services/audioflinger/Effects.h - platform/frameworks/av - Git at Google

 /*
 **
 ** Copyright 2012, 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 INCLUDING_FROM_AUDIOFLINGER_H
     #error This header file should only be included from AudioFlinger.h
 #endif

 //--- Audio Effect Management

 // EffectModule and EffectChain classes both have their own mutex to protect
 // state changes or resource modifications. Always respect the following order
 // if multiple mutexes must be acquired to avoid cross deadlock:
 // AudioFlinger -> ThreadBase -> EffectChain -> EffectModule

 // The EffectModule class is a wrapper object controlling the effect engine implementation
 // in the effect library. It prevents concurrent calls to process() and command() functions
 // from different client threads. It keeps a list of EffectHandle objects corresponding
 // to all client applications using this effect and notifies applications of effect state,
 // control or parameter changes. It manages the activation state machine to send appropriate
 // reset, enable, disable commands to effect engine and provide volume
 // ramping when effects are activated/deactivated.
 // When controlling an auxiliary effect, the EffectModule also provides an input buffer used by
 // the attached track(s) to accumulate their auxiliary channel.
 class EffectModule : public RefBase {
 public:
     EffectModule(ThreadBase *thread,
                     const wp<AudioFlinger::EffectChain>& chain,
                     effect_descriptor_t *desc,
                     int id,
                     int sessionId);
     virtual ~EffectModule();

     enum effect_state {
         IDLE,
         RESTART,
         STARTING,
         ACTIVE,
         STOPPING,
         STOPPED,
         DESTROYED
     };

     int         id() const { return mId; }
     void process();
     void updateState();
     status_t command(uint32_t cmdCode,
                      uint32_t cmdSize,
                      void *pCmdData,
                      uint32_t *replySize,
                      void *pReplyData);

     void reset_l();
     status_t configure();
     status_t init();
     effect_state state() const {
         return mState;
     }
     uint32_t status() {
         return mStatus;
     }
     int sessionId() const {
         return mSessionId;
     }
     status_t    setEnabled(bool enabled);
     status_t    setEnabled_l(bool enabled);
     bool isEnabled() const;
     bool isProcessEnabled() const;

     void        setInBuffer(int16_t *buffer) { mConfig.inputCfg.buffer.s16 = buffer; }
     int16_t     *inBuffer() { return mConfig.inputCfg.buffer.s16; }
     void        setOutBuffer(int16_t *buffer) { mConfig.outputCfg.buffer.s16 = buffer; }
     int16_t     *outBuffer() { return mConfig.outputCfg.buffer.s16; }
     void        setChain(const wp<EffectChain>& chain) { mChain = chain; }
     void        setThread(const wp<ThreadBase>& thread) { mThread = thread; }
     const wp<ThreadBase>& thread() { return mThread; }

     status_t addHandle(EffectHandle *handle);
     size_t disconnect(EffectHandle *handle, bool unpinIfLast);
     size_t removeHandle(EffectHandle *handle);

     const effect_descriptor_t& desc() const { return mDescriptor; }
     wp<EffectChain>&     chain() { return mChain; }

     status_t         setDevice(audio_devices_t device);
     status_t         setVolume(uint32_t *left, uint32_t *right, bool controller);
     status_t         setMode(audio_mode_t mode);
     status_t         setAudioSource(audio_source_t source);
     status_t         start();
     status_t         stop();
     void             setSuspended(bool suspended);
     bool             suspended() const;

     EffectHandle*    controlHandle_l();

     bool             isPinned() const { return mPinned; }
     void             unPin() { mPinned = false; }
     bool             purgeHandles();
     void             lock() { mLock.lock(); }
     void             unlock() { mLock.unlock(); }

     void             dump(int fd, const Vector<String16>& args);

 protected:
     friend class AudioFlinger;      // for mHandles
     bool                mPinned;

     // Maximum time allocated to effect engines to complete the turn off sequence
     static const uint32_t MAX_DISABLE_TIME_MS = 10000;

     EffectModule(const EffectModule&);
     EffectModule& operator = (const EffectModule&);

     status_t start_l();
     status_t stop_l();

 mutable Mutex               mLock;      // mutex for process, commands and handles list protection
     wp<ThreadBase>      mThread;    // parent thread
     wp<EffectChain>     mChain;     // parent effect chain
     const int           mId;        // this instance unique ID
     const int           mSessionId; // audio session ID
     const effect_descriptor_t mDescriptor;// effect descriptor received from effect engine
     effect_config_t     mConfig;    // input and output audio configuration
     effect_handle_t  mEffectInterface; // Effect module C API
     status_t            mStatus;    // initialization status
     effect_state        mState;     // current activation state
     Vector<EffectHandle *> mHandles;    // list of client handles
                 // First handle in mHandles has highest priority and controls the effect module
     uint32_t mMaxDisableWaitCnt;    // maximum grace period before forcing an effect off after
                                     // sending disable command.
     uint32_t mDisableWaitCnt;       // current process() calls count during disable period.
     bool     mSuspended;            // effect is suspended: temporarily disabled by framework
 };

 // The EffectHandle class implements the IEffect interface. It provides resources
 // to receive parameter updates, keeps track of effect control
 // ownership and state and has a pointer to the EffectModule object it is controlling.
 // There is one EffectHandle object for each application controlling (or using)
 // an effect module.
 // The EffectHandle is obtained by calling AudioFlinger::createEffect().
 class EffectHandle: public android::BnEffect {
 public:

     EffectHandle(const sp<EffectModule>& effect,
             const sp<AudioFlinger::Client>& client,
             const sp<IEffectClient>& effectClient,
             int32_t priority);
     virtual ~EffectHandle();

     // IEffect
     virtual status_t enable();
     virtual status_t disable();
     virtual status_t command(uint32_t cmdCode,
                              uint32_t cmdSize,
                              void *pCmdData,
                              uint32_t *replySize,
                              void *pReplyData);
     virtual void disconnect();
 private:
             void disconnect(bool unpinIfLast);
 public:
     virtual sp<IMemory> getCblk() const { return mCblkMemory; }
     virtual status_t onTransact(uint32_t code, const Parcel& data,
             Parcel* reply, uint32_t flags);


     // Give or take control of effect module
     // - hasControl: true if control is given, false if removed
     // - signal: true client app should be signaled of change, false otherwise
     // - enabled: state of the effect when control is passed
     void setControl(bool hasControl, bool signal, bool enabled);
     void commandExecuted(uint32_t cmdCode,
                          uint32_t cmdSize,
                          void *pCmdData,
                          uint32_t replySize,
                          void *pReplyData);
     void setEnabled(bool enabled);
     bool enabled() const { return mEnabled; }

     // Getters
     int id() const { return mEffect->id(); }
     int priority() const { return mPriority; }
     bool hasControl() const { return mHasControl; }
     sp<EffectModule> effect() const { return mEffect; }
     // destroyed_l() must be called with the associated EffectModule mLock held
     bool destroyed_l() const { return mDestroyed; }

     void dump(char* buffer, size_t size);

 protected:
     friend class AudioFlinger;          // for mEffect, mHasControl, mEnabled
     EffectHandle(const EffectHandle&);
     EffectHandle& operator =(const EffectHandle&);

     sp<EffectModule> mEffect;           // pointer to controlled EffectModule
     sp<IEffectClient> mEffectClient;    // callback interface for client notifications
     /*const*/ sp<Client> mClient;       // client for shared memory allocation, see disconnect()
     sp<IMemory>         mCblkMemory;    // shared memory for control block
     effect_param_cblk_t* mCblk;         // control block for deferred parameter setting via
                                         // shared memory
     uint8_t*            mBuffer;        // pointer to parameter area in shared memory
     int mPriority;                      // client application priority to control the effect
     bool mHasControl;                   // true if this handle is controlling the effect
     bool mEnabled;                      // cached enable state: needed when the effect is
                                         // restored after being suspended
     bool mDestroyed;                    // Set to true by destructor. Access with EffectModule
                                         // mLock held
 };

 // the EffectChain class represents a group of effects associated to one audio session.
 // There can be any number of EffectChain objects per output mixer thread (PlaybackThread).
 // The EffecChain with session ID 0 contains global effects applied to the output mix.
 // Effects in this chain can be insert or auxiliary. Effects in other chains (attached to
 // tracks) are insert only. The EffectChain maintains an ordered list of effect module, the
 // order corresponding in the effect process order. When attached to a track (session ID != 0),
 // it also provide it's own input buffer used by the track as accumulation buffer.
 class EffectChain : public RefBase {
 public:
     EffectChain(const wp<ThreadBase>& wThread, int sessionId);
     EffectChain(ThreadBase *thread, int sessionId);
     virtual ~EffectChain();

     // special key used for an entry in mSuspendedEffects keyed vector
     // corresponding to a suspend all request.
     static const int        kKeyForSuspendAll = 0;

     // minimum duration during which we force calling effect process when last track on
     // a session is stopped or removed to allow effect tail to be rendered
     static const int        kProcessTailDurationMs = 1000;

     void process_l();

     void lock() {
         mLock.lock();
     }
     void unlock() {
         mLock.unlock();
     }

     status_t addEffect_l(const sp<EffectModule>& handle);
     size_t removeEffect_l(const sp<EffectModule>& handle);

     int sessionId() const { return mSessionId; }
     void setSessionId(int sessionId) { mSessionId = sessionId; }

     sp<EffectModule> getEffectFromDesc_l(effect_descriptor_t *descriptor);
     sp<EffectModule> getEffectFromId_l(int id);
     sp<EffectModule> getEffectFromType_l(const effect_uuid_t *type);
     bool setVolume_l(uint32_t *left, uint32_t *right);
     void setDevice_l(audio_devices_t device);
     void setMode_l(audio_mode_t mode);
     void setAudioSource_l(audio_source_t source);

     void setInBuffer(int16_t *buffer, bool ownsBuffer = false) {
         mInBuffer = buffer;
         mOwnInBuffer = ownsBuffer;
     }
     int16_t *inBuffer() const {
         return mInBuffer;
     }
     void setOutBuffer(int16_t *buffer) {
         mOutBuffer = buffer;
     }
     int16_t *outBuffer() const {
         return mOutBuffer;
     }

     void incTrackCnt() { android_atomic_inc(&mTrackCnt); }
     void decTrackCnt() { android_atomic_dec(&mTrackCnt); }
     int32_t trackCnt() const { return android_atomic_acquire_load(&mTrackCnt); }

     void incActiveTrackCnt() { android_atomic_inc(&mActiveTrackCnt);
                                mTailBufferCount = mMaxTailBuffers; }
     void decActiveTrackCnt() { android_atomic_dec(&mActiveTrackCnt); }
     int32_t activeTrackCnt() const { return android_atomic_acquire_load(&mActiveTrackCnt); }

     uint32_t strategy() const { return mStrategy; }
     void setStrategy(uint32_t strategy)
             { mStrategy = strategy; }

     // suspend effect of the given type
     void setEffectSuspended_l(const effect_uuid_t *type,
                               bool suspend);
     // suspend all eligible effects
     void setEffectSuspendedAll_l(bool suspend);
     // check if effects should be suspend or restored when a given effect is enable or disabled
     void checkSuspendOnEffectEnabled(const sp<EffectModule>& effect,
                                           bool enabled);

     void clearInputBuffer();

     void dump(int fd, const Vector<String16>& args);

 protected:
     friend class AudioFlinger;  // for mThread, mEffects
     EffectChain(const EffectChain&);
     EffectChain& operator =(const EffectChain&);

     class SuspendedEffectDesc : public RefBase {
     public:
         SuspendedEffectDesc() : mRefCount(0) {}

         int mRefCount;
         effect_uuid_t mType;
         wp<EffectModule> mEffect;
     };

     // get a list of effect modules to suspend when an effect of the type
     // passed is enabled.
     void                       getSuspendEligibleEffects(Vector< sp<EffectModule> > &effects);

     // get an effect module if it is currently enable
     sp<EffectModule> getEffectIfEnabled(const effect_uuid_t *type);
     // true if the effect whose descriptor is passed can be suspended
     // OEMs can modify the rules implemented in this method to exclude specific effect
     // types or implementations from the suspend/restore mechanism.
     bool isEffectEligibleForSuspend(const effect_descriptor_t& desc);

     void clearInputBuffer_l(sp<ThreadBase> thread);

     wp<ThreadBase> mThread;     // parent mixer thread
     Mutex mLock;                // mutex protecting effect list
     Vector< sp<EffectModule> > mEffects; // list of effect modules
     int mSessionId;             // audio session ID
     int16_t *mInBuffer;         // chain input buffer
     int16_t *mOutBuffer;        // chain output buffer

     // 'volatile' here means these are accessed with atomic operations instead of mutex
     volatile int32_t mActiveTrackCnt;    // number of active tracks connected
     volatile int32_t mTrackCnt;          // number of tracks connected

     int32_t mTailBufferCount;   // current effect tail buffer count
     int32_t mMaxTailBuffers;    // maximum effect tail buffers
     bool mOwnInBuffer;          // true if the chain owns its input buffer
     int mVolumeCtrlIdx;         // index of insert effect having control over volume
     uint32_t mLeftVolume;       // previous volume on left channel
     uint32_t mRightVolume;      // previous volume on right channel
     uint32_t mNewLeftVolume;       // new volume on left channel
     uint32_t mNewRightVolume;      // new volume on right channel
     uint32_t mStrategy; // strategy for this effect chain
     // mSuspendedEffects lists all effects currently suspended in the chain.
     // Use effect type UUID timelow field as key. There is no real risk of identical
     // timeLow fields among effect type UUIDs.
     // Updated by updateSuspendedSessions_l() only.
     KeyedVector< int, sp<SuspendedEffectDesc> > mSuspendedEffects;
 };
	/*
	**
	** Copyright 2012, 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 INCLUDING_FROM_AUDIOFLINGER_H
	#error This header file should only be included from AudioFlinger.h
	#endif

	//--- Audio Effect Management

	// EffectModule and EffectChain classes both have their own mutex to protect
	// state changes or resource modifications. Always respect the following order
	// if multiple mutexes must be acquired to avoid cross deadlock:
	// AudioFlinger -> ThreadBase -> EffectChain -> EffectModule

	// The EffectModule class is a wrapper object controlling the effect engine implementation
	// in the effect library. It prevents concurrent calls to process() and command() functions
	// from different client threads. It keeps a list of EffectHandle objects corresponding
	// to all client applications using this effect and notifies applications of effect state,
	// control or parameter changes. It manages the activation state machine to send appropriate
	// reset, enable, disable commands to effect engine and provide volume
	// ramping when effects are activated/deactivated.
	// When controlling an auxiliary effect, the EffectModule also provides an input buffer used by
	// the attached track(s) to accumulate their auxiliary channel.
	class EffectModule : public RefBase {
	public:
	EffectModule(ThreadBase *thread,
	const wp<AudioFlinger::EffectChain>& chain,
	effect_descriptor_t *desc,
	int id,
	int sessionId);
	virtual ~EffectModule();

	enum effect_state {
	IDLE,
	RESTART,
	STARTING,
	ACTIVE,
	STOPPING,
	STOPPED,
	DESTROYED
	};

	int id() const { return mId; }
	void process();
	void updateState();
	status_t command(uint32_t cmdCode,
	uint32_t cmdSize,
	void *pCmdData,
	uint32_t *replySize,
	void *pReplyData);

	void reset_l();
	status_t configure();
	status_t init();
	effect_state state() const {
	return mState;
	}
	uint32_t status() {
	return mStatus;
	}
	int sessionId() const {
	return mSessionId;
	}
	status_t setEnabled(bool enabled);
	status_t setEnabled_l(bool enabled);
	bool isEnabled() const;
	bool isProcessEnabled() const;

	void setInBuffer(int16_t *buffer) { mConfig.inputCfg.buffer.s16 = buffer; }
	int16_t *inBuffer() { return mConfig.inputCfg.buffer.s16; }
	void setOutBuffer(int16_t *buffer) { mConfig.outputCfg.buffer.s16 = buffer; }
	int16_t *outBuffer() { return mConfig.outputCfg.buffer.s16; }
	void setChain(const wp<EffectChain>& chain) { mChain = chain; }
	void setThread(const wp<ThreadBase>& thread) { mThread = thread; }
	const wp<ThreadBase>& thread() { return mThread; }

	status_t addHandle(EffectHandle *handle);
	size_t disconnect(EffectHandle *handle, bool unpinIfLast);
	size_t removeHandle(EffectHandle *handle);

	const effect_descriptor_t& desc() const { return mDescriptor; }
	wp<EffectChain>& chain() { return mChain; }

	status_t setDevice(audio_devices_t device);
	status_t setVolume(uint32_t left, uint32_t right, bool controller);
	status_t setMode(audio_mode_t mode);
	status_t setAudioSource(audio_source_t source);
	status_t start();
	status_t stop();
	void setSuspended(bool suspended);
	bool suspended() const;

	EffectHandle* controlHandle_l();

	bool isPinned() const { return mPinned; }
	void unPin() { mPinned = false; }
	bool purgeHandles();
	void lock() { mLock.lock(); }
	void unlock() { mLock.unlock(); }

	void dump(int fd, const Vector<String16>& args);

	protected:
	friend class AudioFlinger; // for mHandles
	bool mPinned;

	// Maximum time allocated to effect engines to complete the turn off sequence
	static const uint32_t MAX_DISABLE_TIME_MS = 10000;

	EffectModule(const EffectModule&);
	EffectModule& operator = (const EffectModule&);

	status_t start_l();
	status_t stop_l();

	mutable Mutex mLock; // mutex for process, commands and handles list protection
	wp<ThreadBase> mThread; // parent thread
	wp<EffectChain> mChain; // parent effect chain
	const int mId; // this instance unique ID
	const int mSessionId; // audio session ID
	const effect_descriptor_t mDescriptor;// effect descriptor received from effect engine
	effect_config_t mConfig; // input and output audio configuration
	effect_handle_t mEffectInterface; // Effect module C API
	status_t mStatus; // initialization status
	effect_state mState; // current activation state
	Vector<EffectHandle *> mHandles; // list of client handles
	// First handle in mHandles has highest priority and controls the effect module
	uint32_t mMaxDisableWaitCnt; // maximum grace period before forcing an effect off after
	// sending disable command.
	uint32_t mDisableWaitCnt; // current process() calls count during disable period.
	bool mSuspended; // effect is suspended: temporarily disabled by framework
	};

	// The EffectHandle class implements the IEffect interface. It provides resources
	// to receive parameter updates, keeps track of effect control
	// ownership and state and has a pointer to the EffectModule object it is controlling.
	// There is one EffectHandle object for each application controlling (or using)
	// an effect module.
	// The EffectHandle is obtained by calling AudioFlinger::createEffect().
	class EffectHandle: public android::BnEffect {
	public:

	EffectHandle(const sp<EffectModule>& effect,
	const sp<AudioFlinger::Client>& client,
	const sp<IEffectClient>& effectClient,
	int32_t priority);
	virtual ~EffectHandle();

	// IEffect
	virtual status_t enable();
	virtual status_t disable();
	virtual status_t command(uint32_t cmdCode,
	uint32_t cmdSize,
	void *pCmdData,
	uint32_t *replySize,
	void *pReplyData);
	virtual void disconnect();
	private:
	void disconnect(bool unpinIfLast);
	public:
	virtual sp<IMemory> getCblk() const { return mCblkMemory; }
	virtual status_t onTransact(uint32_t code, const Parcel& data,
	Parcel* reply, uint32_t flags);


	// Give or take control of effect module
	// - hasControl: true if control is given, false if removed
	// - signal: true client app should be signaled of change, false otherwise
	// - enabled: state of the effect when control is passed
	void setControl(bool hasControl, bool signal, bool enabled);
	void commandExecuted(uint32_t cmdCode,
	uint32_t cmdSize,
	void *pCmdData,
	uint32_t replySize,
	void *pReplyData);
	void setEnabled(bool enabled);
	bool enabled() const { return mEnabled; }

	// Getters
	int id() const { return mEffect->id(); }
	int priority() const { return mPriority; }
	bool hasControl() const { return mHasControl; }
	sp<EffectModule> effect() const { return mEffect; }
	// destroyed_l() must be called with the associated EffectModule mLock held
	bool destroyed_l() const { return mDestroyed; }

	void dump(char* buffer, size_t size);

	protected:
	friend class AudioFlinger; // for mEffect, mHasControl, mEnabled
	EffectHandle(const EffectHandle&);
	EffectHandle& operator =(const EffectHandle&);

	sp<EffectModule> mEffect; // pointer to controlled EffectModule
	sp<IEffectClient> mEffectClient; // callback interface for client notifications
	/const/ sp<Client> mClient; // client for shared memory allocation, see disconnect()
	sp<IMemory> mCblkMemory; // shared memory for control block
	effect_param_cblk_t* mCblk; // control block for deferred parameter setting via
	// shared memory
	uint8_t* mBuffer; // pointer to parameter area in shared memory
	int mPriority; // client application priority to control the effect
	bool mHasControl; // true if this handle is controlling the effect
	bool mEnabled; // cached enable state: needed when the effect is
	// restored after being suspended
	bool mDestroyed; // Set to true by destructor. Access with EffectModule
	// mLock held
	};

	// the EffectChain class represents a group of effects associated to one audio session.
	// There can be any number of EffectChain objects per output mixer thread (PlaybackThread).
	// The EffecChain with session ID 0 contains global effects applied to the output mix.
	// Effects in this chain can be insert or auxiliary. Effects in other chains (attached to
	// tracks) are insert only. The EffectChain maintains an ordered list of effect module, the
	// order corresponding in the effect process order. When attached to a track (session ID != 0),
	// it also provide it's own input buffer used by the track as accumulation buffer.
	class EffectChain : public RefBase {
	public:
	EffectChain(const wp<ThreadBase>& wThread, int sessionId);
	EffectChain(ThreadBase *thread, int sessionId);
	virtual ~EffectChain();

	// special key used for an entry in mSuspendedEffects keyed vector
	// corresponding to a suspend all request.
	static const int kKeyForSuspendAll = 0;

	// minimum duration during which we force calling effect process when last track on
	// a session is stopped or removed to allow effect tail to be rendered
	static const int kProcessTailDurationMs = 1000;

	void process_l();

	void lock() {
	mLock.lock();
	}
	void unlock() {
	mLock.unlock();
	}

	status_t addEffect_l(const sp<EffectModule>& handle);
	size_t removeEffect_l(const sp<EffectModule>& handle);

	int sessionId() const { return mSessionId; }
	void setSessionId(int sessionId) { mSessionId = sessionId; }

	sp<EffectModule> getEffectFromDesc_l(effect_descriptor_t *descriptor);
	sp<EffectModule> getEffectFromId_l(int id);
	sp<EffectModule> getEffectFromType_l(const effect_uuid_t *type);
	bool setVolume_l(uint32_t left, uint32_t right);
	void setDevice_l(audio_devices_t device);
	void setMode_l(audio_mode_t mode);
	void setAudioSource_l(audio_source_t source);

	void setInBuffer(int16_t *buffer, bool ownsBuffer = false) {
	mInBuffer = buffer;
	mOwnInBuffer = ownsBuffer;
	}
	int16_t *inBuffer() const {
	return mInBuffer;
	}
	void setOutBuffer(int16_t *buffer) {
	mOutBuffer = buffer;
	}
	int16_t *outBuffer() const {
	return mOutBuffer;
	}

	void incTrackCnt() { android_atomic_inc(&mTrackCnt); }
	void decTrackCnt() { android_atomic_dec(&mTrackCnt); }
	int32_t trackCnt() const { return android_atomic_acquire_load(&mTrackCnt); }

	void incActiveTrackCnt() { android_atomic_inc(&mActiveTrackCnt);
	mTailBufferCount = mMaxTailBuffers; }
	void decActiveTrackCnt() { android_atomic_dec(&mActiveTrackCnt); }
	int32_t activeTrackCnt() const { return android_atomic_acquire_load(&mActiveTrackCnt); }

	uint32_t strategy() const { return mStrategy; }
	void setStrategy(uint32_t strategy)
	{ mStrategy = strategy; }

	// suspend effect of the given type
	void setEffectSuspended_l(const effect_uuid_t *type,
	bool suspend);
	// suspend all eligible effects
	void setEffectSuspendedAll_l(bool suspend);
	// check if effects should be suspend or restored when a given effect is enable or disabled
	void checkSuspendOnEffectEnabled(const sp<EffectModule>& effect,
	bool enabled);

	void clearInputBuffer();

	void dump(int fd, const Vector<String16>& args);

	protected:
	friend class AudioFlinger; // for mThread, mEffects
	EffectChain(const EffectChain&);
	EffectChain& operator =(const EffectChain&);

	class SuspendedEffectDesc : public RefBase {
	public:
	SuspendedEffectDesc() : mRefCount(0) {}

	int mRefCount;
	effect_uuid_t mType;
	wp<EffectModule> mEffect;
	};

	// get a list of effect modules to suspend when an effect of the type
	// passed is enabled.
	void getSuspendEligibleEffects(Vector< sp<EffectModule> > &effects);

	// get an effect module if it is currently enable
	sp<EffectModule> getEffectIfEnabled(const effect_uuid_t *type);
	// true if the effect whose descriptor is passed can be suspended
	// OEMs can modify the rules implemented in this method to exclude specific effect
	// types or implementations from the suspend/restore mechanism.
	bool isEffectEligibleForSuspend(const effect_descriptor_t& desc);

	void clearInputBuffer_l(sp<ThreadBase> thread);

	wp<ThreadBase> mThread; // parent mixer thread
	Mutex mLock; // mutex protecting effect list
	Vector< sp<EffectModule> > mEffects; // list of effect modules
	int mSessionId; // audio session ID
	int16_t *mInBuffer; // chain input buffer
	int16_t *mOutBuffer; // chain output buffer

	// 'volatile' here means these are accessed with atomic operations instead of mutex
	volatile int32_t mActiveTrackCnt; // number of active tracks connected
	volatile int32_t mTrackCnt; // number of tracks connected

	int32_t mTailBufferCount; // current effect tail buffer count
	int32_t mMaxTailBuffers; // maximum effect tail buffers
	bool mOwnInBuffer; // true if the chain owns its input buffer
	int mVolumeCtrlIdx; // index of insert effect having control over volume
	uint32_t mLeftVolume; // previous volume on left channel
	uint32_t mRightVolume; // previous volume on right channel
	uint32_t mNewLeftVolume; // new volume on left channel
	uint32_t mNewRightVolume; // new volume on right channel
	uint32_t mStrategy; // strategy for this effect chain
	// mSuspendedEffects lists all effects currently suspended in the chain.
	// Use effect type UUID timelow field as key. There is no real risk of identical
	// timeLow fields among effect type UUIDs.
	// Updated by updateSuspendedSessions_l() only.
	KeyedVector< int, sp<SuspendedEffectDesc> > mSuspendedEffects;
	};