#include <stdio.h>
#include <stdlib.h>
#include <wiringSerial.h>
#include <termios.h>

int recvmsg(int fd, char *msg, int maxlen)
{
   // Receive a response message from the EMG101 laser,
   // looking for a capital letter status code as a message
   // terminator. The return value is the number of characters
   // received including the status code letter but not the
   // string-terminating null. Two error exits values exist:
   //    -1) means it timed out waiting for a response (10s)
   //   -99) means the input buffer overflowed

   int len = 0;
   while (len < maxlen - 1) {
      int resp = serialGetchar(fd);
      if (resp == -1) {
         msg[len] = 0;
         return -1;
      }
      msg[len++] = resp;
      if (resp >= 'A' && resp <= 'Z') {
         msg[len] = 0;
         return len;
      }
   }
   return -9;
}

int main()
{
   int fd = serialOpen("/dev/ttyUSB0", 300);
   printf("serialOpen returns fd=%d\n",fd);

   // set the com port attributes
   struct termios portset;
   tcgetattr(fd, &portset);
   portset.c_iflag &= ~(IGNBRK | BRKINT | ICRNL | INLCR |
                        PARMRK | INPCK | ISTRIP | IXON);
   portset.c_oflag = 0;
   portset.c_cflag &= ~(CSIZE | PARENB | CSTOPB);
   portset.c_cflag |= (CS8 | CRTSCTS);
   int ret = tcsetattr(fd, TCSAFLUSH, &portset);
   if (ret != 0) {
      printf("Error from tcsetattr: %d\n", ret);
   }

   // try a test message
   serialPrintf(fd, "C");
   char response[999];
   ret = recvmsg(fd, response, 999);
   if (ret > 0) {
      printf("received response: %s\n", response);
   }
   else {
      printf("error receiving response: %d\n", ret);
   }

   serialClose(fd);
}