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