lzma-purejs-requirejs/lib/LZMA/Base.js

pure JavaScript LZMA de/compression, for node.js, volo, and the browser.

'use strict';

const freeze = require('../freeze');

var Base = Object.create(null);
Base.kNumRepDistances = 4;
Base.kNumStates = 12;

Base.stateInit = function() {
  return 0;
};

Base.stateUpdateChar = function(index) {
  if (index < 4) {
    return 0;
  }
  if (index < 10) {
    return index - 3;
  }
  return index - 6;
};

Base.stateUpdateMatch = function(index) {
  return (index < 7 ? 7 : 10);
};

Base.stateUpdateRep = function(index) {
  return (index < 7 ? 8 : 11);
};

Base.stateUpdateShortRep = function(index) {
  return (index < 7 ? 9 : 11);
};

Base.stateIsCharState = function(index) {
  return index < 7;
};

Base.kNumPosSlotBits = 6;
Base.kDicLogSizeMin = 0;
// Base.kDicLogSizeMax = 28;
// Base.kDistTableSizeMax = Base.kDicLogSizeMax * 2;

Base.kNumLenToPosStatesBits = 2; // it's for speed optimization
Base.kNumLenToPosStates = 1 << Base.kNumLenToPosStatesBits;

Base.kMatchMinLen = 2;

Base.getLenToPosState = function(len) {
  len -= Base.kMatchMinLen;
  if (len < Base.kNumLenToPosStates) {
    return len;
  }
  return (Base.kNumLenToPosStates - 1);
};

Base.kNumAlignBits = 4;
Base.kAlignTableSize = 1 << Base.kNumAlignBits;
Base.kAlignMask = (Base.kAlignTableSize - 1);

Base.kStartPosModelIndex = 4;
Base.kEndPosModelIndex = 14;
Base.kNumPosModels = Base.kEndPosModelIndex - Base.kStartPosModelIndex;

Base.kNumFullDistances = 1 << (Base.kEndPosModelIndex / 2);

Base.kNumLitPosStatesBitsEncodingMax = 4;
Base.kNumLitContextBitsMax = 8;

Base.kNumPosStatesBitsMax = 4;
Base.kNumPosStatesMax = (1 << Base.kNumPosStatesBitsMax);
Base.kNumPosStatesBitsEncodingMax = 4;
Base.kNumPosStatesEncodingMax = (1 << Base.kNumPosStatesBitsEncodingMax);

Base.kNumLowLenBits = 3;
Base.kNumMidLenBits = 3;
Base.kNumHighLenBits = 8;
Base.kNumLowLenSymbols = 1 << Base.kNumLowLenBits;
Base.kNumMidLenSymbols = 1 << Base.kNumMidLenBits;
Base.kNumLenSymbols = Base.kNumLowLenSymbols + Base.kNumMidLenSymbols +
  (1 << Base.kNumHighLenBits);
Base.kMatchMaxLen = Base.kMatchMinLen + Base.kNumLenSymbols - 1;

module.exports = freeze(Base);