| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2002 Jeff Dike (jdike@karaya.com) |
| 3 | * Licensed under the GPL |
| 4 | */ |
| 5 | |
| 6 | #ifndef __UM_SLIP_PROTO_H__ |
| 7 | #define __UM_SLIP_PROTO_H__ |
| 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 | |
| 15 | static inline int slip_unesc(unsigned char c,char *buf,int *pos, int *esc) |
| 16 | { |
| 17 | int ret; |
| 18 | |
| 19 | switch(c){ |
| 20 | case SLIP_END: |
| 21 | *esc = 0; |
| 22 | ret=*pos; |
| 23 | *pos=0; |
| 24 | return(ret); |
| 25 | case SLIP_ESC: |
| 26 | *esc = 1; |
| 27 | return(0); |
| 28 | case SLIP_ESC_ESC: |
| 29 | if(*esc){ |
| 30 | *esc = 0; |
| 31 | c = SLIP_ESC; |
| 32 | } |
| 33 | break; |
| 34 | case SLIP_ESC_END: |
| 35 | if(*esc){ |
| 36 | *esc = 0; |
| 37 | c = SLIP_END; |
| 38 | } |
| 39 | break; |
| 40 | } |
| 41 | buf[(*pos)++] = c; |
| 42 | return(0); |
| 43 | } |
| 44 | |
| 45 | static inline int slip_esc(unsigned char *s, unsigned char *d, int len) |
| 46 | { |
| 47 | unsigned char *ptr = d; |
| 48 | unsigned char c; |
| 49 | |
| 50 | /* |
| 51 | * Send an initial END character to flush out any |
| 52 | * data that may have accumulated in the receiver |
| 53 | * due to line noise. |
| 54 | */ |
| 55 | |
| 56 | *ptr++ = SLIP_END; |
| 57 | |
| 58 | /* |
| 59 | * For each byte in the packet, send the appropriate |
| 60 | * character sequence, according to the SLIP protocol. |
| 61 | */ |
| 62 | |
| 63 | while (len-- > 0) { |
| 64 | switch(c = *s++) { |
| 65 | case SLIP_END: |
| 66 | *ptr++ = SLIP_ESC; |
| 67 | *ptr++ = SLIP_ESC_END; |
| 68 | break; |
| 69 | case SLIP_ESC: |
| 70 | *ptr++ = SLIP_ESC; |
| 71 | *ptr++ = SLIP_ESC_ESC; |
| 72 | break; |
| 73 | default: |
| 74 | *ptr++ = c; |
| 75 | break; |
| 76 | } |
| 77 | } |
| 78 | *ptr++ = SLIP_END; |
| 79 | return (ptr - d); |
| 80 | } |
| 81 | |
| 82 | #endif |
| 83 | |
| 84 | /* |
| 85 | * Overrides for Emacs so that we follow Linus's tabbing style. |
| 86 | * Emacs will notice this stuff at the end of the file and automatically |
| 87 | * adjust the settings for this buffer only. This must remain at the end |
| 88 | * of the file. |
| 89 | * --------------------------------------------------------------------------- |
| 90 | * Local variables: |
| 91 | * c-file-style: "linux" |
| 92 | * End: |
| 93 | */ |