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