shaka-player/lib/util/uint8array_utils.js

DASH/EME video player library

/*! @license
 * Shaka Player
 * Copyright 2016 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

goog.provide('shaka.util.Uint8ArrayUtils');

goog.require('shaka.util.BufferUtils');
goog.require('shaka.util.StringUtils');


// TODO: revisit this when Closure Compiler supports partially-exported classes.
/**
 * @summary A set of Uint8Array utility functions.
 * @export
 */
shaka.util.Uint8ArrayUtils = class {
  /**
   * Convert a buffer to a base64 string. The output will be standard
   * alphabet as opposed to base64url safe alphabet.
   * @param {BufferSource} data
   * @return {string}
   * @export
   */
  static toStandardBase64(data) {
    const arr = shaka.util.BufferUtils.toUint8(data);
    // eslint-disable-next-line no-restricted-syntax
    if (!Uint8Array.prototype.toBase64) {
      const bytes = shaka.util.StringUtils.fromCharCode(arr);
      return btoa(bytes);
    }
    return arr.toBase64({alphabet: 'base64', omitPadding: false});
  }

  /**
   * Convert a buffer to a base64 string.  The output will always use the
   * alternate encoding/alphabet also known as "base64url".
   * @param {BufferSource} data
   * @param {boolean=} padding If true, pad the output with equals signs.
   *   Defaults to true.
   * @return {string}
   * @export
   */
  static toBase64(data, padding) {
    padding = (padding == undefined) ? true : padding;
    // eslint-disable-next-line no-restricted-syntax
    if (!Uint8Array.prototype.toBase64) {
      const base64 = shaka.util.Uint8ArrayUtils.toStandardBase64(data)
          .replace(/\+/g, '-').replace(/\//g, '_');
      return padding ? base64 : base64.replace(/[=]*$/, '');
    }
    const arr = shaka.util.BufferUtils.toUint8(data);
    return arr.toBase64({alphabet: 'base64url', omitPadding: !padding});
  }

  /**
   * Convert a base64 string to a Uint8Array.  Accepts either the standard
   * alphabet or the alternate "base64url" alphabet.
   * @param {string} str
   * @return {!Uint8Array}
   * @export
   */
  static fromBase64(str) {
    if (!('fromBase64' in Uint8Array)) {
      // atob creates a "raw string" where each character is interpreted as a
      // byte.
      const bytes = window.atob(str.replace(/-/g, '+').replace(/_/g, '/'));
      const result = new Uint8Array(bytes.length);
      for (let i = 0; i < bytes.length; ++i) {
        result[i] = bytes.charCodeAt(i);
      }
      return result;
    }
    const input = str.replace(/\s+/g, '');
    const usesUrlAlphabet = /[-_]/.test(input);
    return Uint8Array.fromBase64(input, {
      alphabet: usesUrlAlphabet ? 'base64url' : 'base64',
    });
  }


  /**
   * Convert a hex string to a Uint8Array.
   * @param {string} str
   * @return {!Uint8Array}
   * @export
   */
  static fromHex(str) {
    if (!('fromHex' in Uint8Array)) {
      const size = str.length / 2;
      const arr = new Uint8Array(size);
      for (let i = 0; i < size; i++) {
        arr[i] = window.parseInt(str.substr(i * 2, 2), 16);
      }
      return arr;
    }
    return Uint8Array.fromHex(str);
  }


  /**
   * Convert a buffer to a hex string.
   * @param {BufferSource} data
   * @return {string}
   * @export
   */
  static toHex(data) {
    const arr = shaka.util.BufferUtils.toUint8(data);
    // eslint-disable-next-line no-restricted-syntax
    if (!Uint8Array.prototype.toHex) {
      let hex = '';
      for (let value of arr) {
        value = value.toString(16);
        if (value.length == 1) {
          value = '0' + value;
        }
        hex += value;
      }
      return hex;
    }
    return arr.toHex();
  }


  /**
   * Concatenate buffers.
   * @param {...BufferSource} varArgs
   * @return {!Uint8Array}
   * @export
   */
  static concat(...varArgs) {
    return shaka.util.Uint8ArrayUtils.concatRange(varArgs, 0, varArgs.length);
  }

  /**
   * Concatenate a range of buffers from a flat array.
   * Avoids a subarray allocation compared to concat(...array.slice(s, e)).
   * @param {!Array<!BufferSource>} array
   * @param {number=} start Inclusive start index.
   * @param {number=} end Exclusive end index.
   * @return {!Uint8Array}
   */
  static concatRange(array, start = 0, end = array.length) {
    const BufferUtils = shaka.util.BufferUtils;
    let totalLength = 0;
    for (let i = start; i < end; ++i) {
      totalLength += array[i].byteLength;
    }

    const result = new Uint8Array(totalLength);
    let offset = 0;

    for (let i = start; i < end; ++i) {
      const value = array[i];
      if (ArrayBuffer.isView(value) &&
      /** @type {TypedArray} */ (value).BYTES_PER_ELEMENT === 1) {
        result.set(/** @type {!Uint8Array} */(value), offset);
      } else {
        result.set(BufferUtils.toUint8(value), offset);
      }
      offset += value.byteLength;
    }

    return result;
  }
};