EEI: charge for memory gas cost in useGas

Author: axic

src/eei.cpp

@@ -146,6 +146,8 @@ namespace HeraVM {
       HERA_DEBUG << "useGas " << gas << "\n";
 
       takeGas(gas);
+      // FIXME: this may overflow
+      takeGas(gas * memory.size() / GasSchedule::memoryPageSize * GasSchedule::memoryCostPerPage);
 
       return Literal();
     }

src/eei.h

@@ -113,9 +113,13 @@ struct EthereumInterface : ShellExternalInterface {
   evm_message const& msg;
   std::vector<uint8_t> lastReturnData;
   ExecutionResult & result;
+
 };
 
 struct GasSchedule {
+  static constexpr unsigned memoryPageSize = 65536;
+  static constexpr unsigned memoryCostPerPage = 1;
+
   static constexpr unsigned storageLoad = 200;
   static constexpr unsigned storageStoreCreate = 20000;
   static constexpr unsigned storageStoreChange = 5000;