Class: Badline::VIC

Inherits:
Cycleable show all
Includes:
Addressable, IntegerHelper
Defined in:
lib/badline/vic.rb,
lib/badline/vic/bank.rb,
lib/badline/vic/sprite.rb,
lib/badline/vic/sprites.rb,
lib/badline/vic/registers.rb,
lib/badline/vic/sequencer.rb,
lib/badline/vic/display_state.rb,
lib/badline/vic/graphics_mode.rb

Defined Under Namespace

Modules: GraphicsMode Classes: Bank, DisplayState, Registers, Sequencer, Sprite, Sprites

Constant Summary collapse

SPRITE_BA_RANGES = 
[
  55..59, 57..61, 59..62,
  0..2, 0..4, 2..6, 4..8, 6..10
].freeze

Instance Attribute Summary collapse

Attributes included from Addressable

#end, #length, #start

Attributes inherited from Cycleable

#cycles

Instance Method Summary collapse

Methods included from IntegerHelper

#bcd, #bcd_to_i, #format16, #format8, #high_byte, #low_byte, #signed_int8, #uint16

Methods included from Addressable

#[], #[]=, #addressable_at, #in_range?, #peek16, #poke16, #range

Methods inherited from Cycleable

#pending_write?

Constructor Details

#initialize(address_bus = nil, debug: false) ⇒ VIC

Returns a new instance of VIC.



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# File 'lib/badline/vic.rb', line 22

def initialize(address_bus = nil, debug: false)
  addressable_at(0xd000, length: 2**10)
  @address_bus = address_bus || AddressBus.new
  @vic_bank = VIC::Bank.new(@address_bus)
  @debug = debug

  @width = 504
  @height = 312

  @registers = VIC::Registers.new
  @display_state = VIC::DisplayState.new(@registers)
  @sequencer = VIC::Sequencer.new(@width, @registers, @vic_bank)
  @sprites = VIC::Sprites.new(@registers, @vic_bank, @width)
  @display = Array.new(@width * @height, 0)
  @dirty_lines = Array.new(@height, true)

  @column = 0
  @rasterline = 0
  @columns_per_line = @width / 8
  @last_line = @height - 1

  @character_buffer = Array.new(40, 0)
  @color_buffer = Array.new(40, 0)
  @sprite_ba = Array.new(@width / 8, false)

  super()
end

Instance Attribute Details

#address_bus ⇒ Object (readonly)

Returns the value of attribute address_bus.



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# File 'lib/badline/vic.rb', line 14

def address_bus
  @address_bus
end

#column ⇒ Object (readonly)

Returns the value of attribute column.



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# File 'lib/badline/vic.rb', line 14

def column
  @column
end

#dirty_lines ⇒ Object (readonly)

Returns the value of attribute dirty_lines.



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# File 'lib/badline/vic.rb', line 14

def dirty_lines
  @dirty_lines
end

#display ⇒ Object (readonly)

Returns the value of attribute display.



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# File 'lib/badline/vic.rb', line 14

def display
  @display
end

#height ⇒ Object (readonly)

Returns the value of attribute height.



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# File 'lib/badline/vic.rb', line 14

def height
  @height
end

#rasterline ⇒ Object (readonly)

Returns the value of attribute rasterline.



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# File 'lib/badline/vic.rb', line 14

def rasterline
  @rasterline
end

#vic_bank ⇒ Object (readonly)

Returns the value of attribute vic_bank.



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# File 'lib/badline/vic.rb', line 14

def vic_bank
  @vic_bank
end

#width ⇒ Object (readonly)

Returns the value of attribute width.



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# File 'lib/badline/vic.rb', line 14

def width
  @width
end

Instance Method Details

#ba_low? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/badline/vic.rb', line 103

def ba_low?
  return true if @sprite_ba[@column]

  @display_state.bad_line? && @column >= 13 && @column < 56
end

#blanking? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/badline/vic.rb', line 117

def blanking?
  @rasterline < 16 || @rasterline > 299 || @column < 10 || @column > 60
end

#clear_dirty_lines! ⇒ Object

Reset the dirty flags once the frontend has consumed them.



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# File 'lib/badline/vic.rb', line 122

def clear_dirty_lines!
  @dirty_lines.fill(false)
end

#cycle! ⇒ Object 



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# File 'lib/badline/vic.rb', line 50

def cycle!
  if @column.zero?
    @display_state.new_frame if @rasterline.zero?
    check_raster_irq!
    @sequencer.new_line(@rasterline)
    @sprites.start_line(@rasterline)
    rebuild_sprite_ba
    @display_state.new_line
  end

  @display_state.cycle(@rasterline, @column)

  fetch_character_data! if dma_active?

  draw!

  @column += 1
  if @column == @columns_per_line
    finish_line!
    @column = 0
    @rasterline = @rasterline == @last_line ? 0 : @rasterline + 1
  end
  nil
end

#dma_active? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/badline/vic.rb', line 99

def dma_active?
  @display_state.bad_line? && @column >= 15 && @column < 55
end

#hblank? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/badline/vic.rb', line 109

def hblank?
  @column < 10 || @column > 60
end

#interrupted? ⇒ Boolean

The IRQ line is held asserted while any enabled latch bit is set in $D019/$D01A, until the program acknowledges it by writing to $D019.

Returns:

  • (Boolean) 


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# File 'lib/badline/vic.rb', line 77

def interrupted?
  @registers.irq_line?
end

#peek(addr) ⇒ Object 



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# File 'lib/badline/vic.rb', line 81

def peek(addr)
  i = index(addr) % (2**6)
  case i
  when 0x11 then (@registers[0x11] & 0x7f) | ((rasterline & 0x100) >> 1)
  when 0x12 then rasterline & 0xff
  when 0x19 then irq_status # Latch + master IRQ bit, unused bits read 1
  else @registers.read(i)
  end
end

#poke(addr, value) ⇒ Object 



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# File 'lib/badline/vic.rb', line 91

def poke(addr, value)
  @registers.write(index(addr) % (2**6), value)
end

#position ⇒ Object 



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# File 'lib/badline/vic.rb', line 95

def position
  (@rasterline * @width) + (@column * 8)
end

#vblank? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/badline/vic.rb', line 113

def vblank?
  @rasterline < 16 || @rasterline > 299
end