1/*
2 * Copyright (C) 2012 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define LOG_TAG "MonoPipeReader"
18//#define LOG_NDEBUG 0
19
20#include <cutils/compiler.h>
21#include <utils/Log.h>
22#include <media/nbaio/MonoPipeReader.h>
23
24namespace android {
25
26MonoPipeReader::MonoPipeReader(MonoPipe* pipe) :
27        NBAIO_Source(pipe->mFormat),
28        mPipe(pipe)
29{
30}
31
32MonoPipeReader::~MonoPipeReader()
33{
34}
35
36ssize_t MonoPipeReader::availableToRead()
37{
38    if (CC_UNLIKELY(!mNegotiated)) {
39        return NEGOTIATE;
40    }
41    ssize_t ret = android_atomic_acquire_load(&mPipe->mRear) - mPipe->mFront;
42    ALOG_ASSERT((0 <= ret) && (ret <= mMaxFrames));
43    return ret;
44}
45
46ssize_t MonoPipeReader::read(void *buffer, size_t count, int64_t readPTS)
47{
48    // Compute the "next read PTS" and cache it.  Callers of read pass a read
49    // PTS indicating the local time for which they are requesting data along
50    // with a count (which is the number of audio frames they are going to
51    // ultimately pass to the next stage of the pipeline).  Offsetting readPTS
52    // by the duration of count will give us the readPTS which will be passed to
53    // us next time, assuming they system continues to operate in steady state
54    // with no discontinuities.  We stash this value so it can be used by the
55    // MonoPipe writer to imlement getNextWriteTimestamp.
56    int64_t nextReadPTS;
57    nextReadPTS = mPipe->offsetTimestampByAudioFrames(readPTS, count);
58
59    // count == 0 is unlikely and not worth checking for explicitly; will be handled automatically
60    ssize_t red = availableToRead();
61    if (CC_UNLIKELY(red <= 0)) {
62        // Uh-oh, looks like we are underflowing.  Update the next read PTS and
63        // get out.
64        mPipe->updateFrontAndNRPTS(mPipe->mFront, nextReadPTS);
65        return red;
66    }
67    if (CC_LIKELY((size_t) red > count)) {
68        red = count;
69    }
70    size_t front = mPipe->mFront & (mPipe->mMaxFrames - 1);
71    size_t part1 = mPipe->mMaxFrames - front;
72    if (part1 > (size_t) red) {
73        part1 = red;
74    }
75    if (CC_LIKELY(part1 > 0)) {
76        memcpy(buffer, (char *) mPipe->mBuffer + (front * mFrameSize), part1 * mFrameSize);
77        if (CC_UNLIKELY(front + part1 == mPipe->mMaxFrames)) {
78            size_t part2 = red - part1;
79            if (CC_LIKELY(part2 > 0)) {
80                memcpy((char *) buffer + (part1 * mFrameSize), mPipe->mBuffer, part2 * mFrameSize);
81            }
82        }
83        mPipe->updateFrontAndNRPTS(red + mPipe->mFront, nextReadPTS);
84        mFramesRead += red;
85    }
86    return red;
87}
88
89void MonoPipeReader::onTimestamp(const AudioTimestamp& timestamp)
90{
91    mPipe->mTimestampMutator.push(timestamp);
92}
93
94}   // namespace android
95