mandelbrot rubinius

mandelbrot.rb

#  The Computer Language Benchmarks Game
#  http://shootout.alioth.debian.org/
#
#  contributed by Karl von Laudermann
#  modified by Jeremy Echols
#  modified by Detlef Reichl
#  modified by Joseph LaFata
#  modified by Peter Zotov
#  modified by Brian Ford
#  modified by Yura Sokolov
require 'benchmark'

size = ARGV.shift.to_i

unless String.respond_to?(:pattern)
  class String
    def self.pattern(n, c)
      ("" << c) * n
    end
  end
end
unless ''.respond_to?(:setbyte)
  class String
    def setbyte(i, b)
      self[i] = b
    end
  end
end

class PointArith
  def initialize
    @ci = @cr = @zrzr = @zr = @zizi = @zi = 0.0
  end

  def init(ci, cr)
    @ci, @cr = ci, cr
    @zrzr = @zr = 0.0
    @zizi = @zi = 0.0
  end

  def step
    tr = @zrzr - @zizi + @cr
    ti = 2.0*@zr*@zi + @ci
    @zr, @zi = tr, ti
    @zrzr = @zr*@zr
    @zizi = @zi*@zi
    @zrzr + @zizi > 4.0
  end
end

def mandelbrot(size, io)
  io.puts "P4\n#{size} #{size}"

  byte_acc = 0
  bit_num = 0
  byte = 0
  image_size = ((size + 7) / 8) * size
  buf = String.pattern image_size, 0

  pnt = PointArith.new

  y = 0
  while y < size
    ci = (2.0*y/size)-1.0

    x = 0
    while x < size
      cr = (2.0*x/size)-1.5
      pnt.init(ci, cr)
      escape = 1
      
      i = 0
      while i < 50
        if pnt.step
          escape = 0
          i = 50
        end
        i += 1
      end

      byte_acc = (byte_acc << 1) | escape
      bit_num += 1

      # Code is very similar for these cases, but using separate blocks
      # ensures we skip the shifting when it's unnecessary, which is most cases.
      if (bit_num == 8)
        buf.setbyte byte, byte_acc
        byte_acc = 0
        bit_num = 0
        byte += 1
      elsif (x == size - 1)
        buf.setbyte byte, (byte_acc << (8 - bit_num))
        byte_acc = 0
        bit_num = 0
        byte += 1
      end
      x += 1
    end
    y += 1
  end
  io.write(buf)
end

File.open('/dev/null', 'w') do |f|
  200.times{ mandelbrot 24, f }
end

duration = Benchmark.measure do
  mandelbrot size, STDOUT
end

STDERR.puts duration