misc/tty_lin_master/lin_common.c

   1 #include <string.h>
   2 #include "lin_common.h"
   3
   4 const unsigned char sllin_id_parity_table[64] = {
   5         0x80,0xc0,0x40,0x00,0xc0,0x80,0x00,0x40,
   6         0x00,0x40,0xc0,0x80,0x40,0x00,0x80,0xc0,
   7         0x40,0x00,0x80,0xc0,0x00,0x40,0xc0,0x80,
   8         0xc0,0x80,0x00,0x40,0x80,0xc0,0x40,0x00,
   9         0x00,0x40,0xc0,0x80,0x40,0x00,0x80,0xc0,
  10         0x80,0xc0,0x40,0x00,0xc0,0x80,0x00,0x40,
  11         0xc0,0x80,0x00,0x40,0x80,0xc0,0x40,0x00,
  12         0x40,0x00,0x80,0xc0,0x00,0x40,0xc0,0x80
  13 };
  14
  15
  16 int sllin_setup_msg(struct sllin *sl, int mode, int id,
  17                 unsigned char *data, int len)
  18 {
  19         if (id > 0x3f)
  20                 return -1;
  21
  22         sl->rx_cnt = 0;
  23         sl->tx_cnt = 0;
  24         sl->rx_expect = 0;
  25
  26         sl->tx_buff[SLLIN_BUFF_BREAK] = 0;
  27         sl->tx_buff[SLLIN_BUFF_SYNC]  = 0x55;
  28         sl->tx_buff[SLLIN_BUFF_ID]    = id | sllin_id_parity_table[id];
  29         sl->tx_lim = SLLIN_BUFF_DATA;
  30
  31         if ((data != NULL) && len) {
  32                 int i;
  33                 unsigned csum  = 0;
  34
  35                 sl->tx_lim += len;
  36                 memcpy(sl->tx_buff + SLLIN_BUFF_DATA, data, len);
  37                 /* compute data parity there */
  38                 for (i = SLLIN_BUFF_DATA; i < sl->tx_lim; i++) {
  39                         csum += sl->tx_buff[i];
  40                         if (csum > 255)
  41                                 csum -= 255;
  42                 }
  43
  44                 sl->tx_buff[sl->tx_lim++] = csum;
  45         }
  46         if (len != 0)
  47                 sl->rx_lim += len + 1;
  48
  49         return 0;
  50 }
  51