core: implement skeletons for NEO/GAS native contracts

pkg/core/state/native_state.go

@@ -0,0 +1,45 @@
+package state
+
+import (
+	"math/big"
+
+	"github.com/nspcc-dev/neo-go/pkg/io"
+	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
+)
+
+// NEP5BalanceState represents balance state of a NEP5-token.
+type NEP5BalanceState struct {
+	Balance big.Int
+}
+
+// NEOBalanceState represents balance state of a NEO-token.
+type NEOBalanceState struct {
+	NEP5BalanceState
+	BalanceHeight uint32
+}
+
+// EncodeBinary implements io.Serializable interface.
+func (s *NEP5BalanceState) EncodeBinary(w *io.BinWriter) {
+	w.WriteVarBytes(emit.IntToBytes(&s.Balance))
+}
+
+// DecodeBinary implements io.Serializable interface.
+func (s *NEP5BalanceState) DecodeBinary(r *io.BinReader) {
+	buf := r.ReadVarBytes()
+	if r.Err != nil {
+		return
+	}
+	s.Balance = *emit.BytesToInt(buf)
+}
+
+// EncodeBinary implements io.Serializable interface.
+func (s *NEOBalanceState) EncodeBinary(w *io.BinWriter) {
+	s.NEP5BalanceState.EncodeBinary(w)
+	w.WriteU32LE(s.BalanceHeight)
+}
+
+// DecodeBinary implements io.Serializable interface.
+func (s *NEOBalanceState) DecodeBinary(r *io.BinReader) {
+	s.NEP5BalanceState.DecodeBinary(r)
+	s.BalanceHeight = r.ReadU32LE()
+}