@tetcoin/util/hex/toU8a.js

A collection of useful utilities for @tetcoin

"use strict";

var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = hexToU8a;

var _assert = _interopRequireDefault(require("../assert"));

var _hex = _interopRequireDefault(require("../is/hex"));

var _stripPrefix = _interopRequireDefault(require("./stripPrefix"));

// Copyright 2017-2019 @polkadot/util authors & contributors
// This software may be modified and distributed under the terms
// of the Apache-2.0 license. See the LICENSE file for details.

/**
 * @name hexToU8a
 * @summary Creates a Buffer object from a hex string.
 * @description
 * `null` inputs returns an empty `Uint8Array` result. Hex input values return the actual bytes value converted to a Uint8Array. Anything that is not a hex string (including the `0x` prefix) throws an error.
 * @example
 * <BR>
 *
 * ```javascript
 * import { hexToU8a } from '@tetcoin/util';
 *
 * hexToU8a('0x80001f'); // Uint8Array([0x80, 0x00, 0x1f])
 * hexToU8a('0x80001f', 32); // Uint8Array([0x00, 0x80, 0x00, 0x1f])
 * ```
 */
function hexToU8a(_value) {
  let bitLength = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : -1;

  if (!_value) {
    return new Uint8Array([]);
  }

  (0, _assert.default)((0, _hex.default)(_value), "Expected hex value to convert, found '".concat(_value, "'"));
  const value = (0, _stripPrefix.default)(_value);
  const valLength = value.length / 2;
  const bufLength = Math.ceil(bitLength === -1 ? valLength : bitLength / 8);
  const result = new Uint8Array(bufLength);
  const offset = Math.max(0, bufLength - valLength);

  for (let index = 0; index < bufLength; index++) {
    result[index + offset] = parseInt(value.substr(index * 2, 2), 16);
  }

  return result;
}