#! /usr/bin/perl -w
# $Id: qm1538.perl,v 1.1 2007/08/30 22:33:52 philip Exp $
use strict;
use Device::SerialPort;

my $device    = "/dev/cuaU0";
my $port=new Device::SerialPort($device) || die "new($device): $!\n";

$port->handshake("none");
$port->baudrate("2400");
$port->databits("8");
$port->parity("none");
$port->stopbits("1");

my @l;
my $minus;
my $p1;
my $p2;
my $p3;
my $d1;
my $d2;
my $d3;
my $d4;

$port->read_char_time(0);     # Don't wait
$port->read_const_time(1000); # 1 second per unfulfilled read call

# lookup table to convert random gibberish into digits.
my @lookup;
$lookup[125] = 0;
$lookup[5]   = 1;
$lookup[91]  = 2;
$lookup[31]  = 3;
$lookup[39]  = 4;
$lookup[62]  = 5;
$lookup[126] = 6;
$lookup[21]  = 7;
$lookup[127] = 8;
$lookup[63]  = 9;

my $timeout = 10;
my $display = "";
while ( $timeout > 0 ){
 # grab a buffer full of data (up to 16 bytes)
 my($count,$saw) = $port->read(16);
 if ( $count > 0 ){
  $timeout = 10;
  my @buffer = split(//,$saw);
  while ( my $b = shift @buffer ){
   $b = unpack('C',$b);
   # mask off high nibble
   my $h = $b & 240;
   $h = $h >> 4;
   # and each bit of low nibble
   $l[$h][0] = $b & 1;
   $l[$h][1] = $b & 2;
   $l[$h][2] = $b & 4;
   $l[$h][3] = $b & 8;
   if ( $h == 14 ){
    $minus = $l[2][3];
    $p1 = $l[4][3];
    $p2 = $l[6][3];
    $p3 = $l[8][3];

    $d1 = hex sprintf("%x%x", $l[2][2] + $l[2][1] + $l[2][0], 
                          $l[3][3] + $l[3][2] + $l[3][1] + $l[3][0]);

    $d2 = hex sprintf("%x%x", $l[4][2] + $l[4][1] + $l[4][0], 
                          $l[5][3] + $l[5][2] + $l[5][1] + $l[5][0]);

    $d3 = hex sprintf("%x%x", $l[6][2] + $l[6][1] + $l[6][0],
                          $l[7][3] + $l[7][2] + $l[7][1] + $l[7][0]);

    $d4 = hex sprintf("%x%x", $l[8][2] + $l[8][1] + $l[8][0],
                          $l[9][3] + $l[9][2] + $l[9][1] + $l[9][0]);
    $display = "";
    if ( $minus ) {
     $display = "-";
    }
    $display .= $lookup[$d1];
    if ( $p1 ) {
     $display .= ".";
    }
    $display .= $lookup[$d2];
    if ( $p2 ) {
     $display .= ".";
    }
    $display .= $lookup[$d3];
    if ( $p3 ) {
     $display .= ".";
    }
    $display .= $lookup[$d4];
  
    print time, "\t$display\n";
   }
  }
 }
 else {
  $timeout--;
 }
}

$port->close or die "Couldn't close serial port: $!\n";

exit;