Add checksum calculation to relevant barcode types

code39/encoder.go

@@ -3,6 +3,7 @@ package code39
 
 import (
 	"errors"
+	"strconv"
 	"strings"
 
 	"github.com/boombuler/barcode"
@@ -143,5 +144,9 @@ func Encode(content string, includeChecksum bool, fullASCIIMode bool) (barcode.B
 		result.AddBit(info.data...)
 	}
 
-	return utils.New1DCode("Code 39", content, result), nil
+	checkSum, err := strconv.ParseInt(getChecksum(content), 10, 64)
+	if err != nil {
+		checkSum = 0
+	}
+	return utils.New1DCode("Code 39", content, result, int(checkSum)), nil
 }