From fc7992bd8220824f1404c0c54ac516d9e28b58c2 Mon Sep 17 00:00:00 2001 From: Glenn Kasten Date: Wed, 29 Aug 2012 11:10:32 -0700 Subject: Move libnbaio out of AudioFlinger libnbaio is now a separate shared library from AudioFlinger, rather than a static library used only by AudioFlinger. AudioBufferProvider interface is now also independent of AudioFlinger, moved to include/media/ Change-Id: I9bb62ffbc38d42a38b0af76e66da5e9ab1e0e21b --- media/libnbaio/MonoPipe.cpp | 299 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 299 insertions(+) create mode 100644 media/libnbaio/MonoPipe.cpp (limited to 'media/libnbaio/MonoPipe.cpp') diff --git a/media/libnbaio/MonoPipe.cpp b/media/libnbaio/MonoPipe.cpp new file mode 100644 index 0000000..c426efb --- /dev/null +++ b/media/libnbaio/MonoPipe.cpp @@ -0,0 +1,299 @@ +/* + * Copyright (C) 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. + */ + +#define LOG_TAG "MonoPipe" +//#define LOG_NDEBUG 0 + +#include +#include +#include +#include +#include +#include +#include +#include +#include + + +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))), + mFront(0), + mRear(0), + mWriteTsValid(false), + // mWriteTs + 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(N); + mSamplesToLocalTime.a_to_b_denom = static_cast(D); +} + +MonoPipe::~MonoPipe() +{ + free(mBuffer); +} + +ssize_t MonoPipe::availableToWrite() const +{ + if (CC_UNLIKELY(!mNegotiated)) { + return NEGOTIATE; + } + // uses mMaxFrames not mReqFrames, so allows "over-filling" the pipe beyond requested limit + ssize_t ret = mMaxFrames - (mRear - android_atomic_acquire_load(&mFront)); + ALOG_ASSERT((0 <= ret) && (ret <= mMaxFrames)); + return ret; +} + +ssize_t MonoPipe::write(const void *buffer, size_t count) +{ + if (CC_UNLIKELY(!mNegotiated)) { + return NEGOTIATE; + } + size_t totalFramesWritten = 0; + while (count > 0) { + // can't return a negative value, as we already checked for !mNegotiated + size_t avail = availableToWrite(); + size_t written = avail; + if (CC_LIKELY(written > count)) { + written = count; + } + size_t rear = mRear & (mMaxFrames - 1); + size_t part1 = mMaxFrames - rear; + if (part1 > written) { + part1 = written; + } + if (CC_LIKELY(part1 > 0)) { + memcpy((char *) mBuffer + (rear << mBitShift), buffer, part1 << mBitShift); + if (CC_UNLIKELY(rear + part1 == mMaxFrames)) { + size_t part2 = written - part1; + if (CC_LIKELY(part2 > 0)) { + memcpy(mBuffer, (char *) buffer + (part1 << mBitShift), part2 << mBitShift); + } + } + android_atomic_release_store(written + mRear, &mRear); + totalFramesWritten += written; + } + if (!mWriteCanBlock) { + break; + } + count -= written; + buffer = (char *) buffer + (written << mBitShift); + // Simulate blocking I/O by sleeping at different rates, depending on a throttle. + // The throttle tries to keep the mean pipe depth near the setpoint, with a slight jitter. + uint32_t ns; + if (written > 0) { + size_t filled = (mMaxFrames - avail) + written; + // FIXME cache these values to avoid re-computation + if (filled <= mSetpoint / 2) { + // pipe is (nearly) empty, fill quickly + ns = written * ( 500000000 / Format_sampleRate(mFormat)); + } else if (filled <= (mSetpoint * 3) / 4) { + // pipe is below setpoint, fill at slightly faster rate + ns = written * ( 750000000 / Format_sampleRate(mFormat)); + } else if (filled <= (mSetpoint * 5) / 4) { + // pipe is at setpoint, fill at nominal rate + ns = written * (1000000000 / Format_sampleRate(mFormat)); + } else if (filled <= (mSetpoint * 3) / 2) { + // pipe is above setpoint, fill at slightly slower rate + ns = written * (1150000000 / Format_sampleRate(mFormat)); + } else if (filled <= (mSetpoint * 7) / 4) { + // pipe is overflowing, fill slowly + ns = written * (1350000000 / Format_sampleRate(mFormat)); + } else { + // pipe is severely overflowing + ns = written * (1750000000 / Format_sampleRate(mFormat)); + } + } else { + ns = count * (1350000000 / Format_sampleRate(mFormat)); + } + if (ns > 999999999) { + ns = 999999999; + } + struct timespec nowTs; + bool nowTsValid = !clock_gettime(CLOCK_MONOTONIC, &nowTs); + // deduct the elapsed time since previous write() completed + if (nowTsValid && mWriteTsValid) { + time_t sec = nowTs.tv_sec - mWriteTs.tv_sec; + long nsec = nowTs.tv_nsec - mWriteTs.tv_nsec; + if (nsec < 0) { + --sec; + nsec += 1000000000; + } + if (sec == 0) { + if ((long) ns > nsec) { + ns -= nsec; + } else { + ns = 0; + } + } + } + if (ns > 0) { + const struct timespec req = {0, ns}; + nanosleep(&req, NULL); + } + // record the time that this write() completed + if (nowTsValid) { + mWriteTs = nowTs; + if ((mWriteTs.tv_nsec += ns) >= 1000000000) { + mWriteTs.tv_nsec -= 1000000000; + ++mWriteTs.tv_sec; + } + } + mWriteTsValid = nowTsValid; + } + mFramesWritten += totalFramesWritten; + return totalFramesWritten; +} + +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 -- cgit v1.1