mce_flow_s sub { draw_line($_) }, 0, $h - 1;

##</code><code>##

# synopsis: perl mandelbrot.pl 1024 > image.pbm
#
# https://github.com/nbraud/benchmarksgame/blob/master/bench/
#         mandelbrot/mandelbrot.perl
#
# The Computer Language Benchmarks Game
#  http://benchmarksgame.alioth.debian.org/
#
#  contributed by Mykola Zubach
#  shorten by Mario Roy from using MCE

use strict;
use threads;
use threads::shared;
use MCE::Flow chunk_size => 1, max_workers => 'auto';

use constant MAXITER => 50;
use constant LIMIT   => 4.0;
use constant XMIN    => -1.5;
use constant YMIN    => -1;
use constant WHITE   => "\0";
use constant BLACK   => "\001";

my ($w, $h, $invN);
my @picture : shared;

sub draw_line($) {
   my $y = shift;
   my $line;
   my $Ci = $y * $invN + YMIN;
X:
   for my $x (0 .. $w - 1) {
      my ($Zr, $Zi, $Tr, $Ti);
      my $Cr = $x * $invN + XMIN;

      for (1 .. MAXITER) {
         $Zi = $Zi * 2 * $Zr + $Ci;
         $Zr = $Tr - $Ti + $Cr;
         $Ti = $Zi * $Zi;
         $Tr = $Zr * $Zr;
         if ($Tr + $Ti > LIMIT) {
            $line .= WHITE;
            next X;
         }
      }
      $line .= BLACK;
   }
   $picture[$y] = pack 'B*', $line;
}

## MAIN()

$w = $h = shift || 200;
$invN = 2 / $w;

mce_flow_s sub { draw_line($_) }, 0, $h - 1;

binmode STDOUT;

print "P4\n$w $h\n"; # PBM image header
print @picture;