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 "Pipe" 18 //#define LOG_NDEBUG 0 19 20 #include <cutils/atomic.h> 21 #include <cutils/compiler.h> 22 #include <utils/Log.h> 23 #include <media/nbaio/Pipe.h> 24 #include <media/nbaio/roundup.h> 25 26 namespace android { 27 28 Pipe::Pipe(size_t maxFrames, const NBAIO_Format& format, void *buffer) : 29 NBAIO_Sink(format), 30 mMaxFrames(roundup(maxFrames)), 31 mBuffer(buffer == NULL ? malloc(mMaxFrames * Format_frameSize(format)) : buffer), 32 mRear(0), 33 mReaders(0), 34 mFreeBufferInDestructor(buffer == NULL) 35 { 36 } 37 38 Pipe::~Pipe() 39 { 40 ALOG_ASSERT(android_atomic_acquire_load(&mReaders) == 0); 41 if (mFreeBufferInDestructor) { 42 free(mBuffer); 43 } 44 } 45 46 ssize_t Pipe::write(const void *buffer, size_t count) 47 { 48 // count == 0 is unlikely and not worth checking for 49 if (CC_UNLIKELY(!mNegotiated)) { 50 return NEGOTIATE; 51 } 52 // write() is not multi-thread safe w.r.t. itself, so no mutex or atomic op needed to read mRear 53 size_t rear = mRear & (mMaxFrames - 1); 54 size_t written = mMaxFrames - rear; 55 if (CC_LIKELY(written > count)) { 56 written = count; 57 } 58 memcpy((char *) mBuffer + (rear * mFrameSize), buffer, written * mFrameSize); 59 if (CC_UNLIKELY(rear + written == mMaxFrames)) { 60 if (CC_UNLIKELY((count -= written) > rear)) { 61 count = rear; 62 } 63 if (CC_LIKELY(count > 0)) { 64 memcpy(mBuffer, (char *) buffer + (written * mFrameSize), count * mFrameSize); 65 written += count; 66 } 67 } 68 android_atomic_release_store(written + mRear, &mRear); 69 mFramesWritten += written; 70 return written; 71 } 72 73 } // namespace android 74