serial/serial_linux.go at master · fugr/serial · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
package serial

/*

Serial syscalls adapted from github.com/dustin/go-rs232 via github.com/schleibinger/sio

1) Original: Copyright (c) 2005-2008 Dustin Sallings <dustin@spy.net>.

2) Mods: Copyright (c) 2012 Schleibinger Gerä Teubert u. Greim GmbH
<info@schleibinger.com>. Blame: Jan Mercl

All rights reserved.  Use of this source code is governed by a MIT-style
license that can be found in the LICENSE file.

*/

import (
	"fmt"
	"os"
	"syscall"
	"unsafe"
)

type Port struct {
	config Config
	handle *os.File
}

func (p *Port) configure(cfg Config) (err error) {
	p.config = cfg

	return
}

func (p *Port) open() (err error) {

	// open serial port handle
	//
	err = p.openHandle()

	if err != nil {
		p.Close()

		return fmt.Errorf("error opening serial device %s: %s", p.config.Device, err)
	}

	return
}

func (p *Port) openHandle() (err error) {

	rate := uint32(settings[p.config.BaudRate])

	p.handle, err = os.OpenFile(p.config.Device, syscall.O_RDWR|syscall.O_NOCTTY|syscall.O_NDELAY, 0666)

	if err != nil {
		return
	}

	fd := p.handle.Fd()

	term := syscall.Termios{
		Iflag:  syscall.IGNPAR,
		Cflag:  syscall.CS8 | syscall.CREAD | syscall.CLOCAL | rate,
		Cc:     [32]uint8{syscall.VMIN: p.config.VMIN, syscall.VTIME: p.config.VTIME},
		Ispeed: rate,
		Ospeed: rate,
	}

	_, _, errno := syscall.Syscall6(
		syscall.SYS_IOCTL,
		uintptr(fd),
		uintptr(syscall.TCSETS),
		uintptr(unsafe.Pointer(&term)),
		0,
		0,
		0,
	)

	if errno != 0 {
		err = errno
	}

	if err != nil {
		return
	}

	err = syscall.SetNonblock(int(fd), false)

	if err != nil {
		return
	}

	return
}

func (p *Port) close() (err error) {
	if p.handle != nil {
		err = p.handle.Close()
	}

	return
}

func (p *Port) read(b []byte) (n int, err error) {
	return p.handle.Read(b)
}

func (p *Port) write(b []byte) (n int, err error) {
	return p.handle.Write(b)
}

var (

	// map the generic constants in serial.go to values for termios
	//
	settings = map[int]int{
		DataBits_5:      5,
		DataBits_6:      6,
		DataBits_7:      7,
		DataBits_8:      8,
		StopBits_1:      0,
		StopBits_1_5:    1,
		StopBits_2:      2,
		Parity_None:     0,
		Parity_Odd:      1,
		Parity_Even:     2,
		Parity_Mark:     3,
		Parity_Space:    4,
		BaudRate_9600:   syscall.B9600,
		BaudRate_19200:  syscall.B19200,
		BaudRate_38400:  syscall.B38400,
		BaudRate_57600:  syscall.B57600,
		BaudRate_115200: syscall.B115200,
	}
)