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      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:
     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