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
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 <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 <media/AudioBufferProvider.h>
+#include <media/nbaio/MonoPipe.h>
+#include <media/nbaio/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))),
+ 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<int32_t>(N);
+ mSamplesToLocalTime.a_to_b_denom = static_cast<uint32_t>(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