core/vm: optimize copy-less data retrievals

1 files changed, 15 insertions, 1 deletions

diff --git a/core/vm/common.go b/core/vm/common.go
index 779cee006..17de38dec 100644
--- a/core/vm/common.go
+++ b/core/vm/common.go
@@ -34,7 +34,21 @@ func calcMemSize(off, l *big.Int) *big.Int {
 
 // getData returns a slice from the data based on the start and size and pads
 // up to size with zero's. This function is overflow safe.
-func getData(data []byte, start, size *big.Int) []byte {
+func getData(data []byte, start uint64, size uint64) []byte {
+	length := uint64(len(data))
+	if start > length {
+		start = length
+	}
+	end := start + size
+	if end > length {
+		end = length
+	}
+	return common.RightPadBytes(data[start:end], int(size))
+}
+
+// getDataBig returns a slice from the data based on the start and size and pads
+// up to size with zero's. This function is overflow safe.
+func getDataBig(data []byte, start *big.Int, size *big.Int) []byte {
 	dlen := big.NewInt(int64(len(data)))
 
 	s := math.BigMin(start, dlen)