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
|
/*
* slip.c
* ------
* SLIP send/recv code, based on RFC 1055
*
* Copyright (c) 2016, NORDUnet A/S All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of the NORDUnet nor the names of its contributors may
* be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "slip_internal.h"
/* SLIP special character codes
*/
#define END 0300 /* indicates end of packet */
#define ESC 0333 /* indicates byte stuffing */
#define ESC_END 0334 /* ESC ESC_END means END data byte */
#define ESC_ESC 0335 /* ESC ESC_ESC means ESC data byte */
#ifndef HAL_SLIP_DEBUG
#define HAL_SLIP_DEBUG 0
#endif
#if HAL_SLIP_DEBUG
#include <stdio.h>
#define check(op) do { const hal_error_t _err_ = (op); if (_err_ != HAL_OK) { printf("%s returned %d (%s)\n", #op, _err_, hal_error_string(_err_)); return _err_; } } while (0)
#else
#define check(op) do { const hal_error_t _err_ = (op); if (_err_ != HAL_OK) { return _err_; } } while (0)
#endif
/* Send a single character with SLIP escaping.
*/
hal_error_t hal_slip_send_char(const uint8_t c)
{
switch (c) {
case END:
check(hal_serial_send_char(ESC));
check(hal_serial_send_char(ESC_END));
break;
case ESC:
check(hal_serial_send_char(ESC));
check(hal_serial_send_char(ESC_ESC));
break;
default:
check(hal_serial_send_char(c));
}
return HAL_OK;
}
/* Send a message with SLIP framing.
*/
hal_error_t hal_slip_send(const uint8_t * const buf, const size_t len)
{
/* send an initial END character to flush out any data that may
* have accumulated in the receiver due to line noise
*/
check(hal_serial_send_char(END));
/* for each byte in the packet, send the appropriate character
* sequence
*/
for (int i = 0; i < len; ++i) {
hal_error_t ret;
if ((ret = hal_slip_send_char(buf[i])) != HAL_OK)
return ret;
}
/* tell the receiver that we're done sending the packet
*/
check(hal_serial_send_char(END));
return HAL_OK;
}
/* Receive a single character into a buffer, with SLIP un-escaping
*/
hal_error_t hal_slip_process_char(uint8_t c, uint8_t * const buf, size_t * const len, const size_t maxlen, int * const complete)
{
#define buf_push(c) do { if (*len < maxlen) buf[(*len)++] = c; } while (0)
static int esc_flag = 0;
*complete = 0;
switch (c) {
case END:
if (*len)
*complete = 1;
break;
case ESC:
esc_flag = 1;
break;
default:
if (esc_flag) {
esc_flag = 0;
switch (c) {
case ESC_END:
buf_push(END);
break;
case ESC_ESC:
buf_push(ESC);
break;
default:
buf_push(c);
}
}
else {
buf_push(c);
}
break;
}
return HAL_OK;
}
hal_error_t hal_slip_recv_char(uint8_t * const buf, size_t * const len, const size_t maxlen, int * const complete)
{
uint8_t c;
check(hal_serial_recv_char(&c));
return hal_slip_process_char(c, buf, len, maxlen, complete);
}
/* Receive a message with SLIP framing, blocking mode.
*/
hal_error_t hal_slip_recv(uint8_t * const buf, size_t * const len, const size_t maxlen)
{
int complete;
hal_error_t ret;
while (1) {
ret = hal_slip_recv_char(buf, len, maxlen, &complete);
if ((ret != HAL_OK) || complete)
return ret;
}
}
|
