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148 lines
3.6 KiB
C++
148 lines
3.6 KiB
C++
/*
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* CCompressedStream.h, part of VCMI engine
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*
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* Authors: listed in file AUTHORS in main folder
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*
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* License: GNU General Public License v2.0 or later
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* Full text of license available in license.txt file, in main folder
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*
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*/
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#pragma once
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#include "CInputStream.h"
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struct z_stream_s;
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VCMI_LIB_NAMESPACE_BEGIN
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class DecompressionException : public std::runtime_error
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{
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public:
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using runtime_error::runtime_error;
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};
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/// Abstract class that provides buffer for one-directional input streams (e.g. compressed data)
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/// Used for zip archives support and in .lod deflate compression
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class CBufferedStream : public CInputStream
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{
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public:
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CBufferedStream();
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/**
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* Reads n bytes from the stream into the data buffer.
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*
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* @param data A pointer to the destination data array.
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* @param size The number of bytes to read.
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* @return the number of bytes read actually.
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*
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* @throws std::runtime_error if the file decompression was not successful
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*/
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si64 read(ui8 * data, si64 size) override;
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/**
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* Seeks the internal read pointer to the specified position.
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* This will cause decompressing data till this position is found
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*
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* @param position The read position from the beginning.
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* @return the position actually moved to, -1 on error.
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*/
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si64 seek(si64 position) override;
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/**
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* Gets the current read position in the stream.
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*
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* @return the read position.
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*/
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si64 tell() override;
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/**
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* Skips delta numbers of bytes.
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*
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* @param delta The count of bytes to skip.
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* @return the count of bytes skipped actually.
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*/
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si64 skip(si64 delta) override;
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/**
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* Gets the length in bytes of the stream.
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* Causes complete data decompression
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*
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* @return the length in bytes of the stream.
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*/
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si64 getSize() override;
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protected:
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/**
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* @brief virtual method to get more data into the buffer
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* @return amount of bytes actually read, non-positive values are considered to be end-of-file mark
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*/
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virtual si64 readMore(ui8 * data, si64 size) = 0;
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/// resets all internal state
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void reset();
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private:
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/// ensures that buffer contains at lest size of bytes. Calls readMore() to fill remaining part
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void ensureSize(si64 size);
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/** buffer with already decompressed data */
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std::vector<ui8> buffer;
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/** Current read position */
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si64 position;
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bool endOfFileReached;
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};
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/**
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* A class which provides method definitions for reading a gzip-compressed file
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* This class implements lazy loading - data will be decompressed (and cached) only by request
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*/
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class DLL_LINKAGE CCompressedStream : public CBufferedStream
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{
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public:
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/**
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* C-tor.
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*
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* @param stream - stream with compressed data
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* @param gzip - this is gzipp'ed file e.g. campaign or maps, false for files in .lod
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* @param decompressedSize - optional parameter to hint size of decompressed data
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*/
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CCompressedStream(std::unique_ptr<CInputStream> stream, bool gzip, size_t decompressedSize=0);
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~CCompressedStream();
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/**
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* Prepare stream for decompression of next block (e.g. next part of h3c)
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* Applicable only for streams that contain multiple concatenated compressed data
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*
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* @return false if next block was not found, true othervice
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*/
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bool getNextBlock();
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private:
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/**
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* Decompresses data to ensure that buffer has newSize bytes or end of stream was reached
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*/
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si64 readMore(ui8 * data, si64 size) override;
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/** The file stream with compressed data. */
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std::unique_ptr<CInputStream> gzipStream;
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/** buffer with not yet decompressed data*/
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std::vector<ui8> compressedBuffer;
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/** struct with current zlib inflate state */
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z_stream_s * inflateState;
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enum EState
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{
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ERROR_OCCURRED,
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INITIALIZED,
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IN_PROGRESS,
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STREAM_END,
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FINISHED
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};
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};
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VCMI_LIB_NAMESPACE_END
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