#!/usr/bin/perl -w

$width = 72;
$height = 21;

$c0 = 0;
$c1 = 1;
$c2 = 2;
$c3 = 3;


$bmp = shift || die;
$sprite = shift || die;


open(BMP, $bmp) || die;
binmode(BMP);
while (<BMP>) {
  $bmp .= $_;
}
close(BMP);

$bitmap = substr($bmp, -$width * $height);

foreach $yy (0 .. $height - 1) {
  $y = $height - $yy - 1;
  $line = substr($bitmap, $width * $yy);
  for ($x = 0; $x < $width; $x += 2) {
    $c = ord(substr($line, $x));
    if ($c == $c0) {
      $out[$y] .= "00";
    } elsif ($c == $c1) {
      $out[$y] .= "01";
    } elsif ($c == $c2) {
      $out[$y] .= "10";
    } elsif ($c == $c3) {
      $out[$y] .= "11";
    } else {
      $out[$y] .= "..";
    }
  }
}

for ($y = 0; $y < $height; $y++) {
  print substr($out[$y], 0, 80) . "\n";
}


for ($s = 0; $s < $width / 24; $s++) {
  print $s . "\n";
  foreach $y (0..20) {
    foreach $x (0..2) {
      $line = substr($out[$y], $s*24 + $x*8, 8);
      $spriteset .= pack("B8", $line);
    }
  }
  $spriteset .= "\x00"; # pad
}


print "Writing " . length($spriteset) . " bytes, plus 2\n";

open(SPRITE, ">$sprite") || die;
binmode(SPRITE);
print SPRITE "\x00\x20";
print SPRITE $spriteset;
close(SPRITE);