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