// +build linux,!cgo package serial import ( "os" "syscall" "time" "unsafe" ) func openPort(name string, baud int, databits byte, parity Parity, stopbits StopBits, readTimeout time.Duration) (p *Port, err error) { var bauds = map[int]uint32{ 50: syscall.B50, 75: syscall.B75, 110: syscall.B110, 134: syscall.B134, 150: syscall.B150, 200: syscall.B200, 300: syscall.B300, 600: syscall.B600, 1200: syscall.B1200, 1800: syscall.B1800, 2400: syscall.B2400, 4800: syscall.B4800, 9600: syscall.B9600, 19200: syscall.B19200, 38400: syscall.B38400, 57600: syscall.B57600, 115200: syscall.B115200, 230400: syscall.B230400, 460800: syscall.B460800, 500000: syscall.B500000, 576000: syscall.B576000, 921600: syscall.B921600, 1000000: syscall.B1000000, 1152000: syscall.B1152000, 1500000: syscall.B1500000, 2000000: syscall.B2000000, 2500000: syscall.B2500000, 3000000: syscall.B3000000, 3500000: syscall.B3500000, 4000000: syscall.B4000000, } rate := bauds[baud] if rate == 0 { return } f, err := os.OpenFile(name, syscall.O_RDWR|syscall.O_NOCTTY|syscall.O_NONBLOCK, 0666) if err != nil { return nil, err } defer func() { if err != nil && f != nil { f.Close() } }() // Base settings cflagToUse := syscall.CREAD | syscall.CLOCAL | rate switch databits { case 5: cflagToUse |= syscall.CS5 case 6: cflagToUse |= syscall.CS6 case 7: cflagToUse |= syscall.CS7 case 8: cflagToUse |= syscall.CS8 default: return nil, ErrBadSize } // Stop bits settings switch stopbits { case Stop1: // default is 1 stop bit case Stop2: cflagToUse |= syscall.CSTOPB default: // Don't know how to set 1.5 return nil, ErrBadStopBits } // Parity settings switch parity { case ParityNone: // default is no parity case ParityOdd: cflagToUse |= syscall.PARENB cflagToUse |= syscall.PARODD case ParityEven: cflagToUse |= syscall.PARENB default: return nil, ErrBadParity } fd := f.Fd() vmin, vtime := posixTimeoutValues(readTimeout) t := syscall.Termios{ Iflag: syscall.IGNPAR, Cflag: cflagToUse, Cc: [32]uint8{syscall.VMIN: vmin, syscall.VTIME: vtime}, Ispeed: rate, Ospeed: rate, } if _, _, errno := syscall.Syscall6( syscall.SYS_IOCTL, uintptr(fd), uintptr(syscall.TCSETS), uintptr(unsafe.Pointer(&t)), 0, 0, 0, ); errno != 0 { return nil, errno } if err = syscall.SetNonblock(int(fd), false); err != nil { return } return &Port{f: f}, nil } type Port struct { // We intentionly do not use an "embedded" struct so that we // don't export File f *os.File } func (p *Port) Read(b []byte) (n int, err error) { return p.f.Read(b) } func (p *Port) Write(b []byte) (n int, err error) { return p.f.Write(b) } // Discards data written to the port but not transmitted, // or data received but not read func (p *Port) Flush() error { const TCFLSH = 0x540B _, _, err := syscall.Syscall( syscall.SYS_IOCTL, uintptr(p.f.Fd()), uintptr(TCFLSH), uintptr(syscall.TCIOFLUSH), ) return err } func (p *Port) Close() (err error) { return p.f.Close() }