stream.h

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/* Copyright (C) 2021 Wildfire Games.
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
 
/*
 * output buffer and 'stream' layered on top of a compression codec
 */
 
#ifndef INCLUDED_STREAM
#define INCLUDED_STREAM
 
#include "lib/file/archive/codec.h"
 
// note: this is similar in function to std::vector, but we don't need
// iterators etc. and would prefer to avoid initializing each byte.
class OutputBufferManager
{
public:
    OutputBufferManager();
 
    void Reset();
    void SetBuffer(u8* buffer, size_t size);
 
    /**
     * allocate a new output buffer.
     *
     * @param size [bytes] to allocate.
     *
     * notes:
     * - if a buffer had previously been allocated and is large enough,
     *   it is reused (this reduces the number of allocations).
     * - this class manages the lifetime of the buffer.
     **/
    void AllocateBuffer(size_t size);
 
    u8* Buffer() const
    {
        return m_buffer;
    }
 
    size_t Size() const
    {
        return m_size;
    }
 
private:
    bool IsAllowableBuffer(u8* buffer, size_t size);
 
    u8* m_buffer;
    size_t m_size;
 
    std::shared_ptr<u8> m_mem;
    // size of m_mem. allows reusing previously allocated buffers
    // (user-specified buffers can't be reused because we have no control
    // over their lifetime)
    size_t m_capacity;
};
 
 
class Stream
{
public:
    Stream(const PICodec& codec);
 
    void SetOutputBuffer(u8* out, size_t outSize);
 
    void AllocateOutputBuffer(size_t outSizeMax);
 
    /**
     * 'feed' the codec with a data block.
     **/
    Status Feed(const u8* in, size_t inSize);
 
    Status Finish();
 
    size_t OutSize() const
    {
        return m_outProduced;
    }
 
    u32 Checksum() const
    {
        return m_checksum;
    }
 
private:
    PICodec m_codec;
    OutputBufferManager m_outputBufferManager;
 
    size_t m_inConsumed;
    size_t m_outProduced;
    u32 m_checksum;
};
 
// avoids the need for std::bind (not supported on all compilers) and boost::bind (can't be
// used at work)
struct StreamFeeder
{
    NONCOPYABLE(StreamFeeder);
public:
    StreamFeeder(Stream& stream)
        : stream(stream)
    {
    }
 
    Status operator()(const u8* data, size_t size) const
    {
        return stream.Feed(data, size);
    }
 
private:
    Stream& stream;
};
 
#endif  // #ifndef INCLUDED_STREAM