-
Notifications
You must be signed in to change notification settings - Fork 0
/
reader.go
167 lines (146 loc) · 3.78 KB
/
reader.go
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
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
package dataflash
import (
"encoding/binary"
"errors"
"io"
)
var (
// ErrMissingHeader means that the magic header was not found when trying to read a message.
ErrMissingHeader = errors.New("missing magic message header")
// ErrUnknownMessageType means that a message with an unknown type definition was found.
ErrUnknownMessageType = errors.New("unknown message type")
)
var (
endian = binary.LittleEndian
)
// NewReader instantiates and returns a dataflash message reader.
func NewReader(input io.Reader) *Reader {
return &Reader{
input: input,
formats: map[uint8]Format{0x80: NewFormat("FMT", 89, "BBnNZ", "Type,Length,Name,Format,Columns")},
}
}
type Reader struct {
input io.Reader
formats map[uint8]Format
}
// https://docs.python.org/3/library/struct.html
// https://github.com/ArduPilot/pymavlink/blob/master/DFReader.py
func (r *Reader) Read() (*Message, error) {
header := make([]byte, 3)
n, err := r.input.Read(header)
if err != nil {
return nil, err
}
if header[0] != Head1 || header[1] != Head2 || n < 3 {
return nil, ErrMissingHeader
}
messageType := header[2]
format, known := r.formats[messageType]
//log.Println(format)
if !known {
return nil, ErrUnknownMessageType
}
var buffer []byte
elements := map[string]interface{}{}
for i, t := range format.types {
column := format.columns[i]
switch t {
case "a":
buffer = make([]byte, 64)
r.input.Read(buffer)
elements[column] = nullts(buffer)
case "b":
var value int8
binary.Read(r.input, endian, &value)
elements[column] = value
case "B":
var value uint8
binary.Read(r.input, endian, &value)
elements[column] = value
case "c":
var value int16
binary.Read(r.input, endian, &value)
elements[column] = float32(value) * 0.01
case "C":
var value uint16
binary.Read(r.input, endian, &value)
elements[column] = float32(value) * 0.01
case "e":
var value int32
binary.Read(r.input, endian, &value)
elements[column] = float32(value) * 0.01
case "d":
var value int32
binary.Read(r.input, endian, &value)
elements[column] = float32(value) * 0.01
case "E":
var value uint32
binary.Read(r.input, endian, &value)
elements[column] = float32(value) * 0.01
case "f":
var value float32
binary.Read(r.input, endian, &value)
elements[column] = value
case "h":
var value int16
binary.Read(r.input, endian, &value)
elements[column] = value
case "H":
var value uint16
binary.Read(r.input, endian, &value)
elements[column] = value
case "i":
var value int32
binary.Read(r.input, endian, &value)
elements[column] = value
case "I":
var value uint32
binary.Read(r.input, endian, &value)
elements[column] = value
case "L":
var value int32
binary.Read(r.input, endian, &value)
elements[column] = float32(value) * 1.0e-7
case "M":
var value int8
binary.Read(r.input, endian, &value)
elements[column] = value
case "n":
buffer = make([]byte, 4)
r.input.Read(buffer)
elements[column] = nullts(buffer)
case "N":
buffer = make([]byte, 16)
r.input.Read(buffer)
elements[column] = nullts(buffer)
case "Z":
buffer = make([]byte, 64)
r.input.Read(buffer)
elements[column] = nullts(buffer)
case "q":
var value int64
binary.Read(r.input, endian, &value)
elements[column] = value
case "Q":
var value uint64
binary.Read(r.input, endian, &value)
elements[column] = value
}
}
if messageType == 128 {
r.formats[elements["Type"].(uint8)] = NewFormat(elements["Name"].(string), elements["Length"].(uint8), elements["Format"].(string), elements["Columns"].(string))
}
return nil, nil
}
func nullts(buffer []byte) string {
return string(buffer[:clen(buffer)])
}
func clen(n []byte) int {
for i := 0; i < len(n); i++ {
if n[i] == 0 {
return i
}
}
return len(n)
}