }
            }
        }
    }

    private void stopNavigating() {
        if (DEBUG) Log.d(TAG, "stopNavigating");
        if (mStarted) {
            mStarted = false;
            mSingleShot = false;
            native_stop();
            mTTFF = 0;
            mLastFixTime = 0;
            mLocationFlags = LOCATION_INVALID;

            // reset SV count to zero
            updateStatus(LocationProvider.TEMPORARILY_UNAVAILABLE, 0);
        }
    }

    private void hibernate() {
        // stop GPS until our next fix interval arrives
        stopNavigating();
        mAlarmManager.cancel(mTimeoutIntent);
        mAlarmManager.cancel(mWakeupIntent);
        long now = SystemClock.elapsedRealtime();
        mAlarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP,
                SystemClock.elapsedRealtime() + mFixInterval, mWakeupIntent);
    }

    private boolean hasCapability(int capability) {
        return ((mEngineCapabilities & capability) != 0);
    }

    /**
     * called from native code to update our position.
     */
    private void reportLocation(int flags, double latitude, double longitude, double altitude,
            float speed, float bearing, float accuracy, long timestamp) {
        if (VERBOSE) Log.v(TAG, "reportLocation lat: " + latitude + " long: " + longitude +
                " timestamp: " + timestamp);

        synchronized (mLocation) {
            mLocationFlags = flags;
            if ((flags & LOCATION_HAS_LAT_LONG) == LOCATION_HAS_LAT_LONG) {
                mLocation.setLatitude(latitude);
                mLocation.setLongitude(longitude);
                mLocation.setTime(timestamp);
            }
            if ((flags & LOCATION_HAS_ALTITUDE) == LOCATION_HAS_ALTITUDE) {
                mLocation.setAltitude(altitude);
            } else {
                mLocation.removeAltitude();
            }
            if ((flags & LOCATION_HAS_SPEED) == LOCATION_HAS_SPEED) {
                mLocation.setSpeed(speed);
            } else {
                mLocation.removeSpeed();
            }
            if ((flags & LOCATION_HAS_BEARING) == LOCATION_HAS_BEARING) {
                mLocation.setBearing(bearing);
            } else {
                mLocation.removeBearing();
            }
            if ((flags & LOCATION_HAS_ACCURACY) == LOCATION_HAS_ACCURACY) {
                mLocation.setAccuracy(accuracy);
            } else {
                mLocation.removeAccuracy();
            }

            try {
                mLocationManager.reportLocation(mLocation, false);
            } catch (RemoteException e) {
                Log.e(TAG, "RemoteException calling reportLocation");
            }
        }

        mLastFixTime = System.currentTimeMillis();
        // report time to first fix
        if (mTTFF == 0 && (flags & LOCATION_HAS_LAT_LONG) == LOCATION_HAS_LAT_LONG) {
            mTTFF = (int)(mLastFixTime - mFixRequestTime);
            if (DEBUG) Log.d(TAG, "TTFF: " + mTTFF);

            // notify status listeners
            synchronized(mListeners) {
                int size = mListeners.size();
                for (int i = 0; i < size; i++) {
                    Listener listener = mListeners.get(i);
                    try {
                        listener.mListener.onFirstFix(mTTFF);
                    } catch (RemoteException e) {
                        Log.w(TAG, "RemoteException in stopNavigating");
                        mListeners.remove(listener);
                        // adjust for size of list changing
                        size--;
                    }
                }
            }
        }

        if (mSingleShot) {
            stopNavigating();
        }
        if (mStarted && mStatus != LocationProvider.AVAILABLE) {
            // we want to time out if we do not receive a fix
            // within the time out and we are requesting infrequent fixes
            if (!hasCapability(GPS_CAPABILITY_SCHEDULING) && mFixInterval < NO_FIX_TIMEOUT) {
                mAlarmManager.cancel(mTimeoutIntent);
            }

            // send an intent to notify that the GPS is receiving fixes.
            Intent intent = new Intent(LocationManager.GPS_FIX_CHANGE_ACTION);
            intent.putExtra(LocationManager.EXTRA_GPS_ENABLED, true);
            mContext.sendBroadcast(intent);
            updateStatus(LocationProvider.AVAILABLE, mSvCount);
        }

       if (!hasCapability(GPS_CAPABILITY_SCHEDULING) && mStarted && mFixInterval > 1000) {
            if (DEBUG) Log.d(TAG, "got fix, hibernating");
            hibernate();
        }
   }

    /**
     * called from native code to update our status
     */
    private void reportStatus(int status) {
        if (VERBOSE) Log.v(TAG, "reportStatus status: " + status);

        synchronized(mListeners) {
            boolean wasNavigating = mNavigating;

            switch (status) {
                case GPS_STATUS_SESSION_BEGIN:
                    mNavigating = true;
                    mEngineOn = true;
                    break;
                case GPS_STATUS_SESSION_END:
                    mNavigating = false;
                    break;
                case GPS_STATUS_ENGINE_ON:
                    mEngineOn = true;
                    break;
                case GPS_STATUS_ENGINE_OFF:
                    mEngineOn = false;
                    mNavigating = false;
                    break;
            }

            if (wasNavigating != mNavigating) {
                int size = mListeners.size();
                for (int i = 0; i < size; i++) {
                    Listener listener = mListeners.get(i);
                    try {
                        if (mNavigating) {
                            listener.mListener.onGpsStarted();
                        } else {
                            listener.mListener.onGpsStopped();
                        }
                    } catch (RemoteException e) {
                        Log.w(TAG, "RemoteException in reportStatus");
                        mListeners.remove(listener);
                        // adjust for size of list changing
                        size--;
                    }
                }

                try {
                    // update battery stats
                    for (int i=mClientUids.size() - 1; i >= 0; i--) {
                        int uid = mClientUids.keyAt(i);
                        if (mNavigating) {
                            mBatteryStats.noteStartGps(uid);
                        } else {
                            mBatteryStats.noteStopGps(uid);
                        }
                    }
                } catch (RemoteException e) {
                    Log.w(TAG, "RemoteException in reportStatus");
                }

                // send an intent to notify that the GPS has been enabled or disabled.
                Intent intent = new Intent(LocationManager.GPS_ENABLED_CHANGE_ACTION);
                intent.putExtra(LocationManager.EXTRA_GPS_ENABLED, mNavigating);
                mContext.sendBroadcast(intent);
            }
        }
    }

    /**
     * called from native code to update SV info
     */
    private void reportSvStatus() {

        int svCount = native_read_sv_status(mSvs, mSnrs, mSvElevations, mSvAzimuths, mSvMasks);

        synchronized(mListeners) {
            int size = mListeners.size();
            for (int i = 0; i < size; i++) {
                Listener listener = mListeners.get(i);
                try {
                    listener.mListener.onSvStatusChanged(svCount, mSvs, mSnrs,
                            mSvElevations, mSvAzimuths, mSvMasks[EPHEMERIS_MASK],
                            mSvMasks[ALMANAC_MASK], mSvMasks[USED_FOR_FIX_MASK]);
                } catch (RemoteException e) {
                    Log.w(TAG, "RemoteException in reportSvInfo");
                    mListeners.remove(listener);
                    // adjust for size of list changing
                    size--;
                }
            }
        }

        if (VERBOSE) {
            Log.v(TAG, "SV count: " + svCount +
                    " ephemerisMask: " + Integer.toHexString(mSvMasks[EPHEMERIS_MASK]) +
                    " almanacMask: " + Integer.toHexString(mSvMasks[ALMANAC_MASK]));
            for (int i = 0; i < svCount; i++) {
                Log.v(TAG, "sv: " + mSvs[i] +
                        " snr: " + (float)mSnrs[i]/10 +
                        " elev: " + mSvElevations[i] +
                        " azimuth: " + mSvAzimuths[i] +
                        ((mSvMasks[EPHEMERIS_MASK] & (1 << (mSvs[i] - 1))) == 0 ? "  " : " E") +
                        ((mSvMasks[ALMANAC_MASK] & (1 << (mSvs[i] - 1))) == 0 ? "  " : " A") +
                        ((mSvMasks[USED_FOR_FIX_MASK] & (1 << (mSvs[i] - 1))) == 0 ? "" : "U"));
            }
        }

        updateStatus(mStatus, svCount);

        if (mNavigating && mStatus == LocationProvider.AVAILABLE && mLastFixTime > 0 &&
            System.currentTimeMillis() - mLastFixTime > RECENT_FIX_TIMEOUT) {
            // send an intent to notify that the GPS is no longer receiving fixes.
            Intent intent = new Intent(LocationManager.GPS_FIX_CHANGE_ACTION);
            intent.putExtra(LocationManager.EXTRA_GPS_ENABLED, false);
            mContext.sendBroadcast(intent);
            updateStatus(LocationProvider.TEMPORARILY_UNAVAILABLE, mSvCount);
        }
    }

    /**
     * called from native code to update AGPS status
     */
    private void reportAGpsStatus(int type, int status) {
        switch (status) {
            case GPS_REQUEST_AGPS_DATA_CONN:
                 int result = mConnMgr.startUsingNetworkFeature(
                        ConnectivityManager.TYPE_MOBILE, Phone.FEATURE_ENABLE_SUPL);
                if (result == Phone.APN_ALREADY_ACTIVE) {
                    if (mAGpsApn != null) {
                        native_agps_data_conn_open(mAGpsApn);
                        mAGpsDataConnectionState = AGPS_DATA_CONNECTION_OPEN;
                    } else {
                        Log.e(TAG, "mAGpsApn not set when receiving Phone.APN_ALREADY_ACTIVE");
                        native_agps_data_conn_failed();
                    }
                } else if (result == Phone.APN_REQUEST_STARTED) {
                    mAGpsDataConnectionState = AGPS_DATA_CONNECTION_OPENING;
                } else {
                    native_agps_data_conn_failed();
                }
                break;
            case GPS_RELEASE_AGPS_DATA_CONN:
                if (mAGpsDataConnectionState != AGPS_DATA_CONNECTION_CLOSED) {
                    mConnMgr.stopUsingNetworkFeature(
                            ConnectivityManager.TYPE_MOBILE, Phone.FEATURE_ENABLE_SUPL);
                    native_agps_data_conn_closed();
                    mAGpsDataConnectionState = AGPS_DATA_CONNECTION_CLOSED;
                }
                break;
            case GPS_AGPS_DATA_CONNECTED:
                // Log.d(TAG, "GPS_AGPS_DATA_CONNECTED");
                break;
            case GPS_AGPS_DATA_CONN_DONE:
                // Log.d(TAG, "GPS_AGPS_DATA_CONN_DONE");
                break;
            case GPS_AGPS_DATA_CONN_FAILED:
                // Log.d(TAG, "GPS_AGPS_DATA_CONN_FAILED");
                break;
        }
    }

    /**
     * called from native code to report NMEA data received
     */
    private void reportNmea(int index, long timestamp) {
        synchronized(mListeners) {
            int size = mListeners.size();
            if (size > 0) {
                // don't bother creating the String if we have no listeners
                int length = native_read_nmea(index, mNmeaBuffer, mNmeaBuffer.length);
                String nmea = new String(mNmeaBuffer, 0, length);

                for (int i = 0; i < size; i++) {
                    Listener listener = mListeners.get(i);
                    try {
                        listener.mListener.onNmeaReceived(timestamp, nmea);
                    } catch (RemoteException e) {
                        Log.w(TAG, "RemoteException in reportNmea");
                        mListeners.remove(listener);
                        // adjust for size of list changing
                        size--;
                    }
                }
            }
        }
    }

    /**
     * called from native code to inform us what the GPS engine capabilities are
     */
    private void setEngineCapabilities(int capabilities) {
        mEngineCapabilities = capabilities;
    }

    /**
     * called from native code to request XTRA data
     */
    private void xtraDownloadRequest() {
        if (DEBUG) Log.d(TAG, "xtraDownloadRequest");
        sendMessage(DOWNLOAD_XTRA_DATA, 0, null);
    }

    //=============================================================
    // NI Client support
	//=============================================================
    private final INetInitiatedListener mNetInitiatedListener = new INetInitiatedListener.Stub() {
    	// Sends a response for an NI reqeust to HAL.
    	public boolean sendNiResponse(int notificationId, int userResponse)
    	{
        	// TODO Add Permission check

    		StringBuilder extrasBuf = new StringBuilder();

    		if (DEBUG) Log.d(TAG, "sendNiResponse, notifId: " + notificationId +
    				", response: " + userResponse);

    		native_send_ni_response(notificationId, userResponse);

    		return true;
    	}
    };

    public INetInitiatedListener getNetInitiatedListener() {
        return mNetInitiatedListener;
    }

    // Called by JNI function to report an NI request.
	@SuppressWarnings("deprecation")
	public void reportNiNotification(
        	int notificationId,
        	int niType,
        	int notifyFlags,
        	int timeout,
        	int defaultResponse,
        	String requestorId,
        	String text,
        	int requestorIdEncoding,
        	int textEncoding,
        	String extras  // Encoded extra data
        )
	{
		Log.i(TAG, "reportNiNotification: entered");
		Log.i(TAG, "notificationId: " + notificationId +
				", niType: " + niType +
				", notifyFlags: " + notifyFlags +
				", timeout: " + timeout +
				", defaultResponse: " + defaultResponse);

		Log.i(TAG, "requestorId: " + requestorId +
				", text: " + text +
				", requestorIdEncoding: " + requestorIdEncoding +
				", textEncoding: " + textEncoding);

		GpsNiNotification notification = new GpsNiNotification();

		notification.notificationId = notificationId;
		notification.niType = niType;
		notification.needNotify = (notifyFlags & GpsNetInitiatedHandler.GPS_NI_NEED_NOTIFY) != 0;
		notification.needVerify = (notifyFlags & GpsNetInitiatedHandler.GPS_NI_NEED_VERIFY) != 0;
		notification.privacyOverride = (notifyFlags & GpsNetInitiatedHandler.GPS_NI_PRIVACY_OVERRIDE) != 0;
		notification.timeout = timeout;
		notification.defaultResponse = defaultResponse;
		notification.requestorId = requestorId;
		notification.text = text;
		notification.requestorIdEncoding = requestorIdEncoding;
		notification.textEncoding = textEncoding;

		// Process extras, assuming the format is
		// one of more lines of "key = value"
		Bundle bundle = new Bundle();

		if (extras == null) extras = "";
		Properties extraProp = new Properties();

		try {
			extraProp.load(new StringBufferInputStream(extras));
		}
		catch (IOException e)
		{
			Log.e(TAG, "reportNiNotification cannot parse extras data: " + extras);
		}

		for (Entry<Object, Object> ent : extraProp.entrySet())
		{
			bundle.putString((String) ent.getKey(), (String) ent.getValue());
		}

		notification.extras = bundle;

		mNIHandler.handleNiNotification(notification);
	}

    // this thread is used to receive events from the native code.
    // native_wait_for_event() will callback to us via reportLocation(), reportStatus(), etc.
    // this is necessary because native code cannot call Java on a thread that the JVM does
    // not know about.
    private final class GpsEventThread extends Thread {

        public GpsEventThread() {
            super("GpsEventThread");
        }

        public void run() {
            if (DEBUG) Log.d(TAG, "GpsEventThread starting");
            // Exit as soon as disable() is called instead of waiting for the GPS to stop.
            while (mEnabled) {
                // this will wait for an event from the GPS,
                // which will be reported via reportLocation or reportStatus
                native_wait_for_event();
            }
            if (DEBUG) Log.d(TAG, "GpsEventThread exiting");
        }
    }

    private void sendMessage(int message, int arg, Object obj) {
        // hold a wake lock while messages are pending
        synchronized (mWakeLock) {
            mPendingMessageBits |= (1 << message);
            mWakeLock.acquire();
            mHandler.removeMessages(message);
            Message m = Message.obtain(mHandler, message);
            m.arg1 = arg;
            m.obj = obj;
            mHandler.sendMessage(m);
        }
    }

    private final class ProviderHandler extends Handler {
        @Override
        public void handleMessage(Message msg)
        {
            int message = msg.what;
            switch (message) {
                case ENABLE:
                    if (msg.arg1 == 1) {
                        handleEnable();
                    } else {
                        handleDisable();
                    }
                    break;
                case ENABLE_TRACKING:
                    handleEnableLocationTracking(msg.arg1 == 1);
                    break;
                case REQUEST_SINGLE_SHOT:
                    handleRequestSingleShot();
                    break;
                case UPDATE_NETWORK_STATE:
                    handleUpdateNetworkState(msg.arg1, (NetworkInfo)msg.obj);
                    break;
                case INJECT_NTP_TIME:
                    handleInjectNtpTime();
                    break;
                case DOWNLOAD_XTRA_DATA:
                    if (native_supports_xtra()) {
                        handleDownloadXtraData();
                    }
                    break;
                case UPDATE_LOCATION:
                    handleUpdateLocation((Location)msg.obj);
                    break;
                case ADD_LISTENER:
                    handleAddListener(msg.arg1);
                    break;
                case REMOVE_LISTENER:
                    handleRemoveListener(msg.arg1);
                    break;
            }
            // release wake lock if no messages are pending
            synchronized (mWakeLock) {
                mPendingMessageBits &= ~(1 << message);
                if (message == ADD_LISTENER || message == REMOVE_LISTENER) {
                    mPendingListenerMessages--;
                }
                if (mPendingMessageBits == 0 && mPendingListenerMessages == 0) {
                    mWakeLock.release();
                }
            }
        }
    };

    private final class GpsLocationProviderThread extends Thread {

        public GpsLocationProviderThread() {
            super("GpsLocationProvider");
        }

        public void run() {
            Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
            initialize();
            Looper.prepare();
            mHandler = new ProviderHandler();
            // signal when we are initialized and ready to go
            mInitializedLatch.countDown();
            Looper.loop();
        }
    }

    // for GPS SV statistics
    private static final int MAX_SVS = 32;
    private static final int EPHEMERIS_MASK = 0;
    private static final int ALMANAC_MASK = 1;
    private static final int USED_FOR_FIX_MASK = 2;

    // preallocated arrays, to avoid memory allocation in reportStatus()
    private int mSvs[] = new int[MAX_SVS];
    private float mSnrs[] = new float[MAX_SVS];
    private float mSvElevations[] = new float[MAX_SVS];
    private float mSvAzimuths[] = new float[MAX_SVS];
    private int mSvMasks[] = new int[3];
    private int mSvCount;
    // preallocated to avoid memory allocation in reportNmea()
    private byte[] mNmeaBuffer = new byte[120];

    static { class_init_native(); }
    private static native void class_init_native();
    private static native boolean native_is_supported();

    private native boolean native_init();
    private native void native_disable();
    private native void native_cleanup();
    private native boolean native_set_position_mode(int mode, int recurrence, int min_interval,
            int preferred_accuracy, int preferred_time);
    private native boolean native_start();
    private native boolean native_stop();
    private native void native_delete_aiding_data(int flags);
    private native void native_wait_for_event();
    // returns number of SVs
    // mask[0] is ephemeris mask and mask[1] is almanac mask
    private native int native_read_sv_status(int[] svs, float[] snrs,
            float[] elevations, float[] azimuths, int[] masks);
    private native int native_read_nmea(int index, byte[] buffer, int bufferSize);
    private native void native_inject_location(double latitude, double longitude, float accuracy);

    // XTRA Support
    private native void native_inject_time(long time, long timeReference, int uncertainty);
    private native boolean native_supports_xtra();
    private native void native_inject_xtra_data(byte[] data, int length);

    // DEBUG Support
    private native String native_get_internal_state();

    // AGPS Support
    private native void native_agps_data_conn_open(String apn);
    private native void native_agps_data_conn_closed();
    private native void native_agps_data_conn_failed();
    private native void native_set_agps_server(int type, String hostname, int port);

    // Network-initiated (NI) Support
    private native void native_send_ni_response(int notificationId, int userResponse);
}