From 5be0087bd589daea6b46e4e9e8678c8d4a0740ab Mon Sep 17 00:00:00 2001
From: Cristian Maglie <c.maglie@bug.st>
Date: Sat, 29 Oct 2016 22:18:24 +0200
Subject: [PATCH] Added interface methods for RS232 signals

---
 example_modem_bits_test.go | 67 ++++++++++++++++++++++++++++++++++++++
 serial.go                  | 19 +++++++++++
 serial_unix.go             | 12 +++++++
 serial_windows.go          | 12 +++++++
 4 files changed, 110 insertions(+)
 create mode 100644 example_modem_bits_test.go

diff --git a/example_modem_bits_test.go b/example_modem_bits_test.go
new file mode 100644
index 0000000..1673aaf
--- /dev/null
+++ b/example_modem_bits_test.go
@@ -0,0 +1,67 @@
+//
+// Copyright 2014-2016 Cristian Maglie. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+//
+
+package serial_test
+
+import "log"
+import "go.bug.st/serial.v1"
+import "fmt"
+import "time"
+
+func ExampleGetSetModemBits() {
+	// Open the first serial port detected at 9600bps N81
+	mode := &serial.Mode{
+		BaudRate: 9600,
+		Parity:   serial.NoParity,
+		DataBits: 8,
+		StopBits: serial.OneStopBit,
+	}
+	port, err := serial.Open("/dev/ttyACM1", mode)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer port.Close()
+
+	count := 0
+	for count < 25 {
+		status, err := port.GetStatus()
+		if err != nil {
+			log.Fatal(err)
+		}
+		fmt.Printf("Status: %+v\n", status)
+
+		time.Sleep(time.Second)
+		count++
+		if count == 5 {
+			err := port.SetDTR(false)
+			if err != nil {
+				log.Fatal(err)
+			}
+			fmt.Println("Set DTR OFF")
+		}
+		if count == 10 {
+			err := port.SetDTR(true)
+			if err != nil {
+				log.Fatal(err)
+			}
+			fmt.Println("Set DTR ON")
+		}
+		if count == 15 {
+			err := port.SetRTS(false)
+			if err != nil {
+				log.Fatal(err)
+			}
+			fmt.Println("Set RTS OFF")
+		}
+		if count == 20 {
+			err := port.SetRTS(true)
+			if err != nil {
+				log.Fatal(err)
+			}
+			fmt.Println("Set RTS ON")
+		}
+	}
+}
diff --git a/serial.go b/serial.go
index 6b932d0..dd218d6 100644
--- a/serial.go
+++ b/serial.go
@@ -22,10 +22,29 @@ type Port interface {
 	// Returns the number of bytes written.
 	Write(p []byte) (n int, err error)
 
+	// SetDTR sets the modem status bit DataTerminalReady
+	SetDTR(dtr bool) error
+
+	// SetRTS sets the modem status bit RequestToSend
+	SetRTS(rts bool) error
+
+	// GetModemStatusBits returns a ModemStatusBits structure containing the
+	// modem status bits for the serial port (CTS, DSR, etc...)
+	GetModemStatusBits() (*ModemStatusBits, error)
+
 	// Close the serial port
 	Close() error
 }
 
+// ModemStatusBits contains all the modem status bits for a serial port (CTS, DSR, etc...).
+// It can be retrieved with the Port.GetModemStatusBits() method.
+type ModemStatusBits struct {
+	CTS bool // ClearToSend status
+	DSR bool // DataSetReady status
+	RI  bool // RingIndicator status
+	DCD bool // DataCarrierDetect status
+}
+
 // Open opens the serial port using the specified modes
 func Open(portName string, mode *Mode) (Port, error) {
 	return nativeOpen(portName, mode)
diff --git a/serial_unix.go b/serial_unix.go
index 2368cdc..857686f 100644
--- a/serial_unix.go
+++ b/serial_unix.go
@@ -51,6 +51,18 @@ func (port *unixPort) SetMode(mode *Mode) error {
 	return port.setTermSettings(settings)
 }
 
+func (port *unixPort) SetDTR(dtr bool) error {
+	return &PortError{}
+}
+
+func (port *unixPort) SetRTS(rts bool) error {
+	return &PortError{}
+}
+
+func (port *unixPort) GetModemStatusBits() (*ModemStatusBits, error) {
+	return nil, &PortError{}
+}
+
 func nativeOpen(portName string, mode *Mode) (*unixPort, error) {
 	h, err := syscall.Open(portName, syscall.O_RDWR|syscall.O_NOCTTY|syscall.O_NDELAY, 0)
 	if err != nil {
diff --git a/serial_windows.go b/serial_windows.go
index dc380f5..9aef79d 100644
--- a/serial_windows.go
+++ b/serial_windows.go
@@ -211,6 +211,18 @@ func (port *windowsPort) SetMode(mode *Mode) error {
 	return nil
 }
 
+func (port *windowsPort) SetDTR(dtr bool) error {
+	return &PortError{}
+}
+
+func (port *windowsPort) SetRTS(rts bool) error {
+	return &PortError{}
+}
+
+func (port *windowsPort) GetModemStatusBits() (*ModemStatusBits, error) {
+	return nil, &PortError{}
+}
+
 func nativeOpen(portName string, mode *Mode) (*windowsPort, error) {
 	portName = "\\\\.\\" + portName
 	path, err := syscall.UTF16PtrFromString(portName)