Merge pull request #147 from cmaglie/remove_windows_timeout_loop

Remove unnecessary code, originally for checking for disconnects when using non-overlapped I/O

serial_windows.go

@@ -26,7 +26,6 @@ import (
 type windowsPort struct {
 	mu     sync.Mutex
 	handle syscall.Handle
-	readTimeoutCycles int64
 }
 
 func nativeGetPortsList() ([]string, error) {
@@ -83,9 +82,7 @@ func (port *windowsPort) Read(p []byte) (int, error) {
 	}
 	defer syscall.CloseHandle(ev.HEvent)
 
-	cycles := int64(0)
-	for {
-		err := syscall.ReadFile(port.handle, p, &readed, ev)
+	err = syscall.ReadFile(port.handle, p, &readed, ev)
 	if err == syscall.ERROR_IO_PENDING {
 		err = getOverlappedResult(port.handle, ev, &readed, true)
 	}
@@ -99,34 +96,13 @@ func (port *windowsPort) Read(p []byte) (int, error) {
 		// error happened
 		return int(readed), err
 	}
-
 	if readed > 0 {
 		return int(readed), nil
 	}
-		if err := resetEvent(ev.HEvent); err != nil {
-			return 0, err
-		}
 
-		if port.readTimeoutCycles != -1 {
-			cycles++
-			if cycles == port.readTimeoutCycles {
 	// Timeout
 	return 0, nil
 }
-		}
-
-		// At the moment it seems that the only reliable way to check if
-		// a serial port is alive in Windows is to check if the SetCommState
-		// function fails.
-
-		params := &dcb{}
-		getCommState(port.handle, params)
-		if err := setCommState(port.handle, params); err != nil {
-			port.Close()
-			return 0, err
-		}
-	}
-}
 
 func (port *windowsPort) Write(p []byte) (int, error) {
 	var writed uint32
@@ -383,26 +359,24 @@ func (port *windowsPort) GetModemStatusBits() (*ModemStatusBits, error) {
 }
 
 func (port *windowsPort) SetReadTimeout(timeout time.Duration) error {
-	var cycles, cycleDuration int64
-	if timeout == NoTimeout {
-		cycles = -1
-		cycleDuration = 1000
-	} else {
-		cycles = timeout.Milliseconds()/1000 + 1
-		cycleDuration = timeout.Milliseconds() / cycles
-	}
-
-	err := setCommTimeouts(port.handle, &commTimeouts{
+	commTimeouts := &commTimeouts{
 		ReadIntervalTimeout:         0xFFFFFFFF,
 		ReadTotalTimeoutMultiplier:  0xFFFFFFFF,
-		ReadTotalTimeoutConstant:    uint32(cycleDuration),
+		ReadTotalTimeoutConstant:    0xFFFFFFFE,
 		WriteTotalTimeoutConstant:   0,
 		WriteTotalTimeoutMultiplier: 0,
-	})
-	if err != nil {
+	}
+	if timeout != NoTimeout {
+		ms := timeout.Milliseconds()
+		if ms > 0xFFFFFFFE || ms < 0 {
+			return &PortError{code: InvalidTimeoutValue}
+		}
+		commTimeouts.ReadTotalTimeoutConstant = uint32(ms)
+	}
+
+	if err := setCommTimeouts(port.handle, commTimeouts); err != nil {
 		return &PortError{code: InvalidTimeoutValue, causedBy: err}
 	}
-	port.readTimeoutCycles = cycles
 
 	return nil
 }