vm: implement BigInteger item serialization

pkg/vm/serialization.go

@@ -2,8 +2,10 @@ package vm
 
 import (
 	"errors"
+	"math/big"
 
 	"github.com/CityOfZion/neo-go/pkg/io"
+	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
 type stackItemType byte
@@ -35,7 +37,8 @@ func serializeItemTo(item StackItem, w *io.BinWriter) {
 		w.WriteLE(byte(booleanT))
 		w.WriteLE(t.value)
 	case *BigIntegerItem:
-		w.Err = errors.New("not implemented")
+		w.WriteLE(byte(integerT))
+		w.WriteBytes(t.Bytes())
 	case *InteropItem:
 		w.Err = errors.New("not supported")
 	case *ArrayItem:
@@ -72,8 +75,11 @@ func deserializeItemFrom(r *io.BinReader) StackItem {
 		r.ReadLE(&b)
 		return NewBoolItem(b)
 	case integerT:
-		r.Err = errors.New("not implemented")
-		return nil
+		data := r.ReadBytes()
+		num := new(big.Int).SetBytes(util.ArrayReverse(data))
+		return &BigIntegerItem{
+			value: num,
+		}
 	case arrayT:
 		r.Err = errors.New("not implemented")
 		return nil

pkg/vm/stack.go

@@ -122,7 +122,7 @@ func (e *Element) Bytes() []byte {
 	case *ByteArrayItem:
 		return t.value
 	case *BigIntegerItem:
-		return util.ArrayReverse(t.value.Bytes()) // neoVM returns in LE
+		return t.Bytes() // neoVM returns in LE
 	case *BoolItem:
 		if t.value {
 			return []byte{1}

pkg/vm/stack_item.go

@@ -6,6 +6,8 @@ import (
 	"fmt"
 	"math/big"
 	"reflect"
+
+	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
 // A StackItem represents the "real" value that is pushed on the stack.
@@ -131,6 +133,11 @@ func NewBigIntegerItem(value int) *BigIntegerItem {
 	}
 }
 
+// Bytes converts i to a slice of bytes.
+func (i *BigIntegerItem) Bytes() []byte {
+	return util.ArrayReverse(i.value.Bytes())
+}
+
 // Value implements StackItem interface.
 func (i *BigIntegerItem) Value() interface{} {
 	return i.value

pkg/vm/vm_test.go

@@ -245,6 +245,17 @@ func TestSerializeByteArray(t *testing.T) {
 	require.Equal(t, value, vm.estack.Top().Bytes())
 }
 
+func TestSerializeInteger(t *testing.T) {
+	vm := load(getSerializeProg())
+	value := int64(123)
+	vm.estack.PushVal(value)
+
+	testSerialize(t, vm)
+
+	require.IsType(t, (*BigIntegerItem)(nil), vm.estack.Top().value)
+	require.Equal(t, value, vm.estack.Top().BigInt().Int64())
+}
+
 func callNTimes(n uint16) []byte {
 	return makeProgram(
 		PUSHBYTES2, Instruction(n), Instruction(n>>8), // little-endian