Ruby brainfuck interpretor

brainfuck.rb

#!/usr/bin/env ruby
# coding: utf-8

class Machine
  RAMSIZE = 256
  def initialize(file)
    @ram = File.open(file).read.each_char.map.to_a
    @eoc = @ram.size
    @ram.fill(0, @eoc..RAMSIZE)
    @p = @eoc
    @pp = 0
  end
  def run
    case @ram[@pp]
    when '>'; @p += 1
    when '<'; @p -= 1
    when '+'; @ram[@p] += 1
    when '-'; @ram[@p] -= 1
    when '.'; putc @ram[@p]
    when ','; @ram[@p] = stdin.readchar
    when '['
      if (@ram[@p] == 0)
        while @ram[@pp] != ']'
          @pp += 1
        end
      end
    when ']'
      if (@ram[@p] != 0)
        while @ram[@pp] != '['
          @pp -= 1
        end
      end
    else
    end
    @pp += 1
  end
  def start
    while true
      self.run
      break if @pp > @eoc
    end
  end
end

vm = Machine.new("./hello.bf")
vm.start

hello.bf

+++++++++[>++++++++>+++++++++++>+++++<<<-]>.>++.+++++++..+++.>-.
------------.<++++++++.--------.+++.------.--------.>+.