From f0083b94c5840114ace6f182a30ca45597f86234 Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Fri, 17 Jan 2020 15:31:37 +0300
Subject: [PATCH] vm: use new big.Int (de-)serialization routines

Also fix a test with CAT.
---
 pkg/vm/json_test.go     | 2 +-
 pkg/vm/serialization.go | 6 ++----
 pkg/vm/stack.go         | 4 +---
 pkg/vm/stack_item.go    | 4 +---
 pkg/vm/vm_test.go       | 2 +-
 5 files changed, 6 insertions(+), 12 deletions(-)

diff --git a/pkg/vm/json_test.go b/pkg/vm/json_test.go
index 6ee5568ae..1cc33681c 100644
--- a/pkg/vm/json_test.go
+++ b/pkg/vm/json_test.go
@@ -196,7 +196,7 @@ func compareItems(t *testing.T, a, b StackItem) {
 		case *BigIntegerItem:
 			require.Equal(t, val, ac.value.Int64())
 		case *ByteArrayItem:
-			require.Equal(t, val, new(big.Int).SetBytes(util.ArrayReverse(ac.value)).Int64())
+			require.Equal(t, val, bytesToInt(ac.value).Int64())
 		case *BoolItem:
 			if ac.value {
 				require.Equal(t, val, int64(1))
diff --git a/pkg/vm/serialization.go b/pkg/vm/serialization.go
index e5a928c2d..c3adf299b 100644
--- a/pkg/vm/serialization.go
+++ b/pkg/vm/serialization.go
@@ -2,10 +2,8 @@ package vm
 
 import (
 	"errors"
-	"math/big"
 
 	"github.com/CityOfZion/neo-go/pkg/io"
-	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
 type stackItemType byte
@@ -50,7 +48,7 @@ func serializeItemTo(item StackItem, w *io.BinWriter, seen map[StackItem]bool) {
 		w.WriteBool(t.value)
 	case *BigIntegerItem:
 		w.WriteBytes([]byte{byte(integerT)})
-		w.WriteVarBytes(t.Bytes())
+		w.WriteVarBytes(intToBytes(t.value))
 	case *InteropItem:
 		w.Err = errors.New("not supported")
 	case *ArrayItem, *StructItem:
@@ -108,7 +106,7 @@ func DecodeBinaryStackItem(r *io.BinReader) StackItem {
 		return NewBoolItem(b)
 	case integerT:
 		data := r.ReadVarBytes()
-		num := new(big.Int).SetBytes(util.ArrayReverse(data))
+		num := bytesToInt(data)
 		return &BigIntegerItem{
 			value: num,
 		}
diff --git a/pkg/vm/stack.go b/pkg/vm/stack.go
index b0a2f72d9..9cdf551ac 100644
--- a/pkg/vm/stack.go
+++ b/pkg/vm/stack.go
@@ -5,8 +5,6 @@ import (
 	"errors"
 	"fmt"
 	"math/big"
-
-	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
 // Stack implementation for the neo-go virtual machine. The stack implements
@@ -83,7 +81,7 @@ func (e *Element) BigInt() *big.Int {
 		return big.NewInt(0)
 	default:
 		b := t.Value().([]uint8)
-		return new(big.Int).SetBytes(util.ArrayReverse(b))
+		return bytesToInt(b)
 	}
 }
 
diff --git a/pkg/vm/stack_item.go b/pkg/vm/stack_item.go
index de277159a..d5ea56cc6 100644
--- a/pkg/vm/stack_item.go
+++ b/pkg/vm/stack_item.go
@@ -7,8 +7,6 @@ import (
 	"fmt"
 	"math/big"
 	"reflect"
-
-	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
 // A StackItem represents the "real" value that is pushed on the stack.
@@ -144,7 +142,7 @@ func NewBigIntegerItem(value int) *BigIntegerItem {
 
 // Bytes converts i to a slice of bytes.
 func (i *BigIntegerItem) Bytes() []byte {
-	return util.ArrayReverse(i.value.Bytes())
+	return intToBytes(i.value)
 }
 
 // Value implements StackItem interface.
diff --git a/pkg/vm/vm_test.go b/pkg/vm/vm_test.go
index a8e02606d..2e9fb9ae2 100644
--- a/pkg/vm/vm_test.go
+++ b/pkg/vm/vm_test.go
@@ -2042,7 +2042,7 @@ func TestCATInt0ByteArray(t *testing.T) {
 	vm.estack.PushVal([]byte{})
 	runVM(t, vm)
 	assert.Equal(t, 1, vm.estack.Len())
-	assert.Equal(t, &ByteArrayItem{[]byte{}}, vm.estack.Pop().value)
+	assert.Equal(t, &ByteArrayItem{[]byte{0}}, vm.estack.Pop().value)
 }
 
 func TestCATByteArrayInt1(t *testing.T) {