core/vm: add comments

core/vm/gascosts.go

@@ -1,7 +1,25 @@
+// Copyright 2026 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
 package vm
 
 import "fmt"
 
+// GasCosts denotes a vector of gas costs in the
+// multidimensional metering paradigm.
 type GasCosts struct {
 	RegularGas uint64
 	StateGas   uint64
@@ -12,6 +30,7 @@ func (g GasCosts) Sum() uint64 {
 	return g.RegularGas + g.StateGas
 }
 
+// String returns a visual representation of the gas vector.
 func (g GasCosts) String() string {
 	return fmt.Sprintf("<%v,%v>", g.RegularGas, g.StateGas)
 }