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 24 namespace android { 25 26 MonoPipeReader::MonoPipeReader(MonoPipe* pipe) : 27 NBAIO_Source(pipe->mFormat), 28 mPipe(pipe) 29 { 30 } 31 32 MonoPipeReader::~MonoPipeReader() 33 { 34 } 35 36 ssize_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) && ((size_t) ret <= mPipe->mMaxFrames)); 43 return ret; 44 } 45 46 ssize_t MonoPipeReader::read(void *buffer, size_t count) 47 { 48 // count == 0 is unlikely and not worth checking for explicitly; will be handled automatically 49 ssize_t red = availableToRead(); 50 if (CC_UNLIKELY(red <= 0)) { 51 return red; 52 } 53 if (CC_LIKELY((size_t) red > count)) { 54 red = count; 55 } 56 size_t front = mPipe->mFront & (mPipe->mMaxFrames - 1); 57 size_t part1 = mPipe->mMaxFrames - front; 58 if (part1 > (size_t) red) { 59 part1 = red; 60 } 61 if (CC_LIKELY(part1 > 0)) { 62 memcpy(buffer, (char *) mPipe->mBuffer + (front * mFrameSize), part1 * mFrameSize); 63 if (CC_UNLIKELY(front + part1 == mPipe->mMaxFrames)) { 64 size_t part2 = red - part1; 65 if (CC_LIKELY(part2 > 0)) { 66 memcpy((char *) buffer + (part1 * mFrameSize), mPipe->mBuffer, part2 * mFrameSize); 67 } 68 } 69 android_atomic_release_store(red + mPipe->mFront, &mPipe->mFront); 70 mFramesRead += red; 71 } 72 return red; 73 } 74 75 void MonoPipeReader::onTimestamp(const ExtendedTimestamp ×tamp) 76 { 77 mPipe->mTimestampMutator.push(timestamp); 78 } 79 80 } // namespace android 81