pdfjs-dist/lib/core/jbig2.js

/**
 * @licstart The following is the entire license notice for the
 * JavaScript code in this page
 *
 * Copyright 2022 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @licend The above is the entire license notice for the
 * JavaScript code in this page
 */
"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.Jbig2Image = void 0;

var _util = require("../shared/util.js");

var _core_utils = require("./core_utils.js");

var _arithmetic_decoder = require("./arithmetic_decoder.js");

var _ccitt = require("./ccitt.js");

class Jbig2Error extends _util.BaseException {
  constructor(msg) {
    super(`JBIG2 error: ${msg}`, "Jbig2Error");
  }

}

class ContextCache {
  getContexts(id) {
    if (id in this) {
      return this[id];
    }

    return this[id] = new Int8Array(1 << 16);
  }

}

class DecodingContext {
  constructor(data, start, end) {
    this.data = data;
    this.start = start;
    this.end = end;
  }

  get decoder() {
    const decoder = new _arithmetic_decoder.ArithmeticDecoder(this.data, this.start, this.end);
    return (0, _util.shadow)(this, "decoder", decoder);
  }

  get contextCache() {
    const cache = new ContextCache();
    return (0, _util.shadow)(this, "contextCache", cache);
  }

}

function decodeInteger(contextCache, procedure, decoder) {
  const contexts = contextCache.getContexts(procedure);
  let prev = 1;

  function readBits(length) {
    let v = 0;

    for (let i = 0; i < length; i++) {
      const bit = decoder.readBit(contexts, prev);
      prev = prev < 256 ? prev << 1 | bit : (prev << 1 | bit) & 511 | 256;
      v = v << 1 | bit;
    }

    return v >>> 0;
  }

  const sign = readBits(1);
  const value = readBits(1) ? readBits(1) ? readBits(1) ? readBits(1) ? readBits(1) ? readBits(32) + 4436 : readBits(12) + 340 : readBits(8) + 84 : readBits(6) + 20 : readBits(4) + 4 : readBits(2);

  if (sign === 0) {
    return value;
  } else if (value > 0) {
    return -value;
  }

  return null;
}

function decodeIAID(contextCache, decoder, codeLength) {
  const contexts = contextCache.getContexts("IAID");
  let prev = 1;

  for (let i = 0; i < codeLength; i++) {
    const bit = decoder.readBit(contexts, prev);
    prev = prev << 1 | bit;
  }

  if (codeLength < 31) {
    return prev & (1 << codeLength) - 1;
  }

  return prev & 0x7fffffff;
}

const SegmentTypes = ["SymbolDictionary", null, null, null, "IntermediateTextRegion", null, "ImmediateTextRegion", "ImmediateLosslessTextRegion", null, null, null, null, null, null, null, null, "PatternDictionary", null, null, null, "IntermediateHalftoneRegion", null, "ImmediateHalftoneRegion", "ImmediateLosslessHalftoneRegion", null, null, null, null, null, null, null, null, null, null, null, null, "IntermediateGenericRegion", null, "ImmediateGenericRegion", "ImmediateLosslessGenericRegion", "IntermediateGenericRefinementRegion", null, "ImmediateGenericRefinementRegion", "ImmediateLosslessGenericRefinementRegion", null, null, null, null, "PageInformation", "EndOfPage", "EndOfStripe", "EndOfFile", "Profiles", "Tables", null, null, null, null, null, null, null, null, "Extension"];
const CodingTemplates = [[{
  x: -1,
  y: -2
}, {
  x: 0,
  y: -2
}, {
  x: 1,
  y: -2
}, {
  x: -2,
  y: -1
}, {
  x: -1,
  y: -1
}, {
  x: 0,
  y: -1
}, {
  x: 1,
  y: -1
}, {
  x: 2,
  y: -1
}, {
  x: -4,
  y: 0
}, {
  x: -3,
  y: 0
}, {
  x: -2,
  y: 0
}, {
  x: -1,
  y: 0
}], [{
  x: -1,
  y: -2
}, {
  x: 0,
  y: -2
}, {
  x: 1,
  y: -2
}, {
  x: 2,
  y: -2
}, {
  x: -2,
  y: -1
}, {
  x: -1,
  y: -1
}, {
  x: 0,
  y: -1
}, {
  x: 1,
  y: -1
}, {
  x: 2,
  y: -1
}, {
  x: -3,
  y: 0
}, {
  x: -2,
  y: 0
}, {
  x: -1,
  y: 0
}], [{
  x: -1,
  y: -2
}, {
  x: 0,
  y: -2
}, {
  x: 1,
  y: -2
}, {
  x: -2,
  y: -1
}, {
  x: -1,
  y: -1
}, {
  x: 0,
  y: -1
}, {
  x: 1,
  y: -1
}, {
  x: -2,
  y: 0
}, {
  x: -1,
  y: 0
}], [{
  x: -3,
  y: -1
}, {
  x: -2,
  y: -1
}, {
  x: -1,
  y: -1
}, {
  x: 0,
  y: -1
}, {
  x: 1,
  y: -1
}, {
  x: -4,
  y: 0
}, {
  x: -3,
  y: 0
}, {
  x: -2,
  y: 0
}, {
  x: -1,
  y: 0
}]];
const RefinementTemplates = [{
  coding: [{
    x: 0,
    y: -1
  }, {
    x: 1,
    y: -1
  }, {
    x: -1,
    y: 0
  }],
  reference: [{
    x: 0,
    y: -1
  }, {
    x: 1,
    y: -1
  }, {
    x: -1,
    y: 0
  }, {
    x: 0,
    y: 0
  }, {
    x: 1,
    y: 0
  }, {
    x: -1,
    y: 1
  }, {
    x: 0,
    y: 1
  }, {
    x: 1,
    y: 1
  }]
}, {
  coding: [{
    x: -1,
    y: -1
  }, {
    x: 0,
    y: -1
  }, {
    x: 1,
    y: -1
  }, {
    x: -1,
    y: 0
  }],
  reference: [{
    x: 0,
    y: -1
  }, {
    x: -1,
    y: 0
  }, {
    x: 0,
    y: 0
  }, {
    x: 1,
    y: 0
  }, {
    x: 0,
    y: 1
  }, {
    x: 1,
    y: 1
  }]
}];
const ReusedContexts = [0x9b25, 0x0795, 0x00e5, 0x0195];
const RefinementReusedContexts = [0x0020, 0x0008];

function decodeBitmapTemplate0(width, height, decodingContext) {
  const decoder = decodingContext.decoder;
  const contexts = decodingContext.contextCache.getContexts("GB");
  const bitmap = [];
  let contextLabel, i, j, pixel, row, row1, row2;
  const OLD_PIXEL_MASK = 0x7bf7;

  for (i = 0; i < height; i++) {
    row = bitmap[i] = new Uint8Array(width);
    row1 = i < 1 ? row : bitmap[i - 1];
    row2 = i < 2 ? row : bitmap[i - 2];
    contextLabel = row2[0] << 13 | row2[1] << 12 | row2[2] << 11 | row1[0] << 7 | row1[1] << 6 | row1[2] << 5 | row1[3] << 4;

    for (j = 0; j < width; j++) {
      row[j] = pixel = decoder.readBit(contexts, contextLabel);
      contextLabel = (contextLabel & OLD_PIXEL_MASK) << 1 | (j + 3 < width ? row2[j + 3] << 11 : 0) | (j + 4 < width ? row1[j + 4] << 4 : 0) | pixel;
    }
  }

  return bitmap;
}

function decodeBitmap(mmr, width, height, templateIndex, prediction, skip, at, decodingContext) {
  if (mmr) {
    const input = new Reader(decodingContext.data, decodingContext.start, decodingContext.end);
    return decodeMMRBitmap(input, width, height, false);
  }

  if (templateIndex === 0 && !skip && !prediction && at.length === 4 && at[0].x === 3 && at[0].y === -1 && at[1].x === -3 && at[1].y === -1 && at[2].x === 2 && at[2].y === -2 && at[3].x === -2 && at[3].y === -2) {
    return decodeBitmapTemplate0(width, height, decodingContext);
  }

  const useskip = !!skip;
  const template = CodingTemplates[templateIndex].concat(at);
  template.sort(function (a, b) {
    return a.y - b.y || a.x - b.x;
  });
  const templateLength = template.length;
  const templateX = new Int8Array(templateLength);
  const templateY = new Int8Array(templateLength);
  const changingTemplateEntries = [];
  let reuseMask = 0,
      minX = 0,
      maxX = 0,
      minY = 0;
  let c, k;

  for (k = 0; k < templateLength; k++) {
    templateX[k] = template[k].x;
    templateY[k] = template[k].y;
    minX = Math.min(minX, template[k].x);
    maxX = Math.max(maxX, template[k].x);
    minY = Math.min(minY, template[k].y);

    if (k < templateLength - 1 && template[k].y === template[k + 1].y && template[k].x === template[k + 1].x - 1) {
      reuseMask |= 1 << templateLength - 1 - k;
    } else {
      changingTemplateEntries.push(k);
    }
  }

  const changingEntriesLength = changingTemplateEntries.length;
  const changingTemplateX = new Int8Array(changingEntriesLength);
  const changingTemplateY = new Int8Array(changingEntriesLength);
  const changingTemplateBit = new Uint16Array(changingEntriesLength);

  for (c = 0; c < changingEntriesLength; c++) {
    k = changingTemplateEntries[c];
    changingTemplateX[c] = template[k].x;
    changingTemplateY[c] = template[k].y;
    changingTemplateBit[c] = 1 << templateLength - 1 - k;
  }

  const sbb_left = -minX;
  const sbb_top = -minY;
  const sbb_right = width - maxX;
  const pseudoPixelContext = ReusedContexts[templateIndex];
  let row = new Uint8Array(width);
  const bitmap = [];
  const decoder = decodingContext.decoder;
  const contexts = decodingContext.contextCache.getContexts("GB");
  let ltp = 0,
      j,
      i0,
      j0,
      contextLabel = 0,
      bit,
      shift;

  for (let i = 0; i < height; i++) {
    if (prediction) {
      const sltp = decoder.readBit(contexts, pseudoPixelContext);
      ltp ^= sltp;

      if (ltp) {
        bitmap.push(row);
        continue;
      }
    }

    row = new Uint8Array(row);
    bitmap.push(row);

    for (j = 0; j < width; j++) {
      if (useskip && skip[i][j]) {
        row[j] = 0;
        continue;
      }

      if (j >= sbb_left && j < sbb_right && i >= sbb_top) {
        contextLabel = contextLabel << 1 & reuseMask;

        for (k = 0; k < changingEntriesLength; k++) {
          i0 = i + changingTemplateY[k];
          j0 = j + changingTemplateX[k];
          bit = bitmap[i0][j0];

          if (bit) {
            bit = changingTemplateBit[k];
            contextLabel |= bit;
          }
        }
      } else {
        contextLabel = 0;
        shift = templateLength - 1;

        for (k = 0; k < templateLength; k++, shift--) {
          j0 = j + templateX[k];

          if (j0 >= 0 && j0 < width) {
            i0 = i + templateY[k];

            if (i0 >= 0) {
              bit = bitmap[i0][j0];

              if (bit) {
                contextLabel |= bit << shift;
              }
            }
          }
        }
      }

      const pixel = decoder.readBit(contexts, contextLabel);
      row[j] = pixel;
    }
  }

  return bitmap;
}

function decodeRefinement(width, height, templateIndex, referenceBitmap, offsetX, offsetY, prediction, at, decodingContext) {
  let codingTemplate = RefinementTemplates[templateIndex].coding;

  if (templateIndex === 0) {
    codingTemplate = codingTemplate.concat([at[0]]);
  }

  const codingTemplateLength = codingTemplate.length;
  const codingTemplateX = new Int32Array(codingTemplateLength);
  const codingTemplateY = new Int32Array(codingTemplateLength);
  let k;

  for (k = 0; k < codingTemplateLength; k++) {
    codingTemplateX[k] = codingTemplate[k].x;
    codingTemplateY[k] = codingTemplate[k].y;
  }

  let referenceTemplate = RefinementTemplates[templateIndex].reference;

  if (templateIndex === 0) {
    referenceTemplate = referenceTemplate.concat([at[1]]);
  }

  const referenceTemplateLength = referenceTemplate.length;
  const referenceTemplateX = new Int32Array(referenceTemplateLength);
  const referenceTemplateY = new Int32Array(referenceTemplateLength);

  for (k = 0; k < referenceTemplateLength; k++) {
    referenceTemplateX[k] = referenceTemplate[k].x;
    referenceTemplateY[k] = referenceTemplate[k].y;
  }

  const referenceWidth = referenceBitmap[0].length;
  const referenceHeight = referenceBitmap.length;
  const pseudoPixelContext = RefinementReusedContexts[templateIndex];
  const bitmap = [];
  const decoder = decodingContext.decoder;
  const contexts = decodingContext.contextCache.getContexts("GR");
  let ltp = 0;

  for (let i = 0; i < height; i++) {
    if (prediction) {
      const sltp = decoder.readBit(contexts, pseudoPixelContext);
      ltp ^= sltp;

      if (ltp) {
        throw new Jbig2Error("prediction is not supported");
      }
    }

    const row = new Uint8Array(width);
    bitmap.push(row);

    for (let j = 0; j < width; j++) {
      let i0, j0;
      let contextLabel = 0;

      for (k = 0; k < codingTemplateLength; k++) {
        i0 = i + codingTemplateY[k];
        j0 = j + codingTemplateX[k];

        if (i0 < 0 || j0 < 0 || j0 >= width) {
          contextLabel <<= 1;
        } else {
          contextLabel = contextLabel << 1 | bitmap[i0][j0];
        }
      }

      for (k = 0; k < referenceTemplateLength; k++) {
        i0 = i + referenceTemplateY[k] - offsetY;
        j0 = j + referenceTemplateX[k] - offsetX;

        if (i0 < 0 || i0 >= referenceHeight || j0 < 0 || j0 >= referenceWidth) {
          contextLabel <<= 1;
        } else {
          contextLabel = contextLabel << 1 | referenceBitmap[i0][j0];
        }
      }

      const pixel = decoder.readBit(contexts, contextLabel);
      row[j] = pixel;
    }
  }

  return bitmap;
}

function decodeSymbolDictionary(huffman, refinement, symbols, numberOfNewSymbols, numberOfExportedSymbols, huffmanTables, templateIndex, at, refinementTemplateIndex, refinementAt, decodingContext, huffmanInput) {
  if (huffman && refinement) {
    throw new Jbig2Error("symbol refinement with Huffman is not supported");
  }

  const newSymbols = [];
  let currentHeight = 0;
  let symbolCodeLength = (0, _core_utils.log2)(symbols.length + numberOfNewSymbols);
  const decoder = decodingContext.decoder;
  const contextCache = decodingContext.contextCache;
  let tableB1, symbolWidths;

  if (huffman) {
    tableB1 = getStandardTable(1);
    symbolWidths = [];
    symbolCodeLength = Math.max(symbolCodeLength, 1);
  }

  while (newSymbols.length < numberOfNewSymbols) {
    const deltaHeight = huffman ? huffmanTables.tableDeltaHeight.decode(huffmanInput) : decodeInteger(contextCache, "IADH", decoder);
    currentHeight += deltaHeight;
    let currentWidth = 0,
        totalWidth = 0;
    const firstSymbol = huffman ? symbolWidths.length : 0;

    while (true) {
      const deltaWidth = huffman ? huffmanTables.tableDeltaWidth.decode(huffmanInput) : decodeInteger(contextCache, "IADW", decoder);

      if (deltaWidth === null) {
        break;
      }

      currentWidth += deltaWidth;
      totalWidth += currentWidth;
      let bitmap;

      if (refinement) {
        const numberOfInstances = decodeInteger(contextCache, "IAAI", decoder);

        if (numberOfInstances > 1) {
          bitmap = decodeTextRegion(huffman, refinement, currentWidth, currentHeight, 0, numberOfInstances, 1, symbols.concat(newSymbols), symbolCodeLength, 0, 0, 1, 0, huffmanTables, refinementTemplateIndex, refinementAt, decodingContext, 0, huffmanInput);
        } else {
          const symbolId = decodeIAID(contextCache, decoder, symbolCodeLength);
          const rdx = decodeInteger(contextCache, "IARDX", decoder);
          const rdy = decodeInteger(contextCache, "IARDY", decoder);
          const symbol = symbolId < symbols.length ? symbols[symbolId] : newSymbols[symbolId - symbols.length];
          bitmap = decodeRefinement(currentWidth, currentHeight, refinementTemplateIndex, symbol, rdx, rdy, false, refinementAt, decodingContext);
        }

        newSymbols.push(bitmap);
      } else if (huffman) {
        symbolWidths.push(currentWidth);
      } else {
        bitmap = decodeBitmap(false, currentWidth, currentHeight, templateIndex, false, null, at, decodingContext);
        newSymbols.push(bitmap);
      }
    }

    if (huffman && !refinement) {
      const bitmapSize = huffmanTables.tableBitmapSize.decode(huffmanInput);
      huffmanInput.byteAlign();
      let collectiveBitmap;

      if (bitmapSize === 0) {
        collectiveBitmap = readUncompressedBitmap(huffmanInput, totalWidth, currentHeight);
      } else {
        const originalEnd = huffmanInput.end;
        const bitmapEnd = huffmanInput.position + bitmapSize;
        huffmanInput.end = bitmapEnd;
        collectiveBitmap = decodeMMRBitmap(huffmanInput, totalWidth, currentHeight, false);
        huffmanInput.end = originalEnd;
        huffmanInput.position = bitmapEnd;
      }

      const numberOfSymbolsDecoded = symbolWidths.length;

      if (firstSymbol === numberOfSymbolsDecoded - 1) {
        newSymbols.push(collectiveBitmap);
      } else {
        let i,
            y,
            xMin = 0,
            xMax,
            bitmapWidth,
            symbolBitmap;

        for (i = firstSymbol; i < numberOfSymbolsDecoded; i++) {
          bitmapWidth = symbolWidths[i];
          xMax = xMin + bitmapWidth;
          symbolBitmap = [];

          for (y = 0; y < currentHeight; y++) {
            symbolBitmap.push(collectiveBitmap[y].subarray(xMin, xMax));
          }

          newSymbols.push(symbolBitmap);
          xMin = xMax;
        }
      }
    }
  }

  const exportedSymbols = [],
        flags = [];
  let currentFlag = false,
      i,
      ii;
  const totalSymbolsLength = symbols.length + numberOfNewSymbols;

  while (flags.length < totalSymbolsLength) {
    let runLength = huffman ? tableB1.decode(huffmanInput) : decodeInteger(contextCache, "IAEX", decoder);

    while (runLength--) {
      flags.push(currentFlag);
    }

    currentFlag = !currentFlag;
  }

  for (i = 0, ii = symbols.length; i < ii; i++) {
    if (flags[i]) {
      exportedSymbols.push(symbols[i]);
    }
  }

  for (let j = 0; j < numberOfNewSymbols; i++, j++) {
    if (flags[i]) {
      exportedSymbols.push(newSymbols[j]);
    }
  }

  return exportedSymbols;
}

function decodeTextRegion(huffman, refinement, width, height, defaultPixelValue, numberOfSymbolInstances, stripSize, inputSymbols, symbolCodeLength, transposed, dsOffset, referenceCorner, combinationOperator, huffmanTables, refinementTemplateIndex, refinementAt, decodingContext, logStripSize, huffmanInput) {
  if (huffman && refinement) {
    throw new Jbig2Error("refinement with Huffman is not supported");
  }

  const bitmap = [];
  let i, row;

  for (i = 0; i < height; i++) {
    row = new Uint8Array(width);

    if (defaultPixelValue) {
      for (let j = 0; j < width; j++) {
        row[j] = defaultPixelValue;
      }
    }

    bitmap.push(row);
  }

  const decoder = decodingContext.decoder;
  const contextCache = decodingContext.contextCache;
  let stripT = huffman ? -huffmanTables.tableDeltaT.decode(huffmanInput) : -decodeInteger(contextCache, "IADT", decoder);
  let firstS = 0;
  i = 0;

  while (i < numberOfSymbolInstances) {
    const deltaT = huffman ? huffmanTables.tableDeltaT.decode(huffmanInput) : decodeInteger(contextCache, "IADT", decoder);
    stripT += deltaT;
    const deltaFirstS = huffman ? huffmanTables.tableFirstS.decode(huffmanInput) : decodeInteger(contextCache, "IAFS", decoder);
    firstS += deltaFirstS;
    let currentS = firstS;

    do {
      let currentT = 0;

      if (stripSize > 1) {
        currentT = huffman ? huffmanInput.readBits(logStripSize) : decodeInteger(contextCache, "IAIT", decoder);
      }

      const t = stripSize * stripT + currentT;
      const symbolId = huffman ? huffmanTables.symbolIDTable.decode(huffmanInput) : decodeIAID(contextCache, decoder, symbolCodeLength);
      const applyRefinement = refinement && (huffman ? huffmanInput.readBit() : decodeInteger(contextCache, "IARI", decoder));
      let symbolBitmap = inputSymbols[symbolId];
      let symbolWidth = symbolBitmap[0].length;
      let symbolHeight = symbolBitmap.length;

      if (applyRefinement) {
        const rdw = decodeInteger(contextCache, "IARDW", decoder);
        const rdh = decodeInteger(contextCache, "IARDH", decoder);
        const rdx = decodeInteger(contextCache, "IARDX", decoder);
        const rdy = decodeInteger(contextCache, "IARDY", decoder);
        symbolWidth += rdw;
        symbolHeight += rdh;
        symbolBitmap = decodeRefinement(symbolWidth, symbolHeight, refinementTemplateIndex, symbolBitmap, (rdw >> 1) + rdx, (rdh >> 1) + rdy, false, refinementAt, decodingContext);
      }

      const offsetT = t - (referenceCorner & 1 ? 0 : symbolHeight - 1);
      const offsetS = currentS - (referenceCorner & 2 ? symbolWidth - 1 : 0);
      let s2, t2, symbolRow;

      if (transposed) {
        for (s2 = 0; s2 < symbolHeight; s2++) {
          row = bitmap[offsetS + s2];

          if (!row) {
            continue;
          }

          symbolRow = symbolBitmap[s2];
          const maxWidth = Math.min(width - offsetT, symbolWidth);

          switch (combinationOperator) {
            case 0:
              for (t2 = 0; t2 < maxWidth; t2++) {
                row[offsetT + t2] |= symbolRow[t2];
              }

              break;

            case 2:
              for (t2 = 0; t2 < maxWidth; t2++) {
                row[offsetT + t2] ^= symbolRow[t2];
              }

              break;

            default:
              throw new Jbig2Error(`operator ${combinationOperator} is not supported`);
          }
        }

        currentS += symbolHeight - 1;
      } else {
        for (t2 = 0; t2 < symbolHeight; t2++) {
          row = bitmap[offsetT + t2];

          if (!row) {
            continue;
          }

          symbolRow = symbolBitmap[t2];

          switch (combinationOperator) {
            case 0:
              for (s2 = 0; s2 < symbolWidth; s2++) {
                row[offsetS + s2] |= symbolRow[s2];
              }

              break;

            case 2:
              for (s2 = 0; s2 < symbolWidth; s2++) {
                row[offsetS + s2] ^= symbolRow[s2];
              }

              break;

            default:
              throw new Jbig2Error(`operator ${combinationOperator} is not supported`);
          }
        }

        currentS += symbolWidth - 1;
      }

      i++;
      const deltaS = huffman ? huffmanTables.tableDeltaS.decode(huffmanInput) : decodeInteger(contextCache, "IADS", decoder);

      if (deltaS === null) {
        break;
      }

      currentS += deltaS + dsOffset;
    } while (true);
  }

  return bitmap;
}

function decodePatternDictionary(mmr, patternWidth, patternHeight, maxPatternIndex, template, decodingContext) {
  const at = [];

  if (!mmr) {
    at.push({
      x: -patternWidth,
      y: 0
    });

    if (template === 0) {
      at.push({
        x: -3,
        y: -1
      }, {
        x: 2,
        y: -2
      }, {
        x: -2,
        y: -2
      });
    }
  }

  const collectiveWidth = (maxPatternIndex + 1) * patternWidth;
  const collectiveBitmap = decodeBitmap(mmr, collectiveWidth, patternHeight, template, false, null, at, decodingContext);
  const patterns = [];

  for (let i = 0; i <= maxPatternIndex; i++) {
    const patternBitmap = [];
    const xMin = patternWidth * i;
    const xMax = xMin + patternWidth;

    for (let y = 0; y < patternHeight; y++) {
      patternBitmap.push(collectiveBitmap[y].subarray(xMin, xMax));
    }

    patterns.push(patternBitmap);
  }

  return patterns;
}

function decodeHalftoneRegion(mmr, patterns, template, regionWidth, regionHeight, defaultPixelValue, enableSkip, combinationOperator, gridWidth, gridHeight, gridOffsetX, gridOffsetY, gridVectorX, gridVectorY, decodingContext) {
  const skip = null;

  if (enableSkip) {
    throw new Jbig2Error("skip is not supported");
  }

  if (combinationOperator !== 0) {
    throw new Jbig2Error(`operator "${combinationOperator}" is not supported in halftone region`);
  }

  const regionBitmap = [];
  let i, j, row;

  for (i = 0; i < regionHeight; i++) {
    row = new Uint8Array(regionWidth);

    if (defaultPixelValue) {
      for (j = 0; j < regionWidth; j++) {
        row[j] = defaultPixelValue;
      }
    }

    regionBitmap.push(row);
  }

  const numberOfPatterns = patterns.length;
  const pattern0 = patterns[0];
  const patternWidth = pattern0[0].length,
        patternHeight = pattern0.length;
  const bitsPerValue = (0, _core_utils.log2)(numberOfPatterns);
  const at = [];

  if (!mmr) {
    at.push({
      x: template <= 1 ? 3 : 2,
      y: -1
    });

    if (template === 0) {
      at.push({
        x: -3,
        y: -1
      }, {
        x: 2,
        y: -2
      }, {
        x: -2,
        y: -2
      });
    }
  }

  const grayScaleBitPlanes = [];
  let mmrInput, bitmap;

  if (mmr) {
    mmrInput = new Reader(decodingContext.data, decodingContext.start, decodingContext.end);
  }

  for (i = bitsPerValue - 1; i >= 0; i--) {
    if (mmr) {
      bitmap = decodeMMRBitmap(mmrInput, gridWidth, gridHeight, true);
    } else {
      bitmap = decodeBitmap(false, gridWidth, gridHeight, template, false, skip, at, decodingContext);
    }

    grayScaleBitPlanes[i] = bitmap;
  }

  let mg, ng, bit, patternIndex, patternBitmap, x, y, patternRow, regionRow;

  for (mg = 0; mg < gridHeight; mg++) {
    for (ng = 0; ng < gridWidth; ng++) {
      bit = 0;
      patternIndex = 0;

      for (j = bitsPerValue - 1; j >= 0; j--) {
        bit ^= grayScaleBitPlanes[j][mg][ng];
        patternIndex |= bit << j;
      }

      patternBitmap = patterns[patternIndex];
      x = gridOffsetX + mg * gridVectorY + ng * gridVectorX >> 8;
      y = gridOffsetY + mg * gridVectorX - ng * gridVectorY >> 8;

      if (x >= 0 && x + patternWidth <= regionWidth && y >= 0 && y + patternHeight <= regionHeight) {
        for (i = 0; i < patternHeight; i++) {
          regionRow = regionBitmap[y + i];
          patternRow = patternBitmap[i];

          for (j = 0; j < patternWidth; j++) {
            regionRow[x + j] |= patternRow[j];
          }
        }
      } else {
        let regionX, regionY;

        for (i = 0; i < patternHeight; i++) {
          regionY = y + i;

          if (regionY < 0 || regionY >= regionHeight) {
            continue;
          }

          regionRow = regionBitmap[regionY];
          patternRow = patternBitmap[i];

          for (j = 0; j < patternWidth; j++) {
            regionX = x + j;

            if (regionX >= 0 && regionX < regionWidth) {
              regionRow[regionX] |= patternRow[j];
            }
          }
        }
      }
    }
  }

  return regionBitmap;
}

function readSegmentHeader(data, start) {
  const segmentHeader = {};
  segmentHeader.number = (0, _core_utils.readUint32)(data, start);
  const flags = data[start + 4];
  const segmentType = flags & 0x3f;

  if (!SegmentTypes[segmentType]) {
    throw new Jbig2Error("invalid segment type: " + segmentType);
  }

  segmentHeader.type = segmentType;
  segmentHeader.typeName = SegmentTypes[segmentType];
  segmentHeader.deferredNonRetain = !!(flags & 0x80);
  const pageAssociationFieldSize = !!(flags & 0x40);
  const referredFlags = data[start + 5];
  let referredToCount = referredFlags >> 5 & 7;
  const retainBits = [referredFlags & 31];
  let position = start + 6;

  if (referredFlags === 7) {
    referredToCount = (0, _core_utils.readUint32)(data, position - 1) & 0x1fffffff;
    position += 3;
    let bytes = referredToCount + 7 >> 3;
    retainBits[0] = data[position++];

    while (--bytes > 0) {
      retainBits.push(data[position++]);
    }
  } else if (referredFlags === 5 || referredFlags === 6) {
    throw new Jbig2Error("invalid referred-to flags");
  }

  segmentHeader.retainBits = retainBits;
  let referredToSegmentNumberSize = 4;

  if (segmentHeader.number <= 256) {
    referredToSegmentNumberSize = 1;
  } else if (segmentHeader.number <= 65536) {
    referredToSegmentNumberSize = 2;
  }

  const referredTo = [];
  let i, ii;

  for (i = 0; i < referredToCount; i++) {
    let number;

    if (referredToSegmentNumberSize === 1) {
      number = data[position];
    } else if (referredToSegmentNumberSize === 2) {
      number = (0, _core_utils.readUint16)(data, position);
    } else {
      number = (0, _core_utils.readUint32)(data, position);
    }

    referredTo.push(number);
    position += referredToSegmentNumberSize;
  }

  segmentHeader.referredTo = referredTo;

  if (!pageAssociationFieldSize) {
    segmentHeader.pageAssociation = data[position++];
  } else {
    segmentHeader.pageAssociation = (0, _core_utils.readUint32)(data, position);
    position += 4;
  }

  segmentHeader.length = (0, _core_utils.readUint32)(data, position);
  position += 4;

  if (segmentHeader.length === 0xffffffff) {
    if (segmentType === 38) {
      const genericRegionInfo = readRegionSegmentInformation(data, position);
      const genericRegionSegmentFlags = data[position + RegionSegmentInformationFieldLength];
      const genericRegionMmr = !!(genericRegionSegmentFlags & 1);
      const searchPatternLength = 6;
      const searchPattern = new Uint8Array(searchPatternLength);

      if (!genericRegionMmr) {
        searchPattern[0] = 0xff;
        searchPattern[1] = 0xac;
      }

      searchPattern[2] = genericRegionInfo.height >>> 24 & 0xff;
      searchPattern[3] = genericRegionInfo.height >> 16 & 0xff;
      searchPattern[4] = genericRegionInfo.height >> 8 & 0xff;
      searchPattern[5] = genericRegionInfo.height & 0xff;

      for (i = position, ii = data.length; i < ii; i++) {
        let j = 0;

        while (j < searchPatternLength && searchPattern[j] === data[i + j]) {
          j++;
        }

        if (j === searchPatternLength) {
          segmentHeader.length = i + searchPatternLength;
          break;
        }
      }

      if (segmentHeader.length === 0xffffffff) {
        throw new Jbig2Error("segment end was not found");
      }
    } else {
      throw new Jbig2Error("invalid unknown segment length");
    }
  }

  segmentHeader.headerEnd = position;
  return segmentHeader;
}

function readSegments(header, data, start, end) {
  const segments = [];
  let position = start;

  while (position < end) {
    const segmentHeader = readSegmentHeader(data, position);
    position = segmentHeader.headerEnd;
    const segment = {
      header: segmentHeader,
      data
    };

    if (!header.randomAccess) {
      segment.start = position;
      position += segmentHeader.length;
      segment.end = position;
    }

    segments.push(segment);

    if (segmentHeader.type === 51) {
      break;
    }
  }

  if (header.randomAccess) {
    for (let i = 0, ii = segments.length; i < ii; i++) {
      segments[i].start = position;
      position += segments[i].header.length;
      segments[i].end = position;
    }
  }

  return segments;
}

function readRegionSegmentInformation(data, start) {
  return {
    width: (0, _core_utils.readUint32)(data, start),
    height: (0, _core_utils.readUint32)(data, start + 4),
    x: (0, _core_utils.readUint32)(data, start + 8),
    y: (0, _core_utils.readUint32)(data, start + 12),
    combinationOperator: data[start + 16] & 7
  };
}

const RegionSegmentInformationFieldLength = 17;

function processSegment(segment, visitor) {
  const header = segment.header;
  const data = segment.data,
        end = segment.end;
  let position = segment.start;
  let args, at, i, atLength;

  switch (header.type) {
    case 0:
      const dictionary = {};
      const dictionaryFlags = (0, _core_utils.readUint16)(data, position);
      dictionary.huffman = !!(dictionaryFlags & 1);
      dictionary.refinement = !!(dictionaryFlags & 2);
      dictionary.huffmanDHSelector = dictionaryFlags >> 2 & 3;
      dictionary.huffmanDWSelector = dictionaryFlags >> 4 & 3;
      dictionary.bitmapSizeSelector = dictionaryFlags >> 6 & 1;
      dictionary.aggregationInstancesSelector = dictionaryFlags >> 7 & 1;
      dictionary.bitmapCodingContextUsed = !!(dictionaryFlags & 256);
      dictionary.bitmapCodingContextRetained = !!(dictionaryFlags & 512);
      dictionary.template = dictionaryFlags >> 10 & 3;
      dictionary.refinementTemplate = dictionaryFlags >> 12 & 1;
      position += 2;

      if (!dictionary.huffman) {
        atLength = dictionary.template === 0 ? 4 : 1;
        at = [];

        for (i = 0; i < atLength; i++) {
          at.push({
            x: (0, _core_utils.readInt8)(data, position),
            y: (0, _core_utils.readInt8)(data, position + 1)
          });
          position += 2;
        }

        dictionary.at = at;
      }

      if (dictionary.refinement && !dictionary.refinementTemplate) {
        at = [];

        for (i = 0; i < 2; i++) {
          at.push({
            x: (0, _core_utils.readInt8)(data, position),
            y: (0, _core_utils.readInt8)(data, position + 1)
          });
          position += 2;
        }

        dictionary.refinementAt = at;
      }

      dictionary.numberOfExportedSymbols = (0, _core_utils.readUint32)(data, position);
      position += 4;
      dictionary.numberOfNewSymbols = (0, _core_utils.readUint32)(data, position);
      position += 4;
      args = [dictionary, header.number, header.referredTo, data, position, end];
      break;

    case 6:
    case 7:
      const textRegion = {};
      textRegion.info = readRegionSegmentInformation(data, position);
      position += RegionSegmentInformationFieldLength;
      const textRegionSegmentFlags = (0, _core_utils.readUint16)(data, position);
      position += 2;
      textRegion.huffman = !!(textRegionSegmentFlags & 1);
      textRegion.refinement = !!(textRegionSegmentFlags & 2);
      textRegion.logStripSize = textRegionSegmentFlags >> 2 & 3;
      textRegion.stripSize = 1 << textRegion.logStripSize;
      textRegion.referenceCorner = textRegionSegmentFlags >> 4 & 3;
      textRegion.transposed = !!(textRegionSegmentFlags & 64);
      textRegion.combinationOperator = textRegionSegmentFlags >> 7 & 3;
      textRegion.defaultPixelValue = textRegionSegmentFlags >> 9 & 1;
      textRegion.dsOffset = textRegionSegmentFlags << 17 >> 27;
      textRegion.refinementTemplate = textRegionSegmentFlags >> 15 & 1;

      if (textRegion.huffman) {
        const textRegionHuffmanFlags = (0, _core_utils.readUint16)(data, position);
        position += 2;
        textRegion.huffmanFS = textRegionHuffmanFlags & 3;
        textRegion.huffmanDS = textRegionHuffmanFlags >> 2 & 3;
        textRegion.huffmanDT = textRegionHuffmanFlags >> 4 & 3;
        textRegion.huffmanRefinementDW = textRegionHuffmanFlags >> 6 & 3;
        textRegion.huffmanRefinementDH = textRegionHuffmanFlags >> 8 & 3;
        textRegion.huffmanRefinementDX = textRegionHuffmanFlags >> 10 & 3;
        textRegion.huffmanRefinementDY = textRegionHuffmanFlags >> 12 & 3;
        textRegion.huffmanRefinementSizeSelector = !!(textRegionHuffmanFlags & 0x4000);
      }

      if (textRegion.refinement && !textRegion.refinementTemplate) {
        at = [];

        for (i = 0; i < 2; i++) {
          at.push({
            x: (0, _core_utils.readInt8)(data, position),
            y: (0, _core_utils.readInt8)(data, position + 1)
          });
          position += 2;
        }

        textRegion.refinementAt = at;
      }

      textRegion.numberOfSymbolInstances = (0, _core_utils.readUint32)(data, position);
      position += 4;
      args = [textRegion, header.referredTo, data, position, end];
      break;

    case 16:
      const patternDictionary = {};
      const patternDictionaryFlags = data[position++];
      patternDictionary.mmr = !!(patternDictionaryFlags & 1);
      patternDictionary.template = patternDictionaryFlags >> 1 & 3;
      patternDictionary.patternWidth = data[position++];
      patternDictionary.patternHeight = data[position++];
      patternDictionary.maxPatternIndex = (0, _core_utils.readUint32)(data, position);
      position += 4;
      args = [patternDictionary, header.number, data, position, end];
      break;

    case 22:
    case 23:
      const halftoneRegion = {};
      halftoneRegion.info = readRegionSegmentInformation(data, position);
      position += RegionSegmentInformationFieldLength;
      const halftoneRegionFlags = data[position++];
      halftoneRegion.mmr = !!(halftoneRegionFlags & 1);
      halftoneRegion.template = halftoneRegionFlags >> 1 & 3;
      halftoneRegion.enableSkip = !!(halftoneRegionFlags & 8);
      halftoneRegion.combinationOperator = halftoneRegionFlags >> 4 & 7;
      halftoneRegion.defaultPixelValue = halftoneRegionFlags >> 7 & 1;
      halftoneRegion.gridWidth = (0, _core_utils.readUint32)(data, position);
      position += 4;
      halftoneRegion.gridHeight = (0, _core_utils.readUint32)(data, position);
      position += 4;
      halftoneRegion.gridOffsetX = (0, _core_utils.readUint32)(data, position) & 0xffffffff;
      position += 4;
      halftoneRegion.gridOffsetY = (0, _core_utils.readUint32)(data, position) & 0xffffffff;
      position += 4;
      halftoneRegion.gridVectorX = (0, _core_utils.readUint16)(data, position);
      position += 2;
      halftoneRegion.gridVectorY = (0, _core_utils.readUint16)(data, position);
      position += 2;
      args = [halftoneRegion, header.referredTo, data, position, end];
      break;

    case 38:
    case 39:
      const genericRegion = {};
      genericRegion.info = readRegionSegmentInformation(data, position);
      position += RegionSegmentInformationFieldLength;
      const genericRegionSegmentFlags = data[position++];
      genericRegion.mmr = !!(genericRegionSegmentFlags & 1);
      genericRegion.template = genericRegionSegmentFlags >> 1 & 3;
      genericRegion.prediction = !!(genericRegionSegmentFlags & 8);

      if (!genericRegion.mmr) {
        atLength = genericRegion.template === 0 ? 4 : 1;
        at = [];

        for (i = 0; i < atLength; i++) {
          at.push({
            x: (0, _core_utils.readInt8)(data, position),
            y: (0, _core_utils.readInt8)(data, position + 1)
          });
          position += 2;
        }

        genericRegion.at = at;
      }

      args = [genericRegion, data, position, end];
      break;

    case 48:
      const pageInfo = {
        width: (0, _core_utils.readUint32)(data, position),
        height: (0, _core_utils.readUint32)(data, position + 4),
        resolutionX: (0, _core_utils.readUint32)(data, position + 8),
        resolutionY: (0, _core_utils.readUint32)(data, position + 12)
      };

      if (pageInfo.height === 0xffffffff) {
        delete pageInfo.height;
      }

      const pageSegmentFlags = data[position + 16];
      (0, _core_utils.readUint16)(data, position + 17);
      pageInfo.lossless = !!(pageSegmentFlags & 1);
      pageInfo.refinement = !!(pageSegmentFlags & 2);
      pageInfo.defaultPixelValue = pageSegmentFlags >> 2 & 1;
      pageInfo.combinationOperator = pageSegmentFlags >> 3 & 3;
      pageInfo.requiresBuffer = !!(pageSegmentFlags & 32);
      pageInfo.combinationOperatorOverride = !!(pageSegmentFlags & 64);
      args = [pageInfo];
      break;

    case 49:
      break;

    case 50:
      break;

    case 51:
      break;

    case 53:
      args = [header.number, data, position, end];
      break;

    case 62:
      break;

    default:
      throw new Jbig2Error(`segment type ${header.typeName}(${header.type}) is not implemented`);
  }

  const callbackName = "on" + header.typeName;

  if (callbackName in visitor) {
    visitor[callbackName].apply(visitor, args);
  }
}

function processSegments(segments, visitor) {
  for (let i = 0, ii = segments.length; i < ii; i++) {
    processSegment(segments[i], visitor);
  }
}

function parseJbig2Chunks(chunks) {
  const visitor = new SimpleSegmentVisitor();

  for (let i = 0, ii = chunks.length; i < ii; i++) {
    const chunk = chunks[i];
    const segments = readSegments({}, chunk.data, chunk.start, chunk.end);
    processSegments(segments, visitor);
  }

  return visitor.buffer;
}

function parseJbig2(data) {
  throw new Error("Not implemented: parseJbig2");
}

class SimpleSegmentVisitor {
  onPageInformation(info) {
    this.currentPageInfo = info;
    const rowSize = info.width + 7 >> 3;
    const buffer = new Uint8ClampedArray(rowSize * info.height);

    if (info.defaultPixelValue) {
      buffer.fill(0xff);
    }

    this.buffer = buffer;
  }

  drawBitmap(regionInfo, bitmap) {
    const pageInfo = this.currentPageInfo;
    const width = regionInfo.width,
          height = regionInfo.height;
    const rowSize = pageInfo.width + 7 >> 3;
    const combinationOperator = pageInfo.combinationOperatorOverride ? regionInfo.combinationOperator : pageInfo.combinationOperator;
    const buffer = this.buffer;
    const mask0 = 128 >> (regionInfo.x & 7);
    let offset0 = regionInfo.y * rowSize + (regionInfo.x >> 3);
    let i, j, mask, offset;

    switch (combinationOperator) {
      case 0:
        for (i = 0; i < height; i++) {
          mask = mask0;
          offset = offset0;

          for (j = 0; j < width; j++) {
            if (bitmap[i][j]) {
              buffer[offset] |= mask;
            }

            mask >>= 1;

            if (!mask) {
              mask = 128;
              offset++;
            }
          }

          offset0 += rowSize;
        }

        break;

      case 2:
        for (i = 0; i < height; i++) {
          mask = mask0;
          offset = offset0;

          for (j = 0; j < width; j++) {
            if (bitmap[i][j]) {
              buffer[offset] ^= mask;
            }

            mask >>= 1;

            if (!mask) {
              mask = 128;
              offset++;
            }
          }

          offset0 += rowSize;
        }

        break;

      default:
        throw new Jbig2Error(`operator ${combinationOperator} is not supported`);
    }
  }

  onImmediateGenericRegion(region, data, start, end) {
    const regionInfo = region.info;
    const decodingContext = new DecodingContext(data, start, end);
    const bitmap = decodeBitmap(region.mmr, regionInfo.width, regionInfo.height, region.template, region.prediction, null, region.at, decodingContext);
    this.drawBitmap(regionInfo, bitmap);
  }

  onImmediateLosslessGenericRegion() {
    this.onImmediateGenericRegion(...arguments);
  }

  onSymbolDictionary(dictionary, currentSegment, referredSegments, data, start, end) {
    let huffmanTables, huffmanInput;

    if (dictionary.huffman) {
      huffmanTables = getSymbolDictionaryHuffmanTables(dictionary, referredSegments, this.customTables);
      huffmanInput = new Reader(data, start, end);
    }

    let symbols = this.symbols;

    if (!symbols) {
      this.symbols = symbols = {};
    }

    const inputSymbols = [];

    for (const referredSegment of referredSegments) {
      const referredSymbols = symbols[referredSegment];

      if (referredSymbols) {
        inputSymbols.push(...referredSymbols);
      }
    }

    const decodingContext = new DecodingContext(data, start, end);
    symbols[currentSegment] = decodeSymbolDictionary(dictionary.huffman, dictionary.refinement, inputSymbols, dictionary.numberOfNewSymbols, dictionary.numberOfExportedSymbols, huffmanTables, dictionary.template, dictionary.at, dictionary.refinementTemplate, dictionary.refinementAt, decodingContext, huffmanInput);
  }

  onImmediateTextRegion(region, referredSegments, data, start, end) {
    const regionInfo = region.info;
    let huffmanTables, huffmanInput;
    const symbols = this.symbols;
    const inputSymbols = [];

    for (const referredSegment of referredSegments) {
      const referredSymbols = symbols[referredSegment];

      if (referredSymbols) {
        inputSymbols.push(...referredSymbols);
      }
    }

    const symbolCodeLength = (0, _core_utils.log2)(inputSymbols.length);

    if (region.huffman) {
      huffmanInput = new Reader(data, start, end);
      huffmanTables = getTextRegionHuffmanTables(region, referredSegments, this.customTables, inputSymbols.length, huffmanInput);
    }

    const decodingContext = new DecodingContext(data, start, end);
    const bitmap = decodeTextRegion(region.huffman, region.refinement, regionInfo.width, regionInfo.height, region.defaultPixelValue, region.numberOfSymbolInstances, region.stripSize, inputSymbols, symbolCodeLength, region.transposed, region.dsOffset, region.referenceCorner, region.combinationOperator, huffmanTables, region.refinementTemplate, region.refinementAt, decodingContext, region.logStripSize, huffmanInput);
    this.drawBitmap(regionInfo, bitmap);
  }

  onImmediateLosslessTextRegion() {
    this.onImmediateTextRegion(...arguments);
  }

  onPatternDictionary(dictionary, currentSegment, data, start, end) {
    let patterns = this.patterns;

    if (!patterns) {
      this.patterns = patterns = {};
    }

    const decodingContext = new DecodingContext(data, start, end);
    patterns[currentSegment] = decodePatternDictionary(dictionary.mmr, dictionary.patternWidth, dictionary.patternHeight, dictionary.maxPatternIndex, dictionary.template, decodingContext);
  }

  onImmediateHalftoneRegion(region, referredSegments, data, start, end) {
    const patterns = this.patterns[referredSegments[0]];
    const regionInfo = region.info;
    const decodingContext = new DecodingContext(data, start, end);
    const bitmap = decodeHalftoneRegion(region.mmr, patterns, region.template, regionInfo.width, regionInfo.height, region.defaultPixelValue, region.enableSkip, region.combinationOperator, region.gridWidth, region.gridHeight, region.gridOffsetX, region.gridOffsetY, region.gridVectorX, region.gridVectorY, decodingContext);
    this.drawBitmap(regionInfo, bitmap);
  }

  onImmediateLosslessHalftoneRegion() {
    this.onImmediateHalftoneRegion(...arguments);
  }

  onTables(currentSegment, data, start, end) {
    let customTables = this.customTables;

    if (!customTables) {
      this.customTables = customTables = {};
    }

    customTables[currentSegment] = decodeTablesSegment(data, start, end);
  }

}

class HuffmanLine {
  constructor(lineData) {
    if (lineData.length === 2) {
      this.isOOB = true;
      this.rangeLow = 0;
      this.prefixLength = lineData[0];
      this.rangeLength = 0;
      this.prefixCode = lineData[1];
      this.isLowerRange = false;
    } else {
      this.isOOB = false;
      this.rangeLow = lineData[0];
      this.prefixLength = lineData[1];
      this.rangeLength = lineData[2];
      this.prefixCode = lineData[3];
      this.isLowerRange = lineData[4] === "lower";
    }
  }

}

class HuffmanTreeNode {
  constructor(line) {
    this.children = [];

    if (line) {
      this.isLeaf = true;
      this.rangeLength = line.rangeLength;
      this.rangeLow = line.rangeLow;
      this.isLowerRange = line.isLowerRange;
      this.isOOB = line.isOOB;
    } else {
      this.isLeaf = false;
    }
  }

  buildTree(line, shift) {
    const bit = line.prefixCode >> shift & 1;

    if (shift <= 0) {
      this.children[bit] = new HuffmanTreeNode(line);
    } else {
      let node = this.children[bit];

      if (!node) {
        this.children[bit] = node = new HuffmanTreeNode(null);
      }

      node.buildTree(line, shift - 1);
    }
  }

  decodeNode(reader) {
    if (this.isLeaf) {
      if (this.isOOB) {
        return null;
      }

      const htOffset = reader.readBits(this.rangeLength);
      return this.rangeLow + (this.isLowerRange ? -htOffset : htOffset);
    }

    const node = this.children[reader.readBit()];

    if (!node) {
      throw new Jbig2Error("invalid Huffman data");
    }

    return node.decodeNode(reader);
  }

}

class HuffmanTable {
  constructor(lines, prefixCodesDone) {
    if (!prefixCodesDone) {
      this.assignPrefixCodes(lines);
    }

    this.rootNode = new HuffmanTreeNode(null);

    for (let i = 0, ii = lines.length; i < ii; i++) {
      const line = lines[i];

      if (line.prefixLength > 0) {
        this.rootNode.buildTree(line, line.prefixLength - 1);
      }
    }
  }

  decode(reader) {
    return this.rootNode.decodeNode(reader);
  }

  assignPrefixCodes(lines) {
    const linesLength = lines.length;
    let prefixLengthMax = 0;

    for (let i = 0; i < linesLength; i++) {
      prefixLengthMax = Math.max(prefixLengthMax, lines[i].prefixLength);
    }

    const histogram = new Uint32Array(prefixLengthMax + 1);

    for (let i = 0; i < linesLength; i++) {
      histogram[lines[i].prefixLength]++;
    }

    let currentLength = 1,
        firstCode = 0,
        currentCode,
        currentTemp,
        line;
    histogram[0] = 0;

    while (currentLength <= prefixLengthMax) {
      firstCode = firstCode + histogram[currentLength - 1] << 1;
      currentCode = firstCode;
      currentTemp = 0;

      while (currentTemp < linesLength) {
        line = lines[currentTemp];

        if (line.prefixLength === currentLength) {
          line.prefixCode = currentCode;
          currentCode++;
        }

        currentTemp++;
      }

      currentLength++;
    }
  }

}

function decodeTablesSegment(data, start, end) {
  const flags = data[start];
  const lowestValue = (0, _core_utils.readUint32)(data, start + 1) & 0xffffffff;
  const highestValue = (0, _core_utils.readUint32)(data, start + 5) & 0xffffffff;
  const reader = new Reader(data, start + 9, end);
  const prefixSizeBits = (flags >> 1 & 7) + 1;
  const rangeSizeBits = (flags >> 4 & 7) + 1;
  const lines = [];
  let prefixLength,
      rangeLength,
      currentRangeLow = lowestValue;

  do {
    prefixLength = reader.readBits(prefixSizeBits);
    rangeLength = reader.readBits(rangeSizeBits);
    lines.push(new HuffmanLine([currentRangeLow, prefixLength, rangeLength, 0]));
    currentRangeLow += 1 << rangeLength;
  } while (currentRangeLow < highestValue);

  prefixLength = reader.readBits(prefixSizeBits);
  lines.push(new HuffmanLine([lowestValue - 1, prefixLength, 32, 0, "lower"]));
  prefixLength = reader.readBits(prefixSizeBits);
  lines.push(new HuffmanLine([highestValue, prefixLength, 32, 0]));

  if (flags & 1) {
    prefixLength = reader.readBits(prefixSizeBits);
    lines.push(new HuffmanLine([prefixLength, 0]));
  }

  return new HuffmanTable(lines, false);
}

const standardTablesCache = {};

function getStandardTable(number) {
  let table = standardTablesCache[number];

  if (table) {
    return table;
  }

  let lines;

  switch (number) {
    case 1:
      lines = [[0, 1, 4, 0x0], [16, 2, 8, 0x2], [272, 3, 16, 0x6], [65808, 3, 32, 0x7]];
      break;

    case 2:
      lines = [[0, 1, 0, 0x0], [1, 2, 0, 0x2], [2, 3, 0, 0x6], [3, 4, 3, 0xe], [11, 5, 6, 0x1e], [75, 6, 32, 0x3e], [6, 0x3f]];
      break;

    case 3:
      lines = [[-256, 8, 8, 0xfe], [0, 1, 0, 0x0], [1, 2, 0, 0x2], [2, 3, 0, 0x6], [3, 4, 3, 0xe], [11, 5, 6, 0x1e], [-257, 8, 32, 0xff, "lower"], [75, 7, 32, 0x7e], [6, 0x3e]];
      break;

    case 4:
      lines = [[1, 1, 0, 0x0], [2, 2, 0, 0x2], [3, 3, 0, 0x6], [4, 4, 3, 0xe], [12, 5, 6, 0x1e], [76, 5, 32, 0x1f]];
      break;

    case 5:
      lines = [[-255, 7, 8, 0x7e], [1, 1, 0, 0x0], [2, 2, 0, 0x2], [3, 3, 0, 0x6], [4, 4, 3, 0xe], [12, 5, 6, 0x1e], [-256, 7, 32, 0x7f, "lower"], [76, 6, 32, 0x3e]];
      break;

    case 6:
      lines = [[-2048, 5, 10, 0x1c], [-1024, 4, 9, 0x8], [-512, 4, 8, 0x9], [-256, 4, 7, 0xa], [-128, 5, 6, 0x1d], [-64, 5, 5, 0x1e], [-32, 4, 5, 0xb], [0, 2, 7, 0x0], [128, 3, 7, 0x2], [256, 3, 8, 0x3], [512, 4, 9, 0xc], [1024, 4, 10, 0xd], [-2049, 6, 32, 0x3e, "lower"], [2048, 6, 32, 0x3f]];
      break;

    case 7:
      lines = [[-1024, 4, 9, 0x8], [-512, 3, 8, 0x0], [-256, 4, 7, 0x9], [-128, 5, 6, 0x1a], [-64, 5, 5, 0x1b], [-32, 4, 5, 0xa], [0, 4, 5, 0xb], [32, 5, 5, 0x1c], [64, 5, 6, 0x1d], [128, 4, 7, 0xc], [256, 3, 8, 0x1], [512, 3, 9, 0x2], [1024, 3, 10, 0x3], [-1025, 5, 32, 0x1e, "lower"], [2048, 5, 32, 0x1f]];
      break;

    case 8:
      lines = [[-15, 8, 3, 0xfc], [-7, 9, 1, 0x1fc], [-5, 8, 1, 0xfd], [-3, 9, 0, 0x1fd], [-2, 7, 0, 0x7c], [-1, 4, 0, 0xa], [0, 2, 1, 0x0], [2, 5, 0, 0x1a], [3, 6, 0, 0x3a], [4, 3, 4, 0x4], [20, 6, 1, 0x3b], [22, 4, 4, 0xb], [38, 4, 5, 0xc], [70, 5, 6, 0x1b], [134, 5, 7, 0x1c], [262, 6, 7, 0x3c], [390, 7, 8, 0x7d], [646, 6, 10, 0x3d], [-16, 9, 32, 0x1fe, "lower"], [1670, 9, 32, 0x1ff], [2, 0x1]];
      break;

    case 9:
      lines = [[-31, 8, 4, 0xfc], [-15, 9, 2, 0x1fc], [-11, 8, 2, 0xfd], [-7, 9, 1, 0x1fd], [-5, 7, 1, 0x7c], [-3, 4, 1, 0xa], [-1, 3, 1, 0x2], [1, 3, 1, 0x3], [3, 5, 1, 0x1a], [5, 6, 1, 0x3a], [7, 3, 5, 0x4], [39, 6, 2, 0x3b], [43, 4, 5, 0xb], [75, 4, 6, 0xc], [139, 5, 7, 0x1b], [267, 5, 8, 0x1c], [523, 6, 8, 0x3c], [779, 7, 9, 0x7d], [1291, 6, 11, 0x3d], [-32, 9, 32, 0x1fe, "lower"], [3339, 9, 32, 0x1ff], [2, 0x0]];
      break;

    case 10:
      lines = [[-21, 7, 4, 0x7a], [-5, 8, 0, 0xfc], [-4, 7, 0, 0x7b], [-3, 5, 0, 0x18], [-2, 2, 2, 0x0], [2, 5, 0, 0x19], [3, 6, 0, 0x36], [4, 7, 0, 0x7c], [5, 8, 0, 0xfd], [6, 2, 6, 0x1], [70, 5, 5, 0x1a], [102, 6, 5, 0x37], [134, 6, 6, 0x38], [198, 6, 7, 0x39], [326, 6, 8, 0x3a], [582, 6, 9, 0x3b], [1094, 6, 10, 0x3c], [2118, 7, 11, 0x7d], [-22, 8, 32, 0xfe, "lower"], [4166, 8, 32, 0xff], [2, 0x2]];
      break;

    case 11:
      lines = [[1, 1, 0, 0x0], [2, 2, 1, 0x2], [4, 4, 0, 0xc], [5, 4, 1, 0xd], [7, 5, 1, 0x1c], [9, 5, 2, 0x1d], [13, 6, 2, 0x3c], [17, 7, 2, 0x7a], [21, 7, 3, 0x7b], [29, 7, 4, 0x7c], [45, 7, 5, 0x7d], [77, 7, 6, 0x7e], [141, 7, 32, 0x7f]];
      break;

    case 12:
      lines = [[1, 1, 0, 0x0], [2, 2, 0, 0x2], [3, 3, 1, 0x6], [5, 5, 0, 0x1c], [6, 5, 1, 0x1d], [8, 6, 1, 0x3c], [10, 7, 0, 0x7a], [11, 7, 1, 0x7b], [13, 7, 2, 0x7c], [17, 7, 3, 0x7d], [25, 7, 4, 0x7e], [41, 8, 5, 0xfe], [73, 8, 32, 0xff]];
      break;

    case 13:
      lines = [[1, 1, 0, 0x0], [2, 3, 0, 0x4], [3, 4, 0, 0xc], [4, 5, 0, 0x1c], [5, 4, 1, 0xd], [7, 3, 3, 0x5], [15, 6, 1, 0x3a], [17, 6, 2, 0x3b], [21, 6, 3, 0x3c], [29, 6, 4, 0x3d], [45, 6, 5, 0x3e], [77, 7, 6, 0x7e], [141, 7, 32, 0x7f]];
      break;

    case 14:
      lines = [[-2, 3, 0, 0x4], [-1, 3, 0, 0x5], [0, 1, 0, 0x0], [1, 3, 0, 0x6], [2, 3, 0, 0x7]];
      break;

    case 15:
      lines = [[-24, 7, 4, 0x7c], [-8, 6, 2, 0x3c], [-4, 5, 1, 0x1c], [-2, 4, 0, 0xc], [-1, 3, 0, 0x4], [0, 1, 0, 0x0], [1, 3, 0, 0x5], [2, 4, 0, 0xd], [3, 5, 1, 0x1d], [5, 6, 2, 0x3d], [9, 7, 4, 0x7d], [-25, 7, 32, 0x7e, "lower"], [25, 7, 32, 0x7f]];
      break;

    default:
      throw new Jbig2Error(`standard table B.${number} does not exist`);
  }

  for (let i = 0, ii = lines.length; i < ii; i++) {
    lines[i] = new HuffmanLine(lines[i]);
  }

  table = new HuffmanTable(lines, true);
  standardTablesCache[number] = table;
  return table;
}

class Reader {
  constructor(data, start, end) {
    this.data = data;
    this.start = start;
    this.end = end;
    this.position = start;
    this.shift = -1;
    this.currentByte = 0;
  }

  readBit() {
    if (this.shift < 0) {
      if (this.position >= this.end) {
        throw new Jbig2Error("end of data while reading bit");
      }

      this.currentByte = this.data[this.position++];
      this.shift = 7;
    }

    const bit = this.currentByte >> this.shift & 1;
    this.shift--;
    return bit;
  }

  readBits(numBits) {
    let result = 0,
        i;

    for (i = numBits - 1; i >= 0; i--) {
      result |= this.readBit() << i;
    }

    return result;
  }

  byteAlign() {
    this.shift = -1;
  }

  next() {
    if (this.position >= this.end) {
      return -1;
    }

    return this.data[this.position++];
  }

}

function getCustomHuffmanTable(index, referredTo, customTables) {
  let currentIndex = 0;

  for (let i = 0, ii = referredTo.length; i < ii; i++) {
    const table = customTables[referredTo[i]];

    if (table) {
      if (index === currentIndex) {
        return table;
      }

      currentIndex++;
    }
  }

  throw new Jbig2Error("can't find custom Huffman table");
}

function getTextRegionHuffmanTables(textRegion, referredTo, customTables, numberOfSymbols, reader) {
  const codes = [];

  for (let i = 0; i <= 34; i++) {
    const codeLength = reader.readBits(4);
    codes.push(new HuffmanLine([i, codeLength, 0, 0]));
  }

  const runCodesTable = new HuffmanTable(codes, false);
  codes.length = 0;

  for (let i = 0; i < numberOfSymbols;) {
    const codeLength = runCodesTable.decode(reader);

    if (codeLength >= 32) {
      let repeatedLength, numberOfRepeats, j;

      switch (codeLength) {
        case 32:
          if (i === 0) {
            throw new Jbig2Error("no previous value in symbol ID table");
          }

          numberOfRepeats = reader.readBits(2) + 3;
          repeatedLength = codes[i - 1].prefixLength;
          break;

        case 33:
          numberOfRepeats = reader.readBits(3) + 3;
          repeatedLength = 0;
          break;

        case 34:
          numberOfRepeats = reader.readBits(7) + 11;
          repeatedLength = 0;
          break;

        default:
          throw new Jbig2Error("invalid code length in symbol ID table");
      }

      for (j = 0; j < numberOfRepeats; j++) {
        codes.push(new HuffmanLine([i, repeatedLength, 0, 0]));
        i++;
      }
    } else {
      codes.push(new HuffmanLine([i, codeLength, 0, 0]));
      i++;
    }
  }

  reader.byteAlign();
  const symbolIDTable = new HuffmanTable(codes, false);
  let customIndex = 0,
      tableFirstS,
      tableDeltaS,
      tableDeltaT;

  switch (textRegion.huffmanFS) {
    case 0:
    case 1:
      tableFirstS = getStandardTable(textRegion.huffmanFS + 6);
      break;

    case 3:
      tableFirstS = getCustomHuffmanTable(customIndex, referredTo, customTables);
      customIndex++;
      break;

    default:
      throw new Jbig2Error("invalid Huffman FS selector");
  }

  switch (textRegion.huffmanDS) {
    case 0:
    case 1:
    case 2:
      tableDeltaS = getStandardTable(textRegion.huffmanDS + 8);
      break;

    case 3:
      tableDeltaS = getCustomHuffmanTable(customIndex, referredTo, customTables);
      customIndex++;
      break;

    default:
      throw new Jbig2Error("invalid Huffman DS selector");
  }

  switch (textRegion.huffmanDT) {
    case 0:
    case 1:
    case 2:
      tableDeltaT = getStandardTable(textRegion.huffmanDT + 11);
      break;

    case 3:
      tableDeltaT = getCustomHuffmanTable(customIndex, referredTo, customTables);
      customIndex++;
      break;

    default:
      throw new Jbig2Error("invalid Huffman DT selector");
  }

  if (textRegion.refinement) {
    throw new Jbig2Error("refinement with Huffman is not supported");
  }

  return {
    symbolIDTable,
    tableFirstS,
    tableDeltaS,
    tableDeltaT
  };
}

function getSymbolDictionaryHuffmanTables(dictionary, referredTo, customTables) {
  let customIndex = 0,
      tableDeltaHeight,
      tableDeltaWidth;

  switch (dictionary.huffmanDHSelector) {
    case 0:
    case 1:
      tableDeltaHeight = getStandardTable(dictionary.huffmanDHSelector + 4);
      break;

    case 3:
      tableDeltaHeight = getCustomHuffmanTable(customIndex, referredTo, customTables);
      customIndex++;
      break;

    default:
      throw new Jbig2Error("invalid Huffman DH selector");
  }

  switch (dictionary.huffmanDWSelector) {
    case 0:
    case 1:
      tableDeltaWidth = getStandardTable(dictionary.huffmanDWSelector + 2);
      break;

    case 3:
      tableDeltaWidth = getCustomHuffmanTable(customIndex, referredTo, customTables);
      customIndex++;
      break;

    default:
      throw new Jbig2Error("invalid Huffman DW selector");
  }

  let tableBitmapSize, tableAggregateInstances;

  if (dictionary.bitmapSizeSelector) {
    tableBitmapSize = getCustomHuffmanTable(customIndex, referredTo, customTables);
    customIndex++;
  } else {
    tableBitmapSize = getStandardTable(1);
  }

  if (dictionary.aggregationInstancesSelector) {
    tableAggregateInstances = getCustomHuffmanTable(customIndex, referredTo, customTables);
  } else {
    tableAggregateInstances = getStandardTable(1);
  }

  return {
    tableDeltaHeight,
    tableDeltaWidth,
    tableBitmapSize,
    tableAggregateInstances
  };
}

function readUncompressedBitmap(reader, width, height) {
  const bitmap = [];

  for (let y = 0; y < height; y++) {
    const row = new Uint8Array(width);
    bitmap.push(row);

    for (let x = 0; x < width; x++) {
      row[x] = reader.readBit();
    }

    reader.byteAlign();
  }

  return bitmap;
}

function decodeMMRBitmap(input, width, height, endOfBlock) {
  const params = {
    K: -1,
    Columns: width,
    Rows: height,
    BlackIs1: true,
    EndOfBlock: endOfBlock
  };
  const decoder = new _ccitt.CCITTFaxDecoder(input, params);
  const bitmap = [];
  let currentByte,
      eof = false;

  for (let y = 0; y < height; y++) {
    const row = new Uint8Array(width);
    bitmap.push(row);
    let shift = -1;

    for (let x = 0; x < width; x++) {
      if (shift < 0) {
        currentByte = decoder.readNextChar();

        if (currentByte === -1) {
          currentByte = 0;
          eof = true;
        }

        shift = 7;
      }

      row[x] = currentByte >> shift & 1;
      shift--;
    }
  }

  if (endOfBlock && !eof) {
    const lookForEOFLimit = 5;

    for (let i = 0; i < lookForEOFLimit; i++) {
      if (decoder.readNextChar() === -1) {
        break;
      }
    }
  }

  return bitmap;
}

class Jbig2Image {
  parseChunks(chunks) {
    return parseJbig2Chunks(chunks);
  }

  parse(data) {
    throw new Error("Not implemented: Jbig2Image.parse");
  }

}

exports.Jbig2Image = Jbig2Image;