/*
* 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),
mIsShutdown(false)
{
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 || mIsShutdown) {
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;
ALOGE_IF(sec < 0 || (sec == 0 && nsec < 0),
"clock_gettime(CLOCK_MONOTONIC) failed: was %ld.%09ld but now %ld.%09ld",
mWriteTs.tv_sec, mWriteTs.tv_nsec, nowTs.tv_sec, nowTs.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;
}
void MonoPipe::shutdown(bool newState)
{
mIsShutdown = newState;
}
bool MonoPipe::isShutdown()
{
return mIsShutdown;
}
} // namespace android