func newHandle(c *Config) (handle syscall.Handle, err error) {
handle, err = syscall.CreateFile(
syscall.StringToUTF16Ptr(c.Address),
syscall.GENERIC_READ|syscall.GENERIC_WRITE,
0, // mode
nil, // security
syscall.OPEN_EXISTING, // create mode
0, // attributes
0) // templates
if err != nil {
return
}
defer func() {
if err != nil {
syscall.CloseHandle(handle)
}
}()
var dcb C.DCB
dcb.BaudRate = C.DWORD(c.BaudRate)
// Data bits
if c.DataBits == 0 {
dcb.ByteSize = 8
} else {
dcb.ByteSize = C.BYTE(c.DataBits)
}
// Stop bits
switch c.StopBits {
case 0, 1:
// Default is one stop bit.
dcb.StopBits = C.ONESTOPBIT
case 2:
dcb.StopBits = C.TWOSTOPBITS
default:
err = fmt.Errorf("serial: unsupported stop bits %v", c.StopBits)
return
}
// Parity
switch c.Parity {
case "", "E":
// Default parity mode is Even.
dcb.Parity = C.EVENPARITY
case "O":
dcb.Parity = C.ODDPARITY
case "N":
dcb.Parity = C.NOPARITY
default:
err = fmt.Errorf("serial: unsupported parity %v", c.Parity)
return
}
if C.SetCommState(C.HANDLE(handle), &dcb) == 0 {
err = fmt.Errorf("serial: could not set device state: %v", syscall.GetLastError())
return
}
return
}
func main() {
handle, err := syscall.CreateFile(syscall.StringToUTF16Ptr(port),
syscall.GENERIC_READ|syscall.GENERIC_WRITE,
0, // mode
nil, // security
syscall.OPEN_EXISTING, // no creating new
0,
0)
if err != nil {
fmt.Print(err)
return
}
fmt.Printf("handle created %d\n", handle)
defer syscall.CloseHandle(handle)
var dcb C.DCB
dcb.BaudRate = 9600
dcb.ByteSize = 8
dcb.StopBits = C.ONESTOPBIT
dcb.Parity = C.NOPARITY
if C.SetCommState(C.HANDLE(handle), &dcb) == 0 {
fmt.Printf("set comm state error %v\n", syscall.GetLastError())
return
}
fmt.Printf("set comm state succeed\n")
var timeouts C.COMMTIMEOUTS
// time-out between charactor for receiving (ms)
timeouts.ReadIntervalTimeout = 1000
timeouts.ReadTotalTimeoutMultiplier = 0
timeouts.ReadTotalTimeoutConstant = 1000
timeouts.WriteTotalTimeoutMultiplier = 0
timeouts.WriteTotalTimeoutConstant = 1000
if C.SetCommTimeouts(C.HANDLE(handle), &timeouts) == 0 {
fmt.Printf("set comm timeouts error %v\n", syscall.GetLastError())
return
}
fmt.Printf("set comm timeouts succeed\n")
var n uint32
data := []byte("abc")
err = syscall.WriteFile(handle, data, &n, nil)
if err != nil {
fmt.Println(err)
return
}
fmt.Printf("write file succeed\n")
fmt.Printf("Press Enter when ready for reading...")
reader := bufio.NewReader(os.Stdin)
_, _ = reader.ReadString('\n')
data = make([]byte, 512)
err = syscall.ReadFile(handle, data, &n, nil)
if err != nil {
fmt.Println(err)
return
}
fmt.Printf("received data %v:\n", n)
fmt.Printf("%x\n", data[:n])
fmt.Printf("closed\n")
}