Loop unrolling on Ruby2600 Tia.rb

gistfile1.rb

    def draw_scanline
      scanline = Array.new(160, 0)
      unroll_count = 16
      loop_count = VISIBLE_CLK_COUNT/unroll_count
      pixel = 0

      while loop_count > 0
        
        draw_pixel(pixel, scanline)
        draw_pixel(pixel+1, scanline)
        draw_pixel(pixel+2, scanline)
        draw_pixel(pixel+3, scanline)
        draw_pixel(pixel+4, scanline)
        draw_pixel(pixel+5, scanline)
        draw_pixel(pixel+6, scanline)
        draw_pixel(pixel+7, scanline)
        draw_pixel(pixel+8, scanline)
        draw_pixel(pixel+9, scanline)
        draw_pixel(pixel+10, scanline)
        draw_pixel(pixel+11, scanline)
        draw_pixel(pixel+12, scanline)
        draw_pixel(pixel+13, scanline)
        draw_pixel(pixel+14, scanline)
        draw_pixel(pixel+15, scanline)

        loop_count -= unroll_count
        pixel += unroll_count

      end

      scanline
    end

    def draw_pixel(pixel, scanline)
        @scanline_stage = @late_reset_hblank && pixel < 8 ? :late_hblank : :visible

        update_collision_flags
        sync_2600_with pixel + HORIZONTAL_BLANK_CLK_COUNT

        scanline[pixel] = topmost_pixel if @scanline_stage == :visible && !vertical_blank?
    end