// WAIT for a packet from base station via serial port over radio link
// need to link with serials.c to get coms stuff and logfile
// we usually talk to /dev/ttyS05 for the radio modem
// and log to a file called /home/km/incoming/basecoms.log
#include <sys/stat.h>
#include <fcntl.h>
// need this to set the serial speed like B9600
#include <termios.h>
#include <stdio.h>
#include <signal.h>

// Royan's packets
// HDR(1 nibble)
// HDRSIZE(1 nibble)
// SRC_ID(1)
// CMD(1)
// data[1-16]
// checksum(1)
#define CURRENT_ID	0xF0	//ID of this device
#define CMD_HEADER_ID	0x30	//command message header (send or rcv)
#define REPLY_HEADER_ID	0x50	//reply message header
#define BROADCAST_ID	0xA0	//the ID boadcasting
#define GROUP_ID		0xA3	//the ID for group response
#define CMD_SYS_BAT_READ	0x12	// battery voltage
#define CMD_SYS_I_AM_AWAKE	20	// to test if things are awake
#define	CMD_SYS_READ_STR_READINGS 0x15	// read stored readings 
#define CMD_GPS_TRANSFER_LOG	0xCC	// ready to download rem GPS
#define CMD_EEPROM_READ_16 0x5D		// read eeprom 
// a load of ugly globals to store packet data in!
unsigned char RX_STATE = 0;
unsigned char RX_HEADER;	// a copy of the packet header
unsigned char RX_SIZE;	//received data field size
unsigned char RX_MODULE;	//target or source module ID
unsigned char RX_COMMAND;	//received or sent command
unsigned char RX_DATA[16];	//data

unsigned char TX_HEADER;	// out packet header
unsigned char TX_SIZE;	//out data field size
unsigned char TX_MODULE;	//out target or source module ID
unsigned char TX_COMMAND;	//out pkt  type
unsigned char TX_DATA[16];	//out data


// CATCH SIGNALS and close us down nicely
void sigcatch(int s)
{
extern FILE *logfd;
//close(serialport);
//fclose(logfd);
 // logging file used by serials.c
logfile("waitforbase exiting due to HUP");
exit(0);
}

void
COMINTInterpret (unsigned char c) 
{
  static unsigned int _checksum;

//printf("got %x\n",c);

  if (RX_STATE == 0)		//handle data in other conditions
    {				//idle	
				//read packet if valid header detected
      if (((c & 0xF0) == CMD_HEADER_ID) || ((c & 0xF0) == REPLY_HEADER_ID))
	{
	  _checksum = c;	//checksum calculation
	  RX_SIZE = c & 0x0F;	//size of data field is lower nibble
		RX_HEADER = c & 0xF0;	// Copy header type for later
	  RX_STATE = 1;		//goto next state
	}
    }
  
  else if (RX_STATE == 1)
    
    {				//module
      RX_MODULE = c;		//read module
      _checksum += RX_MODULE;	//checksum
      RX_STATE = 2;		//goto next state
    }
  
  else if (RX_STATE == 2)
    
    {				//command
      RX_COMMAND = c;		//read command
      _checksum += RX_COMMAND;	//checksum
      RX_STATE = 3;		//goto next state
    }
  
  else if (RX_STATE == (RX_SIZE + 4))	// Whole packet read, check & exec
    
    {
      if ((_checksum % 256) == c)
	
	if( RX_HEADER == CMD_HEADER_ID)
		{			//checksum tallies with data
		  if ((RX_MODULE == CURRENT_ID) || (RX_MODULE == BROADCAST_ID)
		      || (RX_MODULE == GROUP_ID))
		    ExecuteCommand ();
		}
	else
		ExecuteReply();
		
      RX_STATE = 0;		//back to idle mode                             
    }
  
  else
    
    {				//data
      RX_DATA[RX_STATE - 3] = c;	//read data
      _checksum += RX_DATA[RX_STATE - 3];	//checksum                      
      RX_STATE++;		//goto next state
    }
}

// tell them I am awake
i_am_awake()
{
TX_HEADER = REPLY_HEADER_ID;
TX_SIZE = 1;
TX_MODULE = CURRENT_ID;
TX_COMMAND = CMD_SYS_I_AM_AWAKE;
TX_DATA[0] = 0; // just for fun
SendPacket();
}

// Write a packet from our global variables, to the serial port
SendPacket()
{
unsigned char firstbyte;
unsigned short checksum;
int n;

firstbyte = TX_HEADER + TX_SIZE -1;
checksum = firstbyte;
putbyte(firstbyte);
putbyte(TX_MODULE);
checksum += TX_MODULE;
putbyte(TX_COMMAND);
checksum += TX_COMMAND;
for(n = 0; n < TX_SIZE; n++){	
	putbyte(TX_DATA[n]);
	checksum += TX_DATA[n];
	}
putbyte((unsigned char)(checksum & 0xFF) );
}

ExecuteCommand () 
{
switch(RX_COMMAND)
        {
        case CMD_GPS_TRANSFER_LOG:
		logfile("waitforbase got CMD_GPS_TRANSFER_LOG and exited\n");
		exit(0);

        case CMD_SYS_I_AM_AWAKE:
		logfile("waitforbase got I am awake\n");
		 i_am_awake(); break;
        }
}

// we got something we need to reply to
ExecuteReply()
{
int n;

switch(RX_COMMAND)
	{
	case CMD_EEPROM_READ_16: 
		break;
	}
}


main (int argc, char **argv) 
{
	int fd, n;
	unsigned char byte;
	int flushcounter=0;
	char tmpname[256];

// catch a signal and exit cleanly
signal(SIGHUP, sigcatch);

// open port
initialise_coms("/dev/ttyS4", B9600, "/home/km/incoming/basecoms.log");

// WE EXIT HERE WHEN WE GET A PACKET TO SAY GO GPS
while(1){
      byte = getbyte();
      COMINTInterpret (byte);
	}
}