skgangaEkam/node_modules/hdr-histogram-js/assembly/packedarray/PackedArrayContext.ts

/*
 * This is a AssemblyScript port of the original Java version, which was written by
 * Gil Tene as described in
 * https://github.com/HdrHistogram/HdrHistogram
 * and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

import { bitCount } from "./bitcount";

/**
 * A packed-value, sparse array context used for storing 64 bit signed values.
 *
 * An array context is optimised for tracking sparsely set (as in mostly zeros) values that tend to not make
 * use pof the full 64 bit value range even when they are non-zero. The array context's internal representation
 * is such that the packed value at each virtual array index may be represented by 0-8 bytes of actual storage.
 *
 * An array context encodes the packed values in 8 "set trees" with each set tree representing one byte of the
 * packed value at the virtual index in question. The {@link #getPackedIndex(int, int, boolean)} method is used
 * to look up the byte-index corresponding to the given (set tree) value byte of the given virtual index, and can
 * be used to add entries to represent that byte as needed. As a succesful {@link #getPackedIndex(int, int, boolean)}
 * may require a resizing of the array, it can throw a {@link ResizeError} to indicate that the requested
 * packed index cannot be found or added without a resize of the physical storage.
 *
 */
export const MINIMUM_INITIAL_PACKED_ARRAY_CAPACITY = 16;
const MAX_SUPPORTED_PACKED_COUNTS_ARRAY_LENGTH = Math.pow(2, 13) - 1; //(Short.MAX_VALUE / 4);  TODO ALEX why ???
const SET_0_START_INDEX = 0;
const NUMBER_OF_SETS = 8;
const LEAF_LEVEL_SHIFT = 3;
const NON_LEAF_ENTRY_SLOT_INDICATORS_OFFSET = 0;
const NON_LEAF_ENTRY_HEADER_SIZE_IN_SHORTS = <u16>1;
const PACKED_ARRAY_GROWTH_INCREMENT = 16;
const PACKED_ARRAY_GROWTH_FRACTION_POW2 = 4;

export class PackedArrayContext {
  public readonly isPacked: boolean;
  physicalLength: i32;

  private array: ArrayBuffer;
  private byteArray: Uint8Array;
  private shortArray: Uint16Array;
  private longArray: Uint64Array;
  private populatedShortLength: i32 = 0;
  private virtualLength: i32;
  private topLevelShift: i32 = i32.MAX_VALUE; // Make it non-sensical until properly initialized.

  constructor(virtualLength: i32, initialPhysicalLength: i32) {
    this.physicalLength = <i32>(
      Math.max(initialPhysicalLength, MINIMUM_INITIAL_PACKED_ARRAY_CAPACITY)
    );
    this.isPacked =
      this.physicalLength <= MAX_SUPPORTED_PACKED_COUNTS_ARRAY_LENGTH;
    if (!this.isPacked) {
      this.physicalLength = virtualLength;
    }
    this.array = new ArrayBuffer(this.physicalLength * 8);
    this.initArrayViews(this.array);
    this.init(virtualLength);
  }

  private initArrayViews(array: ArrayBuffer): void {
    this.byteArray = Uint8Array.wrap(array);
    this.shortArray = Uint16Array.wrap(array);
    this.longArray = Uint64Array.wrap(array);
  }

  private init(virtualLength: i32): void {
    if (!this.isPacked) {
      // Deal with non-packed context init:
      this.virtualLength = virtualLength;
      return;
    }

    this.populatedShortLength = SET_0_START_INDEX + 8;

    // Populate empty root entries, and point to them from the root indexes:
    for (let i = 0; i < NUMBER_OF_SETS; i++) {
      this.setAtShortIndex(SET_0_START_INDEX + i, 0);
    }

    this.setVirtualLength(virtualLength);
  }

  public clear(): void {
    this.byteArray.fill(0);
    this.init(this.virtualLength);
  }

  public copyAndIncreaseSize(
    newPhysicalArrayLength: i32,
    newVirtualArrayLength: i32
  ): PackedArrayContext {
    const ctx = new PackedArrayContext(
      newVirtualArrayLength,
      newPhysicalArrayLength
    );
    if (this.isPacked) {
      ctx.populateEquivalentEntriesWithEntriesFromOther(this);
    }
    return ctx;
  }

  public getPopulatedShortLength(): i32 {
    return this.populatedShortLength;
  }

  public getPopulatedLongLength(): i32 {
    return (this.getPopulatedShortLength() + 3) >> 2; // round up
  }

  public setAtByteIndex(byteIndex: i32, value: u8): void {
    this.byteArray[byteIndex] = value;
  }

  public getAtByteIndex(byteIndex: i32): u8 {
    return this.byteArray[byteIndex];
  }

  /**
   * add a byte value to a current byte value in the array
   * @param byteIndex index of byte value to add to
   * @param valueToAdd byte value to add
   * @return the afterAddValue. ((afterAddValue & 0x100) != 0) indicates a carry.
   */
  public addAtByteIndex(byteIndex: i32, valueToAdd: u8): u8 {
    const newValue = this.byteArray[byteIndex] + valueToAdd;
    this.byteArray[byteIndex] = newValue;
    return newValue;
  }

  setPopulatedLongLength(newPopulatedLongLength: i32): void {
    this.populatedShortLength = newPopulatedLongLength << 2;
  }

  public getVirtualLength(): i32 {
    return this.virtualLength;
  }
  public length(): i32 {
    return this.physicalLength;
  }

  setAtShortIndex(shortIndex: i32, value: u16): void {
    this.shortArray[shortIndex] = value;
  }

  setAtLongIndex(longIndex: i32, value: u64): void {
    this.longArray[longIndex] = value;
  }

  getAtShortIndex(shortIndex: i32): u16 {
    return this.shortArray[shortIndex];
  }

  getIndexAtShortIndex(shortIndex: i32): u16 {
    return this.shortArray[shortIndex];
  }

  setPackedSlotIndicators(entryIndex: i32, newPackedSlotIndicators: u16): void {
    this.setAtShortIndex(
      entryIndex + NON_LEAF_ENTRY_SLOT_INDICATORS_OFFSET,
      newPackedSlotIndicators
    );
  }

  getPackedSlotIndicators(entryIndex: i32): u16 {
    return (
      this.shortArray[entryIndex + NON_LEAF_ENTRY_SLOT_INDICATORS_OFFSET] &
      0xffff
    );
  }

  private getIndexAtEntrySlot(entryIndex: i32, slot: i32): u16 {
    return this.getAtShortIndex(
      entryIndex + NON_LEAF_ENTRY_HEADER_SIZE_IN_SHORTS + slot
    );
  }

  setIndexAtEntrySlot(entryIndex: i32, slot: i32, newIndexValue: u16): void {
    this.setAtShortIndex(
      entryIndex + NON_LEAF_ENTRY_HEADER_SIZE_IN_SHORTS + slot,
      newIndexValue
    );
  }

  private expandArrayIfNeeded(entryLengthInLongs: i32): void {
    const currentLength = this.length();
    if (currentLength < this.getPopulatedLongLength() + entryLengthInLongs) {
      const growthIncrement = <i32>(
        max(
          max(entryLengthInLongs, PACKED_ARRAY_GROWTH_INCREMENT),
          this.getPopulatedLongLength() >> PACKED_ARRAY_GROWTH_FRACTION_POW2
        )
      );
      this.resizeArray(currentLength + growthIncrement);
    }
  }

  private newEntry(entryLengthInShorts: i32): i32 {
    // Add entry at the end of the array:

    const newEntryIndex = this.populatedShortLength;
    this.expandArrayIfNeeded((entryLengthInShorts >> 2) + 1);
    this.populatedShortLength = newEntryIndex + entryLengthInShorts;

    for (let i = 0; i < entryLengthInShorts; i++) {
      this.setAtShortIndex(newEntryIndex + i, <u16>-1); // Poison value -1. Must be overriden before reads
    }
    return newEntryIndex;
  }

  private newLeafEntry(): i32 {
    // Add entry at the end of the array:
    let newEntryIndex = this.getPopulatedLongLength();
    this.expandArrayIfNeeded(1);

    this.setPopulatedLongLength(newEntryIndex + 1);

    this.setAtLongIndex(newEntryIndex, 0);

    return newEntryIndex;
  }

  /**
   * Consolidate entry with previous entry version if one exists
   *
   * @param entryIndex The shortIndex of the entry to be consolidated
   * @param previousVersionIndex the index of the previous version of the entry
   */
  private consolidateEntry(entryIndex: i32, previousVersionIndex: i32): void {
    const previousVersionPackedSlotsIndicators = this.getPackedSlotIndicators(
      previousVersionIndex
    );
    // Previous version exists, needs consolidation

    const packedSlotsIndicators = this.getPackedSlotIndicators(entryIndex);

    const insertedSlotMask =
      packedSlotsIndicators ^ previousVersionPackedSlotsIndicators; // the only bit that differs
    const slotsBelowBitNumber = packedSlotsIndicators & (insertedSlotMask - 1);
    const insertedSlotIndex = bitCount(slotsBelowBitNumber);
    const numberOfSlotsInEntry = bitCount(packedSlotsIndicators);

    // Copy the entry slots from previous version, skipping the newly inserted slot in the target:
    let sourceSlot = 0;
    for (
      let targetSlot: u8 = 0;
      targetSlot < numberOfSlotsInEntry;
      targetSlot++
    ) {
      if (targetSlot !== insertedSlotIndex) {
        const indexAtSlot = this.getIndexAtEntrySlot(
          previousVersionIndex,
          sourceSlot
        );
        if (indexAtSlot !== 0) {
          this.setIndexAtEntrySlot(entryIndex, targetSlot, indexAtSlot);
        }
        sourceSlot++;
      }
    }
  }

  /**
   * Expand entry as indicated.
   *
   * @param existingEntryIndex the index of the entry
   * @param entryPointerIndex  index to the slot pointing to the entry (needs to be fixed up)
   * @param insertedSlotIndex  realtive [packed] index of slot being inserted into entry
   * @param insertedSlotMask   mask value fo slot being inserted
   * @param nextLevelIsLeaf    the level below this one is a leaf level
   * @return the updated index of the entry (-1 if epansion failed due to conflict)
   * @throws RetryException if expansion fails due to concurrent conflict, and caller should try again.
   */
  expandEntry(
    existingEntryIndex: i32,
    entryPointerIndex: i32,
    insertedSlotIndex: i32,
    insertedSlotMask: i32,
    nextLevelIsLeaf: boolean
  ): i32 {
    let packedSlotIndicators =
      (<i32>this.getAtShortIndex(existingEntryIndex)) & 0xffff;
    packedSlotIndicators |= insertedSlotMask;
    const numberOfslotsInExpandedEntry = bitCount(packedSlotIndicators);

    if (insertedSlotIndex >= <i32>numberOfslotsInExpandedEntry) {
      throw new Error(
        "inserted slot index is out of range given provided masks"
      );
    }

    const expandedEntryLength =
      numberOfslotsInExpandedEntry + NON_LEAF_ENTRY_HEADER_SIZE_IN_SHORTS;

    // Create new next-level entry to refer to from slot at this level:
    let indexOfNewNextLevelEntry = 0;
    if (nextLevelIsLeaf) {
      indexOfNewNextLevelEntry = this.newLeafEntry(); // Establish long-index to new leaf entry
    } else {
      // TODO: Optimize this by creating the whole sub-tree here, rather than a step that will immediaterly expand

      // Create a new 1 word (empty, no slots set) entry for the next level:
      indexOfNewNextLevelEntry = this.newEntry(
        NON_LEAF_ENTRY_HEADER_SIZE_IN_SHORTS
      ); // Establish short-index to new leaf entry

      this.setPackedSlotIndicators(indexOfNewNextLevelEntry, 0);
    }

    const insertedSlotValue = indexOfNewNextLevelEntry;

    const expandedEntryIndex = this.newEntry(expandedEntryLength);

    // populate the packed indicators word:
    this.setPackedSlotIndicators(expandedEntryIndex, <u16>packedSlotIndicators);

    // Populate the inserted slot with the index of the new next level entry:
    this.setIndexAtEntrySlot(
      expandedEntryIndex,
      insertedSlotIndex,
      <u16>insertedSlotValue
    );

    this.setAtShortIndex(entryPointerIndex, <u16>expandedEntryIndex);
    this.consolidateEntry(expandedEntryIndex, existingEntryIndex);

    return expandedEntryIndex;
  }

  //
  //   ######   ######## ########    ##     ##    ###    ##             ## #### ##    ## ########  ######## ##     ##
  //  ##    ##  ##          ##       ##     ##   ## ##   ##            ##   ##  ###   ## ##     ## ##        ##   ##
  //  ##        ##          ##       ##     ##  ##   ##  ##           ##    ##  ####  ## ##     ## ##         ## ##
  //  ##   #### ######      ##       ##     ## ##     ## ##          ##     ##  ## ## ## ##     ## ######      ###
  //  ##    ##  ##          ##        ##   ##  ######### ##         ##      ##  ##  #### ##     ## ##         ## ##
  //  ##    ##  ##          ##         ## ##   ##     ## ##        ##       ##  ##   ### ##     ## ##        ##   ##
  //   ######   ########    ##          ###    ##     ## ######## ##       #### ##    ## ########  ######## ##     ##
  //

  getRootEntry(setNumber: i32, insertAsNeeded: boolean = false): i32 {
    const entryPointerIndex = SET_0_START_INDEX + setNumber;
    let entryIndex = <i32>this.getIndexAtShortIndex(entryPointerIndex);

    if (entryIndex == 0) {
      if (!insertAsNeeded) {
        return 0; // Index does not currently exist in packed array;
      }

      entryIndex = this.newEntry(NON_LEAF_ENTRY_HEADER_SIZE_IN_SHORTS);
      // Create a new empty (no slots set) entry for the next level:
      this.setPackedSlotIndicators(entryIndex, 0);

      this.setAtShortIndex(entryPointerIndex, <u16>entryIndex);
    }
    return entryIndex;
  }

  /**
   * Get the byte-index (into the packed array) corresponding to a given (set tree) value byte of given virtual index.
   * Inserts new set tree nodes as needed if indicated.
   *
   * @param setNumber      The set tree number (0-7, 0 corresponding with the LSByte set tree)
   * @param virtualIndex   The virtual index into the PackedArray
   * @param insertAsNeeded If true, will insert new set tree nodes as needed if they do not already exist
   * @return the byte-index corresponding to the given (set tree) value byte of the given virtual index
   */
  getPackedIndex(
    setNumber: i32,
    virtualIndex: i32,
    insertAsNeeded: boolean
  ): i32 {
    if (virtualIndex >= this.virtualLength) {
      throw new Error(
        `Attempting access at index ${virtualIndex}, beyond virtualLength ${this.virtualLength}`
      );
    }

    let entryPointerIndex = SET_0_START_INDEX + setNumber; // TODO init needed ?
    let entryIndex = this.getRootEntry(setNumber, insertAsNeeded);
    if (entryIndex == 0) {
      return -1; // Index does not currently exist in packed array;
    }

    // Work down the levels of non-leaf entries:
    for (
      let indexShift = this.topLevelShift;
      indexShift >= LEAF_LEVEL_SHIFT;
      indexShift -= 4
    ) {
      const nextLevelIsLeaf = indexShift === LEAF_LEVEL_SHIFT;
      // Target is a packedSlotIndicators entry
      const packedSlotIndicators = this.getPackedSlotIndicators(entryIndex);
      const slotBitNumber = (virtualIndex >>> indexShift) & 0xf;
      const slotMask = 1 << slotBitNumber;
      const slotsBelowBitNumber = packedSlotIndicators & (slotMask - 1);
      const slotNumber = bitCount(slotsBelowBitNumber);

      if ((packedSlotIndicators & slotMask) === 0) {
        // The entryIndex slot does not have the contents we want
        if (!insertAsNeeded) {
          return -1; // Index does not currently exist in packed array;
        }

        // Expand the entry, adding the index to new entry at the proper slot:
        entryIndex = this.expandEntry(
          entryIndex,
          entryPointerIndex,
          slotNumber,
          slotMask,
          nextLevelIsLeaf
        );
      }

      // Next level's entry pointer index is in the appropriate slot in in the entries array in this entry:
      entryPointerIndex =
        entryIndex + NON_LEAF_ENTRY_HEADER_SIZE_IN_SHORTS + slotNumber;

      entryIndex = this.getIndexAtShortIndex(entryPointerIndex);
    }

    // entryIndex is the long-index of a leaf entry that contains the value byte for the given set

    const byteIndex = (entryIndex << 3) + (virtualIndex & 0x7); // Determine byte index offset within leaf entry
    return byteIndex;
  }

  determineTopLevelShiftForVirtualLength(virtualLength: i32): i32 {
    const sizeMagnitude = <i32>ceil(Math.log2(virtualLength));
    const eightsSizeMagnitude = sizeMagnitude - 3;
    let multipleOfFourSizeMagnitude =
      <i32>ceil(<f64>eightsSizeMagnitude / 4.0) * 4;
    multipleOfFourSizeMagnitude = max(multipleOfFourSizeMagnitude, 8);
    const topLevelShiftNeeded = multipleOfFourSizeMagnitude - 4 + 3;
    return topLevelShiftNeeded;
  }

  setVirtualLength(virtualLength: i32): void {
    if (!this.isPacked) {
      throw new Error(
        "Should never be adjusting the virtual size of a non-packed context"
      );
    }
    this.topLevelShift = this.determineTopLevelShiftForVirtualLength(
      virtualLength
    );
    this.virtualLength = virtualLength;
  }

  getTopLevelShift(): i32 {
    return this.topLevelShift;
  }

  //
  //  ##     ##         ########   #######  ########  ##     ## ##          ###    ######## ########
  //   ##   ##          ##     ## ##     ## ##     ## ##     ## ##         ## ##      ##    ##
  //    ## ##           ##     ## ##     ## ##     ## ##     ## ##        ##   ##     ##    ##
  //     ###    ####### ########  ##     ## ########  ##     ## ##       ##     ##    ##    ######
  //    ## ##           ##        ##     ## ##        ##     ## ##       #########    ##    ##
  //   ##   ##          ##        ##     ## ##        ##     ## ##       ##     ##    ##    ##
  //  ##     ##         ##         #######  ##         #######  ######## ##     ##    ##    ########
  //

  public resizeArray(newLength: i32): void {
    const tmp = new Uint8Array(newLength * 8);
    tmp.set(this.byteArray);
    this.array = tmp.buffer;
    this.initArrayViews(this.array);
    this.physicalLength = newLength;
  }

  private populateEquivalentEntriesWithEntriesFromOther(
    other: PackedArrayContext
  ): void {
    if (this.virtualLength < other.getVirtualLength()) {
      throw new Error("Cannot populate array of smaller virtual length");
    }

    for (let i = 0; i < NUMBER_OF_SETS; i++) {
      const otherEntryIndex = other.getAtShortIndex(SET_0_START_INDEX + i);
      if (otherEntryIndex == 0) continue; // No tree to duplicate
      let entryIndexPointer = SET_0_START_INDEX + i;
      for (let i = this.topLevelShift; i > other.topLevelShift; i -= 4) {
        // for each inserted level:
        // Allocate entry in other:
        const sizeOfEntry = NON_LEAF_ENTRY_HEADER_SIZE_IN_SHORTS + 1;
        const newEntryIndex = this.newEntry(sizeOfEntry);

        // Link new level in.
        this.setAtShortIndex(entryIndexPointer, <u16>newEntryIndex);
        // Populate new level entry, use pointer to slot 0 as place to populate under:
        this.setPackedSlotIndicators(newEntryIndex, 0x1); // Slot 0 populated
        entryIndexPointer =
          newEntryIndex + NON_LEAF_ENTRY_HEADER_SIZE_IN_SHORTS; // Where the slot 0 index goes.
      }
      this.copyEntriesAtLevelFromOther(
        other,
        otherEntryIndex,
        entryIndexPointer,
        other.topLevelShift
      );
    }
  }

  private copyEntriesAtLevelFromOther(
    other: PackedArrayContext,
    otherLevelEntryIndex: i32,
    levelEntryIndexPointer: i32,
    otherIndexShift: i32
  ): void {
    const nextLevelIsLeaf = otherIndexShift == LEAF_LEVEL_SHIFT;
    const packedSlotIndicators = other.getPackedSlotIndicators(
      otherLevelEntryIndex
    );
    const numberOfSlots = bitCount(packedSlotIndicators);
    const sizeOfEntry = NON_LEAF_ENTRY_HEADER_SIZE_IN_SHORTS + numberOfSlots;
    const entryIndex = this.newEntry(sizeOfEntry);

    this.setAtShortIndex(levelEntryIndexPointer, <u16>entryIndex);
    this.setAtShortIndex(
      entryIndex + NON_LEAF_ENTRY_SLOT_INDICATORS_OFFSET,
      packedSlotIndicators
    );

    for (let i: u8 = 0; i < numberOfSlots; i++) {
      if (nextLevelIsLeaf) {
        // Make leaf in other:
        const leafEntryIndex = this.newLeafEntry();

        this.setIndexAtEntrySlot(entryIndex, i, <u16>leafEntryIndex);

        // OPTIM
        // avoid iteration on all the values of the source ctx
        const otherNextLevelEntryIndex = other.getIndexAtEntrySlot(
          otherLevelEntryIndex,
          i
        );
        this.longArray[leafEntryIndex] =
          other.longArray[otherNextLevelEntryIndex];
      } else {
        const otherNextLevelEntryIndex = other.getIndexAtEntrySlot(
          otherLevelEntryIndex,
          i
        );
        this.copyEntriesAtLevelFromOther(
          other,
          otherNextLevelEntryIndex,
          entryIndex + NON_LEAF_ENTRY_HEADER_SIZE_IN_SHORTS + i,
          otherIndexShift - 4
        );
      }
    }
  }

  getAtUnpackedIndex(index: i32): u64 {
    return this.longArray[index];
  }

  setAtUnpackedIndex(index: i32, newValue: u64): void {
    this.longArray[index] = newValue;
  }

  lazysetAtUnpackedIndex(index: i32, newValue: u64): void {
    this.longArray[index] = newValue;
  }

  incrementAndGetAtUnpackedIndex(index: i32): u64 {
    this.longArray[index]++;
    return this.longArray[index];
  }

  addAndGetAtUnpackedIndex(index: i32, valueToAdd: u64): u64 {
    this.longArray[index] += valueToAdd;
    return this.longArray[index];
  }

  //
  //   ########  #######           ######  ######## ########  #### ##    ##  ######
  //      ##    ##     ##         ##    ##    ##    ##     ##  ##  ###   ## ##    ##
  //      ##    ##     ##         ##          ##    ##     ##  ##  ####  ## ##
  //      ##    ##     ## #######  ######     ##    ########   ##  ## ## ## ##   ####
  //      ##    ##     ##               ##    ##    ##   ##    ##  ##  #### ##    ##
  //      ##    ##     ##         ##    ##    ##    ##    ##   ##  ##   ### ##    ##
  //      ##     #######           ######     ##    ##     ## #### ##    ##  ######
  //

  private nonLeafEntryToString(
    entryIndex: i32,
    indexShift: i32,
    indentLevel: i32
  ): string {
    let output = "";
    for (let i = 0; i < indentLevel; i++) {
      output += "  ";
    }
    const packedSlotIndicators = this.getPackedSlotIndicators(entryIndex);
    output +=
      "slotIndiators: 0x" +
      toHex(packedSlotIndicators) +
      ", prevVersionIndex: 0: [ ";

    const numberOfslotsInEntry = bitCount(packedSlotIndicators);
    for (let i: u8 = 0; i < numberOfslotsInEntry; i++) {
      output += this.getIndexAtEntrySlot(entryIndex, i).toString();
      if (i < numberOfslotsInEntry - 1) {
        output += ", ";
      }
    }
    output += " ] (indexShift = " + indexShift.toString() + ")\n";
    const nextLevelIsLeaf = indexShift == LEAF_LEVEL_SHIFT;
    for (let i: u8 = 0; i < numberOfslotsInEntry; i++) {
      const nextLevelEntryIndex = this.getIndexAtEntrySlot(entryIndex, i);
      if (nextLevelIsLeaf) {
        output += this.leafEntryToString(nextLevelEntryIndex, indentLevel + 4);
      } else {
        output += this.nonLeafEntryToString(
          nextLevelEntryIndex,
          indexShift - 4,
          indentLevel + 4
        );
      }
    }

    return output;
  }

  private leafEntryToString(entryIndex: i32, indentLevel: i32): string {
    let output = "";
    for (let i = 0; i < indentLevel; i++) {
      output += "  ";
    }

    output += "Leaf bytes : ";
    for (let i = 0; i < 8; i++) {
      output += "0x" + toHex(this.byteArray[entryIndex * 8 + i]) + " ";
    }
    output += "\n";

    return output;
  }

  public toString(): string {
    let output = "PackedArrayContext:\n";
    if (!this.isPacked) {
      return output + "Context is unpacked:\n"; // unpackedToString();
    }
    for (let setNumber = 0; setNumber < NUMBER_OF_SETS; setNumber++) {
      const entryPointerIndex = SET_0_START_INDEX + setNumber;
      const entryIndex = this.getIndexAtShortIndex(entryPointerIndex);
      output +=
        "Set " +
        setNumber.toString() +
        ": root = " +
        entryIndex.toString() +
        " \n";
      if (entryIndex == 0) continue;
      output += this.nonLeafEntryToString(entryIndex, this.topLevelShift, 4);
    }
    //output += recordedValuesToString();
    return output;
  }
}

const hexaCode = [
  "0",
  "1",
  "2",
  "3",
  "4",
  "5",
  "6",
  "7",
  "8",
  "9",
  "a",
  "b",
  "c",
  "d",
  "e",
  "f",
];

export function toHex(n: u64): string {
  let i = n;
  let result = "";
  do {
    const current = <i32>(i & 0xf);
    result = hexaCode[current] + result;
    i = i >> 4;
  } while (i > 0);

  return result.padStart(2, "0");
}