Class: Rubyboy::Cartridge::Mbc1

Inherits:
Object
  • Object
show all
Defined in:
lib/rubyboy/cartridge/mbc1.rb

Instance Method Summary collapse

Constructor Details

#initialize(rom, ram) ⇒ Mbc1

Returns a new instance of Mbc1.



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# File 'lib/rubyboy/cartridge/mbc1.rb', line 6

def initialize(rom, ram)
  @rom = rom
  @ram = ram
  @rom_bank = 1
  @ram_bank = 0
  @ram_enable = false
  @ram_banking_mode = false

  @read_methods = Array.new(0xc000)
  @write_methods = Array.new(0xc000)

  set_methods
end

Instance Method Details

#read_byte(addr) ⇒ Object 



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# File 'lib/rubyboy/cartridge/mbc1.rb', line 66

def read_byte(addr)
  @read_methods[addr].call
end

#set_methods ⇒ Object 



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# File 'lib/rubyboy/cartridge/mbc1.rb', line 20

def set_methods
  0xc000.times do |addr|
    @read_methods[addr] =
      case addr
      when 0x0000..0x3fff then -> { @rom.data[addr] }
      when 0x4000..0x7fff then -> { @rom.data[addr + (@rom_bank - 1) * 0x4000] }
      when 0xa000..0xbfff
        lambda do
          if @ram_enable
            if @ram_banking_mode
              @ram.eram[addr - 0xa000 + @ram_bank * 0x800]
            else
              @ram.eram[addr - 0xa000]
            end
          else
            0xff
          end
        end
      end
  end

  0xc000.times do |addr|
    @write_methods[addr] =
      case addr
      when 0x0000..0x1fff then ->(value) { @ram_enable = value & 0x0f == 0x0a }
      when 0x2000..0x3fff
        lambda do |value|
          @rom_bank = value & 0x1f
          @rom_bank = 1 if @rom_bank == 0
        end
      when 0x4000..0x5fff then ->(value) { @ram_bank = value & 0x03 }
      when 0x6000..0x7fff then ->(value) { @ram_banking_mode = value & 0x01 == 0x01 }
      when 0xa000..0xbfff
        lambda do |value|
          if @ram_enable
            if @ram_banking_mode
              @ram.eram[addr - 0xa000 + @ram_bank * 0x800] = value
            else
              @ram.eram[addr - 0xa000] = value
            end
          end
        end
      end
  end
end

#write_byte(addr, value) ⇒ Object 



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# File 'lib/rubyboy/cartridge/mbc1.rb', line 70

def write_byte(addr, value)
  @write_methods[addr].call(value)
end