Encoder.hpp

#pragma once

#include "Predictor.hpp"
#include "ArithmeticEncoder.hpp"
#include "Shared.hpp"
#include "PredictorMain.hpp"
#include "PredictorBlock.hpp"

typedef enum {
    COMPRESS, DECOMPRESS
} Mode;

/**
 * An Encoder encodes or decodes bytes using a Predictor and arithmetic encoding.
 * If shared->level is 0, then data is stored in 'archive' without arithmetic coding.
 */
class Encoder {
private:
  ArithmeticEncoder ari;
  const Mode mode; /**< Compress or decompress? */
  File* archive; /**< Compressed data file */
  File *alt; /**< decompressByte() source in COMPRESS mode */
  float p1 {}, p2 {}; /**< percentages for progress indicator: 0.0 .. 1.0 */
  bool doEncoding; /**<  false when compression level is 0 */
  Shared sharedBlock;

  void updateModels(Predictor* predictor, uint32_t p, int y);

public:

  PredictorMain predictorMain;
  PredictorBlock predictorBlock;

  /**
    * Encoder(COMPRESS, f) creates encoder for compression to archive @ref f, which
    * must be open past any header for writing in binary mode.
    * Encoder(DECOMPRESS, f) creates encoder for decompression from archive @ref f,
    * which must be open past any header for reading in binary mode.
    * @param m the mode to operate in
    * @param f the file to read from or write to
    */
  Encoder(Shared* const sh, bool doEncoding, Mode m, File *f);
  Mode getMode() const;

  /**
    * Returns current length of archive
    * @return length of archive so far
    */
  uint64_t size() const;

  /**
    * Should be called exactly once after compression is done and
    * before closing @ref f. It does nothing in DECOMPRESS mode.
    */
  void flush();

  /**
    * Sets alternate source to @ref f for decompressByte() in COMPRESS mode (for testing transforms).
    * @param f
    */
  void setFile(File *f);
    
  /**
    * compressByte(c) in COMPRESS mode compresses one byte.
    * @param c the byte to be compressed
    */
  void compressByte(Predictor *predictor, uint8_t c);

  /**
    * decompressByte() in DECOMPRESS mode decompresses and returns one byte.
    * @return the decompressed byte
    */
  uint8_t decompressByte(Predictor *predictor);

  void setStatusRange(float perc1, float perc2);
  void printStatus(uint64_t n, uint64_t size) const;
  void printStatus() const;
};