Added buffer flush methods

+ serial.Port.ResetInputBuffer()
+ serial.Port.ResetOutputBuffer()

serial.go

@@ -24,6 +24,12 @@ type Port interface {
 	// Returns the number of bytes written.
 	Write(p []byte) (n int, err error)
 
+	// ResetInputBuffer Purges port read buffer
+	ResetInputBuffer() error
+
+	// ResetOutputBuffer Purges port write buffer
+	ResetOutputBuffer() error
+
 	// SetDTR sets the modem status bit DataTerminalReady
 	SetDTR(dtr bool) error
 

serial_darwin.go

@@ -13,3 +13,4 @@ const regexFilter = "^(cu|tty)\\..*"
 
 const ioctlTcgetattr = unix.TIOCGETA
 const ioctlTcsetattr = unix.TIOCSETA
+const ioctlTcflsh = unix.TIOCFLUSH

serial_freebsd.go

@@ -55,3 +55,4 @@ const tcCRTSCTS uint32 = tcCCTS_OFLOW
 
 const ioctlTcgetattr = unix.TIOCGETA
 const ioctlTcsetattr = unix.TIOCSETA
+const ioctlTcflsh = unix.TIOCFLUSH

serial_linux.go

@@ -62,3 +62,4 @@ const tcCRTSCTS uint32 = 0x80000000
 
 const ioctlTcgetattr = unix.TCGETS
 const ioctlTcsetattr = unix.TCSETS
+const ioctlTcflsh = unix.TCFLSH

serial_unix.go

@@ -74,6 +74,14 @@ func (port *unixPort) Write(p []byte) (n int, err error) {
 	return unix.Write(port.handle, p)
 }
 
+func (port *unixPort) ResetInputBuffer() error {
+	return ioctl(port.handle, ioctlTcflsh, unix.TCIFLUSH)
+}
+
+func (port *unixPort) ResetOutputBuffer() error {
+	return ioctl(port.handle, ioctlTcflsh, unix.TCOFLUSH)
+}
+
 func (port *unixPort) SetMode(mode *Mode) error {
 	settings, err := port.getTermSettings()
 	if err != nil {

serial_windows.go

@@ -115,6 +115,21 @@ func (port *windowsPort) Write(p []byte) (int, error) {
 	return int(writed), err
 }
 
+const (
+	purgeRxAbort uint32 = 0x0002
+	purgeRxClear        = 0x0008
+	purgeTxAbort        = 0x0001
+	purgeTxClear        = 0x0004
+)
+
+func (port *windowsPort) ResetInputBuffer() error {
+	return purgeComm(port.handle, purgeRxClear|purgeRxAbort)
+}
+
+func (port *windowsPort) ResetOutputBuffer() error {
+	return purgeComm(port.handle, purgeTxClear|purgeTxAbort)
+}
+
 const (
 	dcbBinary                uint32 = 0x00000001
 	dcbParity                       = 0x00000002

syscall_windows.go

@@ -23,3 +23,6 @@ package serial // import "go.bug.st/serial.v1"
 //sys resetEvent(handle syscall.Handle) (err error) = ResetEvent
 
 //sys getOverlappedResult(handle syscall.Handle, overlapEvent *syscall.Overlapped, n *uint32, wait bool) (err error) = GetOverlappedResult
+
+//sys purgeComm(handle syscall.Handle, flags uint32) (err error) = PurgeComm
+

zsyscall_windows.go

@@ -49,6 +49,7 @@ var (
 	procCreateEventW        = modkernel32.NewProc("CreateEventW")
 	procResetEvent          = modkernel32.NewProc("ResetEvent")
 	procGetOverlappedResult = modkernel32.NewProc("GetOverlappedResult")
+	procPurgeComm           = modkernel32.NewProc("PurgeComm")
 )
 
 func regEnumValue(key syscall.Handle, index uint32, name *uint16, nameLen *uint32, reserved *uint32, class *uint16, value *uint16, valueLen *uint32) (regerrno error) {
@@ -161,3 +162,15 @@ func getOverlappedResult(handle syscall.Handle, overlapEvent *syscall.Overlapped
 	}
 	return
 }
+
+func purgeComm(handle syscall.Handle, flags uint32) (err error) {
+	r1, _, e1 := syscall.Syscall(procPurgeComm.Addr(), 2, uintptr(handle), uintptr(flags), 0)
+	if r1 == 0 {
+		if e1 != 0 {
+			err = errnoErr(e1)
+		} else {
+			err = syscall.EINVAL
+		}
+	}
+	return
+}