git.sesse.net Git - ultimatescore/blob - client/bodet.cpp

   1 // Bodet BT-6000 decoder.
   2
   3 #include <stdio.h>
   4 #include <unistd.h>
   5
   6 #include <string>
   7 #include <vector>
   8
   9 using namespace std;
  10
  11 void process(const string &buf)
  12 {
  13         unsigned char checksum = 0;
  14         for (size_t i = 1; i <= buf.size() - 2; ++i) {
  15                 checksum ^= buf[i];
  16         }
  17         checksum &= 0x7f;
  18         if (checksum < 0x20) {
  19                 checksum += 0x20;
  20         }
  21         if (checksum != buf.back()) {
  22         //      fprintf(stderr, "discarding message with broken checksum: [%s] [%x vs. %x]\n", buf.c_str(), checksum, buf.back());
  23         } else {
  24                 string realmsg = buf.substr(3, buf.size() - 5);
  25                 fprintf(stderr, "msg: [%s]\n", realmsg.c_str());
  26         }
  27 }
  28
  29 int main(int argc, char **argv)
  30 {
  31         // TODO: open serial port
  32
  33         string buf;
  34
  35         for ( ;; ) {
  36                 char ch;
  37                 int ret = read(0, &ch, 1);
  38                 if (ret == -1) {
  39                         perror("read");
  40                         exit(1);
  41                 }
  42                 if (ret == 0) {
  43                         fprintf(stderr, "short read\n");
  44                         exit(1);
  45                 }
  46
  47                 if (ch == 1) {  // SOH
  48                         buf = ch;
  49                         continue;
  50                 }
  51                 if (buf.size() == 1) {
  52                         // Address
  53                         buf.push_back(ch);
  54                         continue;
  55                 }
  56                 if (ch == 2) {  // STX
  57                         if (buf.size() == 2) {
  58                                 buf.push_back(ch);
  59                         } else {
  60                                 buf.clear();  // STX out-of-order
  61                         }
  62                         continue;
  63                 }
  64
  65                 if (!buf.empty() && buf.back() == 3) {  // Last was ETX, so this is LTC.
  66                         buf.push_back(ch);
  67                         process(buf);
  68                         buf.clear();
  69                         continue;
  70                 }
  71
  72                 if (ch == 3) {  // ETX
  73                         if (buf.size() >= 4) {
  74                                 buf.push_back(ch);
  75                         } else {
  76                                 buf.clear();  // ETX out-of-order
  77                         }
  78                         continue;
  79                 }
  80                 buf.push_back(ch);
  81         }
  82 }