diff --git a/soundtrigger/2.3/default/SoundTriggerHw.h b/soundtrigger/2.3/default/SoundTriggerHw.h
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+++ b/soundtrigger/2.3/default/SoundTriggerHw.h
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+/*
+ * Copyright (C) 2019 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.
+ */
+
+#ifndef ANDROID_HARDWARE_SOUNDTRIGGER_V2_3_SOUNDTRIGGERHW_H
+#define ANDROID_HARDWARE_SOUNDTRIGGER_V2_3_SOUNDTRIGGERHW_H
+
+#include <android/hardware/soundtrigger/2.0/ISoundTriggerHw.h>
+#include <android/hardware/soundtrigger/2.0/ISoundTriggerHwCallback.h>
+#include <android/hardware/soundtrigger/2.3/ISoundTriggerHw.h>
+#include <android/hardware/soundtrigger/2.3/types.h>
+#include <hardware/sound_trigger.h>
+#include <hidl/MQDescriptor.h>
+#include <hidl/Status.h>
+#include <stdatomic.h>
+#include <system/sound_trigger.h>
+#include <utils/KeyedVector.h>
+#include <utils/threads.h>
+
+namespace android {
+namespace hardware {
+namespace soundtrigger {
+namespace V2_3 {
+namespace implementation {
+
+using ::android::sp;
+using ::android::hardware::hidl_array;
+using ::android::hardware::hidl_memory;
+using ::android::hardware::hidl_string;
+using ::android::hardware::hidl_vec;
+using ::android::hardware::Return;
+using ::android::hardware::Void;
+using ::android::hardware::audio::common::V2_0::Uuid;
+
+/**
+ * According to the HIDL C++ Users Guide: client and server implementations
+ * should never directly refer to anything other than the interface header
+ * generated from the HIDL definition file (ie. ISoundTriggerHw.hal), so
+ * this V2_3 implementation copies the previous implementations and
+ * then adds the new implementation.
+ */
+struct SoundTriggerHw : public ISoundTriggerHw {
+    // Methods from V2_0::ISoundTriggerHw follow.
+    Return<void> getProperties(getProperties_cb _hidl_cb) override;
+    Return<void> loadSoundModel(const V2_0::ISoundTriggerHw::SoundModel& soundModel,
+                                const sp<V2_0::ISoundTriggerHwCallback>& callback, int32_t cookie,
+                                loadSoundModel_cb _hidl_cb) override;
+    Return<void> loadPhraseSoundModel(const V2_0::ISoundTriggerHw::PhraseSoundModel& soundModel,
+                                      const sp<V2_0::ISoundTriggerHwCallback>& callback,
+                                      int32_t cookie, loadPhraseSoundModel_cb _hidl_cb) override;
+    Return<int32_t> unloadSoundModel(int32_t modelHandle) override;
+    Return<int32_t> startRecognition(int32_t modelHandle,
+                                     const V2_0::ISoundTriggerHw::RecognitionConfig& config,
+                                     const sp<V2_0::ISoundTriggerHwCallback>& callback,
+                                     int32_t cookie) override;
+    Return<int32_t> stopRecognition(int32_t modelHandle) override;
+    Return<int32_t> stopAllRecognitions() override;
+
+    // Methods from V2_1::ISoundTriggerHw follow.
+    Return<void> loadSoundModel_2_1(const V2_1::ISoundTriggerHw::SoundModel& soundModel,
+                                    const sp<V2_1::ISoundTriggerHwCallback>& callback,
+                                    int32_t cookie, loadSoundModel_2_1_cb _hidl_cb) override;
+    Return<void> loadPhraseSoundModel_2_1(const V2_1::ISoundTriggerHw::PhraseSoundModel& soundModel,
+                                          const sp<V2_1::ISoundTriggerHwCallback>& callback,
+                                          int32_t cookie,
+                                          loadPhraseSoundModel_2_1_cb _hidl_cb) override;
+    Return<int32_t> startRecognition_2_1(int32_t modelHandle,
+                                         const V2_1::ISoundTriggerHw::RecognitionConfig& config,
+                                         const sp<V2_1::ISoundTriggerHwCallback>& callback,
+                                         int32_t cookie) override;
+
+    // Methods from V2_2::ISoundTriggerHw follow.
+    Return<int32_t> getModelState(int32_t modelHandle) override;
+
+    // Methods from V2_3::ISoundTriggerHw follow.
+    Return<int32_t> setParameter(V2_0::SoundModelHandle modelHandle, ModelParameter modelParam,
+                                 int32_t value) override;
+    Return<void> getParameter(V2_0::SoundModelHandle modelHandle, ModelParameter modelParam,
+                              ISoundTriggerHw::getParameter_cb _hidl_cb) override;
+    Return<void> queryParameter(V2_0::SoundModelHandle modelHandle, ModelParameter modelParam,
+                                ISoundTriggerHw::queryParameter_cb _hidl_cb) override;
+
+    SoundTriggerHw();
+
+    // Copied from hardware/interfaces/soundtrigger/2.0/default/SoundTriggerHalImpl.h
+
+    /**
+     * Client object holding active handles and callback sctructures. Used for referencing
+     * which models map to which client of the HAL. SoundModelClients are stored in the
+     * mClients object while the model is active.
+     */
+    class SoundModelClient : public RefBase {
+      public:
+        SoundModelClient(uint32_t id, V2_0::ISoundTriggerHwCallback::CallbackCookie cookie)
+            : mId(id), mCookie(cookie) {}
+        virtual ~SoundModelClient() {}
+
+        uint32_t getId() const { return mId; }
+        sound_model_handle_t getHalHandle() const { return mHalHandle; }
+        void setHalHandle(sound_model_handle_t handle) { mHalHandle = handle; }
+
+        virtual void recognitionCallback(struct sound_trigger_recognition_event* halEvent) = 0;
+        virtual void soundModelCallback(struct sound_trigger_model_event* halEvent) = 0;
+
+      protected:
+        const uint32_t mId;
+        sound_model_handle_t mHalHandle;
+        V2_0::ISoundTriggerHwCallback::CallbackCookie mCookie;
+    };
+
+  private:
+    static void convertPhaseRecognitionEventFromHal(
+            V2_0::ISoundTriggerHwCallback::PhraseRecognitionEvent* event,
+            const struct sound_trigger_phrase_recognition_event* halEvent);
+    static void convertRecognitionEventFromHal(
+            V2_0::ISoundTriggerHwCallback::RecognitionEvent* event,
+            const struct sound_trigger_recognition_event* halEvent);
+    static void convertSoundModelEventFromHal(V2_0::ISoundTriggerHwCallback::ModelEvent* event,
+                                              const struct sound_trigger_model_event* halEvent);
+
+    virtual ~SoundTriggerHw();
+
+    uint32_t nextUniqueModelId();
+    int doLoadSoundModel(const V2_0::ISoundTriggerHw::SoundModel& soundModel,
+                         sp<SoundModelClient> client);
+
+    // RefBase
+    void onFirstRef() override;
+
+    class SoundModelClient_2_0 : public SoundModelClient {
+      public:
+        SoundModelClient_2_0(uint32_t id, V2_0::ISoundTriggerHwCallback::CallbackCookie cookie,
+                             sp<V2_0::ISoundTriggerHwCallback> callback)
+            : SoundModelClient(id, cookie), mCallback(callback) {}
+
+        void recognitionCallback(struct sound_trigger_recognition_event* halEvent) override;
+        void soundModelCallback(struct sound_trigger_model_event* halEvent) override;
+
+      private:
+        sp<V2_0::ISoundTriggerHwCallback> mCallback;
+    };
+
+    void convertUuidFromHal(Uuid* uuid, const sound_trigger_uuid_t* halUuid);
+    void convertUuidToHal(sound_trigger_uuid_t* halUuid, const Uuid* uuid);
+    void convertPropertiesFromHal(V2_0::ISoundTriggerHw::Properties* properties,
+                                  const struct sound_trigger_properties* halProperties);
+    static sound_trigger_model_parameter_t convertModelParameterToHal(ModelParameter param);
+    void convertTriggerPhraseToHal(struct sound_trigger_phrase* halTriggerPhrase,
+                                   const V2_0::ISoundTriggerHw::Phrase* triggerPhrase);
+    // returned HAL sound model must be freed by caller
+    struct sound_trigger_sound_model* convertSoundModelToHal(
+            const V2_0::ISoundTriggerHw::SoundModel* soundModel);
+    void convertPhraseRecognitionExtraToHal(struct sound_trigger_phrase_recognition_extra* halExtra,
+                                            const V2_0::PhraseRecognitionExtra* extra);
+    // returned recognition config must be freed by caller
+    struct sound_trigger_recognition_config* convertRecognitionConfigToHal(
+            const V2_0::ISoundTriggerHw::RecognitionConfig* config);
+
+    static void convertPhraseRecognitionExtraFromHal(
+            V2_0::PhraseRecognitionExtra* extra,
+            const struct sound_trigger_phrase_recognition_extra* halExtra);
+
+    static void soundModelCallback(struct sound_trigger_model_event* halEvent, void* cookie);
+    static void recognitionCallback(struct sound_trigger_recognition_event* halEvent, void* cookie);
+
+    const char* mModuleName;
+    struct sound_trigger_hw_device* mHwDevice;
+    volatile atomic_uint_fast32_t mNextModelId;
+    DefaultKeyedVector<int32_t, sp<SoundModelClient>> mClients;
+    Mutex mLock;
+
+    // Copied from hardware/interfaces/soundtrigger/2.1/default/SoundTriggerHw.h
+    class SoundModelClient_2_1 : public SoundModelClient {
+      public:
+        SoundModelClient_2_1(uint32_t id, V2_1::ISoundTriggerHwCallback::CallbackCookie cookie,
+                             sp<V2_1::ISoundTriggerHwCallback> callback)
+            : SoundModelClient(id, cookie), mCallback(callback) {}
+
+        void recognitionCallback(struct sound_trigger_recognition_event* halEvent) override;
+        void soundModelCallback(struct sound_trigger_model_event* halEvent) override;
+
+      private:
+        sp<V2_1::ISoundTriggerHwCallback> mCallback;
+    };
+};
+
+extern "C" ISoundTriggerHw* HIDL_FETCH_ISoundTriggerHw(const char* name);
+
+}  // namespace implementation
+}  // namespace V2_3
+}  // namespace soundtrigger
+}  // namespace hardware
+}  // namespace android
+
+#endif  // ANDROID_HARDWARE_SOUNDTRIGGER_V2_2_SOUNDTRIGGERHW_H