arch/um/drivers/slip_proto.h

   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  */