kontainer-js/core/Util.js

A media file format generator/parser that exposes a React-like API.

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.isNegative = isNegative;
exports.convertToNegative = convertToNegative;
exports.throwException = throwException;
exports.getUTF8Length = getUTF8Length;
function isNegative(value, bitLength) {
  return !!(value & 1 << bitLength - 1);
}

function convertToNegative(value, bitLength) {
  var mask = (1 << bitLength) - 1;
  return -((~value & mask) + 1);
}

function throwException(message) {
  throw new Error(message);
}

function getUTF8Length(string) {
  return string.split('').map(function (ch) {
    var charCode = ch.charCodeAt(0);
    if (charCode < 0x80) {
      return 1;
    } else if (charCode >= 0x80 && charCode < 0x800) {
      return 2;
    } else if (charCode >= 0x800 && charCode < 0x10000) {
      return 3;
    } else if (charCode >= 0x10000 && charCode < 0x200000) {
      return 4;
    } else if (charCode >= 0x200000 && charCode < 0x4000000) {
      return 5;
    } else if (charCode >= 0x4000000 && charCode < 0x80000000) {
      return 6;
    } else {
      return 0;
    }
  }).reduce(function (a, b) {
    return a + b;
  });
}