diff --git a/services/soundtrigger/SoundTriggerHalLegacy.h b/services/soundtrigger/SoundTriggerHalLegacy.h
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+++ b/services/soundtrigger/SoundTriggerHalLegacy.h
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+/*
+ * Copyright (C) 2016 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_HAL_LEGACY_H
+#define ANDROID_HARDWARE_SOUNDTRIGGER_HAL_LEGACY_H
+
+#include "SoundTriggerHalInterface.h"
+
+namespace android {
+
+class SoundTriggerHalLegacy : public SoundTriggerHalInterface
+
+{
+public:
+        virtual             ~SoundTriggerHalLegacy();
+
+        virtual int getProperties(struct sound_trigger_properties *properties);
+
+        /*
+         * Load a sound model. Once loaded, recognition of this model can be started and stopped.
+         * Only one active recognition per model at a time. The SoundTrigger service will handle
+         * concurrent recognition requests by different users/applications on the same model.
+         * The implementation returns a unique handle used by other functions (unload_sound_model(),
+         * start_recognition(), etc...
+         */
+        virtual int loadSoundModel(struct sound_trigger_sound_model *sound_model,
+                                sound_model_callback_t callback,
+                                void *cookie,
+                                sound_model_handle_t *handle);
+
+        /*
+         * Unload a sound model. A sound model can be unloaded to make room for a new one to overcome
+         * implementation limitations.
+         */
+        virtual int unloadSoundModel(sound_model_handle_t handle);
+
+        /* Start recognition on a given model. Only one recognition active at a time per model.
+         * Once recognition succeeds of fails, the callback is called.
+         * TODO: group recognition configuration parameters into one struct and add key phrase options.
+         */
+        virtual int startRecognition(sound_model_handle_t handle,
+                                 const struct sound_trigger_recognition_config *config,
+                                 recognition_callback_t callback,
+                                 void *cookie);
+
+        /* Stop recognition on a given model.
+         * The implementation does not have to call the callback when stopped via this method.
+         */
+        virtual int stopRecognition(sound_model_handle_t handle);
+
+        /* Stop recognition on all models.
+         * Only supported for device api versions SOUND_TRIGGER_DEVICE_API_VERSION_1_1 or above.
+         * If no implementation is provided, stop_recognition will be called for each running model.
+         */
+        int stopAllRecognitions();
+
+        // RefBase
+        virtual     void        onFirstRef();
+
+private:
+
+        friend class SoundTriggerHalInterface;
+
+        explicit SoundTriggerHalLegacy(const char *moduleName = NULL);
+
+        const char *mModuleName;
+        struct sound_trigger_hw_device*        mHwDevice;
+};
+
+} // namespace android
+
+#endif // ANDROID_HARDWARE_SOUNDTRIGGER_HAL_LEGACY_H