windows: setting buffer sizes with SetupComm

serial.go

@@ -49,6 +49,11 @@ type Port interface {
 	// to disable read timeout.
 	SetReadTimeout(t time.Duration) error
 
+	// SetBufferSize sets internal buffer sizes for the Read and Write operations.
+	// Please note that this function may not be available on all OS:
+	// in that case a FunctionNotImplemented error is returned.
+	SetBufferSize(txSize, rxSize int) error
+
 	// Close the serial port
 	Close() error
 
@@ -159,6 +164,8 @@ const (
 	InvalidStopBits
 	// InvalidTimeoutValue the timeout value is not valid or not supported
 	InvalidTimeoutValue
+	// InvalidBufferSize the requested buffer size is not valid or not supported
+	InvalidBufferSize
 	// ErrorEnumeratingPorts an error occurred while listing serial port
 	ErrorEnumeratingPorts
 	// PortClosed the port has been closed while the operation is in progress
@@ -188,6 +195,8 @@ func (e PortError) EncodedErrorString() string {
 		return "Port stop bits invalid or not supported"
 	case InvalidTimeoutValue:
 		return "Timeout value invalid or not supported"
+	case InvalidBufferSize:
+		return "Buffer size value invalid or not supported"
 	case ErrorEnumeratingPorts:
 		return "Could not enumerate serial ports"
 	case PortClosed:

serial_unix.go

@@ -198,6 +198,12 @@ func (port *unixPort) SetReadTimeout(timeout time.Duration) error {
 	return nil
 }
 
+func (port *unixPort) SetBufferSize(rxSize, txSize int) error {
+	// Unix does not provide any means to change the buffer size from 4096 bytes.
+	// The only reported way to do so is the kernel recompilation.
+	return &PortError{code: FunctionNotImplemented, causedBy: nil}
+}
+
 func (port *unixPort) GetModemStatusBits() (*ModemStatusBits, error) {
 	status, err := port.getModemBitsStatus()
 	if err != nil {

serial_windows.go

@@ -385,6 +385,17 @@ func (port *windowsPort) SetReadTimeout(timeout time.Duration) error {
 	return nil
 }
 
+func (port *windowsPort) SetBufferSize(rxSize, txSize int) error {
+	rxSize_ := uint32(rxSize)
+	txSize_ := uint32(txSize)
+
+	if err := setupComm(port.handle, rxSize_, txSize_); err != nil {
+		return &PortError{code: InvalidBufferSize, causedBy: err}
+	}
+
+	return nil
+}
+
 func (port *windowsPort) Break(d time.Duration) error {
 	if err := setCommBreak(port.handle); err != nil {
 		return &PortError{causedBy: err}

syscall_windows.go

@@ -12,6 +12,8 @@ package serial
 
 //sys setCommState(handle syscall.Handle, dcb *dcb) (err error) = SetCommState
 
+//sys setupComm(handle syscall.Handle, rxSize uint32, txSize uint32) (err error) = SetupComm
+
 //sys setCommTimeouts(handle syscall.Handle, timeouts *commTimeouts) (err error) = SetCommTimeouts
 
 //sys escapeCommFunction(handle syscall.Handle, function uint32) (res bool) = EscapeCommFunction