test-bsb/gen.c

   1 #include <stdio.h>
   2 #include <stdint.h>
   3
   4 typedef unsigned char byte;
   5 typedef unsigned int uint;
   6 typedef uint16_t u16;
   7
   8 u16 crc_update(u16 crc, byte data)
   9 {
  10         crc = crc ^ (data << 8);
  11         for (uint i=0; i<8; i++) {
  12                 if (crc & 0x8000)
  13                         crc = (crc << 1) ^ 0x1021;
  14                 else
  15                         crc <<= 1;
  16         }
  17         return crc;
  18 }
  19
  20 byte msg[] = {
  21         0xdc,                   // sync
  22         0x80 | 0x42,            // src
  23         0x00,                   // dest
  24         0x00,                   // length (will be filled)
  25         0x06,                   // command
  26         0x3d, 0x2e, 0x11, 0x25,
  27 };
  28
  29 int main(void)
  30 {
  31         msg[3] = sizeof(msg) + 2;
  32
  33         u16 crc = 0;
  34         for (uint i=0; i < sizeof(msg); i++) {
  35                 printf("%02x ", msg[i]);
  36                 crc = crc_update(crc, msg[i]);
  37         }
  38         printf("%02x %02x\n", crc >> 8, crc & 0xff);
  39
  40         return 0;
  41 }