parse cartridge type to enum

src/crab/gb/cartridge.cr

@@ -49,16 +49,14 @@ module GB
         bytes
       end
 
-      cartridge_type = rom[0x0147]
+      cartridge_type = CartridgeType.new(rom[0x0147].to_i)
       cartridge = case cartridge_type
-                  when 0x00, 0x08, 0x09 then ROM.new rom
-                  when 0x01, 0x02, 0x03 then MBC1.new rom
-                  when 0x05, 0x06       then MBC2.new rom
-                  when 0x0F, 0x10, 0x11,
-                       0x12, 0x13 then MBC3.new rom
-                  when 0x19, 0x1A, 0x1B,
-                       0x1C, 0x1D, 0x1E then MBC5.new rom
-                  else raise "Unimplemented cartridge type: #{hex_str cartridge_type}"
+                  when .is_rom?  then ROM.new rom, cartridge_type
+                  when .is_mbc1? then MBC1.new rom, cartridge_type
+                  when .is_mbc2? then MBC2.new rom, cartridge_type
+                  when .is_mbc3? then MBC3.new rom, cartridge_type
+                  when .is_mbc5? then MBC5.new rom, cartridge_type
+                  else                abort "Unimplemented cartridge type: #{hex_str cartridge_type.value.to_u8!}"
                   end
 
       cartridge.sav_file_path = rom_path.rpartition('.')[0] + ".sav"

src/crab/gb/mbc/enums.cr

@@ -0,0 +1,68 @@
+module GB
+  enum CartridgeType
+    ROM                            = 0x00
+    ROM_RAM                        = 0x08
+    ROM_RAM_BATTERY                = 0x09
+    MBC1                           = 0x01
+    MBC1_RAM                       = 0x02
+    MBC1_RAM_BATTERY               = 0x03
+    MBC2                           = 0x05
+    MBC2_BATTERY                   = 0x06
+    MBC3_TIMER_BATTERY             = 0x0F
+    MBC3_TIMER_RAM_BATTERY         = 0x10
+    MBC3                           = 0x11
+    MBC3_RAM                       = 0x12
+    MBC3_RAM_BATTERY               = 0x13
+    MBC5                           = 0x19
+    MBC5_RAM                       = 0x1A
+    MBC5_RAM_BATTERY               = 0x1B
+    MBC5_RUMBLE                    = 0x1C
+    MBC5_RUMBLE_RAM                = 0x1D
+    MBC5_RUMBLE_RAM_BATTERY        = 0x1E
+    MBC6                           = 0x20
+    MBC7_SENSOR_RUMBLE_RAM_BATTERY = 0x22
+    MMM01                          = 0x0B
+    MMM01_RAM                      = 0x0C
+    MMM01_RAM_BATTERY              = 0x0D
+    POCKET_CAMERA                  = 0xFC
+    BANDAI_TAMA5                   = 0xFD
+    HuC3                           = 0xFE
+    HuC1_RAM_BATTERY               = 0xFF
+
+    def is_rom? : Bool
+      to_s.starts_with? "ROM"
+    end
+
+    def is_mbc1? : Bool
+      to_s.starts_with? "MBC1"
+    end
+
+    def is_mbc2? : Bool
+      to_s.starts_with? "MBC2"
+    end
+
+    def is_mbc3? : Bool
+      to_s.starts_with? "MBC3"
+    end
+
+    def is_mbc5? : Bool
+      to_s.starts_with? "MBC5"
+    end
+
+    def has_ram? : Bool
+      to_s.includes? "RAM"
+    end
+
+    def has_battery? : Bool
+      to_s.includes? "BATTERY"
+    end
+
+    def has_timer? : Bool
+      to_s.includes? "TIMER"
+    end
+
+    def has_rumble? : Bool
+      to_s.includes? "RUMBLE"
+    end
+  end
+end

src/crab/gb/mbc/mbc1.cr

@@ -1,6 +1,6 @@
 module GB
   class MBC1 < Cartridge
-    def initialize(@rom : Bytes)
+    def initialize(@rom : Bytes, @cartridge_type : CartridgeType)
       if ram_size == 0 && (@rom[0x0147] == 0x02 || @rom[0x0147] == 0x03)
         STDERR.puts "MBC1 cartridge has ram, but `ram_size` was reported as 0. Ignoring `ram_size` and using 8kB of ram."
         @ram = Bytes.new 0x2000

src/crab/gb/mbc/mbc2.cr

@@ -2,7 +2,7 @@ module GB
   class MBC2 < Cartridge
     getter ram_size : Int32 { 0x0200 }
 
-    def initialize(@rom : Bytes)
+    def initialize(@rom : Bytes, @cartridge_type : CartridgeType)
       @ram = Bytes.new ram_size
       @ram_enabled = false
       @rom_bank = 1_u8

src/crab/gb/mbc/mbc3.cr

@@ -1,6 +1,6 @@
 module GB
   class MBC3 < Cartridge
-    def initialize(@rom : Bytes)
+    def initialize(@rom : Bytes, @cartridge_type : CartridgeType)
       @ram = Bytes.new ram_size
       @ram_enabled = false
       @rom_bank_number = 1_u8 # 7-bit register

src/crab/gb/mbc/mbc5.cr

@@ -1,6 +1,6 @@
 module GB
   class MBC5 < Cartridge
-    def initialize(@rom : Bytes)
+    def initialize(@rom : Bytes, @cartridge_type : CartridgeType)
       @ram = Bytes.new ram_size
       @ram_enabled = false
       @rom_bank_number = 1_u16 # 9-bit register

src/crab/gb/mbc/rom.cr

@@ -1,6 +1,6 @@
 module GB
   class ROM < Cartridge
-    def initialize(@rom : Bytes)
+    def initialize(@rom : Bytes, @cartridge_type : CartridgeType)
       @ram = Bytes.new ram_size
     end