CyberChef/src/js/operations/Endian.js

/**
 * Endian operations.
 *
 * @author n1474335 [n1474335@gmail.com]
 * @copyright Crown Copyright 2016
 * @license Apache-2.0
 *
 * @namespace
 */
const Endian = {

    /**
     * @constant
     * @default
     */
  DATA_FORMAT: ['Hex', 'Raw'],
    /**
     * @constant
     * @default
     */
  WORD_LENGTH: 4,
    /**
     * @constant
     * @default
     */
  PAD_INCOMPLETE_WORDS: true,

    /**
     * Swap endianness operation.
     *
     * @param {string} input
     * @param {Object[]} args
     * @returns {string}
     */
  run_swap_endianness(input, args) {
    let data_format = args[0],
      word_length = args[1],
      pad_incomplete_words = args[2],
      data = [],
      result = [],
      words = [],
      i = 0,
      j = 0;

    if (word_length <= 0) {
      return 'Word length must be greater than 0';
    }

        // Convert input to raw data based on specified data format
    switch (data_format) {
      case 'Hex':
        data = Utils.from_hex(input);
        break;
      case 'Raw':
        data = Utils.str_to_byte_array(input);
        break;
      default:
        data = input;
    }

        // Split up into words
    for (i = 0; i < data.length; i += word_length) {
      const word = data.slice(i, i + word_length);

            // Pad word if too short
      if (pad_incomplete_words && word.length < word_length) {
        for (j = word.length; j < word_length; j++) {
          word.push(0);
        }
      }

      words.push(word);
    }

        // Swap endianness and flatten
    for (i = 0; i < words.length; i++) {
      j = words[i].length;
      while (j--) {
        result.push(words[i][j]);
      }
    }

        // Convert data back to specified data format
    switch (data_format) {
      case 'Hex':
        return Utils.to_hex(result);
      case 'Raw':
        return Utils.byte_array_to_utf8(result);
      default:
        return result;
    }
  },

};