Added SetDataBits function (linux only for now)

serial.go

@@ -20,6 +20,9 @@ type SerialPort interface {
 
 	// Set port parity
 	SetParity(parity Parity) error
+
+	// Set data bits
+	SetDataBits(bits int) error
 }
 
 type Parity int
@@ -44,6 +47,7 @@ const (
 	ERROR_INVALID_SERIAL_PORT
 	ERROR_PERMISSION_DENIED
 	ERROR_INVALID_PORT_SPEED
+	ERROR_INVALID_PORT_DATA_BITS
 	ERROR_ENUMERATING_PORTS
 	ERROR_OTHER
 )
@@ -60,6 +64,8 @@ func (e SerialPortError) Error() string {
 		return "Permission denied"
 	case ERROR_INVALID_PORT_SPEED:
 		return "Invalid port speed"
+	case ERROR_INVALID_PORT_DATA_BITS:
+		return "Invalid port data bits"
 	case ERROR_ENUMERATING_PORTS:
 		return "Could not enumerate serial ports"
 	}

serial_linux.go

@@ -245,6 +245,27 @@ func (port *linuxSerialPort) SetParity(parity Parity) error {
 	return setTermSettings(port.Handle, settings)
 }
 
+var databitsMap = map[int]C.tcflag_t{
+	5: C.CS5,
+	6: C.CS6,
+	7: C.CS7,
+	8: C.CS8,
+}
+
+func (port *linuxSerialPort) SetDataBits(bits int) error {
+	databits, ok := databitsMap[bits]
+	if !ok {
+		return &SerialPortError{code: ERROR_INVALID_PORT_DATA_BITS}
+	}
+	settings, err := getTermSettings(port.Handle)
+	if err != nil {
+		return err
+	}
+	settings.c_cflag &= ^C.tcflag_t(syscall.CSIZE)
+	settings.c_cflag |= databits
+	return setTermSettings(port.Handle, settings)
+}
+
 func OpenPort(portName string, exclusive bool) (SerialPort, error) {
 	handle, err := syscall.Open(portName, syscall.O_RDWR|syscall.O_NOCTTY|syscall.O_NDELAY, 0)
 	if err != nil {

test/serial_test.go

@@ -33,6 +33,9 @@ func ExampleCommunication() {
 	if err := port.SetParity(serial.PARITY_NONE); err != nil {
 		log.Fatal(err)
 	}
+	if err := port.SetDataBits(8); err != nil {
+		log.Fatal(err)
+	}
 
 	n, err := port.Write([]byte("10,20,30\n\r"))
 	if err != nil {