#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/signal.h>
#include <sys/types.h>

#include <linux/termios.h>

int fd;
int counter;   /* kw1281 protocol block counter */

/* manually set serial lines */

static void _set_bit(int bit)
{
   int flags;

   ioctl (fd, TIOCMGET, &flags);
   if (bit) {
      ioctl (fd, TIOCCBRK, 0);
      flags &= ~TIOCM_RTS;
   } else {
      ioctl (fd, TIOCSBRK, 0);
      flags |= TIOCM_RTS;
   }
   ioctl (fd, TIOCMSET, &flags);
}

/* receive one byte and acknowledge it */

unsigned char kw1281_recv_byte_ack()
{
   unsigned char c, d;

   read (fd, &c, 1);
   d = 0xff-c;
   usleep (10000);
   write (fd, &d, 1);
   read (fd, &d, 1);
   if (0xff-c != d)
      printf ("kw1281_recv_byte_ack: echo error (0x%02x != 0x%02x)\n", 0xff-c, d);
   return c;
}

/* send one byte and wait for acknowledgement */

void kw1281_send_byte_ack(unsigned char c)
{
   unsigned char d;
   int in;

   usleep (10000);
   write (fd, &c, 1);
   read (fd, &d, 1);
   if (c != d)
      printf ("kw1281_send_byte_ack: echo error (0x%02x0x%02x != 0x%02x)\n", c, d);
   read (fd, &d, 1);
   if (0xff-c != d)
      printf ("kw1281_send_byte_ack: ack error (0x%02x != 0x%02x)\n", 0xff-c, d);
}

/* write 7O1 address byte at 5 baud and wait for sync/keyword bytes */

void kw1281_init(int address)
{
   int i, p, flags;
   unsigned char c;

   int out,in;

   /* prepare to send (clear dtr and rts) */
   ioctl (fd, TIOCMGET, &flags);
   flags &= ~(TIOCM_DTR | TIOCM_RTS);
   ioctl (fd, TIOCMSET, &flags);
   usleep (200000);

   _set_bit (0);      /* start bit */
   usleep (200000);   /* 5 baud */
   p = 1;
   for (i=0; i<7; i++) {   /* address bits, lsb first */
      int bit = (address >> i) & 0x1;
      _set_bit (bit);
      p = p ^ bit;
      usleep (200000);
   }
   _set_bit (p);      /* odd parity */
   usleep (200000);
   _set_bit (1);      /* stop bit */
   usleep (200000);

   /* set dtr */
   ioctl (fd, TIOCMGET, &flags);
   flags |= TIOCM_DTR;
   ioctl (fd, TIOCMSET, &flags);

   /* read bogus values, if any */
   ioctl(fd, FIONREAD, &in);
   while (in--) {
      read (fd, &c, 1);
      printf ("ignore 0x%02x\n", c);
   }

   read (fd, &c, 1);
   if (c != 0x55)
      printf ("kw1281_init: sync error (0x55 != 0x%02x)\n", c);

   read (fd, &c, 1);
   if (c != 0x01)
      printf ("kw1281_init: keyword error (0x01 != 0x%02x)\n", c);

   c = kw1281_recv_byte_ack ();
   if (c != 0x8a)
      printf ("kw1281_init: keyword error (0x8a != 0x%02x)\n", c);

   counter = 1;
}

/* receive a complete block */

void kw1281_recv_block()
{
   int i;
   unsigned char c, l, t;
   char buf[256];

   /* block length */
   l = kw1281_recv_byte_ack();

   c = kw1281_recv_byte_ack();
   if (c != counter) {
      printf ("counter error (%d != %d)\n", counter, c);

      printf ("IN   OUT\t(block dump)\n");
      printf ("0x%02x\n", l);
      printf ("     0x%02x\n", 0xff-l);
      printf ("0x%02x\n", c);
      printf ("     0x%02x\n", 0xff-c);
      while (1) {
         c = kw1281_recv_byte_ack();
         printf ("0x%02x\n", c);
         printf ("     0x%02x\n", 0xff-c);
   }   }

   t = kw1281_recv_byte_ack();
   switch (t) {
      case 0xf6:
         printf ("got ASCII block %d\n", counter);
         break;
      case 0x09:
         printf ("got ACK block %d\n", counter);
         break;
      default:
         printf ("block title: 0x%02x (block %d)\n", t, counter);
   }
   l -= 2;

   i = 0;
   while (--l) {
      c = kw1281_recv_byte_ack();
      buf[i++] = c;
      printf ("0x%02x ", c);
   }
   buf[i] = 0;
   if (t == 0xf6)
      printf ("= \"%s\"\n", buf);
   else
      printf ("\n");

   /* read block end */
   read (fd, &c, 1);
   if (c != 0x03)
      printf ("block end error (0x03 != 0x%02x)\n", c);

   counter++;
}

/* send an ACK block */

void kw1281_send_ack() {
   unsigned char c;

   printf ("send ACK block %d\n", counter);

   /* block length */
   kw1281_send_byte_ack (0x03);

   kw1281_send_byte_ack (counter++);

   /* ack command */
   kw1281_send_byte_ack (0x09);

   /* block end */
   c = 0x03;
   usleep (10000);
   write (fd, &c, 1);
   read (fd, &c, 1);
   if (c != 0x03)
      printf ("echo error (0x03 != 0x%02x)\n", c);
}


int main(int arc, unsigned char *argv[]) {

   unsigned char c;
   struct termios oldtio, newtio;
   struct sigaction saio;

   fd = open ("/dev/ttyS0", O_SYNC | O_RDWR | O_NOCTTY);
   if (fd < 0) {
      exit(-1);
   }

   tcgetattr (fd, &oldtio);

   newtio.c_cflag = B9600 | CS8 | CLOCAL | CREAD;
   newtio.c_iflag =  IGNPAR | ICRNL;
   newtio.c_oflag = 0;
   newtio.c_cc[VMIN] = 1;
   newtio.c_cc[VTIME] = 0;
   tcflush (fd, TCIFLUSH);
   tcsetattr (fd, TCSANOW, &newtio);

   printf ("init\n");   /* ECU: 0x01, INSTR: 0x17 */
   kw1281_init (0x01);      /* send 5baud address, read sync byte + key word */

   printf ("receive blocks\n");
   kw1281_recv_block ();   /* controller ID */
   kw1281_send_ack ();

   kw1281_recv_block ();   /* component # */
   kw1281_send_ack ();

   kw1281_recv_block ();   /* software coding */
   kw1281_send_ack ();

   kw1281_recv_block ();   /* dealer part # */
   kw1281_send_ack ();

   printf ("main loop\n");
   while (1) {
      kw1281_recv_block ();
      usleep (100000);
      kw1281_send_ack ();
   }

   /* tcsetattr (fd, TCSANOW, &oldtio); */
}

/* read block end */