diff --git a/pkg/ckb/syscalls.cell b/pkg/ckb/syscalls.cell
index 567fb3c..e049bb1 100644
--- a/pkg/ckb/syscalls.cell
+++ b/pkg/ckb/syscalls.cell
@@ -122,17 +122,19 @@ func loadCellData(index uint32, source uint32) []byte {
 	__slice_set_len(&data, size)
 	return data
 }
+// load cell data from cells grouped by script
 func loadInputCellData(index uint32) []byte {
-	return loadCellData(index, CKB_SOURCE_INPUT)
+	return loadCellData(index, CKB_SOURCE_GROUP_INPUT)
 }
 func loadOutputCellData(index uint32) []byte {
-	return loadCellData(index, CKB_SOURCE_OUTPUT)
+	return loadCellData(index, CKB_SOURCE_GROUP_OUTPUT)
 }
 func VMVersion() uint64 {
 	return ckb_vm_version()
 }
 
 // load cell as CellOutput pattern
+// equals load cell by field {capacity, lock, type}
 func inputCell(index uint) blockchain.CellOutput {
 	data := make([]byte, SIZE_CELL, SIZE_CELL)
 	ptr := __slice_get_ptr(&data)
diff --git a/pkg/encoding/binary/binary.cell b/pkg/encoding/binary/binary.cell
index 9563301..39cbbdc 100644
--- a/pkg/encoding/binary/binary.cell
+++ b/pkg/encoding/binary/binary.cell
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"io"
 	"bytes"
+	"debug"
 )
 
 type ByteOrder interface {
@@ -204,5 +205,20 @@ func ReadUint32(r io.Reader, order ByteOrder) uint32 {
 	if err.NotNone() {
 		return uint32(0)
 	}
+	// for i, v := range bs {
+	// 	debug.Printf("bs i %d", v)
+	// }
 	return order.Uint32(bs)
 }
+
+func ReadUint64(r io.Reader, order ByteOrder) uint64 {
+	bs := make([]byte, 8)
+	for i, v := range bs {
+		debug.Printf("bs i %x", v)
+	}
+	n, err := io.ReadFull(r, bs)
+	if err.NotNone() {
+		return 0
+	}
+	return order.Uint64(bs)
+}