hexToBn function

BigInt hexToBn(dynamic value, { Endian endian = Endian.big, bool isNegative = false, })

Function for convert a hex String to BigInt.

Implementation

BigInt hexToBn(
  dynamic value, {
  Endian endian = Endian.big,
  bool isNegative = false,
}) {
  if (value == null) {
    return BigInt.from(0);
  }
  if (isNegative == false) {
    final sValue = value is num
        ? int.parse(value.toString(), radix: 10).toRadixString(16)
        : value;
    if (endian == Endian.big) {
      return BigInt.parse(sValue, radix: 16);
    }
    return decodeBigInt(
      hexToBytes(sValue),
    );
  } else {
    String hex = value is num
        ? int.parse(value.toString(), radix: 10).toRadixString(16)
        : value;
    if (hex.length % 2 > 0) {
      hex = '0$hex';
    }
    hex = decodeBigInt(
      hexToBytes(hex),
      endian: endian,
    ).toRadixString(16);
    BigInt bn = BigInt.parse(hex, radix: 16);

    final result = 0x80 &
        int.parse(hex.substring(0, 2 > hex.length ? hex.length : 2), radix: 16);
    if (result > 0) {
      BigInt some = BigInt.parse(
        bn.toRadixString(2).split('').map((i) {
          return '0' == i ? 1 : 0;
        }).join(),
        radix: 2,
      );
      some += BigInt.one;
      bn = -some;
    }
    return bn;
  }
}