#!/usr/bin/perl

use Device::SerialPort;

my $port_path = '/dev/ttyS1';

my %map = ();

# devices.map file is a <sender address> <message processing module> list
# Message processing module must expose a gotMessage and a terminate method.
# The gotMessage method receives the sender address and the data values as integer as arguments.
open(my $f, '<devices.map') or die('Cannot open device map !');
while(<$f>) {
	if($_ =~ /([0-9]{1, 3})\s+([a-z][a-z0-9_]+)/) {
		if(int($1) && -f $2.'.pm') {
			use $2;
			$map{int($1)} = $2;
		}
	}
}
close $f;

our $end = 0;
$SIG{'TERM'} = sub {
	$end = 1;
};

my $port = Device::SerialPort->new($port_path) or die('Cannot open port !');
$port->baudrate(4800) or die('Failed to set baudrate !');
$port->parity('even') or die('Failed to set parity !');
$port->databits(8) or die('Failed to set data length !');
$port->stty_icml(1) or die('Failed to set cr as new line !');
$port->handshake('none') or die('Failed to set handshaking !');
$port->write_settings or die('Failed to write settings !');

sub readPort {
	my $port = shift;
	my ($n, $c) = $port->read(1);
	return ord($c);
}

sub fletcher {
	my $sum1 = 15, $sum2 = 15;
	$sum2 += ($sum1 += shift) for(my $i=0; $i<=17; $i++);
	$sum1 = ($sum1 & 0x0f) + int($sum1 / 16);
	$sum1 = ($sum1 & 0x0f) + int($sum1 / 16);
	$sum2 = ($sum2 & 0x0f) + int($sum2 / 16);
	$sum2 = ($sum2 & 0x0f) + int($sum2 / 16);
	return 16*$sum2 + $sum1;
}

my $i, $n, $c, @d, $s;

while(!$end) {
	if(readPort($port) == 2) { # STX
		@d = ();
		for($i=0; $i<17; $i++) {
			push(@d, readPort($port));
		}
		$s = readPort($port);
		if(
			(readPort($port) == 3) # ETX
			&& $d[0]
			&& (fletcher(@d) == $s)
		) {
			eval $map{$d[0]}.'::gotMessage('.join(', ', @d).')' if(defined $map{$d[0]});
		}
	}
}

my %m = ();
$m{$map{$_}} = 1 foreach(keys %map);
eval $_.'::terminate()' foreach(keys %m);

undef $port;

0;