diff options
Diffstat (limited to 'services/audioflinger/MonoPipe.cpp')
| -rw-r--r-- | services/audioflinger/MonoPipe.cpp | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/services/audioflinger/MonoPipe.cpp b/services/audioflinger/MonoPipe.cpp index f3fc19a..bd876b4 100644 --- a/services/audioflinger/MonoPipe.cpp +++ b/services/audioflinger/MonoPipe.cpp @@ -17,17 +17,22 @@ #define LOG_TAG "MonoPipe" //#define LOG_NDEBUG 0 +#include <common_time/cc_helper.h> #include <cutils/atomic.h> #include <cutils/compiler.h> +#include <utils/LinearTransform.h> #include <utils/Log.h> #include <utils/Trace.h> +#include "AudioBufferProvider.h" #include "MonoPipe.h" #include "roundup.h" + namespace android { MonoPipe::MonoPipe(size_t reqFrames, NBAIO_Format format, bool writeCanBlock) : NBAIO_Sink(format), + mUpdateSeq(0), mReqFrames(reqFrames), mMaxFrames(roundup(reqFrames)), mBuffer(malloc(mMaxFrames * Format_frameSize(format))), @@ -38,6 +43,37 @@ MonoPipe::MonoPipe(size_t reqFrames, NBAIO_Format format, bool writeCanBlock) : mSetpoint((reqFrames * 11) / 16), mWriteCanBlock(writeCanBlock) { + CCHelper tmpHelper; + status_t res; + uint64_t N, D; + + mNextRdPTS = AudioBufferProvider::kInvalidPTS; + + mSamplesToLocalTime.a_zero = 0; + mSamplesToLocalTime.b_zero = 0; + mSamplesToLocalTime.a_to_b_numer = 0; + mSamplesToLocalTime.a_to_b_denom = 0; + + D = Format_sampleRate(format); + if (OK != (res = tmpHelper.getLocalFreq(&N))) { + ALOGE("Failed to fetch local time frequency when constructing a" + " MonoPipe (res = %d). getNextWriteTimestamp calls will be" + " non-functional", res); + return; + } + + LinearTransform::reduce(&N, &D); + static const uint64_t kSignedHiBitsMask = ~(0x7FFFFFFFull); + static const uint64_t kUnsignedHiBitsMask = ~(0xFFFFFFFFull); + if ((N & kSignedHiBitsMask) || (D & kUnsignedHiBitsMask)) { + ALOGE("Cannot reduce sample rate to local clock frequency ratio to fit" + " in a 32/32 bit rational. (max reduction is 0x%016llx/0x%016llx" + "). getNextWriteTimestamp calls will be non-functional", N, D); + return; + } + + mSamplesToLocalTime.a_to_b_numer = static_cast<int32_t>(N); + mSamplesToLocalTime.a_to_b_denom = static_cast<uint32_t>(D); } MonoPipe::~MonoPipe() @@ -162,4 +198,102 @@ void MonoPipe::setAvgFrames(size_t setpoint) mSetpoint = setpoint; } +status_t MonoPipe::getNextWriteTimestamp(int64_t *timestamp) +{ + int32_t front; + + ALOG_ASSERT(NULL != timestamp); + + if (0 == mSamplesToLocalTime.a_to_b_denom) + return UNKNOWN_ERROR; + + observeFrontAndNRPTS(&front, timestamp); + + if (AudioBufferProvider::kInvalidPTS != *timestamp) { + // If we have a valid read-pointer and next read timestamp pair, then + // use the current value of the write pointer to figure out how many + // frames are in the buffer, and offset the timestamp by that amt. Then + // next time we write to the MonoPipe, the data will hit the speakers at + // the next read timestamp plus the current amount of data in the + // MonoPipe. + size_t pendingFrames = (mRear - front) & (mMaxFrames - 1); + *timestamp = offsetTimestampByAudioFrames(*timestamp, pendingFrames); + } + + return OK; +} + +void MonoPipe::updateFrontAndNRPTS(int32_t newFront, int64_t newNextRdPTS) +{ + // Set the MSB of the update sequence number to indicate that there is a + // multi-variable update in progress. Use an atomic store with an "acquire" + // barrier to make sure that the next operations cannot be re-ordered and + // take place before the change to mUpdateSeq is commited.. + int32_t tmp = mUpdateSeq | 0x80000000; + android_atomic_acquire_store(tmp, &mUpdateSeq); + + // Update mFront and mNextRdPTS + mFront = newFront; + mNextRdPTS = newNextRdPTS; + + // We are finished with the update. Compute the next sequnce number (which + // should be the old sequence number, plus one, and with the MSB cleared) + // and then store it in mUpdateSeq using an atomic store with a "release" + // barrier so our update operations cannot be re-ordered past the update of + // the sequence number. + tmp = (tmp + 1) & 0x7FFFFFFF; + android_atomic_release_store(tmp, &mUpdateSeq); +} + +void MonoPipe::observeFrontAndNRPTS(int32_t *outFront, int64_t *outNextRdPTS) +{ + // Perform an atomic observation of mFront and mNextRdPTS. Basically, + // atomically observe the sequence number, then observer the variables, then + // atomically observe the sequence number again. If the two observations of + // the sequence number match, and the update-in-progress bit was not set, + // then we know we have a successful atomic observation. Otherwise, we loop + // around and try again. + // + // Note, it is very important that the observer be a lower priority thread + // than the updater. If the updater is lower than the observer, or they are + // the same priority and running with SCHED_FIFO (implying that quantum + // based premption is disabled) then we run the risk of deadlock. + int32_t seqOne, seqTwo; + + do { + seqOne = android_atomic_acquire_load(&mUpdateSeq); + *outFront = mFront; + *outNextRdPTS = mNextRdPTS; + seqTwo = android_atomic_release_load(&mUpdateSeq); + } while ((seqOne != seqTwo) || (seqOne & 0x80000000)); +} + +int64_t MonoPipe::offsetTimestampByAudioFrames(int64_t ts, size_t audFrames) +{ + if (0 == mSamplesToLocalTime.a_to_b_denom) + return AudioBufferProvider::kInvalidPTS; + + if (ts == AudioBufferProvider::kInvalidPTS) + return AudioBufferProvider::kInvalidPTS; + + int64_t frame_lt_duration; + if (!mSamplesToLocalTime.doForwardTransform(audFrames, + &frame_lt_duration)) { + // This should never fail, but if there is a bug which is causing it + // to fail, this message would probably end up flooding the logs + // because the conversion would probably fail forever. Log the + // error, but then zero out the ratio in the linear transform so + // that we don't try to do any conversions from now on. This + // MonoPipe's getNextWriteTimestamp is now broken for good. + ALOGE("Overflow when attempting to convert %d audio frames to" + " duration in local time. getNextWriteTimestamp will fail from" + " now on.", audFrames); + mSamplesToLocalTime.a_to_b_numer = 0; + mSamplesToLocalTime.a_to_b_denom = 0; + return AudioBufferProvider::kInvalidPTS; + } + + return ts + frame_lt_duration; +} + } // namespace android |