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/*
* 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 "MonoPipeReader"
//#define LOG_NDEBUG 0
#include <cutils/compiler.h>
#include <utils/Log.h>
#include <media/nbaio/MonoPipeReader.h>
namespace android {
MonoPipeReader::MonoPipeReader(MonoPipe* pipe) :
NBAIO_Source(pipe->mFormat),
mPipe(pipe)
{
}
MonoPipeReader::~MonoPipeReader()
{
}
ssize_t MonoPipeReader::availableToRead()
{
if (CC_UNLIKELY(!mNegotiated)) {
return NEGOTIATE;
}
ssize_t ret = android_atomic_acquire_load(&mPipe->mRear) - mPipe->mFront;
ALOG_ASSERT((0 <= ret) && (ret <= mMaxFrames));
return ret;
}
ssize_t MonoPipeReader::read(void *buffer, size_t count, int64_t readPTS)
{
// Compute the "next read PTS" and cache it. Callers of read pass a read
// PTS indicating the local time for which they are requesting data along
// with a count (which is the number of audio frames they are going to
// ultimately pass to the next stage of the pipeline). Offsetting readPTS
// by the duration of count will give us the readPTS which will be passed to
// us next time, assuming they system continues to operate in steady state
// with no discontinuities. We stash this value so it can be used by the
// MonoPipe writer to imlement getNextWriteTimestamp.
int64_t nextReadPTS;
nextReadPTS = mPipe->offsetTimestampByAudioFrames(readPTS, count);
// count == 0 is unlikely and not worth checking for explicitly; will be handled automatically
ssize_t red = availableToRead();
if (CC_UNLIKELY(red <= 0)) {
// Uh-oh, looks like we are underflowing. Update the next read PTS and
// get out.
mPipe->updateFrontAndNRPTS(mPipe->mFront, nextReadPTS);
return red;
}
if (CC_LIKELY((size_t) red > count)) {
red = count;
}
size_t front = mPipe->mFront & (mPipe->mMaxFrames - 1);
size_t part1 = mPipe->mMaxFrames - front;
if (part1 > (size_t) red) {
part1 = red;
}
if (CC_LIKELY(part1 > 0)) {
memcpy(buffer, (char *) mPipe->mBuffer + (front * mFrameSize), part1 * mFrameSize);
if (CC_UNLIKELY(front + part1 == mPipe->mMaxFrames)) {
size_t part2 = red - part1;
if (CC_LIKELY(part2 > 0)) {
memcpy((char *) buffer + (part1 * mFrameSize), mPipe->mBuffer, part2 * mFrameSize);
}
}
mPipe->updateFrontAndNRPTS(red + mPipe->mFront, nextReadPTS);
mFramesRead += red;
}
return red;
}
void MonoPipeReader::onTimestamp(const AudioTimestamp& timestamp)
{
mPipe->mTimestampMutator.push(timestamp);
}
} // namespace android
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