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serial_linux.go
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serial_linux.go
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// +build linux
package serial
import (
"fmt"
"os"
"time"
"unsafe"
"golang.org/x/sys/unix"
)
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: unix.B50,
75: unix.B75,
110: unix.B110,
134: unix.B134,
150: unix.B150,
200: unix.B200,
300: unix.B300,
600: unix.B600,
1200: unix.B1200,
1800: unix.B1800,
2400: unix.B2400,
4800: unix.B4800,
9600: unix.B9600,
19200: unix.B19200,
38400: unix.B38400,
57600: unix.B57600,
115200: unix.B115200,
230400: unix.B230400,
460800: unix.B460800,
500000: unix.B500000,
576000: unix.B576000,
921600: unix.B921600,
1000000: unix.B1000000,
1152000: unix.B1152000,
1500000: unix.B1500000,
2000000: unix.B2000000,
2500000: unix.B2500000,
3000000: unix.B3000000,
3500000: unix.B3500000,
4000000: unix.B4000000,
}
rate, ok := bauds[baud]
if !ok {
return nil, fmt.Errorf("Unrecognized baud rate")
}
f, err := os.OpenFile(name, unix.O_RDWR|unix.O_NOCTTY|unix.O_NONBLOCK, 0666)
if err != nil {
return nil, err
}
defer func() {
if err != nil && f != nil {
f.Close()
}
}()
// Base settings
cflagToUse := unix.CREAD | unix.CLOCAL | rate
switch databits {
case 5:
cflagToUse |= unix.CS5
case 6:
cflagToUse |= unix.CS6
case 7:
cflagToUse |= unix.CS7
case 8:
cflagToUse |= unix.CS8
default:
return nil, ErrBadSize
}
// Stop bits settings
switch stopbits {
case Stop1:
// default is 1 stop bit
case Stop2:
cflagToUse |= unix.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 |= unix.PARENB
cflagToUse |= unix.PARODD
case ParityEven:
cflagToUse |= unix.PARENB
default:
return nil, ErrBadParity
}
fd := f.Fd()
vmin, vtime := posixTimeoutValues(readTimeout)
t := unix.Termios{
Iflag: unix.IGNPAR,
Cflag: cflagToUse,
Ispeed: rate,
Ospeed: rate,
}
t.Cc[unix.VMIN] = vmin
t.Cc[unix.VTIME] = vtime
if _, _, errno := unix.Syscall(
unix.SYS_IOCTL,
uintptr(fd),
uintptr(unix.TCSETS),
uintptr(unsafe.Pointer(&t)),
); errno != 0 {
return nil, errno
}
if err = unix.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
_, _, errno := unix.Syscall(
unix.SYS_IOCTL,
uintptr(p.f.Fd()),
uintptr(TCFLSH),
uintptr(unix.TCIOFLUSH),
)
if errno == 0 {
return nil
}
return errno
}
func (p *Port) GetStatus() (n uint, err error) {
var status uint
if _, _, errno := unix.Syscall(
unix.SYS_IOCTL,
uintptr(p.f.Fd()),
uintptr(unix.TIOCMGET),
uintptr(unsafe.Pointer(&status)),
); errno != 0 {
return status, errno
} else {
return status, nil
}
}
func (p *Port) SetDTR(v byte) (err error) {
req := unix.TIOCMBIS
if 0 == v {
req = unix.TIOCMBIC
}
var m uint = unix.TIOCM_DTR
if _, _, errno := unix.Syscall(
unix.SYS_IOCTL,
uintptr(p.f.Fd()),
uintptr(req),
uintptr(unsafe.Pointer(&m)),
); errno != 0 {
return errno
} else {
return nil
}
}
func (p *Port) SetRTS(v byte) (err error) {
req := unix.TIOCMBIS
if 0 == v {
req = unix.TIOCMBIC
}
var m uint = unix.TIOCM_RTS
if _, _, errno := unix.Syscall(
unix.SYS_IOCTL,
uintptr(p.f.Fd()),
uintptr(req),
uintptr(unsafe.Pointer(&m)),
); errno != 0 {
return errno
} else {
return nil
}
}
func (p *Port) Close() (err error) {
return p.f.Close()
}