SharedRingBuffer.cpp revision c0c70e3c7dd10bc2c0caffcab1f3f5fb406b35fb 
1/*
2 * Copyright (C) 2016 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 "AAudioService"
18//#define LOG_NDEBUG 0
19#include <utils/Log.h>
20
21#include "binding/RingBufferParcelable.h"
22#include "binding/AudioEndpointParcelable.h"
23
24#include "SharedRingBuffer.h"
25
26using namespace android;
27using namespace aaudio;
28
29SharedRingBuffer::~SharedRingBuffer()
30{
31    if (mSharedMemory != nullptr) {
32        delete mFifoBuffer;
33        munmap(mSharedMemory, mSharedMemorySizeInBytes);
34        close(mFileDescriptor);
35        mSharedMemory = nullptr;
36    }
37}
38
39aaudio_result_t SharedRingBuffer::allocate(fifo_frames_t   bytesPerFrame,
40                                         fifo_frames_t   capacityInFrames) {
41    mCapacityInFrames = capacityInFrames;
42
43    // Create shared memory large enough to hold the data and the read and write counters.
44    mDataMemorySizeInBytes = bytesPerFrame * capacityInFrames;
45    mSharedMemorySizeInBytes = mDataMemorySizeInBytes + (2 * (sizeof(fifo_counter_t)));
46    mFileDescriptor = ashmem_create_region("AAudioSharedRingBuffer", mSharedMemorySizeInBytes);
47    if (mFileDescriptor < 0) {
48        ALOGE("SharedRingBuffer::allocate() ashmem_create_region() failed %d", errno);
49        return AAUDIO_ERROR_INTERNAL;
50    }
51    int err = ashmem_set_prot_region(mFileDescriptor, PROT_READ|PROT_WRITE); // TODO error handling?
52    if (err < 0) {
53        ALOGE("SharedRingBuffer::allocate() ashmem_set_prot_region() failed %d", errno);
54        close(mFileDescriptor);
55        return AAUDIO_ERROR_INTERNAL; // TODO convert errno to a better AAUDIO_ERROR;
56    }
57
58    // Map the fd to memory addresses.
59    mSharedMemory = (uint8_t *) mmap(0, mSharedMemorySizeInBytes,
60                         PROT_READ|PROT_WRITE,
61                         MAP_SHARED,
62                         mFileDescriptor, 0);
63    if (mSharedMemory == MAP_FAILED) {
64        ALOGE("SharedRingBuffer::allocate() mmap() failed %d", errno);
65        close(mFileDescriptor);
66        return AAUDIO_ERROR_INTERNAL; // TODO convert errno to a better AAUDIO_ERROR;
67    }
68
69    // Get addresses for our counters and data from the shared memory.
70    fifo_counter_t *readCounterAddress =
71            (fifo_counter_t *) &mSharedMemory[SHARED_RINGBUFFER_READ_OFFSET];
72    fifo_counter_t *writeCounterAddress =
73            (fifo_counter_t *) &mSharedMemory[SHARED_RINGBUFFER_WRITE_OFFSET];
74    uint8_t *dataAddress = &mSharedMemory[SHARED_RINGBUFFER_DATA_OFFSET];
75
76    mFifoBuffer = new(std::nothrow) FifoBuffer(bytesPerFrame, capacityInFrames,
77                                 readCounterAddress, writeCounterAddress, dataAddress);
78    return (mFifoBuffer == nullptr) ? AAUDIO_ERROR_NO_MEMORY : AAUDIO_OK;
79}
80
81void SharedRingBuffer::fillParcelable(AudioEndpointParcelable &endpointParcelable,
82                    RingBufferParcelable &ringBufferParcelable) {
83    int fdIndex = endpointParcelable.addFileDescriptor(mFileDescriptor, mSharedMemorySizeInBytes);
84    ringBufferParcelable.setupMemory(fdIndex,
85                                     SHARED_RINGBUFFER_DATA_OFFSET,
86                                     mDataMemorySizeInBytes,
87                                     SHARED_RINGBUFFER_READ_OFFSET,
88                                     SHARED_RINGBUFFER_WRITE_OFFSET,
89                                     sizeof(fifo_counter_t));
90    ringBufferParcelable.setBytesPerFrame(mFifoBuffer->getBytesPerFrame());
91    ringBufferParcelable.setFramesPerBurst(1);
92    ringBufferParcelable.setCapacityInFrames(mCapacityInFrames);
93}
94