core/jni/android_hardware_SensorManager.cpp - platform/frameworks/base - Git at Google

 /*
  * Copyright 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.
  */
 #define LOG_TAG "SensorManager"

 #include "JNIHelp.h"
 #include "android_os_MessageQueue.h"
 #include "core_jni_helpers.h"
 #include "jni.h"

 #include <ScopedUtfChars.h>
 #include <ScopedLocalRef.h>
 #include <android_runtime/AndroidRuntime.h>
 #include <gui/Sensor.h>
 #include <gui/SensorEventQueue.h>
 #include <gui/SensorManager.h>
 #include <utils/Log.h>
 #include <utils/Looper.h>
 #include <utils/Vector.h>

 #include <map>

 namespace {

 using namespace android;

 struct {
     jclass clazz;
     jmethodID dispatchSensorEvent;
     jmethodID dispatchFlushCompleteEvent;
     jmethodID dispatchAdditionalInfoEvent;
 } gBaseEventQueueClassInfo;

 struct SensorOffsets
 {
     jclass      clazz;
     //fields
     jfieldID    name;
     jfieldID    vendor;
     jfieldID    version;
     jfieldID    handle;
     jfieldID    range;
     jfieldID    resolution;
     jfieldID    power;
     jfieldID    minDelay;
     jfieldID    fifoReservedEventCount;
     jfieldID    fifoMaxEventCount;
     jfieldID    stringType;
     jfieldID    requiredPermission;
     jfieldID    maxDelay;
     jfieldID    flags;
     //methods
     jmethodID   setType;
     jmethodID   setUuid;
     jmethodID   init;
 } gSensorOffsets;

 struct ListOffsets {
     jclass      clazz;
     jmethodID   add;
 } gListOffsets;

 /*
  * nativeClassInit is not inteneded to be thread-safe. It should be called before other native...
  * functions (except nativeCreate).
  */
 static void
 nativeClassInit (JNIEnv *_env, jclass _this)
 {
     //android.hardware.Sensor
     SensorOffsets& sensorOffsets = gSensorOffsets;
     jclass sensorClass = (jclass) _env->NewGlobalRef(_env->FindClass("android/hardware/Sensor"));
     sensorOffsets.clazz       = sensorClass;
     sensorOffsets.name        = _env->GetFieldID(sensorClass, "mName",      "Ljava/lang/String;");
     sensorOffsets.vendor      = _env->GetFieldID(sensorClass, "mVendor",    "Ljava/lang/String;");
     sensorOffsets.version     = _env->GetFieldID(sensorClass, "mVersion",   "I");
     sensorOffsets.handle      = _env->GetFieldID(sensorClass, "mHandle",    "I");
     sensorOffsets.range       = _env->GetFieldID(sensorClass, "mMaxRange",  "F");
     sensorOffsets.resolution  = _env->GetFieldID(sensorClass, "mResolution","F");
     sensorOffsets.power       = _env->GetFieldID(sensorClass, "mPower",     "F");
     sensorOffsets.minDelay    = _env->GetFieldID(sensorClass, "mMinDelay",  "I");
     sensorOffsets.fifoReservedEventCount =
             _env->GetFieldID(sensorClass, "mFifoReservedEventCount",  "I");
     sensorOffsets.fifoMaxEventCount = _env->GetFieldID(sensorClass, "mFifoMaxEventCount",  "I");
     sensorOffsets.stringType = _env->GetFieldID(sensorClass, "mStringType", "Ljava/lang/String;");
     sensorOffsets.requiredPermission = _env->GetFieldID(sensorClass, "mRequiredPermission",
                                                         "Ljava/lang/String;");
     sensorOffsets.maxDelay    = _env->GetFieldID(sensorClass, "mMaxDelay",  "I");
     sensorOffsets.flags = _env->GetFieldID(sensorClass, "mFlags",  "I");

     sensorOffsets.setType = _env->GetMethodID(sensorClass, "setType", "(I)Z");
     sensorOffsets.setUuid = _env->GetMethodID(sensorClass, "setUuid", "(JJ)V");
     sensorOffsets.init = _env->GetMethodID(sensorClass, "<init>", "()V");

     // java.util.List;
     ListOffsets& listOffsets = gListOffsets;
     jclass listClass = (jclass) _env->NewGlobalRef(_env->FindClass("java/util/List"));
     listOffsets.clazz = listClass;
     listOffsets.add = _env->GetMethodID(listClass, "add", "(Ljava/lang/Object;)Z");
 }

 /**
  * A key comparator predicate.
  * It is used to intern strings associated with Sensor data.
  * It defines a 'Strict weak ordering' for the interned strings.
  */
 class InternedStringCompare {
 public:
     bool operator()(const String8* string1, const String8* string2) const {
         if (string1 == NULL) {
             return string2 != NULL;
         }
         if (string2 == NULL) {
             return false;
         }
         return string1->compare(*string2) < 0;
     }
 };

 /**
  * A localized interning mechanism for Sensor strings.
  * We implement our own interning to avoid the overhead of using java.lang.String#intern().
  * It is common that Vendor, StringType, and RequirePermission data is common between many of the
  * Sensors, by interning the memory usage to represent Sensors is optimized.
  */
 static jstring
 getInternedString(JNIEnv *env, const String8* string) {
     static std::map<const String8*, jstring, InternedStringCompare> internedStrings;

     jstring internedString;
     std::map<const String8*, jstring>::iterator iterator = internedStrings.find(string);
     if (iterator != internedStrings.end()) {
         internedString = iterator->second;
     } else {
         jstring localString = env->NewStringUTF(string->string());
         // we are implementing our own interning so expect these strings to be backed by global refs
         internedString = (jstring) env->NewGlobalRef(localString);
         internedStrings.insert(std::make_pair(string, internedString));
         env->DeleteLocalRef(localString);
     }
     return internedString;
 }

 static jlong
 nativeCreate
 (JNIEnv *env, jclass clazz, jstring opPackageName)
 {
     ScopedUtfChars opPackageNameUtf(env, opPackageName);
     return (jlong) &SensorManager::getInstanceForPackage(String16(opPackageNameUtf.c_str()));
 }

 static jobject
 translateNativeSensorToJavaSensor(JNIEnv *env, jobject sensor, const Sensor& nativeSensor) {
     const SensorOffsets& sensorOffsets(gSensorOffsets);

     if (sensor == NULL) {
         // Sensor sensor = new Sensor();
         sensor = env->NewObject(sensorOffsets.clazz, sensorOffsets.init, "");
     }

     if (sensor != NULL) {
         jstring name = env->NewStringUTF(nativeSensor.getName().string());
         jstring vendor = env->NewStringUTF(nativeSensor.getVendor().string());
         jstring requiredPermission =
                 env->NewStringUTF(nativeSensor.getRequiredPermission().string());

         env->SetObjectField(sensor, sensorOffsets.name,      name);
         env->SetObjectField(sensor, sensorOffsets.vendor,    vendor);
         env->SetIntField(sensor, sensorOffsets.version,      nativeSensor.getVersion());
         env->SetIntField(sensor, sensorOffsets.handle,       nativeSensor.getHandle());
         env->SetFloatField(sensor, sensorOffsets.range,      nativeSensor.getMaxValue());
         env->SetFloatField(sensor, sensorOffsets.resolution, nativeSensor.getResolution());
         env->SetFloatField(sensor, sensorOffsets.power,      nativeSensor.getPowerUsage());
         env->SetIntField(sensor, sensorOffsets.minDelay,     nativeSensor.getMinDelay());
         env->SetIntField(sensor, sensorOffsets.fifoReservedEventCount,
                          nativeSensor.getFifoReservedEventCount());
         env->SetIntField(sensor, sensorOffsets.fifoMaxEventCount,
                          nativeSensor.getFifoMaxEventCount());
         env->SetObjectField(sensor, sensorOffsets.requiredPermission,
                             requiredPermission);
         env->SetIntField(sensor, sensorOffsets.maxDelay, nativeSensor.getMaxDelay());
         env->SetIntField(sensor, sensorOffsets.flags, nativeSensor.getFlags());

         if (env->CallBooleanMethod(sensor, sensorOffsets.setType, nativeSensor.getType())
                 == JNI_FALSE) {
             jstring stringType = getInternedString(env, &nativeSensor.getStringType());
             env->SetObjectField(sensor, sensorOffsets.stringType, stringType);
         }

         // TODO(b/29547335): Rename "setUuid" method to "setId".
         int64_t id = nativeSensor.getId();
         env->CallVoidMethod(sensor, sensorOffsets.setUuid, id, 0);
     }
     return sensor;
 }

 static jboolean
 nativeGetSensorAtIndex(JNIEnv *env, jclass clazz, jlong sensorManager, jobject sensor, jint index)
 {
     SensorManager* mgr = reinterpret_cast<SensorManager*>(sensorManager);

     Sensor const* const* sensorList;
     ssize_t count = mgr->getSensorList(&sensorList);
     if (ssize_t(index) >= count) {
         return false;
     }

     return translateNativeSensorToJavaSensor(env, sensor, *sensorList[index]) != NULL;
 }

 static void
 nativeGetDynamicSensors(JNIEnv *env, jclass clazz, jlong sensorManager, jobject sensorList) {

     SensorManager* mgr = reinterpret_cast<SensorManager*>(sensorManager);
     const ListOffsets& listOffsets(gListOffsets);

     Vector<Sensor> nativeList;

     mgr->getDynamicSensorList(nativeList);

     ALOGI("DYNS native SensorManager.getDynamicSensorList return %d sensors", nativeList.size());
     for (size_t i = 0; i < nativeList.size(); ++i) {
         jobject sensor = translateNativeSensorToJavaSensor(env, NULL, nativeList[i]);
         // add to list
         env->CallBooleanMethod(sensorList, listOffsets.add, sensor);
     }
 }

 static jboolean nativeIsDataInjectionEnabled(JNIEnv *_env, jclass _this, jlong sensorManager) {
     SensorManager* mgr = reinterpret_cast<SensorManager*>(sensorManager);
     return mgr->isDataInjectionEnabled();
 }

 //----------------------------------------------------------------------------

 class Receiver : public LooperCallback {
     sp<SensorEventQueue> mSensorQueue;
     sp<MessageQueue> mMessageQueue;
     jobject mReceiverWeakGlobal;
     jfloatArray mFloatScratch;
     jintArray   mIntScratch;
 public:
     Receiver(const sp<SensorEventQueue>& sensorQueue,
             const sp<MessageQueue>& messageQueue,
             jobject receiverWeak) {
         JNIEnv* env = AndroidRuntime::getJNIEnv();
         mSensorQueue = sensorQueue;
         mMessageQueue = messageQueue;
         mReceiverWeakGlobal = env->NewGlobalRef(receiverWeak);

         mIntScratch = (jintArray) env->NewGlobalRef(env->NewIntArray(16));
         mFloatScratch = (jfloatArray) env->NewGlobalRef(env->NewFloatArray(16));
     }
     ~Receiver() {
         JNIEnv* env = AndroidRuntime::getJNIEnv();
         env->DeleteGlobalRef(mReceiverWeakGlobal);
         env->DeleteGlobalRef(mFloatScratch);
         env->DeleteGlobalRef(mIntScratch);
     }
     sp<SensorEventQueue> getSensorEventQueue() const {
         return mSensorQueue;
     }

     void destroy() {
         mMessageQueue->getLooper()->removeFd( mSensorQueue->getFd() );
     }

 private:
     virtual void onFirstRef() {
         LooperCallback::onFirstRef();
         mMessageQueue->getLooper()->addFd(mSensorQueue->getFd(), 0,
                 ALOOPER_EVENT_INPUT, this, mSensorQueue.get());
     }

     virtual int handleEvent(int fd, int events, void* data) {
         JNIEnv* env = AndroidRuntime::getJNIEnv();
         sp<SensorEventQueue> q = reinterpret_cast<SensorEventQueue *>(data);
         ScopedLocalRef<jobject> receiverObj(env, jniGetReferent(env, mReceiverWeakGlobal));

         ssize_t n;
         ASensorEvent buffer[16];
         while ((n = q->read(buffer, 16)) > 0) {
             for (int i=0 ; i<n ; i++) {
                 if (buffer[i].type == SENSOR_TYPE_STEP_COUNTER) {
                     // step-counter returns a uint64, but the java API only deals with floats
                     float value = float(buffer[i].u64.step_counter);
                     env->SetFloatArrayRegion(mFloatScratch, 0, 1, &value);
                 } else if (buffer[i].type == SENSOR_TYPE_DYNAMIC_SENSOR_META) {
                     float value[2];
                     value[0] = buffer[i].dynamic_sensor_meta.connected ? 1.f: 0.f;
                     value[1] = float(buffer[i].dynamic_sensor_meta.handle);
                     env->SetFloatArrayRegion(mFloatScratch, 0, 2, value);
                 } else if (buffer[i].type == SENSOR_TYPE_ADDITIONAL_INFO) {
                     env->SetIntArrayRegion(mIntScratch, 0, 14,
                                            buffer[i].additional_info.data_int32);
                     env->SetFloatArrayRegion(mFloatScratch, 0, 14,
                                              buffer[i].additional_info.data_float);
                 } else {
                     env->SetFloatArrayRegion(mFloatScratch, 0, 16, buffer[i].data);
                 }

                 if (buffer[i].type == SENSOR_TYPE_META_DATA) {
                     // This is a flush complete sensor event. Call dispatchFlushCompleteEvent
                     // method.
                     if (receiverObj.get()) {
                         env->CallVoidMethod(receiverObj.get(),
                                             gBaseEventQueueClassInfo.dispatchFlushCompleteEvent,
                                             buffer[i].meta_data.sensor);
                     }
                 } else if (buffer[i].type == SENSOR_TYPE_ADDITIONAL_INFO) {
                     // This is a flush complete sensor event. Call dispatchAdditionalInfoEvent
                     // method.
                     if (receiverObj.get()) {
                         int type = buffer[i].additional_info.type;
                         int serial = buffer[i].additional_info.serial;
                         env->CallVoidMethod(receiverObj.get(),
                                             gBaseEventQueueClassInfo.dispatchAdditionalInfoEvent,
                                             buffer[i].sensor,
                                             type, serial,
                                             mFloatScratch,
                                             mIntScratch,
                                             buffer[i].timestamp);
                     }
                 }else {
                     int8_t status;
                     switch (buffer[i].type) {
                     case SENSOR_TYPE_ORIENTATION:
                     case SENSOR_TYPE_MAGNETIC_FIELD:
                     case SENSOR_TYPE_ACCELEROMETER:
                     case SENSOR_TYPE_GYROSCOPE:
                     case SENSOR_TYPE_GRAVITY:
                     case SENSOR_TYPE_LINEAR_ACCELERATION:
                         status = buffer[i].vector.status;
                         break;
                     case SENSOR_TYPE_HEART_RATE:
                         status = buffer[i].heart_rate.status;
                         break;
                     default:
                         status = SENSOR_STATUS_ACCURACY_HIGH;
                         break;
                     }
                     if (receiverObj.get()) {
                         env->CallVoidMethod(receiverObj.get(),
                                             gBaseEventQueueClassInfo.dispatchSensorEvent,
                                             buffer[i].sensor,
                                             mFloatScratch,
                                             status,
                                             buffer[i].timestamp);
                     }
                 }
                 if (env->ExceptionCheck()) {
                     mSensorQueue->sendAck(buffer, n);
                     ALOGE("Exception dispatching input event.");
                     return 1;
                 }
             }
             mSensorQueue->sendAck(buffer, n);
         }
         if (n<0 && n != -EAGAIN) {
             // FIXME: error receiving events, what to do in this case?
         }
         return 1;
     }
 };

 static jlong nativeInitSensorEventQueue(JNIEnv *env, jclass clazz, jlong sensorManager,
         jobject eventQWeak, jobject msgQ, jstring packageName, jint mode) {
     SensorManager* mgr = reinterpret_cast<SensorManager*>(sensorManager);
     ScopedUtfChars packageUtf(env, packageName);
     String8 clientName(packageUtf.c_str());
     sp<SensorEventQueue> queue(mgr->createEventQueue(clientName, mode));

     sp<MessageQueue> messageQueue = android_os_MessageQueue_getMessageQueue(env, msgQ);
     if (messageQueue == NULL) {
         jniThrowRuntimeException(env, "MessageQueue is not initialized.");
         return 0;
     }

     sp<Receiver> receiver = new Receiver(queue, messageQueue, eventQWeak);
     receiver->incStrong((void*)nativeInitSensorEventQueue);
     return jlong(receiver.get());
 }

 static jint nativeEnableSensor(JNIEnv *env, jclass clazz, jlong eventQ, jint handle, jint rate_us,
                                jint maxBatchReportLatency) {
     sp<Receiver> receiver(reinterpret_cast<Receiver *>(eventQ));
     return receiver->getSensorEventQueue()->enableSensor(handle, rate_us, maxBatchReportLatency,
                                                          0);
 }

 static jint nativeDisableSensor(JNIEnv *env, jclass clazz, jlong eventQ, jint handle) {
     sp<Receiver> receiver(reinterpret_cast<Receiver *>(eventQ));
     return receiver->getSensorEventQueue()->disableSensor(handle);
 }

 static void nativeDestroySensorEventQueue(JNIEnv *env, jclass clazz, jlong eventQ) {
     sp<Receiver> receiver(reinterpret_cast<Receiver *>(eventQ));
     receiver->destroy();
     receiver->decStrong((void*)nativeInitSensorEventQueue);
 }

 static jint nativeFlushSensor(JNIEnv *env, jclass clazz, jlong eventQ) {
     sp<Receiver> receiver(reinterpret_cast<Receiver *>(eventQ));
     return receiver->getSensorEventQueue()->flush();
 }

 static jint nativeInjectSensorData(JNIEnv *env, jclass clazz, jlong eventQ, jint handle,
         jfloatArray values, jint accuracy, jlong timestamp) {
     sp<Receiver> receiver(reinterpret_cast<Receiver *>(eventQ));
     // Create a sensor_event from the above data which can be injected into the HAL.
     ASensorEvent sensor_event;
     memset(&sensor_event, 0, sizeof(sensor_event));
     sensor_event.sensor = handle;
     sensor_event.timestamp = timestamp;
     env->GetFloatArrayRegion(values, 0, env->GetArrayLength(values), sensor_event.data);
     return receiver->getSensorEventQueue()->injectSensorEvent(sensor_event);
 }
 //----------------------------------------------------------------------------

 static const JNINativeMethod gSystemSensorManagerMethods[] = {
     {"nativeClassInit",
             "()V",
             (void*)nativeClassInit },
     {"nativeCreate",
              "(Ljava/lang/String;)J",
              (void*)nativeCreate },

     {"nativeGetSensorAtIndex",
             "(JLandroid/hardware/Sensor;I)Z",
             (void*)nativeGetSensorAtIndex },

     {"nativeGetDynamicSensors",
             "(JLjava/util/List;)V",
             (void*)nativeGetDynamicSensors },

     {"nativeIsDataInjectionEnabled",
             "(J)Z",
             (void*)nativeIsDataInjectionEnabled},
 };

 static const JNINativeMethod gBaseEventQueueMethods[] = {
     {"nativeInitBaseEventQueue",
              "(JLjava/lang/ref/WeakReference;Landroid/os/MessageQueue;Ljava/lang/String;ILjava/lang/String;)J",
              (void*)nativeInitSensorEventQueue },

     {"nativeEnableSensor",
             "(JIII)I",
             (void*)nativeEnableSensor },

     {"nativeDisableSensor",
             "(JI)I",
             (void*)nativeDisableSensor },

     {"nativeDestroySensorEventQueue",
             "(J)V",
             (void*)nativeDestroySensorEventQueue },

     {"nativeFlushSensor",
             "(J)I",
             (void*)nativeFlushSensor },

     {"nativeInjectSensorData",
             "(JI[FIJ)I",
             (void*)nativeInjectSensorData },
 };

 } //unnamed namespace

 int register_android_hardware_SensorManager(JNIEnv *env)
 {
     RegisterMethodsOrDie(env, "android/hardware/SystemSensorManager",
             gSystemSensorManagerMethods, NELEM(gSystemSensorManagerMethods));

     RegisterMethodsOrDie(env, "android/hardware/SystemSensorManager$BaseEventQueue",
             gBaseEventQueueMethods, NELEM(gBaseEventQueueMethods));

     gBaseEventQueueClassInfo.clazz = FindClassOrDie(env,
             "android/hardware/SystemSensorManager$BaseEventQueue");

     gBaseEventQueueClassInfo.dispatchSensorEvent = GetMethodIDOrDie(env,
             gBaseEventQueueClassInfo.clazz, "dispatchSensorEvent", "(I[FIJ)V");

     gBaseEventQueueClassInfo.dispatchFlushCompleteEvent = GetMethodIDOrDie(env,
             gBaseEventQueueClassInfo.clazz, "dispatchFlushCompleteEvent", "(I)V");

     gBaseEventQueueClassInfo.dispatchAdditionalInfoEvent = GetMethodIDOrDie(env,
             gBaseEventQueueClassInfo.clazz, "dispatchAdditionalInfoEvent", "(III[F[I)V");

     return 0;
 }
	/*
	* Copyright 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.
	*/
	#define LOG_TAG "SensorManager"

	#include "JNIHelp.h"
	#include "android_os_MessageQueue.h"
	#include "core_jni_helpers.h"
	#include "jni.h"

	#include <ScopedUtfChars.h>
	#include <ScopedLocalRef.h>
	#include <android_runtime/AndroidRuntime.h>
	#include <gui/Sensor.h>
	#include <gui/SensorEventQueue.h>
	#include <gui/SensorManager.h>
	#include <utils/Log.h>
	#include <utils/Looper.h>
	#include <utils/Vector.h>

	#include <map>

	namespace {

	using namespace android;

	struct {
	jclass clazz;
	jmethodID dispatchSensorEvent;
	jmethodID dispatchFlushCompleteEvent;
	jmethodID dispatchAdditionalInfoEvent;
	} gBaseEventQueueClassInfo;

	struct SensorOffsets
	{
	jclass clazz;
	//fields
	jfieldID name;
	jfieldID vendor;
	jfieldID version;
	jfieldID handle;
	jfieldID range;
	jfieldID resolution;
	jfieldID power;
	jfieldID minDelay;
	jfieldID fifoReservedEventCount;
	jfieldID fifoMaxEventCount;
	jfieldID stringType;
	jfieldID requiredPermission;
	jfieldID maxDelay;
	jfieldID flags;
	//methods
	jmethodID setType;
	jmethodID setUuid;
	jmethodID init;
	} gSensorOffsets;

	struct ListOffsets {
	jclass clazz;
	jmethodID add;
	} gListOffsets;

	/*
	* nativeClassInit is not inteneded to be thread-safe. It should be called before other native...
	* functions (except nativeCreate).
	*/
	static void
	nativeClassInit (JNIEnv *_env, jclass _this)
	{
	//android.hardware.Sensor
	SensorOffsets& sensorOffsets = gSensorOffsets;
	jclass sensorClass = (jclass) _env->NewGlobalRef(_env->FindClass("android/hardware/Sensor"));
	sensorOffsets.clazz = sensorClass;
	sensorOffsets.name = _env->GetFieldID(sensorClass, "mName", "Ljava/lang/String;");
	sensorOffsets.vendor = _env->GetFieldID(sensorClass, "mVendor", "Ljava/lang/String;");
	sensorOffsets.version = _env->GetFieldID(sensorClass, "mVersion", "I");
	sensorOffsets.handle = _env->GetFieldID(sensorClass, "mHandle", "I");
	sensorOffsets.range = _env->GetFieldID(sensorClass, "mMaxRange", "F");
	sensorOffsets.resolution = _env->GetFieldID(sensorClass, "mResolution","F");
	sensorOffsets.power = _env->GetFieldID(sensorClass, "mPower", "F");
	sensorOffsets.minDelay = _env->GetFieldID(sensorClass, "mMinDelay", "I");
	sensorOffsets.fifoReservedEventCount =
	_env->GetFieldID(sensorClass, "mFifoReservedEventCount", "I");
	sensorOffsets.fifoMaxEventCount = _env->GetFieldID(sensorClass, "mFifoMaxEventCount", "I");
	sensorOffsets.stringType = _env->GetFieldID(sensorClass, "mStringType", "Ljava/lang/String;");
	sensorOffsets.requiredPermission = _env->GetFieldID(sensorClass, "mRequiredPermission",
	"Ljava/lang/String;");
	sensorOffsets.maxDelay = _env->GetFieldID(sensorClass, "mMaxDelay", "I");
	sensorOffsets.flags = _env->GetFieldID(sensorClass, "mFlags", "I");

	sensorOffsets.setType = _env->GetMethodID(sensorClass, "setType", "(I)Z");
	sensorOffsets.setUuid = _env->GetMethodID(sensorClass, "setUuid", "(JJ)V");
	sensorOffsets.init = _env->GetMethodID(sensorClass, "<init>", "()V");

	// java.util.List;
	ListOffsets& listOffsets = gListOffsets;
	jclass listClass = (jclass) _env->NewGlobalRef(_env->FindClass("java/util/List"));
	listOffsets.clazz = listClass;
	listOffsets.add = _env->GetMethodID(listClass, "add", "(Ljava/lang/Object;)Z");
	}

	/**
	* A key comparator predicate.
	* It is used to intern strings associated with Sensor data.
	* It defines a 'Strict weak ordering' for the interned strings.
	*/
	class InternedStringCompare {
	public:
	bool operator()(const String8* string1, const String8* string2) const {
	if (string1 == NULL) {
	return string2 != NULL;
	}
	if (string2 == NULL) {
	return false;
	}
	return string1->compare(*string2) < 0;
	}
	};

	/**
	* A localized interning mechanism for Sensor strings.
	* We implement our own interning to avoid the overhead of using java.lang.String#intern().
	* It is common that Vendor, StringType, and RequirePermission data is common between many of the
	* Sensors, by interning the memory usage to represent Sensors is optimized.
	*/
	static jstring
	getInternedString(JNIEnv env, const String8 string) {
	static std::map<const String8*, jstring, InternedStringCompare> internedStrings;

	jstring internedString;
	std::map<const String8*, jstring>::iterator iterator = internedStrings.find(string);
	if (iterator != internedStrings.end()) {
	internedString = iterator->second;
	} else {
	jstring localString = env->NewStringUTF(string->string());
	// we are implementing our own interning so expect these strings to be backed by global refs
	internedString = (jstring) env->NewGlobalRef(localString);
	internedStrings.insert(std::make_pair(string, internedString));
	env->DeleteLocalRef(localString);
	}
	return internedString;
	}

	static jlong
	nativeCreate
	(JNIEnv *env, jclass clazz, jstring opPackageName)
	{
	ScopedUtfChars opPackageNameUtf(env, opPackageName);
	return (jlong) &SensorManager::getInstanceForPackage(String16(opPackageNameUtf.c_str()));
	}

	static jobject
	translateNativeSensorToJavaSensor(JNIEnv *env, jobject sensor, const Sensor& nativeSensor) {
	const SensorOffsets& sensorOffsets(gSensorOffsets);

	if (sensor == NULL) {
	// Sensor sensor = new Sensor();
	sensor = env->NewObject(sensorOffsets.clazz, sensorOffsets.init, "");
	}

	if (sensor != NULL) {
	jstring name = env->NewStringUTF(nativeSensor.getName().string());
	jstring vendor = env->NewStringUTF(nativeSensor.getVendor().string());
	jstring requiredPermission =
	env->NewStringUTF(nativeSensor.getRequiredPermission().string());

	env->SetObjectField(sensor, sensorOffsets.name, name);
	env->SetObjectField(sensor, sensorOffsets.vendor, vendor);
	env->SetIntField(sensor, sensorOffsets.version, nativeSensor.getVersion());
	env->SetIntField(sensor, sensorOffsets.handle, nativeSensor.getHandle());
	env->SetFloatField(sensor, sensorOffsets.range, nativeSensor.getMaxValue());
	env->SetFloatField(sensor, sensorOffsets.resolution, nativeSensor.getResolution());
	env->SetFloatField(sensor, sensorOffsets.power, nativeSensor.getPowerUsage());
	env->SetIntField(sensor, sensorOffsets.minDelay, nativeSensor.getMinDelay());
	env->SetIntField(sensor, sensorOffsets.fifoReservedEventCount,
	nativeSensor.getFifoReservedEventCount());
	env->SetIntField(sensor, sensorOffsets.fifoMaxEventCount,
	nativeSensor.getFifoMaxEventCount());
	env->SetObjectField(sensor, sensorOffsets.requiredPermission,
	requiredPermission);
	env->SetIntField(sensor, sensorOffsets.maxDelay, nativeSensor.getMaxDelay());
	env->SetIntField(sensor, sensorOffsets.flags, nativeSensor.getFlags());

	if (env->CallBooleanMethod(sensor, sensorOffsets.setType, nativeSensor.getType())
	== JNI_FALSE) {
	jstring stringType = getInternedString(env, &nativeSensor.getStringType());
	env->SetObjectField(sensor, sensorOffsets.stringType, stringType);
	}

	// TODO(b/29547335): Rename "setUuid" method to "setId".
	int64_t id = nativeSensor.getId();
	env->CallVoidMethod(sensor, sensorOffsets.setUuid, id, 0);
	}
	return sensor;
	}

	static jboolean
	nativeGetSensorAtIndex(JNIEnv *env, jclass clazz, jlong sensorManager, jobject sensor, jint index)
	{
	SensorManager* mgr = reinterpret_cast<SensorManager*>(sensorManager);

	Sensor const* const* sensorList;
	ssize_t count = mgr->getSensorList(&sensorList);
	if (ssize_t(index) >= count) {
	return false;
	}

	return translateNativeSensorToJavaSensor(env, sensor, *sensorList[index]) != NULL;
	}

	static void
	nativeGetDynamicSensors(JNIEnv *env, jclass clazz, jlong sensorManager, jobject sensorList) {

	SensorManager* mgr = reinterpret_cast<SensorManager*>(sensorManager);
	const ListOffsets& listOffsets(gListOffsets);

	Vector<Sensor> nativeList;

	mgr->getDynamicSensorList(nativeList);

	ALOGI("DYNS native SensorManager.getDynamicSensorList return %d sensors", nativeList.size());
	for (size_t i = 0; i < nativeList.size(); ++i) {
	jobject sensor = translateNativeSensorToJavaSensor(env, NULL, nativeList[i]);
	// add to list
	env->CallBooleanMethod(sensorList, listOffsets.add, sensor);
	}
	}

	static jboolean nativeIsDataInjectionEnabled(JNIEnv *_env, jclass _this, jlong sensorManager) {
	SensorManager* mgr = reinterpret_cast<SensorManager*>(sensorManager);
	return mgr->isDataInjectionEnabled();
	}

	//----------------------------------------------------------------------------

	class Receiver : public LooperCallback {
	sp<SensorEventQueue> mSensorQueue;
	sp<MessageQueue> mMessageQueue;
	jobject mReceiverWeakGlobal;
	jfloatArray mFloatScratch;
	jintArray mIntScratch;
	public:
	Receiver(const sp<SensorEventQueue>& sensorQueue,
	const sp<MessageQueue>& messageQueue,
	jobject receiverWeak) {
	JNIEnv* env = AndroidRuntime::getJNIEnv();
	mSensorQueue = sensorQueue;
	mMessageQueue = messageQueue;
	mReceiverWeakGlobal = env->NewGlobalRef(receiverWeak);

	mIntScratch = (jintArray) env->NewGlobalRef(env->NewIntArray(16));
	mFloatScratch = (jfloatArray) env->NewGlobalRef(env->NewFloatArray(16));
	}
	~Receiver() {
	JNIEnv* env = AndroidRuntime::getJNIEnv();
	env->DeleteGlobalRef(mReceiverWeakGlobal);
	env->DeleteGlobalRef(mFloatScratch);
	env->DeleteGlobalRef(mIntScratch);
	}
	sp<SensorEventQueue> getSensorEventQueue() const {
	return mSensorQueue;
	}

	void destroy() {
	mMessageQueue->getLooper()->removeFd( mSensorQueue->getFd() );
	}

	private:
	virtual void onFirstRef() {
	LooperCallback::onFirstRef();
	mMessageQueue->getLooper()->addFd(mSensorQueue->getFd(), 0,
	ALOOPER_EVENT_INPUT, this, mSensorQueue.get());
	}

	virtual int handleEvent(int fd, int events, void* data) {
	JNIEnv* env = AndroidRuntime::getJNIEnv();
	sp<SensorEventQueue> q = reinterpret_cast<SensorEventQueue *>(data);
	ScopedLocalRef<jobject> receiverObj(env, jniGetReferent(env, mReceiverWeakGlobal));

	ssize_t n;
	ASensorEvent buffer[16];
	while ((n = q->read(buffer, 16)) > 0) {
	for (int i=0 ; i<n ; i++) {
	if (buffer[i].type == SENSOR_TYPE_STEP_COUNTER) {
	// step-counter returns a uint64, but the java API only deals with floats
	float value = float(buffer[i].u64.step_counter);
	env->SetFloatArrayRegion(mFloatScratch, 0, 1, &value);
	} else if (buffer[i].type == SENSOR_TYPE_DYNAMIC_SENSOR_META) {
	float value[2];
	value[0] = buffer[i].dynamic_sensor_meta.connected ? 1.f: 0.f;
	value[1] = float(buffer[i].dynamic_sensor_meta.handle);
	env->SetFloatArrayRegion(mFloatScratch, 0, 2, value);
	} else if (buffer[i].type == SENSOR_TYPE_ADDITIONAL_INFO) {
	env->SetIntArrayRegion(mIntScratch, 0, 14,
	buffer[i].additional_info.data_int32);
	env->SetFloatArrayRegion(mFloatScratch, 0, 14,
	buffer[i].additional_info.data_float);
	} else {
	env->SetFloatArrayRegion(mFloatScratch, 0, 16, buffer[i].data);
	}

	if (buffer[i].type == SENSOR_TYPE_META_DATA) {
	// This is a flush complete sensor event. Call dispatchFlushCompleteEvent
	// method.
	if (receiverObj.get()) {
	env->CallVoidMethod(receiverObj.get(),
	gBaseEventQueueClassInfo.dispatchFlushCompleteEvent,
	buffer[i].meta_data.sensor);
	}
	} else if (buffer[i].type == SENSOR_TYPE_ADDITIONAL_INFO) {
	// This is a flush complete sensor event. Call dispatchAdditionalInfoEvent
	// method.
	if (receiverObj.get()) {
	int type = buffer[i].additional_info.type;
	int serial = buffer[i].additional_info.serial;
	env->CallVoidMethod(receiverObj.get(),
	gBaseEventQueueClassInfo.dispatchAdditionalInfoEvent,
	buffer[i].sensor,
	type, serial,
	mFloatScratch,
	mIntScratch,
	buffer[i].timestamp);
	}
	}else {
	int8_t status;
	switch (buffer[i].type) {
	case SENSOR_TYPE_ORIENTATION:
	case SENSOR_TYPE_MAGNETIC_FIELD:
	case SENSOR_TYPE_ACCELEROMETER:
	case SENSOR_TYPE_GYROSCOPE:
	case SENSOR_TYPE_GRAVITY:
	case SENSOR_TYPE_LINEAR_ACCELERATION:
	status = buffer[i].vector.status;
	break;
	case SENSOR_TYPE_HEART_RATE:
	status = buffer[i].heart_rate.status;
	break;
	default:
	status = SENSOR_STATUS_ACCURACY_HIGH;
	break;
	}
	if (receiverObj.get()) {
	env->CallVoidMethod(receiverObj.get(),
	gBaseEventQueueClassInfo.dispatchSensorEvent,
	buffer[i].sensor,
	mFloatScratch,
	status,
	buffer[i].timestamp);
	}
	}
	if (env->ExceptionCheck()) {
	mSensorQueue->sendAck(buffer, n);
	ALOGE("Exception dispatching input event.");
	return 1;
	}
	}
	mSensorQueue->sendAck(buffer, n);
	}
	if (n<0 && n != -EAGAIN) {
	// FIXME: error receiving events, what to do in this case?
	}
	return 1;
	}
	};

	static jlong nativeInitSensorEventQueue(JNIEnv *env, jclass clazz, jlong sensorManager,
	jobject eventQWeak, jobject msgQ, jstring packageName, jint mode) {
	SensorManager* mgr = reinterpret_cast<SensorManager*>(sensorManager);
	ScopedUtfChars packageUtf(env, packageName);
	String8 clientName(packageUtf.c_str());
	sp<SensorEventQueue> queue(mgr->createEventQueue(clientName, mode));

	sp<MessageQueue> messageQueue = android_os_MessageQueue_getMessageQueue(env, msgQ);
	if (messageQueue == NULL) {
	jniThrowRuntimeException(env, "MessageQueue is not initialized.");
	return 0;
	}

	sp<Receiver> receiver = new Receiver(queue, messageQueue, eventQWeak);
	receiver->incStrong((void*)nativeInitSensorEventQueue);
	return jlong(receiver.get());
	}

	static jint nativeEnableSensor(JNIEnv *env, jclass clazz, jlong eventQ, jint handle, jint rate_us,
	jint maxBatchReportLatency) {
	sp<Receiver> receiver(reinterpret_cast<Receiver *>(eventQ));
	return receiver->getSensorEventQueue()->enableSensor(handle, rate_us, maxBatchReportLatency,
	0);
	}

	static jint nativeDisableSensor(JNIEnv *env, jclass clazz, jlong eventQ, jint handle) {
	sp<Receiver> receiver(reinterpret_cast<Receiver *>(eventQ));
	return receiver->getSensorEventQueue()->disableSensor(handle);
	}

	static void nativeDestroySensorEventQueue(JNIEnv *env, jclass clazz, jlong eventQ) {
	sp<Receiver> receiver(reinterpret_cast<Receiver *>(eventQ));
	receiver->destroy();
	receiver->decStrong((void*)nativeInitSensorEventQueue);
	}

	static jint nativeFlushSensor(JNIEnv *env, jclass clazz, jlong eventQ) {
	sp<Receiver> receiver(reinterpret_cast<Receiver *>(eventQ));
	return receiver->getSensorEventQueue()->flush();
	}

	static jint nativeInjectSensorData(JNIEnv *env, jclass clazz, jlong eventQ, jint handle,
	jfloatArray values, jint accuracy, jlong timestamp) {
	sp<Receiver> receiver(reinterpret_cast<Receiver *>(eventQ));
	// Create a sensor_event from the above data which can be injected into the HAL.
	ASensorEvent sensor_event;
	memset(&sensor_event, 0, sizeof(sensor_event));
	sensor_event.sensor = handle;
	sensor_event.timestamp = timestamp;
	env->GetFloatArrayRegion(values, 0, env->GetArrayLength(values), sensor_event.data);
	return receiver->getSensorEventQueue()->injectSensorEvent(sensor_event);
	}
	//----------------------------------------------------------------------------

	static const JNINativeMethod gSystemSensorManagerMethods[] = {
	{"nativeClassInit",
	"()V",
	(void*)nativeClassInit },
	{"nativeCreate",
	"(Ljava/lang/String;)J",
	(void*)nativeCreate },

	{"nativeGetSensorAtIndex",
	"(JLandroid/hardware/Sensor;I)Z",
	(void*)nativeGetSensorAtIndex },

	{"nativeGetDynamicSensors",
	"(JLjava/util/List;)V",
	(void*)nativeGetDynamicSensors },

	{"nativeIsDataInjectionEnabled",
	"(J)Z",
	(void*)nativeIsDataInjectionEnabled},
	};

	static const JNINativeMethod gBaseEventQueueMethods[] = {
	{"nativeInitBaseEventQueue",
	"(JLjava/lang/ref/WeakReference;Landroid/os/MessageQueue;Ljava/lang/String;ILjava/lang/String;)J",
	(void*)nativeInitSensorEventQueue },

	{"nativeEnableSensor",
	"(JIII)I",
	(void*)nativeEnableSensor },

	{"nativeDisableSensor",
	"(JI)I",
	(void*)nativeDisableSensor },

	{"nativeDestroySensorEventQueue",
	"(J)V",
	(void*)nativeDestroySensorEventQueue },

	{"nativeFlushSensor",
	"(J)I",
	(void*)nativeFlushSensor },

	{"nativeInjectSensorData",
	"(JI[FIJ)I",
	(void*)nativeInjectSensorData },
	};

	} //unnamed namespace

	int register_android_hardware_SensorManager(JNIEnv *env)
	{
	RegisterMethodsOrDie(env, "android/hardware/SystemSensorManager",
	gSystemSensorManagerMethods, NELEM(gSystemSensorManagerMethods));

	RegisterMethodsOrDie(env, "android/hardware/SystemSensorManager$BaseEventQueue",
	gBaseEventQueueMethods, NELEM(gBaseEventQueueMethods));

	gBaseEventQueueClassInfo.clazz = FindClassOrDie(env,
	"android/hardware/SystemSensorManager$BaseEventQueue");

	gBaseEventQueueClassInfo.dispatchSensorEvent = GetMethodIDOrDie(env,
	gBaseEventQueueClassInfo.clazz, "dispatchSensorEvent", "(I[FIJ)V");

	gBaseEventQueueClassInfo.dispatchFlushCompleteEvent = GetMethodIDOrDie(env,
	gBaseEventQueueClassInfo.clazz, "dispatchFlushCompleteEvent", "(I)V");

	gBaseEventQueueClassInfo.dispatchAdditionalInfoEvent = GetMethodIDOrDie(env,
	gBaseEventQueueClassInfo.clazz, "dispatchAdditionalInfoEvent", "(III[F[I)V");

	return 0;
	}