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