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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
a3c77c67 JD |
2 | #ifndef __UM_SLIP_COMMON_H |
3 | #define __UM_SLIP_COMMON_H | |
1da177e4 | 4 | |
a3c77c67 JD |
5 | #define BUF_SIZE 1500 |
6 | /* two bytes each for a (pathological) max packet of escaped chars + * | |
7 | * terminating END char + initial END char */ | |
8 | #define ENC_BUF_SIZE (2 * BUF_SIZE + 2) | |
1da177e4 LT |
9 | |
10 | /* SLIP protocol characters. */ | |
11 | #define SLIP_END 0300 /* indicates end of frame */ | |
12 | #define SLIP_ESC 0333 /* indicates byte stuffing */ | |
13 | #define SLIP_ESC_END 0334 /* ESC ESC_END means END 'data' */ | |
14 | #define SLIP_ESC_ESC 0335 /* ESC ESC_ESC means ESC 'data' */ | |
15 | ||
da00d9a5 JD |
16 | static inline int slip_unesc(unsigned char c, unsigned char *buf, int *pos, |
17 | int *esc) | |
1da177e4 LT |
18 | { |
19 | int ret; | |
20 | ||
21 | switch(c){ | |
22 | case SLIP_END: | |
23 | *esc = 0; | |
24 | ret=*pos; | |
25 | *pos=0; | |
26 | return(ret); | |
27 | case SLIP_ESC: | |
28 | *esc = 1; | |
29 | return(0); | |
30 | case SLIP_ESC_ESC: | |
31 | if(*esc){ | |
32 | *esc = 0; | |
33 | c = SLIP_ESC; | |
34 | } | |
35 | break; | |
36 | case SLIP_ESC_END: | |
37 | if(*esc){ | |
38 | *esc = 0; | |
39 | c = SLIP_END; | |
40 | } | |
41 | break; | |
42 | } | |
43 | buf[(*pos)++] = c; | |
44 | return(0); | |
45 | } | |
46 | ||
47 | static inline int slip_esc(unsigned char *s, unsigned char *d, int len) | |
48 | { | |
49 | unsigned char *ptr = d; | |
50 | unsigned char c; | |
51 | ||
52 | /* | |
53 | * Send an initial END character to flush out any | |
54 | * data that may have accumulated in the receiver | |
55 | * due to line noise. | |
56 | */ | |
57 | ||
58 | *ptr++ = SLIP_END; | |
59 | ||
60 | /* | |
61 | * For each byte in the packet, send the appropriate | |
62 | * character sequence, according to the SLIP protocol. | |
63 | */ | |
64 | ||
65 | while (len-- > 0) { | |
66 | switch(c = *s++) { | |
67 | case SLIP_END: | |
68 | *ptr++ = SLIP_ESC; | |
69 | *ptr++ = SLIP_ESC_END; | |
70 | break; | |
71 | case SLIP_ESC: | |
72 | *ptr++ = SLIP_ESC; | |
73 | *ptr++ = SLIP_ESC_ESC; | |
74 | break; | |
75 | default: | |
76 | *ptr++ = c; | |
77 | break; | |
78 | } | |
79 | } | |
80 | *ptr++ = SLIP_END; | |
81 | return (ptr - d); | |
82 | } | |
83 | ||
a3c77c67 JD |
84 | struct slip_proto { |
85 | unsigned char ibuf[ENC_BUF_SIZE]; | |
86 | unsigned char obuf[ENC_BUF_SIZE]; | |
87 | int more; /* more data: do not read fd until ibuf has been drained */ | |
88 | int pos; | |
89 | int esc; | |
90 | }; | |
91 | ||
854e981c PBG |
92 | static inline void slip_proto_init(struct slip_proto * slip) |
93 | { | |
94 | memset(slip->ibuf, 0, sizeof(slip->ibuf)); | |
95 | memset(slip->obuf, 0, sizeof(slip->obuf)); | |
96 | slip->more = 0; | |
97 | slip->pos = 0; | |
98 | slip->esc = 0; | |
a3c77c67 | 99 | } |
1da177e4 | 100 | |
a3c77c67 JD |
101 | extern int slip_proto_read(int fd, void *buf, int len, |
102 | struct slip_proto *slip); | |
103 | extern int slip_proto_write(int fd, void *buf, int len, | |
104 | struct slip_proto *slip); | |
105 | ||
106 | #endif |