text: /**
   * @license
   * Copyright 2016 Google Inc.
   *
   * 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.
   */
  
  goog.provide('shaka.util.EbmlElement');
  goog.provide('shaka.util.EbmlParser');
  
  goog.require('shaka.util.DataViewReader');
  goog.require('shaka.util.Error');
  goog.require('shaka.util.Uint8ArrayUtils');
  
  
  /**
   * Creates an Extensible Binary Markup Language (EBML) parser.
   * @param {!DataView} dataView The EBML data.
   * @constructor
   * @struct
   */
  shaka.util.EbmlParser = function(dataView) {
    /** @private {!DataView} */
    this.dataView_ = dataView;
  
    /** @private {!shaka.util.DataViewReader} */
    this.reader_ = new shaka.util.DataViewReader(
        dataView,
        shaka.util.DataViewReader.Endianness.BIG_ENDIAN);
  
    // If not already constructed, build a list of EBML dynamic size constants.
    // This is not done at load-time to avoid exceptions on unsupported browsers.
    if (!shaka.util.EbmlParser.DYNAMIC_SIZES) {
      shaka.util.EbmlParser.DYNAMIC_SIZES = [
        new Uint8Array([0xff]),
        new Uint8Array([0x7f, 0xff]),
        new Uint8Array([0x3f, 0xff, 0xff]),
        new Uint8Array([0x1f, 0xff, 0xff, 0xff]),
        new Uint8Array([0x0f, 0xff, 0xff, 0xff, 0xff]),
        new Uint8Array([0x07, 0xff, 0xff, 0xff, 0xff, 0xff]),
        new Uint8Array([0x03, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff]),
        new Uint8Array([0x01, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff]),
      ];
    }
  };
  
  
  /** @const {!Array.<!Uint8Array>} */
  shaka.util.EbmlParser.DYNAMIC_SIZES;
  
  
  /**
   * @return {boolean} True if the parser has more data, false otherwise.
   */
  shaka.util.EbmlParser.prototype.hasMoreData = function() {
    return this.reader_.hasMoreData();
  };
  
  
  /**
   * Parses an EBML element from the parser's current position, and advances
   * the parser.
   * @return {!shaka.util.EbmlElement} The EBML element.
   * @throws {shaka.util.Error}
   * @see http://matroska.org/technical/specs/rfc/index.html
   */
  shaka.util.EbmlParser.prototype.parseElement = function() {
    let id = this.parseId_();
  
    // Parse the element's size.
    let vint = this.parseVint_();
    let size;
    if (shaka.util.EbmlParser.isDynamicSizeValue_(vint)) {
      // If this has an unknown size, assume that it takes up the rest of the
      // data.
      size = this.dataView_.byteLength - this.reader_.getPosition();
    } else {
      size = shaka.util.EbmlParser.getVintValue_(vint);
    }
  
    // Note that if the element's size is larger than the buffer then we are
    // parsing a "partial element". This may occur if for example we are
    // parsing the beginning of some WebM container data, but our buffer does
    // not contain the entire WebM container data.
    let elementSize =
        this.reader_.getPosition() + size <= this.dataView_.byteLength ?
        size :
        this.dataView_.byteLength - this.reader_.getPosition();
  
    let dataView = new DataView(
        this.dataView_.buffer,
        this.dataView_.byteOffset + this.reader_.getPosition(), elementSize);
  
    this.reader_.skip(elementSize);
  
    return new shaka.util.EbmlElement(id, dataView);
  };
  
  
  /**
   * Parses an EBML ID from the parser's current position, and advances the
   * parser.
   * @throws {shaka.util.Error}
   * @return {number} The EBML ID.
   * @private
   */
  shaka.util.EbmlParser.prototype.parseId_ = function() {
    let vint = this.parseVint_();
  
    if (vint.length > 7) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.MEDIA,
          shaka.util.Error.Code.EBML_OVERFLOW);
    }
  
    let id = 0;
    for (let i = 0; i < vint.length; i++) {
      // Note that we cannot use << since |value| may exceed 32 bits.
      id = (256 * id) + vint[i];
    }
  
    return id;
  };
  
  
  /**
   * Parses a variable sized integer from the parser's current position, and
   * advances the parser.
   * For example:
   *   1 byte  wide: 1xxx xxxx
   *   2 bytes wide: 01xx xxxx xxxx xxxx
   *   3 bytes wide: 001x xxxx xxxx xxxx xxxx xxxx
   * @throws {shaka.util.Error}
   * @return {!Uint8Array} The variable sized integer.
   * @private
   */
  shaka.util.EbmlParser.prototype.parseVint_ = function() {
    let firstByte = this.reader_.readUint8();
    let numBytes;
  
    // Determine the byte width of the variable sized integer.
    for (numBytes = 1; numBytes <= 8; numBytes++) {
      let mask = 0x1 << (8 - numBytes);
      if (firstByte & mask) {
        break;
      }
    }
  
    if (numBytes > 8) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.MEDIA,
          shaka.util.Error.Code.EBML_OVERFLOW);
    }
  
    let vint = new Uint8Array(numBytes);
    vint[0] = firstByte;
  
    // Include the remaining bytes.
    for (let i = 1; i < numBytes; i++) {
      vint[i] = this.reader_.readUint8();
    }
  
    return vint;
  };
  
  
  /**
   * Gets the value of a variable sized integer.
   * For example, the x's below are part of the vint's value.
   *    7-bit value: 1xxx xxxx
   *   14-bit value: 01xx xxxx xxxx xxxx
   *   21-bit value: 001x xxxx xxxx xxxx xxxx xxxx
   * @param {!Uint8Array} vint The variable sized integer.
   * @throws {shaka.util.Error}
   * @return {number} The value of the variable sized integer.
   * @private
   */
  shaka.util.EbmlParser.getVintValue_ = function(vint) {
    // If |vint| is 8 bytes wide then we must ensure that it does not have more
    // than 53 meaningful bits. For example, assume |vint| is 8 bytes wide,
    // so it has the following structure,
    // 0000 0001 | xxxx xxxx ...
    // Thus, the first 3 bits following the first byte of |vint| must be 0.
    if ((vint.length == 8) && (vint[1] & 0xe0)) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.MEDIA,
          shaka.util.Error.Code.JS_INTEGER_OVERFLOW);
    }
  
    // Mask out the first few bits of |vint|'s first byte to get the most
    // significant bits of |vint|'s value. If |vint| is 8 bytes wide then |value|
    // will be set to 0.
    let mask = 0x1 << (8 - vint.length);
    let value = vint[0] & (mask - 1);
  
    // Add the remaining bytes.
    for (let i = 1; i < vint.length; i++) {
      // Note that we cannot use << since |value| may exceed 32 bits.
      value = (256 * value) + vint[i];
    }
  
    return value;
  };
  
  
  /**
   * Checks if the given variable sized integer represents a dynamic size value.
   * @param {!Uint8Array} vint The variable sized integer.
   * @return {boolean} true if |vint| represents a dynamic size value,
   *   false otherwise.
   * @private
   */
  shaka.util.EbmlParser.isDynamicSizeValue_ = function(vint) {
    const EbmlParser = shaka.util.EbmlParser;
    let uint8ArrayEqual = shaka.util.Uint8ArrayUtils.equal;
  
    for (let i = 0; i < EbmlParser.DYNAMIC_SIZES.length; i++) {
      if (uint8ArrayEqual(vint, EbmlParser.DYNAMIC_SIZES[i])) {
        return true;
      }
    }
  
    return false;
  };
  
  
  /**
   * Creates an EbmlElement.
   * @param {number} id The ID.
   * @param {!DataView} dataView The DataView.
   * @constructor
   */
  shaka.util.EbmlElement = function(id, dataView) {
    /** @type {number} */
    this.id = id;
  
    /** @private {!DataView} */
    this.dataView_ = dataView;
  };
  
  
  /**
   * Gets the element's offset from the beginning of the buffer.
   * @return {number}
   */
  shaka.util.EbmlElement.prototype.getOffset = function() {
    return this.dataView_.byteOffset;
  };
  
  
  /**
   * Interpret the element's data as a list of sub-elements.
   * @throws {shaka.util.Error}
   * @return {!shaka.util.EbmlParser} A parser over the sub-elements.
   */
  shaka.util.EbmlElement.prototype.createParser = function() {
    return new shaka.util.EbmlParser(this.dataView_);
  };
  
  
  /**
   * Interpret the element's data as an unsigned integer.
   * @throws {shaka.util.Error}
   * @return {number}
   */
  shaka.util.EbmlElement.prototype.getUint = function() {
    if (this.dataView_.byteLength > 8) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.MEDIA,
          shaka.util.Error.Code.EBML_OVERFLOW);
    }
  
    // Ensure we have at most 53 meaningful bits.
    if ((this.dataView_.byteLength == 8) && (this.dataView_.getUint8(0) & 0xe0)) {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.MEDIA,
          shaka.util.Error.Code.JS_INTEGER_OVERFLOW);
    }
  
    let value = 0;
  
    for (let i = 0; i < this.dataView_.byteLength; i++) {
      let chunk = this.dataView_.getUint8(i);
      value = (256 * value) + chunk;
    }
  
    return value;
  };
  
  
  /**
   * Interpret the element's data as a floating point number (32 bits or 64 bits).
   * 80-bit floating point numbers are not supported.
   * @throws {shaka.util.Error}
   * @return {number}
   */
  shaka.util.EbmlElement.prototype.getFloat = function() {
    if (this.dataView_.byteLength == 4) {
      return this.dataView_.getFloat32(0);
    } else if (this.dataView_.byteLength == 8) {
      return this.dataView_.getFloat64(0);
    } else {
      throw new shaka.util.Error(
          shaka.util.Error.Severity.CRITICAL,
          shaka.util.Error.Category.MEDIA,
          shaka.util.Error.Code.EBML_BAD_FLOATING_POINT_SIZE);
    }
  };
  
  