@polkadot/util/hex/toBn.js

A collection of useful utilities for @polkadot

// Copyright 2017-2022 @polkadot/util authors & contributors
// SPDX-License-Identifier: Apache-2.0
import { BN } from "../bn/bn.js";
import { isBoolean } from "../is/boolean.js";
import { objectSpread } from "../object/spread.js";
import { hexStripPrefix } from "./stripPrefix.js";
/**
 * @name hexToBn
 * @summary Creates a BN.js object from a hex string.
 * @description
 * `null` inputs returns a `BN(0)` result. Hex input values return the actual value converted to a BN. Anything that is not a hex string (including the `0x` prefix) throws an error.
 * @param _value The value to convert
 * @param _options Options to pass while converting
 * @param _options.isLe Convert using Little Endian
 * @param _options.isNegative Convert using two's complement
 * @example
 * <BR>
 *
 * ```javascript
 * import { hexToBn } from '@polkadot/util';
 *
 * hexToBn('0x123480001f'); // => BN(0x123480001f)
 * ```
 */

/** @deprecated Use hexToBn (value?: string | null, options?: ToBnOptions) */
function hexToBn(value, options = {}) {
  if (!value || value === '0x') {
    return new BN(0);
  } // For hex, default to BE


  const {
    isLe,
    isNegative
  } = objectSpread({
    isLe: false,
    isNegative: false
  }, isBoolean(options) ? {
    isLe: options
  } : options);
  const stripped = hexStripPrefix(value);
  const bn = new BN(stripped, 16, isLe ? 'le' : 'be'); // fromTwos takes as parameter the number of bits, which is the hex length
  // multiplied by 4 (2 bytes being 8 bits)

  return isNegative ? bn.fromTwos(stripped.length * 4) : bn;
}

export { hexToBn };