Draco Bitstream Specification (Draft)

Traversal_DecodeSymbol() {
  symbol_buffer_.DecodeLeastSignificantBits32(1, &symbol);                   bits1
  if (symbol != TOPOLOGY_C) {
    symbol_buffer_.DecodeLeastSignificantBits32(2, &symbol_suffix);          bits2
    symbol |= (symbol_suffix << 1);
  }
  return symbol
}

DecodeAttributeSeam(int attribute) {
  return attribute_connectivity_decoders_[attribute].DecodeNextBit();
}

EdgeBreakerTraversalValence_Start(num_vertices, num_attribute_data) {
  out_buffer = EdgebreakerTraversal_Start()
  num_split_symbols                                                          I32
  mode == 0                                                                  I8
  num_vertices_ += num_split_symbols
  vertex_valences_ init to 0
  vertex_valences_.resize(num_vertices_, 0);
  min_valence_ = 2;
  max_valence_ = 7;
  num_unique_valences = 6 (max_valence_ - min_valence_ + 1)
  for (i = 0; i < num_unique_valences; ++i) {
    DecodeVarint<UI32>(&num_symbols, out_buffer)
    If (num_symbols > 0) {
      DecodeSymbols(num_symbols, out_buffer, &context_symbols_[i])
    }
    context_counters_[i] = num_symbols
  }
  return out_buffer;
}

TraversalValence_DecodeSymbol() {
  if (active_context_ != -1) {
    symbol_id  = context_symbols_[active_context_]
                                                      [--context_counters_[active_context_]]
    last_symbol_ = edge_breaker_symbol_to_topology_id[symbol_id]
  } else {
    last_symbol_ = Traversal_DecodeSymbol()
  }
  return last_symbol_
}

TraversalValence_NewActiveCornerReached(corner) {
  switch (last_symbol_) {
    case TOPOLOGY_C:
    case TOPOLOGY_S:
      vertex_valences_[ct(next)] += 1;
      vertex_valences_[ct(prev)] += 1;
      break;
    case TOPOLOGY_R:
      vertex_valences_[corner] += 1;
      vertex_valences_[ct(next)] += 1;
      vertex_valences_[ct(prev)] += 2;
      break;
    case TOPOLOGY_L:
      vertex_valences_[corner] += 1;
      vertex_valences_[ct(next)] += 2;
      vertex_valences_[ct(prev)] += 1;
      break;
    case TOPOLOGY_E:
      vertex_valences_[corner] += 2;
      vertex_valences_[ct(next)] += 2;
      vertex_valences_[ct(prev)] += 2;
      break;
  }
  valence = vertex_valences_[ct(next)]
  valence = max(valence, min_valence_)
  valence = min(valence, max_valence_)
  active_context_ = (valence - min_valence_);
}

TraversalValence_MergeVertices(dest, source) {
  vertex_valences_[dest] += vertex_valences_[source];
}

DecodeAttributesDecoderData(buffer) {
  num_attributes                                                             I32
  point_attribute_ids_.resize(num_attributes);
  for (i = 0; i < num_attributes; ++i) {
    att_type                                                                 UI8
    data_type                                                                UI8
    components_count                                                         UI8
    normalized                                                               UI8
    custom_id                                                                UI16
    Initialize GeometryAttribute ga
    att_id = pc->AddAttribute(new PointAttribute(ga));
    point_attribute_ids_[i] = att_id;
}

DecodeAttributesDecoderData(buffer) {
  AttributesDecoder_DecodeAttributesDecoderData(buffer)
  sequential_decoders_.resize(num_attributes());
  for (i = 0; i < num_attributes(); ++i) {
    decoder_type                                                             UI8
    sequential_decoders_[i] = CreateSequentialDecoder(decoder_type);
    sequential_decoders_[i]->Initialize(decoder(), GetAttributeId(i))
}

DecodeAttributes(buffer) {
  sequencer_->GenerateSequence(&point_ids_)
  for (i = 0; i < num_attributes(); ++i) {
    pa = decoder()->point_cloud()->attribute(GetAttributeId(i));
    sequencer_->UpdatePointToAttributeIndexMapping(pa)
  }
  for (i = 0; i < num_attributes(); ++i) {
    sequential_decoders_[i]->Decode(point_ids_, buffer)
    //SequentialAttributeDecoder_Decode()
  }
}

CreateSequentialDecoder(type) {
  switch (type) {
    case SEQUENTIAL_ATTRIBUTE_ENCODER_GENERIC:
      return new SequentialAttributeDecoder()
    case SEQUENTIAL_ATTRIBUTE_ENCODER_INTEGER:
      return new SequentialIntegerAttributeDecoder()
    case SEQUENTIAL_ATTRIBUTE_ENCODER_QUANTIZATION:
      return new SequentialQuantizationAttributeDecoder()
    case SEQUENTIAL_ATTRIBUTE_ENCODER_NORMALS:
      return new SequentialNormalAttributeDecoder()
  }
}

Initialize(...) {
  // Init some members
}

DecodeValues(const std::vector<PointIndex> &point_ids) {
  num_values = point_ids.size();
  entry_size = attribute_->byte_stride();
  std::unique_ptr<uint8_t[]> value_data_ptr(new uint8_t[entry_size]);
  out_byte_pos = 0;
  for (i = 0; i < num_values; ++i) {
   value_data                                                         UI8 * entry_size
    attribute_->buffer()->Write(out_byte_pos, value_data, entry_size);
    out_byte_pos += entry_size;
  }
}

Initialize(...) {
  SequentialAttributeDecoder_Initialize()
}

DecodeValues(point_ids) {
  prediction_scheme_method                                                   I8
  if (prediction_scheme_method != PREDICTION_NONE) {
    prediction_transform_type                                                I8
    prediction_scheme_ = CreateIntPredictionScheme(...)
  }
  if (prediction_scheme_) {
  }
  DecodeIntegerValues(point_ids)
  //SequentialQuantizationAttributeDecoder_DecodeIntegerValues()
  //StoreValues()
  DequantizeValues(num_values)
}

DecodeIntegerValues(point_ids) {
  compressed                                                                 UI8
  if (compressed) {
    DecodeSymbols(..., values_.data())
  } else {
  // TODO
  }
  if (!prediction_scheme_->AreCorrectionsPositive()) {
    ConvertSymbolsToSignedInts(...)
  }
  if (prediction_scheme_) {
    prediction_scheme_->DecodePredictionData(buffer)
    // DecodeTransformData(buffer)
    if (!values_.empty()) {
      prediction_scheme_->Decode(values_.data(), &values_[0],
                                      values_.size(), num_components, point_ids.data())
      // MeshPredictionSchemeParallelogram_Decode()
}

Initialize(...) {
  SequentialIntegerAttributeDecoder_Initialize()
}

DecodeIntegerValues(point_ids) {
  // DecodeQuantizedDataInfo()
  num_components = attribute()->components_count();
  for (i = 0; i < num_components; ++i) {
    min_value_[i]                                                            F32
  }
  max_value_dif_                                                             F32
  quantization_bits_                                                         UI8
  SequentialIntegerAttributeDecoder::DecodeIntegerValues()
}

DequantizeValues(num_values) {
  max_quantized_value = (1 << (quantization_bits_)) - 1;
  num_components = attribute()->components_count();
  entry_size = sizeof(float) * num_components;
  quant_val_id = 0;
  out_byte_pos = 0;
  for (i = 0; i < num_values; ++i) {
    for (c = 0; c < num_components; ++c) {
      value = dequantizer.DequantizeFloat(values()->at(quant_val_id++));
      value = value + min_value_[c];
      att_val[c] = value;
    }
    attribute()->buffer()->Write(out_byte_pos, att_val.get(), entry_size);
    out_byte_pos += entry_size;
  }
}

ComputeOriginalValue(const DataTypeT *predicted_vals,
                                   const CorrTypeT *corr_vals,
                                   DataTypeT *out_original_vals, int val_id) {
  for (i = 0; i < num_components_; ++i) {
    out_original_vals[i] = predicted_vals[i] + corr_vals[val_id + i];
  }
}

DecodeTransformData(buffer) {
  min_value_                                                                 DT
  max_value_                                                                 DT
}

ComputeOriginalValue(const DataTypeT *predicted_vals,
                                   const CorrTypeT *corr_vals,
                                   DataTypeT *out_original_vals, int val_id) {
  clamped_vals = ClampPredictedValue(predicted_vals);
  ComputeOriginalValue(clamped_vals, corr_vals, out_original_vals, val_id)
  // PredictionSchemeTransform_ComputeOriginalValue()
  for (i = 0; i < this->num_components(); ++i) {
    if (out_original_vals[i] > max_value_) {
      out_original_vals[i] -= max_dif_;
    } else if (out_original_vals[i] < min_value_) {
      out_original_vals[i] += max_dif_;
    }
}

ClampPredictedValue(const DataTypeT *predicted_val) {
  for (i = 0; i < this->num_components(); ++i) {
    clamped_value_[i] = min(predicted_val[i], max_value_)
    clamped_value_[i] = max(predicted_val[i], min_value_)
  }
  return &clamped_value_[0];
}

Decode(...) {
  this->transform().InitializeDecoding(num_components);
  // restore the first value
  this->transform().ComputeOriginalValue(pred_vals.get(),
                                       in_corr, out_data, 0);
  // PredictionSchemeWrapTransform_ComputeOriginalValue()
  corner_map_size = this->mesh_data().data_to_corner_map()->size();
  for (p = 1; p < corner_map_size; ++p) {
    corner_id = this->mesh_data().data_to_corner_map()->at(p);
    dst_offset = p * num_components;
    b= ComputeParallelogramPrediction(p, corner_id, table,
                                        *vertex_to_data_map, out_data,
                                        num_components, pred_vals.get())
    if (!b) {
      src_offset = (p - 1) * num_components;
      this->transform().ComputeOriginalValue(out_data + src_offset, in_corr,
                                             out_data + dst_offset, dst_offset);
      // PredictionSchemeWrapTransform_ComputeOriginalValue()
    } else {
      this->transform().ComputeOriginalValue(pred_vals.get(), in_corr,
                                             out_data + dst_offset, dst_offset);
      // PredictionSchemeWrapTransform_ComputeOriginalValue()
    }
  }
}

ComputeParallelogramPrediction(...) {
  oci = table->Opposite(ci);
  vert_opp = vertex_to_data_map[table->Vertex(ci)];
  vert_next = vertex_to_data_map[table->Vertex(table->Next(ci))];
  vert_prev = vertex_to_data_map[table->Vertex(table->Previous(ci))];
  if (vert_opp < data_entry_id && vert_next < data_entry_id &&
      vert_prev < data_entry_id) {
    v_opp_off = vert_opp * num_components;
    v_next_off = vert_next * num_components;
    v_prev_off = vert_prev * num_components;
    for (c = 0; c < num_components; ++c) {
      out_prediction[c] = (in_data[v_next_off + c] + in_data[v_prev_off + c]) -
                          in_data[v_opp_off + c];
    }
    Return true;
  }
  return false;
}

IsFaceVisited(corner_id) {
  if (corner_id < 0)
    return true
  return is_face_visited_[corner_id / 3];
}

MarkFaceVisited(face_id) {
  is_face_visited_[face_id] = true;
}

IsVertexVisited(vert_id) {
  return is_vertex_visited_[vert_id];
}

MarkVertexVisited(vert_id) {
  is_vertex_visited_[vert_id] = true;
}

OnNewVertexVisited(vertex, corner) {
  point_id = mesh_->face(corner / 3)[corner % 3];
  sequencer_->AddPointId(point_id);
  // Keep track of visited corners.
  encoding_data_->encoded_attribute_value_index_to_corner_map.push_back(corner);
  encoding_data_
        ->vertex_to_encoded_attribute_value_index_map[vertex] =
        encoding_data_->num_values;
  encoding_data_->num_values++;
}

TraverseFromCorner(corner_id) {
  if (processor_.IsFaceVisited(corner_id))
    return
  corner_traversal_stack_.clear();
  corner_traversal_stack_.push_back(corner_id);
  next_vert = corner_table_->Vertex(corner_table_->Next(corner_id));
  prev_vert = corner_table_->Vertex(corner_table_->Previous(corner_id));
  if (!processor_.IsVertexVisited(next_vert)) {
    processor_.MarkVertexVisited(next_vert);
    traversal_observer_.OnNewVertexVisited(next_vert,
                                        corner_table_->Next(corner_id));
  }
  if (!processor_.IsVertexVisited(prev_vert)) {
    processor_.MarkVertexVisited(prev_vert);
    traversal_observer_.OnNewVertexVisited(prev_vert,
                                        corner_table_->Previous(corner_id));
  }
  while (!corner_traversal_stack_.empty()) {
    corner_id = corner_traversal_stack_.back();
    face_id =corner_id / 3;
    if (processor_.IsFaceVisited(face_id)) {
      corner_traversal_stack_.pop_back();
      continue
    }
    while(true) {
      face_id = corner_id / 3;
      processor_.MarkFaceVisited(face_id);
      traversal_observer_.OnNewFaceVisited(face_id);
      vert_id = corner_table_->Vertex(corner_id);
      on_boundary = corner_table_->IsOnBoundary(vert_id);
      if (!processor_.IsVertexVisited(vert_id)) {
        processor_.MarkVertexVisited(vert_id);
        traversal_observer_.OnNewVertexVisited(vert_id, corner_id);
        if (!on_boundary) {
          corner_id = corner_table_->GetRightCorner(corner_id);
          continue;
        }
      }
      // The current vertex has been already visited or it was on a boundary.
      right_corner_id = corner_table_->GetRightCorner(corner_id);
      left_corner_id = corner_table_->GetLeftCorner(corner_id);
      right_face_id((right_corner_id < 0 ? -1 : right_corner_id / 3));
      left_face_id((left_corner_id < 0 ? -1 : left_corner_id / 3));
      if (processor_.IsFaceVisited(right_face_id)) {
        if (processor_.IsFaceVisited(left_face_id)) {
          corner_traversal_stack_.pop_back();
          break; // Break from while(true) loop
        } else {
          corner_id = left_corner_id;
        }
      } else {
        if (processor_.IsFaceVisited(left_face_id)) {
          corner_id = right_corner_id;
       } else {
          // Split the traversal.
          corner_traversal_stack_.back() = left_corner_id;
          corner_traversal_stack_.push_back(right_corner_id);
          break; // Break from while(true) loop
        }
      }
    }
  }
}

GenerateSequenceInternal() {
  traverser_.OnTraversalStart();
   If (corner_order_) {
    // TODO
  } else {
    int32_t num_faces = traverser_.corner_table()->num_faces();
    for (i = 0; i < num_faces; ++i) {
      ProcessCorner(3 * i)
    }
  }
  traverser_.OnTraversalEnd();
}

ProcessCorner(corner_id) {
  traverser_.TraverseFromCorner(corner_id);
}

UpdatePointToAttributeIndexMapping(PointAttribute *attribute) {
  corner_table = traverser_.corner_table();
  attribute->SetExplicitMapping(mesh_->num_points());
  num_faces = mesh_->num_faces();
  num_points = mesh_->num_points();
  for (f = 0; f < num_faces; ++f) {
    face = mesh_->face(f);
    for (p = 0; p < 3; ++p) {
      point_id = face[p];
      vert_id = corner_table->Vertex(3 * f + p);
      att_entry_id(
            encoding_data_
                ->vertex_to_encoded_attribute_value_index_map[vert_id]);
      attribute->SetPointMapEntry(point_id, att_entry_id);
    }
  }
}

AddPointId(point_id) {
  out_point_ids_->push_back(point_id);
}

Opposite(corner) {
  return opposite_corners_[corner];
}

Next(corner) {
  return LocalIndex(++corner) ? corner : corner - 3;
}

Previous(corner) {
  return LocalIndex(corner) ? corner - 1 : corner + 2;
}

Vertex(corner) {
  faces_[Face(corner)][LocalIndex(corner)];
}

Face(corner) {
  return corner / 3;
}

LocalIndex(corner) {
  return corner % 3;
}

num_vertices() {
  return vertex_corners_.size();
}

num_corners() {
  return faces_.size() * 3;
}

num_faces() {
  return faces_.size();
}

bool IsOnBoundary(vert) {
  corner = LeftMostCorner(vert);
  if (SwingLeft(corner) < 0)
    return true;
  return false;
}

SwingRight(corner) {
  return Previous(Opposite(Previous(corner)));
}

SwingLeft(corner) {
  return Next(Opposite(Next(corner)));
}

GetLeftCorner(corner_id) {
  if (corner_id < 0)
     return kInvalidCornerIndex;
  return Opposite(Previous(corner_id));
}

GetRightCorner(corner_id) {
  if (corner_id < 0)
     return kInvalidCornerIndex;
  return Opposite(Next(corner_id));
}

SetOppositeCorner(corner_id, pp_corner_id) {
  opposite_corners_[corner_id] = opp_corner_id;
}

MapCornerToVertex(corner_id, vert_id) {
  face = Face(corner_id);
  faces_[face][LocalIndex(corner_id)] = vert_id;
  if (vert_id >= 0) {
    vertex_corners_[vert_id] = corner_id;
  }
}

UpdateVertexToCornerMap(vert) {
  first_c = vertex_corners_[vert];
  if (first_c < 0)
    return;
  act_c = SwingLeft(first_c);
  c = first_c;
  while (act_c >= 0 && act_c != first_c) {
    c = act_c;
    act_c = SwingLeft(act_c);
  }
  if (act_c != first_c) {
    vertex_corners_[vert] = c;
  }
}

LeftMostCorner(v) {
  return vertex_corners_[v];
}

MakeVertexIsolated(vert) {
  vertex_corners_[vert] = kInvalidCornerIndex;
}

bool IsCornerOnSeam(corner) {
  return is_vertex_on_seam_[corner_table_->Vertex(corner)];
}

AddSeamEdge(c) {
  MarkSeam(c)
  opp_corner = corner_table_->Opposite(c);
  if (opp_corner >= 0) {
    no_interior_seams_ = false;
    MarkSeam(opp_corner)
  }
}

MarkSeam(c) {
  is_edge_on_seam_[c] = true;
  is_vertex_on_seam_[corner_table_->Vertex(corner_table_->Next(c))] = true;
  is_vertex_on_seam_[corner_table_->Vertex(corner_table_->Previous(c))
                         ] = true;
}

RecomputeVertices() {
  // in code RecomputeVerticesInternal<false>(nullptr, nullptr)
  num_new_vertices = 0;
  for (v = 0; v < corner_table_->num_vertices(); ++v) {
    c = corner_table_->LeftMostCorner(v);
    if (c < 0)
      continue;
    first_vert_id(num_new_vertices++);
    vertex_to_attribute_entry_id_map_.push_back(first_vert_id);
    first_c = c;
    if (is_vertex_on_seam_[v]) {
      act_c = SwingLeft(first_c);
      while (act_c >= 0) {
        first_c = act_c;
        act_c = SwingLeft(act_c);
      }
    }
    corner_to_vertex_map_[first_c] =first_vert_id;
    vertex_to_left_most_corner_map_.push_back(first_c);
    act_c = corner_table_->SwingRight(first_c);
    while (act_c >= 0 && act_c != first_c) {
      if (is_edge_on_seam_[corner_table_->Next(act_c)]) {
        // in code IsCornerOppositeToSeamEdge()
        first_vert_id = AttributeValueIndex(num_new_vertices++);
        vertex_to_attribute_entry_id_map_.push_back(first_vert_id);
        vertex_to_left_most_corner_map_.push_back(act_c);
      }
      corner_to_vertex_map_[act_c] = first_vert_id;
      act_c = corner_table_->SwingRight(act_c);
    }
  }
}

DecodeSymbols(num_symbols, out_buffer, out_values) {
  scheme                                                                     UI8
  If (scheme == 0) {
    DecodeTaggedSymbols<>(num_symbols, src_buffer, out_values)
  } else if (scheme == 1) {
    DecodeRawSymbols<>(num_symbols, src_buffer, out_values)
  }
}

DecodeTaggedSymbols() {
  FIXME
}

DecodeRawSymbols() {
  max_bit_length                                                             UI8
  DecodeRawSymbolsInternal(max_bit_length, out_values)
  return symbols
}

DecodeRawSymbolsInternal(max_bit_length, out_values) {
  decoder = CreateRansSymbolDecoder(max_bit_length)
  decoder.StartDecoding()
  // RansSymbolDecoder_StartDecoding
  for (i = 0; i < num_values; ++i) {
    out_values[i] = decoder.DecodeSymbol()
    // RansSymbolDecoder_DecodeSymbol
  }
}

CreateRansSymbolDecoder(max_bit_length) {
  rans_precision_bits  = (3 * max_bit_length) / 2;
  rans_precision_bits = min(rans_precision_bits, 20)
  rans_precision_bits = max(rans_precision_bits, 12)
  rans_precision = 1 << rans_precision_bits_;
  l_rans_base = rans_precision * 4;
  num_symbols_                                                               UI32
  for (i = 0; i < num_symbols_; ++i) {
    prob_data                                                                UI8
    if ((prob_data & 3) == 3) {
      offset = prob_data >> 2
      for (j = 0; j < offset + 1; ++j) {
        probability_table_[i + j] = 0;
      }
      i += offset;
    } else {
      prob = prob_data >> 2
      for (j = 0; j < token; ++j) {
        eb                                                                   UI8
        prob = prob | (eb << (8 * (j + 1) - 2)
      }
      probability_table_[i] = prob;
    }
  }
  rans_build_look_up_table()
}

RansSymbolDecoder_StartDecoding() {
  bytes_encoded                                                              UI64
  buffer                                                                     bytes_encoded * UI8
  rans_read_init(buffer, bytes_encoded)
}

RansSymbolDecoder_DecodeSymbol() {
  ans_.rans_read()
}

ans_read_init(struct AnsDecoder *const ans, const uint8_t *const buf,
                       int offset) {
  x = buf[offset - 1] >> 6
  If (x == 0) {
    ans->buf_offset = offset - 1;
    ans->state = buf[offset - 1] & 0x3F;
  } else if (x == 1) {
    ans->buf_offset = offset - 2;
    ans->state = mem_get_le16(buf + offset - 2) & 0x3FFF;
  } else if (x == 2) {
    ans->buf_offset = offset - 3;
    ans->state = mem_get_le24(buf + offset - 3) & 0x3FFFFF;
  } else if (x == 3) {
   // x == 3 implies this byte is a superframe marker
    return 1;
  }
  ans->state += l_base;
}

int rabs_desc_read(struct AnsDecoder *ans, AnsP8 p0) {
  AnsP8 p = ans_p8_precision - p0;
  if (ans->state < l_base) {
    ans->state = ans->state * io_base + ans->buf[--ans->buf_offset];
  }
  x = ans->state;
  quot = x / ans_p8_precision;
  rem = x % ans_p8_precision;
  xn = quot * p;
  val = rem < p;
  if (val) {
    ans->state = xn + rem;
  } else {
    ans->state = x - xn - p;
  }
  return val;
}

rans_read_init(UI8 *buf, int offset) {
  ans_.buf = buf;
  x = buf[offset - 1] >> 6
  If (x == 0) {
    ans_.buf_offset = offset - 1;
    ans_.state = buf[offset - 1] & 0x3F;
  } else if (x == 1) {
    ans_.buf_offset = offset - 2;
    ans_.state = mem_get_le16(buf + offset - 2) & 0x3FFF;
  } else if (x == 2) {
    ans_.buf_offset = offset - 3;
    ans_.state = mem_get_le24(buf + offset - 3) & 0x3FFFFF;
  } else if (x == 3) {
    ans_.buf_offset = offset - 4;
    ans_.state = mem_get_le32(buf + offset - 4) & 0x3FFFFFFF;
  }
  ans_.state += l_rans_base;
}

rans_build_look_up_table() {
  cum_prob = 0
  act_prob = 0
  for (i = 0; i < num_symbols; ++i) {
    probability_table_[i].prob = token_probs[i];
    probability_table_[i].cum_prob = cum_prob;
    cum_prob += token_probs[i];
    for (j = act_prob; j < cum_prob; ++j) {
      Lut_table_[j] = i
    }
    act_prob = cum_prob
}

rans_read() {
  while (ans_.state < l_rans_base) {
    ans_.state = ans_.state * io_base + ans_.buf[--ans_.buf_offset];
  }
  quo = ans_.state / rans_precision;
  rem = ans_.state % rans_precision;
  sym = fetch_sym()
  ans_.state = quo * sym.prob + rem - sym.cum_prob;
  return sym.val;
}

fetch_sym() {
  symbol = lut_table[rem]
  out->val = symbol
  out->prob = probability_table_[symbol].prob;
  out->cum_prob = probability_table_[symbol].cum_prob;
}

RansBitDecoder_StartDecoding(DecoderBuffer *source_buffer) {
  prob_zero_                                                                 UI8
  size                                                                       UI32
  buffer_                                                                    size * UI8
  ans_read_init(&ans_decoder_, buffer_, size)
}

DecodeNextBit() {
  uint8_t bit = rabs_desc_read(&ans_decoder_, prob_zero_);
  return bit > 0;
}

DecodeVarint<IT>() {
  If (std::is_unsigned<IT>::value) {
    in                                                                       UI8
    If (in & (1 << 7)) {
      out = DecodeVarint<IT>()
      out = (out << 7) | (in & ((1 << 7) - 1))
    } else {
      typename std::make_unsigned<IT>::type UIT;
      out = DecodeVarint<UIT>()
      out = ConvertSymbolToSignedInt(out)
    }
    return out;
}

ConvertSymbolToSignedInt() {
  abs_val = val >> 1
  If (val & 1 == 0) {
    return abs_val
  } else {
    signed_val = -abs_val - 1
  }
  return signed_val
}

decode_connectivity() {
  num_faces                                                       I32
  num_points                                                      I32
  connectivity _method                                            UI8
  If (connectivity _method == 0) {
    // TODO
  } else {
    loop num_faces {
      If (num_points < 256) {
        face[]                                                    UI8
      } else if (num_points < (1 << 16)) {
        face[]                                                    UI16
      } else {
        face[]                                                    UI32
      }
    }
  }
}