private static BigInteger extractParameter(
      final Bytes input, final int offset, final int length) {
    if (offset > input.size() || length == 0) {
      return BigInteger.ZERO;
    }
    final byte[] raw = Arrays.copyOfRange(input.toArray(), offset, offset + length);
    return new BigInteger(1, raw);
  }
Create Istanbul AltBN128Add precompiled contract.

@param gasCalculator the gas calculator
@return the AltBN128Add precompiled contract
evm/src/main/java/org/hyperledger/besu/evm/precompile/AltBN128AddPrecompiledContract.java