/*
 * listener.c -- joins a multicast group and echoes all data it receives from
 *		the group to its stdout...
 *
 * Antony Courtney,	25/11/94
 * Modified by: Frédéric Bastien (25/03/04)
 * to compile without warning and work correctly
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <time.h>
#include <string.h>
#include <stdio.h>


#define HELLO_PORT 47391
#define HELLO_GROUP "239.255.171.51"
#define MSGBUFSIZE 256
#define MYNICA "10.5.5.251"

main(int argc, char *argv[])
{
     struct sockaddr_in addr;
     int fd, nbytes,addrlen,ctr;
     struct ip_mreq mreq;
     char msgbuf[MSGBUFSIZE];
     int d,m=0,pos;
     unsigned vv,ref=0,pt=0,delta,frqno=0;
     signed sum;

     u_int yes=1;            /*** MODIFICATION TO ORIGINAL */

     /* create what looks like an ordinary UDP socket */
     if ((fd=socket(AF_INET,SOCK_DGRAM,0)) < 0) {
	  perror("socket");
	  return(1);
     }


/**** MODIFICATION TO ORIGINAL */
    /* allow multiple sockets to use the same PORT number */
    if (setsockopt(fd,SOL_SOCKET,SO_REUSEADDR,&yes,sizeof(yes)) < 0) {
       perror("Reusing ADDR failed");
       return(1);
       }
/*** END OF MODIFICATION TO ORIGINAL */

     /* set up destination address */
     memset(&addr,0,sizeof(addr));
     addr.sin_family=AF_INET;
     addr.sin_addr.s_addr=htonl(INADDR_ANY); /* N.B.: differs from sender */
     addr.sin_port=htons(HELLO_PORT);
     
     /* bind to receive address */
     if (bind(fd,(struct sockaddr *) &addr,sizeof(addr)) < 0) {
	  perror("bind");
	  return(1);
     }
     
     /* use setsockopt() to request that the kernel join a multicast group */
     mreq.imr_multiaddr.s_addr=inet_addr(HELLO_GROUP);
     mreq.imr_interface.s_addr=inet_addr(MYNICA);
     if (setsockopt(fd,IPPROTO_IP,IP_ADD_MEMBERSHIP,&mreq,sizeof(mreq)) < 0) {
	  perror("setsockopt");
	  return(1);
     }

     /* now just enter a read-print loop */
     while (1) {
	  addrlen=sizeof(addr);
	  if ((nbytes=recvfrom(fd,msgbuf,MSGBUFSIZE,0,
			       (struct sockaddr *) &addr,&addrlen)) < 0) {
	       perror("recvfrom");
	       return(1);
	  }
	  d=0;
	  if (msgbuf[0]) d|=1;
	  if (msgbuf[5]) d|=2;
	  if (msgbuf[10]) d|=4;
	  if (msgbuf[15]) d|=8;
	  if (msgbuf[20]) d|=16;
	  if (msgbuf[25]) d|=32;
	  if (msgbuf[30]) d|=64;
	  if (msgbuf[35]) d|=128;
//	     printf(":: %x\n",d);

restart:
	  switch (m) {
	   case 0: //if (d==0xBE) m=1; break;
	   case 1: if (d==0xBD) {m=2; break;} m=0; break;
	   case 2: if (d==0x14) {m=3; break;} 
	           if (d==0x15) {m=20; break;} 
                   if (d==0x1F) {m=10; break;} 
                   m=0; 
	           goto restart;
 //	   case 2: if (d==0x14) {m=3; break;} m=0; goto restart;
	   case 3: vv=d; m=4; break;
	   case 4: vv<<=8; vv|=d; m=5; break;
	   case 5: vv<<=8; vv|=d; m=6; break;
	   case 6: vv<<=8; vv|=d; m=0;
	   delta=vv-ref;
	   ref=vv;
	   ++pt;
	   sum+=delta;
	   sum-=20000000-1900;
//	   printf("%u %u\n",pt,delta);
	   printf("pps info n=%u abs=%u delta=%u\n",pt,vv,delta);
	   break;
	   
	   case 10:
	     if (d) printf("%c",d); else m=0;
	     fflush(stdout);
	     break;

	   case 20: vv=d; m=21; break;
	   case 21: vv<<=8; vv|=d; m=22; break;
	   case 22: vv<<=8; vv|=d; m=23; break;
	   case 23: vv<<=8; vv|=d; m=24;
	           //fprintf(stdout,"%u %0.1f ",++frqno,((signed)vv)*0.1);
	           fprintf(stderr,"Frequency error %0.1f ppb, ",((signed)vv)*0.1);
	           break;
	   case 24: vv=d; m=25; break;
	   case 25: vv<<=8; vv|=d; m=0;
	   fprintf(stderr,"dac %u\n",vv);
	   fflush(stdout);

	  }
     }
}