aggregate coinbase rewards (#239)

[bytom/vapor.git] / common / arithmetic / calculate.go

diff --git a/common/arithmetic/calculate.go b/common/arithmetic/calculate.go
new file mode 100644 (file)
index 0000000..394666c
--- /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
+}