X-Git-Url: http://git.osdn.net/view?p=bytom%2Fvapor.git;a=blobdiff_plain;f=common%2Farithmetic%2Fcalculate.go;fp=common%2Farithmetic%2Fcalculate.go;h=394666c32f26a2339d965aa6f4311bb5dc3e2852;hp=0000000000000000000000000000000000000000;hb=1005d5aeca37334f61be9ffb3631137eb7d6088d;hpb=547c06b0e63278088b547195522d570c76d22b22

diff --git a/common/arithmetic/calculate.go b/common/arithmetic/calculate.go
new file mode 100644
index 00000000..394666c3
--- /dev/null
+++ b/common/arithmetic/calculate.go
@@ -0,0 +1,31 @@
+package arithmetic
+
+import (
+	"github.com/vapor/consensus"
+	"github.com/vapor/math/checked"
+	"github.com/vapor/protocol/bc/types"
+)
+
+// CalculateTxFee calculate transaction fee
+func CalculateTxFee(tx *types.Tx) (fee uint64, err error) {
+	var ok bool
+	for _, input := range tx.Inputs {
+		if input.InputType() == types.CoinbaseInputType {
+			return 0, nil
+		}
+		if input.AssetID() == *consensus.BTMAssetID {
+			if fee, ok = checked.AddUint64(fee, input.Amount()); !ok {
+				return 0, checked.ErrOverflow
+			}
+		}
+	}
+
+	for _, output := range tx.Outputs {
+		if *output.AssetAmount().AssetId == *consensus.BTMAssetID {
+			if fee, ok = checked.SubUint64(fee, output.AssetAmount().Amount); !ok {
+				return 0, checked.ErrOverflow
+			}
+		}
+	}
+	return
+}