1 /*
2  * Copyright (C) 2017 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 #ifndef AAUDIO_FIXED_BLOCK_ADAPTER_H
18 #define AAUDIO_FIXED_BLOCK_ADAPTER_H
19 
20 #include <stdio.h>
21 
22 /**
23  * Interface for a class that needs fixed-size blocks.
24  */
25 class FixedBlockProcessor {
26 public:
27     virtual ~FixedBlockProcessor() = default;
28     virtual int32_t onProcessFixedBlock(uint8_t *buffer, int32_t numBytes) = 0;
29 };
30 
31 /**
32  * Base class for a variable-to-fixed-size block adapter.
33  */
34 class FixedBlockAdapter
35 {
36 public:
FixedBlockAdapter(FixedBlockProcessor & fixedBlockProcessor)37     FixedBlockAdapter(FixedBlockProcessor &fixedBlockProcessor)
38     : mFixedBlockProcessor(fixedBlockProcessor) {}
39 
40     virtual ~FixedBlockAdapter();
41 
42     /**
43      * Allocate internal resources needed for buffering data.
44      */
45     virtual int32_t open(int32_t bytesPerFixedBlock);
46 
47     /**
48      * Note that if the fixed-sized blocks must be aligned, then the variable-sized blocks
49      * must have the same alignment.
50      * For example, if the fixed-size blocks must be a multiple of 8, then the variable-sized
51      * blocks must also be a multiple of 8.
52      *
53      * @param buffer
54      * @param numBytes
55      * @return zero if OK or a non-zero code
56      */
57     virtual int32_t processVariableBlock(uint8_t *buffer, int32_t numBytes) = 0;
58 
59     /**
60      * Free internal resources.
61      */
62     int32_t close();
63 
64 protected:
65     FixedBlockProcessor  &mFixedBlockProcessor;
66     uint8_t              *mStorage = nullptr;    // Store data here while assembling buffers.
67     int32_t               mSize = 0;             // Size in bytes of the fixed size buffer.
68     int32_t               mPosition = 0;         // Offset of the last byte read or written.
69 };
70 
71 #endif /* AAUDIO_FIXED_BLOCK_ADAPTER_H */
72