src/common/FixedBlockReader.h

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef AAUDIO_FIXED_BLOCK_READER_H
#define AAUDIO_FIXED_BLOCK_READER_H

#include <stdint.h>

#include "FixedBlockAdapter.h"

/**
 * Read from a fixed-size block to a variable sized block.
 *
 * This can be used to convert a pull data flow from fixed sized buffers to variable sized buffers.
 * An example would be an audio output callback that reads from the app.
 */
class FixedBlockReader : public FixedBlockAdapter
{
public:
    FixedBlockReader(FixedBlockProcessor &fixedBlockProcessor);

    virtual ~FixedBlockReader() = default;

    int32_t open(int32_t bytesPerFixedBlock) override;

    /**
     * Read into a variable sized block.
     *
     * Note that if the fixed-sized blocks must be aligned, then the variable-sized blocks
     * must have the same alignment.
     * For example, if the fixed-size blocks must be a multiple of 8, then the variable-sized
     * blocks must also be a multiple of 8.
     *
     * @param buffer
     * @param numBytes
     * @return Number of bytes read or a negative error code.
     */
    int32_t read(uint8_t *buffer, int32_t numBytes);

private:
    int32_t readFromStorage(uint8_t *buffer, int32_t numBytes);

    int32_t               mValid = 0;            // Number of valid bytes in mStorage.
};


#endif /* AAUDIO_FIXED_BLOCK_READER_H */