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 <audio_utils/roundup.h>
25
26 namespace android {
27
Pipe(size_t maxFrames,const NBAIO_Format & format,void * buffer)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
~Pipe()38 Pipe::~Pipe()
39 {
40 ALOG_ASSERT(android_atomic_acquire_load(&mReaders) == 0);
41 if (mFreeBufferInDestructor) {
42 free(mBuffer);
43 }
44 }
45
write(const void * buffer,size_t count)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