AudioTrack.cpp revision 38f5d71e72f3b76c5b519614d27f051d53cd2712 
1/* frameworks/base/media/libmedia/AudioTrack.cpp
2**
3** Copyright 2007, The Android Open Source Project
4**
5** Licensed under the Apache License, Version 2.0 (the "License");
6** you may not use this file except in compliance with the License.
7** You may obtain a copy of the License at
8**
9**     http://www.apache.org/licenses/LICENSE-2.0
10**
11** Unless required by applicable law or agreed to in writing, software
12** distributed under the License is distributed on an "AS IS" BASIS,
13** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14** See the License for the specific language governing permissions and
15** limitations under the License.
16*/
17
18
19//#define LOG_NDEBUG 0
20#define LOG_TAG "AudioTrack"
21
22#include <stdint.h>
23#include <sys/types.h>
24#include <limits.h>
25
26#include <sched.h>
27#include <sys/resource.h>
28
29#include <private/media/AudioTrackShared.h>
30
31#include <media/AudioSystem.h>
32#include <media/AudioTrack.h>
33
34#include <utils/Log.h>
35#include <binder/Parcel.h>
36#include <binder/IPCThreadState.h>
37#include <utils/Timers.h>
38#include <utils/Atomic.h>
39
40#include <cutils/bitops.h>
41#include <cutils/compiler.h>
42
43#include <system/audio.h>
44#include <system/audio_policy.h>
45
46#include <audio_utils/primitives.h>
47
48namespace android {
49// ---------------------------------------------------------------------------
50
51// static
52status_t AudioTrack::getMinFrameCount(
53        int* frameCount,
54        audio_stream_type_t streamType,
55        uint32_t sampleRate)
56{
57    int afSampleRate;
58    if (AudioSystem::getOutputSamplingRate(&afSampleRate, streamType) != NO_ERROR) {
59        return NO_INIT;
60    }
61    int afFrameCount;
62    if (AudioSystem::getOutputFrameCount(&afFrameCount, streamType) != NO_ERROR) {
63        return NO_INIT;
64    }
65    uint32_t afLatency;
66    if (AudioSystem::getOutputLatency(&afLatency, streamType) != NO_ERROR) {
67        return NO_INIT;
68    }
69
70    // Ensure that buffer depth covers at least audio hardware latency
71    uint32_t minBufCount = afLatency / ((1000 * afFrameCount) / afSampleRate);
72    if (minBufCount < 2) minBufCount = 2;
73
74    *frameCount = (sampleRate == 0) ? afFrameCount * minBufCount :
75              afFrameCount * minBufCount * sampleRate / afSampleRate;
76    return NO_ERROR;
77}
78
79// ---------------------------------------------------------------------------
80
81AudioTrack::AudioTrack()
82    : mStatus(NO_INIT),
83      mPreviousPriority(ANDROID_PRIORITY_NORMAL), mPreviousSchedulingGroup(ANDROID_TGROUP_DEFAULT)
84{
85}
86
87AudioTrack::AudioTrack(
88        audio_stream_type_t streamType,
89        uint32_t sampleRate,
90        audio_format_t format,
91        int channelMask,
92        int frameCount,
93        uint32_t flags,
94        callback_t cbf,
95        void* user,
96        int notificationFrames,
97        int sessionId)
98    : mStatus(NO_INIT),
99      mPreviousPriority(ANDROID_PRIORITY_NORMAL), mPreviousSchedulingGroup(ANDROID_TGROUP_DEFAULT)
100{
101    mStatus = set(streamType, sampleRate, format, channelMask,
102            frameCount, flags, cbf, user, notificationFrames,
103            0, false, sessionId);
104}
105
106AudioTrack::AudioTrack(
107        int streamType,
108        uint32_t sampleRate,
109        int format,
110        int channelMask,
111        int frameCount,
112        uint32_t flags,
113        callback_t cbf,
114        void* user,
115        int notificationFrames,
116        int sessionId)
117    : mStatus(NO_INIT),
118      mPreviousPriority(ANDROID_PRIORITY_NORMAL), mPreviousSchedulingGroup(ANDROID_TGROUP_DEFAULT)
119{
120    mStatus = set((audio_stream_type_t)streamType, sampleRate, (audio_format_t)format, channelMask,
121            frameCount, flags, cbf, user, notificationFrames,
122            0, false, sessionId);
123}
124
125AudioTrack::AudioTrack(
126        audio_stream_type_t streamType,
127        uint32_t sampleRate,
128        audio_format_t format,
129        int channelMask,
130        const sp<IMemory>& sharedBuffer,
131        uint32_t flags,
132        callback_t cbf,
133        void* user,
134        int notificationFrames,
135        int sessionId)
136    : mStatus(NO_INIT),
137      mPreviousPriority(ANDROID_PRIORITY_NORMAL), mPreviousSchedulingGroup(ANDROID_TGROUP_DEFAULT)
138{
139    mStatus = set(streamType, sampleRate, format, channelMask,
140            0, flags, cbf, user, notificationFrames,
141            sharedBuffer, false, sessionId);
142}
143
144AudioTrack::~AudioTrack()
145{
146    ALOGV_IF(mSharedBuffer != 0, "Destructor sharedBuffer: %p", mSharedBuffer->pointer());
147
148    if (mStatus == NO_ERROR) {
149        // Make sure that callback function exits in the case where
150        // it is looping on buffer full condition in obtainBuffer().
151        // Otherwise the callback thread will never exit.
152        stop();
153        if (mAudioTrackThread != 0) {
154            mAudioTrackThread->requestExitAndWait();
155            mAudioTrackThread.clear();
156        }
157        mAudioTrack.clear();
158        IPCThreadState::self()->flushCommands();
159        AudioSystem::releaseAudioSessionId(mSessionId);
160    }
161}
162
163status_t AudioTrack::set(
164        audio_stream_type_t streamType,
165        uint32_t sampleRate,
166        audio_format_t format,
167        int channelMask,
168        int frameCount,
169        uint32_t flags,
170        callback_t cbf,
171        void* user,
172        int notificationFrames,
173        const sp<IMemory>& sharedBuffer,
174        bool threadCanCallJava,
175        int sessionId)
176{
177
178    ALOGV_IF(sharedBuffer != 0, "sharedBuffer: %p, size: %d", sharedBuffer->pointer(), sharedBuffer->size());
179
180    AutoMutex lock(mLock);
181    if (mAudioTrack != 0) {
182        ALOGE("Track already in use");
183        return INVALID_OPERATION;
184    }
185
186    int afSampleRate;
187    if (AudioSystem::getOutputSamplingRate(&afSampleRate, streamType) != NO_ERROR) {
188        return NO_INIT;
189    }
190    uint32_t afLatency;
191    if (AudioSystem::getOutputLatency(&afLatency, streamType) != NO_ERROR) {
192        return NO_INIT;
193    }
194
195    // handle default values first.
196    if (streamType == AUDIO_STREAM_DEFAULT) {
197        streamType = AUDIO_STREAM_MUSIC;
198    }
199    if (sampleRate == 0) {
200        sampleRate = afSampleRate;
201    }
202    // these below should probably come from the audioFlinger too...
203    if (format == AUDIO_FORMAT_DEFAULT) {
204        format = AUDIO_FORMAT_PCM_16_BIT;
205    }
206    if (channelMask == 0) {
207        channelMask = AUDIO_CHANNEL_OUT_STEREO;
208    }
209
210    // validate parameters
211    if (!audio_is_valid_format(format)) {
212        ALOGE("Invalid format");
213        return BAD_VALUE;
214    }
215
216    // force direct flag if format is not linear PCM
217    if (!audio_is_linear_pcm(format)) {
218        flags |= AUDIO_POLICY_OUTPUT_FLAG_DIRECT;
219    }
220
221    if (!audio_is_output_channel(channelMask)) {
222        ALOGE("Invalid channel mask");
223        return BAD_VALUE;
224    }
225    uint32_t channelCount = popcount(channelMask);
226
227    audio_io_handle_t output = AudioSystem::getOutput(
228                                    streamType,
229                                    sampleRate, format, channelMask,
230                                    (audio_policy_output_flags_t)flags);
231
232    if (output == 0) {
233        ALOGE("Could not get audio output for stream type %d", streamType);
234        return BAD_VALUE;
235    }
236
237    mVolume[LEFT] = 1.0f;
238    mVolume[RIGHT] = 1.0f;
239    mSendLevel = 0.0f;
240    mFrameCount = frameCount;
241    mNotificationFramesReq = notificationFrames;
242    mSessionId = sessionId;
243    mAuxEffectId = 0;
244
245    // create the IAudioTrack
246    status_t status = createTrack_l(streamType,
247                                  sampleRate,
248                                  format,
249                                  (uint32_t)channelMask,
250                                  frameCount,
251                                  flags,
252                                  sharedBuffer,
253                                  output,
254                                  true);
255
256    if (status != NO_ERROR) {
257        return status;
258    }
259
260    if (cbf != NULL) {
261        mAudioTrackThread = new AudioTrackThread(*this, threadCanCallJava);
262    }
263
264    mStatus = NO_ERROR;
265
266    mStreamType = streamType;
267    mFormat = format;
268    mChannelMask = (uint32_t)channelMask;
269    mChannelCount = channelCount;
270    mSharedBuffer = sharedBuffer;
271    mMuted = false;
272    mActive = false;
273    mCbf = cbf;
274    mUserData = user;
275    mLoopCount = 0;
276    mMarkerPosition = 0;
277    mMarkerReached = false;
278    mNewPosition = 0;
279    mUpdatePeriod = 0;
280    mFlushed = false;
281    mFlags = flags;
282    AudioSystem::acquireAudioSessionId(mSessionId);
283    mRestoreStatus = NO_ERROR;
284    return NO_ERROR;
285}
286
287status_t AudioTrack::initCheck() const
288{
289    return mStatus;
290}
291
292// -------------------------------------------------------------------------
293
294uint32_t AudioTrack::latency() const
295{
296    return mLatency;
297}
298
299audio_stream_type_t AudioTrack::streamType() const
300{
301    return mStreamType;
302}
303
304audio_format_t AudioTrack::format() const
305{
306    return mFormat;
307}
308
309int AudioTrack::channelCount() const
310{
311    return mChannelCount;
312}
313
314uint32_t AudioTrack::frameCount() const
315{
316    return mCblk->frameCount;
317}
318
319size_t AudioTrack::frameSize() const
320{
321    if (audio_is_linear_pcm(mFormat)) {
322        return channelCount()*audio_bytes_per_sample(mFormat);
323    } else {
324        return sizeof(uint8_t);
325    }
326}
327
328sp<IMemory>& AudioTrack::sharedBuffer()
329{
330    return mSharedBuffer;
331}
332
333// -------------------------------------------------------------------------
334
335void AudioTrack::start()
336{
337    sp<AudioTrackThread> t = mAudioTrackThread;
338    status_t status = NO_ERROR;
339
340    ALOGV("start %p", this);
341    if (t != 0) {
342        if (t->exitPending()) {
343            if (t->requestExitAndWait() == WOULD_BLOCK) {
344                ALOGE("AudioTrack::start called from thread");
345                return;
346            }
347        }
348     }
349
350    AutoMutex lock(mLock);
351    // acquire a strong reference on the IMemory and IAudioTrack so that they cannot be destroyed
352    // while we are accessing the cblk
353    sp <IAudioTrack> audioTrack = mAudioTrack;
354    sp <IMemory> iMem = mCblkMemory;
355    audio_track_cblk_t* cblk = mCblk;
356
357    if (!mActive) {
358        mFlushed = false;
359        mActive = true;
360        mNewPosition = cblk->server + mUpdatePeriod;
361        cblk->lock.lock();
362        cblk->bufferTimeoutMs = MAX_STARTUP_TIMEOUT_MS;
363        cblk->waitTimeMs = 0;
364        android_atomic_and(~CBLK_DISABLED_ON, &cblk->flags);
365        if (t != 0) {
366            t->run("AudioTrackThread", ANDROID_PRIORITY_AUDIO);
367        } else {
368            mPreviousPriority = getpriority(PRIO_PROCESS, 0);
369            mPreviousSchedulingGroup = androidGetThreadSchedulingGroup(0);
370            androidSetThreadPriority(0, ANDROID_PRIORITY_AUDIO);
371        }
372
373        ALOGV("start %p before lock cblk %p", this, mCblk);
374        if (!(cblk->flags & CBLK_INVALID_MSK)) {
375            cblk->lock.unlock();
376            status = mAudioTrack->start();
377            cblk->lock.lock();
378            if (status == DEAD_OBJECT) {
379                android_atomic_or(CBLK_INVALID_ON, &cblk->flags);
380            }
381        }
382        if (cblk->flags & CBLK_INVALID_MSK) {
383            status = restoreTrack_l(cblk, true);
384        }
385        cblk->lock.unlock();
386        if (status != NO_ERROR) {
387            ALOGV("start() failed");
388            mActive = false;
389            if (t != 0) {
390                t->requestExit();
391            } else {
392                setpriority(PRIO_PROCESS, 0, mPreviousPriority);
393                androidSetThreadSchedulingGroup(0, mPreviousSchedulingGroup);
394            }
395        }
396    }
397
398}
399
400void AudioTrack::stop()
401{
402    sp<AudioTrackThread> t = mAudioTrackThread;
403
404    ALOGV("stop %p", this);
405
406    AutoMutex lock(mLock);
407    if (mActive) {
408        mActive = false;
409        mCblk->cv.signal();
410        mAudioTrack->stop();
411        // Cancel loops (If we are in the middle of a loop, playback
412        // would not stop until loopCount reaches 0).
413        setLoop_l(0, 0, 0);
414        // the playback head position will reset to 0, so if a marker is set, we need
415        // to activate it again
416        mMarkerReached = false;
417        // Force flush if a shared buffer is used otherwise audioflinger
418        // will not stop before end of buffer is reached.
419        if (mSharedBuffer != 0) {
420            flush_l();
421        }
422        if (t != 0) {
423            t->requestExit();
424        } else {
425            setpriority(PRIO_PROCESS, 0, mPreviousPriority);
426            androidSetThreadSchedulingGroup(0, mPreviousSchedulingGroup);
427        }
428    }
429
430}
431
432bool AudioTrack::stopped() const
433{
434    AutoMutex lock(mLock);
435    return stopped_l();
436}
437
438void AudioTrack::flush()
439{
440    AutoMutex lock(mLock);
441    flush_l();
442}
443
444// must be called with mLock held
445void AudioTrack::flush_l()
446{
447    ALOGV("flush");
448
449    // clear playback marker and periodic update counter
450    mMarkerPosition = 0;
451    mMarkerReached = false;
452    mUpdatePeriod = 0;
453
454    if (!mActive) {
455        mFlushed = true;
456        mAudioTrack->flush();
457        // Release AudioTrack callback thread in case it was waiting for new buffers
458        // in AudioTrack::obtainBuffer()
459        mCblk->cv.signal();
460    }
461}
462
463void AudioTrack::pause()
464{
465    ALOGV("pause");
466    AutoMutex lock(mLock);
467    if (mActive) {
468        mActive = false;
469        mAudioTrack->pause();
470    }
471}
472
473void AudioTrack::mute(bool e)
474{
475    mAudioTrack->mute(e);
476    mMuted = e;
477}
478
479bool AudioTrack::muted() const
480{
481    return mMuted;
482}
483
484status_t AudioTrack::setVolume(float left, float right)
485{
486    if (left < 0.0f || left > 1.0f || right < 0.0f || right > 1.0f) {
487        return BAD_VALUE;
488    }
489
490    AutoMutex lock(mLock);
491    mVolume[LEFT] = left;
492    mVolume[RIGHT] = right;
493
494    mCblk->setVolumeLR((uint32_t(uint16_t(right * 0x1000)) << 16) | uint16_t(left * 0x1000));
495
496    return NO_ERROR;
497}
498
499void AudioTrack::getVolume(float* left, float* right) const
500{
501    if (left != NULL) {
502        *left  = mVolume[LEFT];
503    }
504    if (right != NULL) {
505        *right = mVolume[RIGHT];
506    }
507}
508
509status_t AudioTrack::setAuxEffectSendLevel(float level)
510{
511    ALOGV("setAuxEffectSendLevel(%f)", level);
512    if (level < 0.0f || level > 1.0f) {
513        return BAD_VALUE;
514    }
515    AutoMutex lock(mLock);
516
517    mSendLevel = level;
518
519    mCblk->setSendLevel(level);
520
521    return NO_ERROR;
522}
523
524void AudioTrack::getAuxEffectSendLevel(float* level) const
525{
526    if (level != NULL) {
527        *level  = mSendLevel;
528    }
529}
530
531status_t AudioTrack::setSampleRate(int rate)
532{
533    int afSamplingRate;
534
535    if (AudioSystem::getOutputSamplingRate(&afSamplingRate, mStreamType) != NO_ERROR) {
536        return NO_INIT;
537    }
538    // Resampler implementation limits input sampling rate to 2 x output sampling rate.
539    if (rate <= 0 || rate > afSamplingRate*2 ) return BAD_VALUE;
540
541    AutoMutex lock(mLock);
542    mCblk->sampleRate = rate;
543    return NO_ERROR;
544}
545
546uint32_t AudioTrack::getSampleRate() const
547{
548    AutoMutex lock(mLock);
549    return mCblk->sampleRate;
550}
551
552status_t AudioTrack::setLoop(uint32_t loopStart, uint32_t loopEnd, int loopCount)
553{
554    AutoMutex lock(mLock);
555    return setLoop_l(loopStart, loopEnd, loopCount);
556}
557
558// must be called with mLock held
559status_t AudioTrack::setLoop_l(uint32_t loopStart, uint32_t loopEnd, int loopCount)
560{
561    audio_track_cblk_t* cblk = mCblk;
562
563    Mutex::Autolock _l(cblk->lock);
564
565    if (loopCount == 0) {
566        cblk->loopStart = UINT_MAX;
567        cblk->loopEnd = UINT_MAX;
568        cblk->loopCount = 0;
569        mLoopCount = 0;
570        return NO_ERROR;
571    }
572
573    if (loopStart >= loopEnd ||
574        loopEnd - loopStart > cblk->frameCount ||
575        cblk->server > loopStart) {
576        ALOGE("setLoop invalid value: loopStart %d, loopEnd %d, loopCount %d, framecount %d, user %d", loopStart, loopEnd, loopCount, cblk->frameCount, cblk->user);
577        return BAD_VALUE;
578    }
579
580    if ((mSharedBuffer != 0) && (loopEnd > cblk->frameCount)) {
581        ALOGE("setLoop invalid value: loop markers beyond data: loopStart %d, loopEnd %d, framecount %d",
582            loopStart, loopEnd, cblk->frameCount);
583        return BAD_VALUE;
584    }
585
586    cblk->loopStart = loopStart;
587    cblk->loopEnd = loopEnd;
588    cblk->loopCount = loopCount;
589    mLoopCount = loopCount;
590
591    return NO_ERROR;
592}
593
594status_t AudioTrack::setMarkerPosition(uint32_t marker)
595{
596    if (mCbf == NULL) return INVALID_OPERATION;
597
598    mMarkerPosition = marker;
599    mMarkerReached = false;
600
601    return NO_ERROR;
602}
603
604status_t AudioTrack::getMarkerPosition(uint32_t *marker) const
605{
606    if (marker == NULL) return BAD_VALUE;
607
608    *marker = mMarkerPosition;
609
610    return NO_ERROR;
611}
612
613status_t AudioTrack::setPositionUpdatePeriod(uint32_t updatePeriod)
614{
615    if (mCbf == NULL) return INVALID_OPERATION;
616
617    uint32_t curPosition;
618    getPosition(&curPosition);
619    mNewPosition = curPosition + updatePeriod;
620    mUpdatePeriod = updatePeriod;
621
622    return NO_ERROR;
623}
624
625status_t AudioTrack::getPositionUpdatePeriod(uint32_t *updatePeriod) const
626{
627    if (updatePeriod == NULL) return BAD_VALUE;
628
629    *updatePeriod = mUpdatePeriod;
630
631    return NO_ERROR;
632}
633
634status_t AudioTrack::setPosition(uint32_t position)
635{
636    AutoMutex lock(mLock);
637
638    if (!stopped_l()) return INVALID_OPERATION;
639
640    Mutex::Autolock _l(mCblk->lock);
641
642    if (position > mCblk->user) return BAD_VALUE;
643
644    mCblk->server = position;
645    android_atomic_or(CBLK_FORCEREADY_ON, &mCblk->flags);
646
647    return NO_ERROR;
648}
649
650status_t AudioTrack::getPosition(uint32_t *position)
651{
652    if (position == NULL) return BAD_VALUE;
653    AutoMutex lock(mLock);
654    *position = mFlushed ? 0 : mCblk->server;
655
656    return NO_ERROR;
657}
658
659status_t AudioTrack::reload()
660{
661    AutoMutex lock(mLock);
662
663    if (!stopped_l()) return INVALID_OPERATION;
664
665    flush_l();
666
667    mCblk->stepUser(mCblk->frameCount);
668
669    return NO_ERROR;
670}
671
672audio_io_handle_t AudioTrack::getOutput()
673{
674    AutoMutex lock(mLock);
675    return getOutput_l();
676}
677
678// must be called with mLock held
679audio_io_handle_t AudioTrack::getOutput_l()
680{
681    return AudioSystem::getOutput(mStreamType,
682            mCblk->sampleRate, mFormat, mChannelMask, (audio_policy_output_flags_t)mFlags);
683}
684
685int AudioTrack::getSessionId() const
686{
687    return mSessionId;
688}
689
690status_t AudioTrack::attachAuxEffect(int effectId)
691{
692    ALOGV("attachAuxEffect(%d)", effectId);
693    status_t status = mAudioTrack->attachAuxEffect(effectId);
694    if (status == NO_ERROR) {
695        mAuxEffectId = effectId;
696    }
697    return status;
698}
699
700// -------------------------------------------------------------------------
701
702// must be called with mLock held
703status_t AudioTrack::createTrack_l(
704        audio_stream_type_t streamType,
705        uint32_t sampleRate,
706        audio_format_t format,
707        uint32_t channelMask,
708        int frameCount,
709        uint32_t flags,
710        const sp<IMemory>& sharedBuffer,
711        audio_io_handle_t output,
712        bool enforceFrameCount)
713{
714    status_t status;
715    const sp<IAudioFlinger>& audioFlinger = AudioSystem::get_audio_flinger();
716    if (audioFlinger == 0) {
717       ALOGE("Could not get audioflinger");
718       return NO_INIT;
719    }
720
721    int afSampleRate;
722    if (AudioSystem::getOutputSamplingRate(&afSampleRate, streamType) != NO_ERROR) {
723        return NO_INIT;
724    }
725    int afFrameCount;
726    if (AudioSystem::getOutputFrameCount(&afFrameCount, streamType) != NO_ERROR) {
727        return NO_INIT;
728    }
729    uint32_t afLatency;
730    if (AudioSystem::getOutputLatency(&afLatency, streamType) != NO_ERROR) {
731        return NO_INIT;
732    }
733
734    mNotificationFramesAct = mNotificationFramesReq;
735    if (!audio_is_linear_pcm(format)) {
736        if (sharedBuffer != 0) {
737            frameCount = sharedBuffer->size();
738        }
739    } else {
740        // Ensure that buffer depth covers at least audio hardware latency
741        uint32_t minBufCount = afLatency / ((1000 * afFrameCount)/afSampleRate);
742        if (minBufCount < 2) minBufCount = 2;
743
744        int minFrameCount = (afFrameCount*sampleRate*minBufCount)/afSampleRate;
745
746        if (sharedBuffer == 0) {
747            if (frameCount == 0) {
748                frameCount = minFrameCount;
749            }
750            if (mNotificationFramesAct == 0) {
751                mNotificationFramesAct = frameCount/2;
752            }
753            // Make sure that application is notified with sufficient margin
754            // before underrun
755            if (mNotificationFramesAct > (uint32_t)frameCount/2) {
756                mNotificationFramesAct = frameCount/2;
757            }
758            if (frameCount < minFrameCount) {
759                if (enforceFrameCount) {
760                    ALOGE("Invalid buffer size: minFrameCount %d, frameCount %d", minFrameCount, frameCount);
761                    return BAD_VALUE;
762                } else {
763                    frameCount = minFrameCount;
764                }
765            }
766        } else {
767            // Ensure that buffer alignment matches channelcount
768            int channelCount = popcount(channelMask);
769            if (((uint32_t)sharedBuffer->pointer() & (channelCount | 1)) != 0) {
770                ALOGE("Invalid buffer alignement: address %p, channelCount %d", sharedBuffer->pointer(), channelCount);
771                return BAD_VALUE;
772            }
773            frameCount = sharedBuffer->size()/channelCount/sizeof(int16_t);
774        }
775    }
776
777    sp<IAudioTrack> track = audioFlinger->createTrack(getpid(),
778                                                      streamType,
779                                                      sampleRate,
780                                                      format,
781                                                      channelMask,
782                                                      frameCount,
783                                                      ((uint16_t)flags) << 16,
784                                                      sharedBuffer,
785                                                      output,
786                                                      &mSessionId,
787                                                      &status);
788
789    if (track == 0) {
790        ALOGE("AudioFlinger could not create track, status: %d", status);
791        return status;
792    }
793    sp<IMemory> cblk = track->getCblk();
794    if (cblk == 0) {
795        ALOGE("Could not get control block");
796        return NO_INIT;
797    }
798    mAudioTrack = track;
799    mCblkMemory = cblk;
800    mCblk = static_cast<audio_track_cblk_t*>(cblk->pointer());
801    android_atomic_or(CBLK_DIRECTION_OUT, &mCblk->flags);
802    if (sharedBuffer == 0) {
803        mCblk->buffers = (char*)mCblk + sizeof(audio_track_cblk_t);
804    } else {
805        mCblk->buffers = sharedBuffer->pointer();
806         // Force buffer full condition as data is already present in shared memory
807        mCblk->stepUser(mCblk->frameCount);
808    }
809
810    mCblk->setVolumeLR((uint32_t(uint16_t(mVolume[RIGHT] * 0x1000)) << 16) | uint16_t(mVolume[LEFT] * 0x1000));
811    mCblk->setSendLevel(mSendLevel);
812    mAudioTrack->attachAuxEffect(mAuxEffectId);
813    mCblk->bufferTimeoutMs = MAX_STARTUP_TIMEOUT_MS;
814    mCblk->waitTimeMs = 0;
815    mRemainingFrames = mNotificationFramesAct;
816    mLatency = afLatency + (1000*mCblk->frameCount) / sampleRate;
817    return NO_ERROR;
818}
819
820status_t AudioTrack::obtainBuffer(Buffer* audioBuffer, int32_t waitCount)
821{
822    AutoMutex lock(mLock);
823    bool active;
824    status_t result = NO_ERROR;
825    audio_track_cblk_t* cblk = mCblk;
826    uint32_t framesReq = audioBuffer->frameCount;
827    uint32_t waitTimeMs = (waitCount < 0) ? cblk->bufferTimeoutMs : WAIT_PERIOD_MS;
828
829    audioBuffer->frameCount  = 0;
830    audioBuffer->size = 0;
831
832    uint32_t framesAvail = cblk->framesAvailable();
833
834    cblk->lock.lock();
835    if (cblk->flags & CBLK_INVALID_MSK) {
836        goto create_new_track;
837    }
838    cblk->lock.unlock();
839
840    if (framesAvail == 0) {
841        cblk->lock.lock();
842        goto start_loop_here;
843        while (framesAvail == 0) {
844            active = mActive;
845            if (CC_UNLIKELY(!active)) {
846                ALOGV("Not active and NO_MORE_BUFFERS");
847                cblk->lock.unlock();
848                return NO_MORE_BUFFERS;
849            }
850            if (CC_UNLIKELY(!waitCount)) {
851                cblk->lock.unlock();
852                return WOULD_BLOCK;
853            }
854            if (!(cblk->flags & CBLK_INVALID_MSK)) {
855                mLock.unlock();
856                result = cblk->cv.waitRelative(cblk->lock, milliseconds(waitTimeMs));
857                cblk->lock.unlock();
858                mLock.lock();
859                if (!mActive) {
860                    return status_t(STOPPED);
861                }
862                cblk->lock.lock();
863            }
864
865            if (cblk->flags & CBLK_INVALID_MSK) {
866                goto create_new_track;
867            }
868            if (CC_UNLIKELY(result != NO_ERROR)) {
869                cblk->waitTimeMs += waitTimeMs;
870                if (cblk->waitTimeMs >= cblk->bufferTimeoutMs) {
871                    // timing out when a loop has been set and we have already written upto loop end
872                    // is a normal condition: no need to wake AudioFlinger up.
873                    if (cblk->user < cblk->loopEnd) {
874                        ALOGW(   "obtainBuffer timed out (is the CPU pegged?) %p "
875                                "user=%08x, server=%08x", this, cblk->user, cblk->server);
876                        //unlock cblk mutex before calling mAudioTrack->start() (see issue #1617140)
877                        cblk->lock.unlock();
878                        result = mAudioTrack->start();
879                        cblk->lock.lock();
880                        if (result == DEAD_OBJECT) {
881                            android_atomic_or(CBLK_INVALID_ON, &cblk->flags);
882create_new_track:
883                            result = restoreTrack_l(cblk, false);
884                        }
885                        if (result != NO_ERROR) {
886                            ALOGW("obtainBuffer create Track error %d", result);
887                            cblk->lock.unlock();
888                            return result;
889                        }
890                    }
891                    cblk->waitTimeMs = 0;
892                }
893
894                if (--waitCount == 0) {
895                    cblk->lock.unlock();
896                    return TIMED_OUT;
897                }
898            }
899            // read the server count again
900        start_loop_here:
901            framesAvail = cblk->framesAvailable_l();
902        }
903        cblk->lock.unlock();
904    }
905
906    // restart track if it was disabled by audioflinger due to previous underrun
907    if (mActive && (cblk->flags & CBLK_DISABLED_MSK)) {
908        android_atomic_and(~CBLK_DISABLED_ON, &cblk->flags);
909        ALOGW("obtainBuffer() track %p disabled, restarting", this);
910        mAudioTrack->start();
911    }
912
913    cblk->waitTimeMs = 0;
914
915    if (framesReq > framesAvail) {
916        framesReq = framesAvail;
917    }
918
919    uint32_t u = cblk->user;
920    uint32_t bufferEnd = cblk->userBase + cblk->frameCount;
921
922    if (u + framesReq > bufferEnd) {
923        framesReq = bufferEnd - u;
924    }
925
926    audioBuffer->flags = mMuted ? Buffer::MUTE : 0;
927    audioBuffer->channelCount = mChannelCount;
928    audioBuffer->frameCount = framesReq;
929    audioBuffer->size = framesReq * cblk->frameSize;
930    if (audio_is_linear_pcm(mFormat)) {
931        audioBuffer->format = AUDIO_FORMAT_PCM_16_BIT;
932    } else {
933        audioBuffer->format = mFormat;
934    }
935    audioBuffer->raw = (int8_t *)cblk->buffer(u);
936    active = mActive;
937    return active ? status_t(NO_ERROR) : status_t(STOPPED);
938}
939
940void AudioTrack::releaseBuffer(Buffer* audioBuffer)
941{
942    AutoMutex lock(mLock);
943    mCblk->stepUser(audioBuffer->frameCount);
944}
945
946// -------------------------------------------------------------------------
947
948ssize_t AudioTrack::write(const void* buffer, size_t userSize)
949{
950
951    if (mSharedBuffer != 0) return INVALID_OPERATION;
952
953    if (ssize_t(userSize) < 0) {
954        // sanity-check. user is most-likely passing an error code.
955        ALOGE("AudioTrack::write(buffer=%p, size=%u (%d)",
956                buffer, userSize, userSize);
957        return BAD_VALUE;
958    }
959
960    ALOGV("write %p: %d bytes, mActive=%d", this, userSize, mActive);
961
962    // acquire a strong reference on the IMemory and IAudioTrack so that they cannot be destroyed
963    // while we are accessing the cblk
964    mLock.lock();
965    sp <IAudioTrack> audioTrack = mAudioTrack;
966    sp <IMemory> iMem = mCblkMemory;
967    mLock.unlock();
968
969    ssize_t written = 0;
970    const int8_t *src = (const int8_t *)buffer;
971    Buffer audioBuffer;
972    size_t frameSz = frameSize();
973
974    do {
975        audioBuffer.frameCount = userSize/frameSz;
976
977        // Calling obtainBuffer() with a negative wait count causes
978        // an (almost) infinite wait time.
979        status_t err = obtainBuffer(&audioBuffer, -1);
980        if (err < 0) {
981            // out of buffers, return #bytes written
982            if (err == status_t(NO_MORE_BUFFERS))
983                break;
984            return ssize_t(err);
985        }
986
987        size_t toWrite;
988
989        if (mFormat == AUDIO_FORMAT_PCM_8_BIT && !(mFlags & AUDIO_POLICY_OUTPUT_FLAG_DIRECT)) {
990            // Divide capacity by 2 to take expansion into account
991            toWrite = audioBuffer.size>>1;
992            memcpy_to_i16_from_u8(audioBuffer.i16, (const uint8_t *) src, toWrite);
993        } else {
994            toWrite = audioBuffer.size;
995            memcpy(audioBuffer.i8, src, toWrite);
996            src += toWrite;
997        }
998        userSize -= toWrite;
999        written += toWrite;
1000
1001        releaseBuffer(&audioBuffer);
1002    } while (userSize >= frameSz);
1003
1004    return written;
1005}
1006
1007// -------------------------------------------------------------------------
1008
1009bool AudioTrack::processAudioBuffer(const sp<AudioTrackThread>& thread)
1010{
1011    Buffer audioBuffer;
1012    uint32_t frames;
1013    size_t writtenSize;
1014
1015    mLock.lock();
1016    // acquire a strong reference on the IMemory and IAudioTrack so that they cannot be destroyed
1017    // while we are accessing the cblk
1018    sp <IAudioTrack> audioTrack = mAudioTrack;
1019    sp <IMemory> iMem = mCblkMemory;
1020    audio_track_cblk_t* cblk = mCblk;
1021    bool active = mActive;
1022    mLock.unlock();
1023
1024    // Manage underrun callback
1025    if (active && (cblk->framesAvailable() == cblk->frameCount)) {
1026        ALOGV("Underrun user: %x, server: %x, flags %04x", cblk->user, cblk->server, cblk->flags);
1027        if (!(android_atomic_or(CBLK_UNDERRUN_ON, &cblk->flags) & CBLK_UNDERRUN_MSK)) {
1028            mCbf(EVENT_UNDERRUN, mUserData, 0);
1029            if (cblk->server == cblk->frameCount) {
1030                mCbf(EVENT_BUFFER_END, mUserData, 0);
1031            }
1032            if (mSharedBuffer != 0) return false;
1033        }
1034    }
1035
1036    // Manage loop end callback
1037    while (mLoopCount > cblk->loopCount) {
1038        int loopCount = -1;
1039        mLoopCount--;
1040        if (mLoopCount >= 0) loopCount = mLoopCount;
1041
1042        mCbf(EVENT_LOOP_END, mUserData, (void *)&loopCount);
1043    }
1044
1045    // Manage marker callback
1046    if (!mMarkerReached && (mMarkerPosition > 0)) {
1047        if (cblk->server >= mMarkerPosition) {
1048            mCbf(EVENT_MARKER, mUserData, (void *)&mMarkerPosition);
1049            mMarkerReached = true;
1050        }
1051    }
1052
1053    // Manage new position callback
1054    if (mUpdatePeriod > 0) {
1055        while (cblk->server >= mNewPosition) {
1056            mCbf(EVENT_NEW_POS, mUserData, (void *)&mNewPosition);
1057            mNewPosition += mUpdatePeriod;
1058        }
1059    }
1060
1061    // If Shared buffer is used, no data is requested from client.
1062    if (mSharedBuffer != 0) {
1063        frames = 0;
1064    } else {
1065        frames = mRemainingFrames;
1066    }
1067
1068    int32_t waitCount = -1;
1069    if (mUpdatePeriod || (!mMarkerReached && mMarkerPosition) || mLoopCount) {
1070        waitCount = 1;
1071    }
1072
1073    do {
1074
1075        audioBuffer.frameCount = frames;
1076
1077        // Calling obtainBuffer() with a wait count of 1
1078        // limits wait time to WAIT_PERIOD_MS. This prevents from being
1079        // stuck here not being able to handle timed events (position, markers, loops).
1080        status_t err = obtainBuffer(&audioBuffer, waitCount);
1081        if (err < NO_ERROR) {
1082            if (err != TIMED_OUT) {
1083                ALOGE_IF(err != status_t(NO_MORE_BUFFERS), "Error obtaining an audio buffer, giving up.");
1084                return false;
1085            }
1086            break;
1087        }
1088        if (err == status_t(STOPPED)) return false;
1089
1090        // Divide buffer size by 2 to take into account the expansion
1091        // due to 8 to 16 bit conversion: the callback must fill only half
1092        // of the destination buffer
1093        if (mFormat == AUDIO_FORMAT_PCM_8_BIT && !(mFlags & AUDIO_POLICY_OUTPUT_FLAG_DIRECT)) {
1094            audioBuffer.size >>= 1;
1095        }
1096
1097        size_t reqSize = audioBuffer.size;
1098        mCbf(EVENT_MORE_DATA, mUserData, &audioBuffer);
1099        writtenSize = audioBuffer.size;
1100
1101        // Sanity check on returned size
1102        if (ssize_t(writtenSize) <= 0) {
1103            // The callback is done filling buffers
1104            // Keep this thread going to handle timed events and
1105            // still try to get more data in intervals of WAIT_PERIOD_MS
1106            // but don't just loop and block the CPU, so wait
1107            usleep(WAIT_PERIOD_MS*1000);
1108            break;
1109        }
1110        if (writtenSize > reqSize) writtenSize = reqSize;
1111
1112        if (mFormat == AUDIO_FORMAT_PCM_8_BIT && !(mFlags & AUDIO_POLICY_OUTPUT_FLAG_DIRECT)) {
1113            // 8 to 16 bit conversion, note that source and destination are the same address
1114            memcpy_to_i16_from_u8(audioBuffer.i16, (const uint8_t *) audioBuffer.i8, writtenSize);
1115            writtenSize <<= 1;
1116        }
1117
1118        audioBuffer.size = writtenSize;
1119        // NOTE: mCblk->frameSize is not equal to AudioTrack::frameSize() for
1120        // 8 bit PCM data: in this case,  mCblk->frameSize is based on a sample size of
1121        // 16 bit.
1122        audioBuffer.frameCount = writtenSize/mCblk->frameSize;
1123
1124        frames -= audioBuffer.frameCount;
1125
1126        releaseBuffer(&audioBuffer);
1127    }
1128    while (frames);
1129
1130    if (frames == 0) {
1131        mRemainingFrames = mNotificationFramesAct;
1132    } else {
1133        mRemainingFrames = frames;
1134    }
1135    return true;
1136}
1137
1138// must be called with mLock and cblk.lock held. Callers must also hold strong references on
1139// the IAudioTrack and IMemory in case they are recreated here.
1140// If the IAudioTrack is successfully restored, the cblk pointer is updated
1141status_t AudioTrack::restoreTrack_l(audio_track_cblk_t*& cblk, bool fromStart)
1142{
1143    status_t result;
1144
1145    if (!(android_atomic_or(CBLK_RESTORING_ON, &cblk->flags) & CBLK_RESTORING_MSK)) {
1146        ALOGW("dead IAudioTrack, creating a new one from %s TID %d",
1147             fromStart ? "start()" : "obtainBuffer()", gettid());
1148
1149        // signal old cblk condition so that other threads waiting for available buffers stop
1150        // waiting now
1151        cblk->cv.broadcast();
1152        cblk->lock.unlock();
1153
1154        // refresh the audio configuration cache in this process to make sure we get new
1155        // output parameters in getOutput_l() and createTrack_l()
1156        AudioSystem::clearAudioConfigCache();
1157
1158        // if the new IAudioTrack is created, createTrack_l() will modify the
1159        // following member variables: mAudioTrack, mCblkMemory and mCblk.
1160        // It will also delete the strong references on previous IAudioTrack and IMemory
1161        result = createTrack_l(mStreamType,
1162                               cblk->sampleRate,
1163                               mFormat,
1164                               mChannelMask,
1165                               mFrameCount,
1166                               mFlags,
1167                               mSharedBuffer,
1168                               getOutput_l(),
1169                               false);
1170
1171        if (result == NO_ERROR) {
1172            uint32_t user = cblk->user;
1173            uint32_t server = cblk->server;
1174            // restore write index and set other indexes to reflect empty buffer status
1175            mCblk->user = user;
1176            mCblk->server = user;
1177            mCblk->userBase = user;
1178            mCblk->serverBase = user;
1179            // restore loop: this is not guaranteed to succeed if new frame count is not
1180            // compatible with loop length
1181            setLoop_l(cblk->loopStart, cblk->loopEnd, cblk->loopCount);
1182            if (!fromStart) {
1183                mCblk->bufferTimeoutMs = MAX_RUN_TIMEOUT_MS;
1184                // Make sure that a client relying on callback events indicating underrun or
1185                // the actual amount of audio frames played (e.g SoundPool) receives them.
1186                if (mSharedBuffer == 0) {
1187                    uint32_t frames = 0;
1188                    if (user > server) {
1189                        frames = ((user - server) > mCblk->frameCount) ?
1190                                mCblk->frameCount : (user - server);
1191                        memset(mCblk->buffers, 0, frames * mCblk->frameSize);
1192                    }
1193                    // restart playback even if buffer is not completely filled.
1194                    android_atomic_or(CBLK_FORCEREADY_ON, &mCblk->flags);
1195                    // stepUser() clears CBLK_UNDERRUN_ON flag enabling underrun callbacks to
1196                    // the client
1197                    mCblk->stepUser(frames);
1198                }
1199            }
1200            if (mActive) {
1201                result = mAudioTrack->start();
1202                ALOGW_IF(result != NO_ERROR, "restoreTrack_l() start() failed status %d", result);
1203            }
1204            if (fromStart && result == NO_ERROR) {
1205                mNewPosition = mCblk->server + mUpdatePeriod;
1206            }
1207        }
1208        if (result != NO_ERROR) {
1209            android_atomic_and(~CBLK_RESTORING_ON, &cblk->flags);
1210            ALOGW_IF(result != NO_ERROR, "restoreTrack_l() failed status %d", result);
1211        }
1212        mRestoreStatus = result;
1213        // signal old cblk condition for other threads waiting for restore completion
1214        android_atomic_or(CBLK_RESTORED_ON, &cblk->flags);
1215        cblk->cv.broadcast();
1216    } else {
1217        if (!(cblk->flags & CBLK_RESTORED_MSK)) {
1218            ALOGW("dead IAudioTrack, waiting for a new one TID %d", gettid());
1219            mLock.unlock();
1220            result = cblk->cv.waitRelative(cblk->lock, milliseconds(RESTORE_TIMEOUT_MS));
1221            if (result == NO_ERROR) {
1222                result = mRestoreStatus;
1223            }
1224            cblk->lock.unlock();
1225            mLock.lock();
1226        } else {
1227            ALOGW("dead IAudioTrack, already restored TID %d", gettid());
1228            result = mRestoreStatus;
1229            cblk->lock.unlock();
1230        }
1231    }
1232    ALOGV("restoreTrack_l() status %d mActive %d cblk %p, old cblk %p flags %08x old flags %08x",
1233         result, mActive, mCblk, cblk, mCblk->flags, cblk->flags);
1234
1235    if (result == NO_ERROR) {
1236        // from now on we switch to the newly created cblk
1237        cblk = mCblk;
1238    }
1239    cblk->lock.lock();
1240
1241    ALOGW_IF(result != NO_ERROR, "restoreTrack_l() error %d TID %d", result, gettid());
1242
1243    return result;
1244}
1245
1246status_t AudioTrack::dump(int fd, const Vector<String16>& args) const
1247{
1248
1249    const size_t SIZE = 256;
1250    char buffer[SIZE];
1251    String8 result;
1252
1253    result.append(" AudioTrack::dump\n");
1254    snprintf(buffer, 255, "  stream type(%d), left - right volume(%f, %f)\n", mStreamType, mVolume[0], mVolume[1]);
1255    result.append(buffer);
1256    snprintf(buffer, 255, "  format(%d), channel count(%d), frame count(%d)\n", mFormat, mChannelCount, mCblk->frameCount);
1257    result.append(buffer);
1258    snprintf(buffer, 255, "  sample rate(%d), status(%d), muted(%d)\n", (mCblk == 0) ? 0 : mCblk->sampleRate, mStatus, mMuted);
1259    result.append(buffer);
1260    snprintf(buffer, 255, "  active(%d), latency (%d)\n", mActive, mLatency);
1261    result.append(buffer);
1262    ::write(fd, result.string(), result.size());
1263    return NO_ERROR;
1264}
1265
1266// =========================================================================
1267
1268AudioTrack::AudioTrackThread::AudioTrackThread(AudioTrack& receiver, bool bCanCallJava)
1269    : Thread(bCanCallJava), mReceiver(receiver)
1270{
1271}
1272
1273bool AudioTrack::AudioTrackThread::threadLoop()
1274{
1275    return mReceiver.processAudioBuffer(this);
1276}
1277
1278status_t AudioTrack::AudioTrackThread::readyToRun()
1279{
1280    return NO_ERROR;
1281}
1282
1283void AudioTrack::AudioTrackThread::onFirstRef()
1284{
1285}
1286
1287// =========================================================================
1288
1289
1290audio_track_cblk_t::audio_track_cblk_t()
1291    : lock(Mutex::SHARED), cv(Condition::SHARED), user(0), server(0),
1292    userBase(0), serverBase(0), buffers(NULL), frameCount(0),
1293    loopStart(UINT_MAX), loopEnd(UINT_MAX), loopCount(0), mVolumeLR(0x10001000),
1294    mSendLevel(0), flags(0)
1295{
1296}
1297
1298uint32_t audio_track_cblk_t::stepUser(uint32_t frameCount)
1299{
1300    uint32_t u = user;
1301
1302    u += frameCount;
1303    // Ensure that user is never ahead of server for AudioRecord
1304    if (flags & CBLK_DIRECTION_MSK) {
1305        // If stepServer() has been called once, switch to normal obtainBuffer() timeout period
1306        if (bufferTimeoutMs == MAX_STARTUP_TIMEOUT_MS-1) {
1307            bufferTimeoutMs = MAX_RUN_TIMEOUT_MS;
1308        }
1309    } else if (u > server) {
1310        ALOGW("stepServer occurred after track reset");
1311        u = server;
1312    }
1313
1314    if (u >= userBase + this->frameCount) {
1315        userBase += this->frameCount;
1316    }
1317
1318    user = u;
1319
1320    // Clear flow control error condition as new data has been written/read to/from buffer.
1321    if (flags & CBLK_UNDERRUN_MSK) {
1322        android_atomic_and(~CBLK_UNDERRUN_MSK, &flags);
1323    }
1324
1325    return u;
1326}
1327
1328bool audio_track_cblk_t::stepServer(uint32_t frameCount)
1329{
1330    if (!tryLock()) {
1331        ALOGW("stepServer() could not lock cblk");
1332        return false;
1333    }
1334
1335    uint32_t s = server;
1336
1337    s += frameCount;
1338    if (flags & CBLK_DIRECTION_MSK) {
1339        // Mark that we have read the first buffer so that next time stepUser() is called
1340        // we switch to normal obtainBuffer() timeout period
1341        if (bufferTimeoutMs == MAX_STARTUP_TIMEOUT_MS) {
1342            bufferTimeoutMs = MAX_STARTUP_TIMEOUT_MS - 1;
1343        }
1344        // It is possible that we receive a flush()
1345        // while the mixer is processing a block: in this case,
1346        // stepServer() is called After the flush() has reset u & s and
1347        // we have s > u
1348        if (s > user) {
1349            ALOGW("stepServer occurred after track reset");
1350            s = user;
1351        }
1352    }
1353
1354    if (s >= loopEnd) {
1355        ALOGW_IF(s > loopEnd, "stepServer: s %u > loopEnd %u", s, loopEnd);
1356        s = loopStart;
1357        if (--loopCount == 0) {
1358            loopEnd = UINT_MAX;
1359            loopStart = UINT_MAX;
1360        }
1361    }
1362    if (s >= serverBase + this->frameCount) {
1363        serverBase += this->frameCount;
1364    }
1365
1366    server = s;
1367
1368    if (!(flags & CBLK_INVALID_MSK)) {
1369        cv.signal();
1370    }
1371    lock.unlock();
1372    return true;
1373}
1374
1375void* audio_track_cblk_t::buffer(uint32_t offset) const
1376{
1377    return (int8_t *)buffers + (offset - userBase) * frameSize;
1378}
1379
1380uint32_t audio_track_cblk_t::framesAvailable()
1381{
1382    Mutex::Autolock _l(lock);
1383    return framesAvailable_l();
1384}
1385
1386uint32_t audio_track_cblk_t::framesAvailable_l()
1387{
1388    uint32_t u = user;
1389    uint32_t s = server;
1390
1391    if (flags & CBLK_DIRECTION_MSK) {
1392        uint32_t limit = (s < loopStart) ? s : loopStart;
1393        return limit + frameCount - u;
1394    } else {
1395        return frameCount + u - s;
1396    }
1397}
1398
1399uint32_t audio_track_cblk_t::framesReady()
1400{
1401    uint32_t u = user;
1402    uint32_t s = server;
1403
1404    if (flags & CBLK_DIRECTION_MSK) {
1405        if (u < loopEnd) {
1406            return u - s;
1407        } else {
1408            // do not block on mutex shared with client on AudioFlinger side
1409            if (!tryLock()) {
1410                ALOGW("framesReady() could not lock cblk");
1411                return 0;
1412            }
1413            uint32_t frames = UINT_MAX;
1414            if (loopCount >= 0) {
1415                frames = (loopEnd - loopStart)*loopCount + u - s;
1416            }
1417            lock.unlock();
1418            return frames;
1419        }
1420    } else {
1421        return s - u;
1422    }
1423}
1424
1425bool audio_track_cblk_t::tryLock()
1426{
1427    // the code below simulates lock-with-timeout
1428    // we MUST do this to protect the AudioFlinger server
1429    // as this lock is shared with the client.
1430    status_t err;
1431
1432    err = lock.tryLock();
1433    if (err == -EBUSY) { // just wait a bit
1434        usleep(1000);
1435        err = lock.tryLock();
1436    }
1437    if (err != NO_ERROR) {
1438        // probably, the client just died.
1439        return false;
1440    }
1441    return true;
1442}
1443
1444// -------------------------------------------------------------------------
1445
1446}; // namespace android
1447