Further compression and png work.

src/compression/DeflateBlock.h

@@ -0,0 +1,60 @@
+#pragma once
+
+#include "BitStream.h"
+
+class DeflateBlock
+{
+public:
+    DeflateBlock(BitStream* inputStream, BitStream* outputStream);
+
+    void readHeader();
+
+    void readDynamicHuffmanTable();
+
+    void buildCodeLengthMapping();
+
+    void readLiteralCodeLengths();
+
+    bool readNextCodeLengthSymbol(unsigned char& buffer);
+
+    bool isFinalBlock() const
+    {
+        return mInFinalBlock;
+    }
+
+    void setCodeLengthAlphabetLengths(const std::vector<unsigned char>& lengths);
+
+    void setCodeLengthLength(unsigned length);
+
+    void setLiteralsTableLength(unsigned length);
+
+    void setDistanceTableLength(unsigned length);
+
+    void setIsFinalBlock(bool isFinal);
+
+    void flushToStream();
+
+private:
+    BitStream* mInputStream;
+    BitStream* mOutputStream;
+
+    unsigned mHlit{0};
+    unsigned mHdist{0};
+    unsigned mHclen{0};
+
+    using CodeLengthEntry = std::pair<unsigned char, unsigned>;
+    using CodeLengthCountEntry = std::pair<unsigned, std::vector<CodeLengthEntry> >;
+    std::vector<CodeLengthCountEntry> mCodeLengthMapping;
+
+    std::vector<unsigned char> mCodeLengthAlphabetLengths;
+    static constexpr unsigned CODE_LENGTH_ALPHABET_PERMUTATION[19]{16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15};
+
+    unsigned char mCompressionType{0};
+
+    bool mInFinalBlock{false};
+
+    static constexpr unsigned char NO_COMPRESSION = 0x00;
+    static constexpr unsigned char FIXED_HUFFMAN = 0x01;
+    static constexpr unsigned char DYNAMIC_HUFFMAN = 0x02;
+    static constexpr unsigned char ERROR = 0x03;
+};