protected long callDataCost(final long payloadSize, final long zeroBytes) {
    return clampedAdd(
        TX_DATA_NON_ZERO_COST * (payloadSize - zeroBytes), TX_DATA_ZERO_COST * zeroBytes);
  }
Calculates the cost of the call data

@param payloadSize the total size of the payload
@param zeroBytes the number of zero bytes in the payload
@return the cost of the call data
evm/src/main/java/org/hyperledger/besu/evm/gascalculator/FrontierGasCalculator.java