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      1 /*
      2  * Copyright (C) 2012 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #ifndef ANDROID_AUDIO_FAST_MIXER_H
     18 #define ANDROID_AUDIO_FAST_MIXER_H
     19 
     20 #include <utils/Debug.h>
     21 #include <utils/Thread.h>
     22 extern "C" {
     23 #include "../private/bionic_futex.h"
     24 }
     25 #include "StateQueue.h"
     26 #include "FastMixerState.h"
     27 
     28 namespace android {
     29 
     30 typedef StateQueue<FastMixerState> FastMixerStateQueue;
     31 
     32 class FastMixer : public Thread {
     33 
     34 public:
     35             FastMixer() : Thread(false /*canCallJava*/) { }
     36     virtual ~FastMixer() { }
     37 
     38             FastMixerStateQueue* sq() { return &mSQ; }
     39 
     40 private:
     41     virtual bool                threadLoop();
     42             FastMixerStateQueue mSQ;
     43 
     44 };  // class FastMixer
     45 
     46 // Describes the underrun status for a single "pull" attempt
     47 enum FastTrackUnderrunStatus {
     48     UNDERRUN_FULL,      // framesReady() is full frame count, no underrun
     49     UNDERRUN_PARTIAL,   // framesReady() is non-zero but < full frame count, partial underrun
     50     UNDERRUN_EMPTY,     // framesReady() is zero, total underrun
     51 };
     52 
     53 // Underrun counters are not reset to zero for new tracks or if track generation changes.
     54 // This packed representation is used to keep the information atomic.
     55 union FastTrackUnderruns {
     56     FastTrackUnderruns() { mAtomic = 0;
     57             COMPILE_TIME_ASSERT_FUNCTION_SCOPE(sizeof(FastTrackUnderruns) == sizeof(uint32_t)); }
     58     FastTrackUnderruns(const FastTrackUnderruns& copyFrom) : mAtomic(copyFrom.mAtomic) { }
     59     FastTrackUnderruns& operator=(const FastTrackUnderruns& rhs)
     60             { if (this != &rhs) mAtomic = rhs.mAtomic; return *this; }
     61     struct {
     62 #define UNDERRUN_BITS 10
     63 #define UNDERRUN_MASK ((1 << UNDERRUN_BITS) - 1)
     64         uint32_t mFull    : UNDERRUN_BITS; // framesReady() is full frame count
     65         uint32_t mPartial : UNDERRUN_BITS; // framesReady() is non-zero but < full frame count
     66         uint32_t mEmpty   : UNDERRUN_BITS; // framesReady() is zero
     67         FastTrackUnderrunStatus mMostRecent : 2;    // status of most recent framesReady()
     68     }        mBitFields;
     69 private:
     70     uint32_t mAtomic;
     71 };
     72 
     73 // Represents the dump state of a fast track
     74 struct FastTrackDump {
     75     FastTrackDump() : mFramesReady(0) { }
     76     /*virtual*/ ~FastTrackDump() { }
     77     FastTrackUnderruns mUnderruns;
     78     size_t mFramesReady;        // most recent value only; no long-term statistics kept
     79 };
     80 
     81 // The FastMixerDumpState keeps a cache of FastMixer statistics that can be logged by dumpsys.
     82 // Each individual native word-sized field is accessed atomically.  But the
     83 // overall structure is non-atomic, that is there may be an inconsistency between fields.
     84 // No barriers or locks are used for either writing or reading.
     85 // Only POD types are permitted, and the contents shouldn't be trusted (i.e. do range checks).
     86 // It has a different lifetime than the FastMixer, and so it can't be a member of FastMixer.
     87 struct FastMixerDumpState {
     88     FastMixerDumpState();
     89     /*virtual*/ ~FastMixerDumpState();
     90 
     91     void dump(int fd);          // should only be called on a stable copy, not the original
     92 
     93     FastMixerState::Command mCommand;   // current command
     94     uint32_t mWriteSequence;    // incremented before and after each write()
     95     uint32_t mFramesWritten;    // total number of frames written successfully
     96     uint32_t mNumTracks;        // total number of active fast tracks
     97     uint32_t mWriteErrors;      // total number of write() errors
     98     uint32_t mUnderruns;        // total number of underruns
     99     uint32_t mOverruns;         // total number of overruns
    100     uint32_t mSampleRate;
    101     size_t   mFrameCount;
    102     struct timespec mMeasuredWarmupTs;  // measured warmup time
    103     uint32_t mWarmupCycles;     // number of loop cycles required to warmup
    104     uint32_t mTrackMask;        // mask of active tracks
    105     FastTrackDump   mTracks[FastMixerState::kMaxFastTracks];
    106 
    107 #ifdef FAST_MIXER_STATISTICS
    108     // Recently collected samples of per-cycle monotonic time, thread CPU time, and CPU frequency.
    109     // kSamplingN is the size of the sampling frame, and must be a power of 2 <= 0x8000.
    110     static const uint32_t kSamplingN = 0x1000;
    111     // The bounds define the interval of valid samples, and are represented as follows:
    112     //      newest open (excluded) endpoint   = lower 16 bits of bounds, modulo N
    113     //      oldest closed (included) endpoint = upper 16 bits of bounds, modulo N
    114     // Number of valid samples is newest - oldest.
    115     uint32_t mBounds;                   // bounds for mMonotonicNs, mThreadCpuNs, and mCpukHz
    116     // The elements in the *Ns arrays are in units of nanoseconds <= 3999999999.
    117     uint32_t mMonotonicNs[kSamplingN];  // delta monotonic (wall clock) time
    118     uint32_t mLoadNs[kSamplingN];       // delta CPU load in time
    119 #ifdef CPU_FREQUENCY_STATISTICS
    120     uint32_t mCpukHz[kSamplingN];       // absolute CPU clock frequency in kHz, bits 0-3 are CPU#
    121 #endif
    122 #endif
    123 };
    124 
    125 }   // namespace android
    126 
    127 #endif  // ANDROID_AUDIO_FAST_MIXER_H
    128