From 153d25b18370ada09945f7dd7c24ac0e0a3a147c Mon Sep 17 00:00:00 2001
From: Hubert Feurstein <hubert.feurstein@stratum9.at>
Date: Mon, 24 Mar 2025 16:55:12 +0100
Subject: [PATCH] add rts/cts flow-control support

---
 serial.go         | 1 +
 serial_unix.go    | 4 ++--
 serial_windows.go | 8 +++++++-
 3 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/serial.go b/serial.go
index a2f7333..2494655 100644
--- a/serial.go
+++ b/serial.go
@@ -101,6 +101,7 @@ type Mode struct {
 	Parity            Parity           // Parity (see Parity type for more info)
 	StopBits          StopBits         // Stop bits (see StopBits type for more info)
 	InitialStatusBits *ModemOutputBits // Initial output modem bits status (if nil defaults to DTR=true and RTS=true)
+	RTSCTSFlowControl bool             // Enable RTS/CTS hardware flow control
 }
 
 // Parity describes a serial port parity setting
diff --git a/serial_unix.go b/serial_unix.go
index e6913c2..b4dda37 100644
--- a/serial_unix.go
+++ b/serial_unix.go
@@ -238,8 +238,8 @@ func nativeOpen(portName string, mode *Mode) (*unixPort, error) {
 	// Set raw mode
 	setRawMode(settings)
 
-	// Explicitly disable RTS/CTS flow control
-	setTermSettingsCtsRts(false, settings)
+	// Explicitly enable/disable RTS/CTS flow control
+	setTermSettingsCtsRts(mode.RTSCTSFlowControl, settings)
 
 	if err = port.setTermSettings(settings); err != nil {
 		port.Close()
diff --git a/serial_windows.go b/serial_windows.go
index 37b3b39..8114cf5 100644
--- a/serial_windows.go
+++ b/serial_windows.go
@@ -388,7 +388,13 @@ func nativeOpen(portName string, mode *Mode) (*windowsPort, error) {
 			params.Flags |= windows.RTS_CONTROL_ENABLE
 		}
 	}
-	params.Flags &^= dcbOutXCTSFlow
+
+	if mode.RTSCTSFlowControl {
+		params.Flags |= dcbOutXCTSFlow
+	} else {
+		params.Flags &^= dcbOutXCTSFlow
+	}
+
 	params.Flags &^= dcbOutXDSRFlow
 	params.Flags &^= dcbDSRSensitivity
 	params.Flags |= dcbTXContinueOnXOFF