From: Adam Shelly <adam.shelly@...>
Date: 2006-08-01T01:43:45+09:00
Subject: Re: [QUIZ] Chip-8 (#88)

On 7/28/06, Ruby Quiz <james@grayproductions.net> wrote:
> Your job is to make an emulator...

My solution:  It's like a clone of my ICFP solution.  Where's the codex.chip8?
-Adam

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class Chip8
  class Instruction
    attr_reader :op,:nn,:x,:y,:kk
    def parse val
      @op = (val&0xF000)>>12
      @nn = (val&0x0FFF)
      @kk = (val&0x00FF)
      @x  = (val&0x0F00)>>8
      @y  = (val&0x00F0)>>4
    end
  end
  def initialize
    @program = []
    @cp = 0
    @v = Array.new(16){0}
  end
  def load filename
    File.open(filename, "rb"){|f|
      while !f.eof
        @program << f.read(2).unpack('n*')[0]
      end
    }
  end
  def run
    halt = false
    i = Instruction.new
    while !halt
      i.parse(@program[@cp])
      @cp+=1
      case i.op
        when 0 then halt=true
        when 1 then @cp = i.nn/2
        when 3 then @cp+=1 if @v[i.x]==i.kk
        when 6 then @v[i.x] = i.kk
        when 7 then @v[0xF],@v[i.x] = (@v[i.x]+ i.kk).divmod 0x100
        when 8
          case i.nn&0xF
            when 0 then @v[i.x] = @v[i.y]
            when 1 then @v[i.x] |= @v[i.y]
            when 2 then @v[i.x] &= @v[i.y]
            when 3 then @v[i.x] ^= @v[i.y]
            when 4 then @v[0xF],@v[i.x] = (@v[i.x]+@v[i.y]).divmod 0x100
            when 5 then @v[0xF],@v[i.x] = (@v[i.x]-@v[i.y]).divmod 0x100
            when 6 then @v[0xF]=@v[i.x][0]
                        @v[i.x]>>=1
            when 7 then c,@v[i.x] = (@v[i.y]-@v[i.x]).divmod 0x100
                        @v[0xF]=1+c
            when 0xE then @v[0xF]=@v[i.x][7]
                          @v[i.x]<<=1
          end
        when 0xC then @v[i.x] = rand(256)&i.kk
      end
    end
  end
  def dump base = 10
    puts @v.map{|e|e.to_s(base)}.inspect
  end
end

if __FILE__ == $0
  c = Chip8.new
  c.load ARGV[0]||"chip8.test"
  c.run
  c.dump(2)
end