SharedRingBuffer.cpp revision 942bdc0aebc88dc8b12c0e7742ec0003bbb8b80f 
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 <sys/mman.h>
22
23#include "binding/RingBufferParcelable.h"
24#include "binding/AudioEndpointParcelable.h"
25
26#include "SharedRingBuffer.h"
27
28using namespace android;
29using namespace aaudio;
30
31SharedRingBuffer::~SharedRingBuffer()
32{
33    if (mSharedMemory != nullptr) {
34        delete mFifoBuffer;
35        munmap(mSharedMemory, mSharedMemorySizeInBytes);
36        mSharedMemory = nullptr;
37    }
38    if (mFileDescriptor != -1) {
39        ALOGV("SharedRingBuffer: LEAK? close(mFileDescriptor = %d)\n", mFileDescriptor);
40        close(mFileDescriptor);
41        mFileDescriptor = -1;
42    }
43}
44
45aaudio_result_t SharedRingBuffer::allocate(fifo_frames_t   bytesPerFrame,
46                                         fifo_frames_t   capacityInFrames) {
47    mCapacityInFrames = capacityInFrames;
48
49    // Create shared memory large enough to hold the data and the read and write counters.
50    mDataMemorySizeInBytes = bytesPerFrame * capacityInFrames;
51    mSharedMemorySizeInBytes = mDataMemorySizeInBytes + (2 * (sizeof(fifo_counter_t)));
52    mFileDescriptor = ashmem_create_region("AAudioSharedRingBuffer", mSharedMemorySizeInBytes);
53    ALOGV("SharedRingBuffer::allocate() LEAK? mFileDescriptor = %d\n", mFileDescriptor);
54    if (mFileDescriptor < 0) {
55        ALOGE("SharedRingBuffer::allocate() ashmem_create_region() failed %d", errno);
56        return AAUDIO_ERROR_INTERNAL;
57    }
58
59    int err = ashmem_set_prot_region(mFileDescriptor, PROT_READ|PROT_WRITE); // TODO error handling?
60    if (err < 0) {
61        ALOGE("SharedRingBuffer::allocate() ashmem_set_prot_region() failed %d", errno);
62        close(mFileDescriptor);
63        return AAUDIO_ERROR_INTERNAL; // TODO convert errno to a better AAUDIO_ERROR;
64    }
65
66    // Map the fd to memory addresses.
67    mSharedMemory = (uint8_t *) mmap(0, mSharedMemorySizeInBytes,
68                         PROT_READ|PROT_WRITE,
69                         MAP_SHARED,
70                         mFileDescriptor, 0);
71    if (mSharedMemory == MAP_FAILED) {
72        ALOGE("SharedRingBuffer::allocate() mmap() failed %d", errno);
73        close(mFileDescriptor);
74        return AAUDIO_ERROR_INTERNAL; // TODO convert errno to a better AAUDIO_ERROR;
75    }
76
77    // Get addresses for our counters and data from the shared memory.
78    fifo_counter_t *readCounterAddress =
79            (fifo_counter_t *) &mSharedMemory[SHARED_RINGBUFFER_READ_OFFSET];
80    fifo_counter_t *writeCounterAddress =
81            (fifo_counter_t *) &mSharedMemory[SHARED_RINGBUFFER_WRITE_OFFSET];
82    uint8_t *dataAddress = &mSharedMemory[SHARED_RINGBUFFER_DATA_OFFSET];
83
84    mFifoBuffer = new FifoBuffer(bytesPerFrame, capacityInFrames,
85                                 readCounterAddress, writeCounterAddress, dataAddress);
86    return AAUDIO_OK;
87}
88
89void SharedRingBuffer::fillParcelable(AudioEndpointParcelable &endpointParcelable,
90                    RingBufferParcelable &ringBufferParcelable) {
91    int fdIndex = endpointParcelable.addFileDescriptor(mFileDescriptor, mSharedMemorySizeInBytes);
92    ringBufferParcelable.setupMemory(fdIndex,
93                                     SHARED_RINGBUFFER_DATA_OFFSET,
94                                     mDataMemorySizeInBytes,
95                                     SHARED_RINGBUFFER_READ_OFFSET,
96                                     SHARED_RINGBUFFER_WRITE_OFFSET,
97                                     sizeof(fifo_counter_t));
98    ringBufferParcelable.setBytesPerFrame(mFifoBuffer->getBytesPerFrame());
99    ringBufferParcelable.setFramesPerBurst(1);
100    ringBufferParcelable.setCapacityInFrames(mCapacityInFrames);
101}
102