core, state: initial implementation of Eip-1283

core/state/statedb.go

@@ -169,11 +169,22 @@ func (self *StateDB) Preimages() map[common.Hash][]byte {
 	return self.preimages
 }
 
+// AddRefund adds gas to the refund counter
 func (self *StateDB) AddRefund(gas uint64) {
 	self.journal.append(refundChange{prev: self.refund})
 	self.refund += gas
 }
 
+// SubRefund removes gas from the refund counter.
+// This method will panic if the refund counter goes below zero
+func (self *StateDB) SubRefund(gas uint64) {
+	self.journal.append(refundChange{prev: self.refund})
+	if gas > self.refund {
+		panic("Refund counter below zero")
+	}
+	self.refund -= gas
+}
+
 // Exist reports whether the given account address exists in the state.
 // Notably this also returns true for suicided accounts.
 func (self *StateDB) Exist(addr common.Address) bool {