chore(cartridge): clean-up code

src/cartridge.rs

@@ -33,23 +33,24 @@ impl Cartridge {
     }
 
     fn detect_mbc(memory: &[u8]) -> Box<dyn MBCIo> {
-        let ram_info = Self::detect_ram_info(memory);
-        let rom_info = Self::detect_rom_info(memory);
+        let ram_size = Self::detect_ram_info(memory);
+        let rom_size = Self::detect_rom_info(memory);
         let mbc_kind = Self::find_mbc(memory);
-        let ram_size = ram_info.size();
+        let ram_cap = ram_size.capacity();
+        let rom_cap = rom_size.capacity();
 
-        eprintln!("Cartridge Ram Size: {} bytes", ram_size);
-        eprintln!("Cartridge ROM Size: {} bytes", rom_info.size());
+        eprintln!("Cartridge Ram Size: {} bytes", ram_cap);
+        eprintln!("Cartridge ROM Size: {} bytes", rom_size.capacity());
         eprintln!("MBC Type: {:?}", mbc_kind);
 
         match mbc_kind {
             MBCKind::None => Box::new(NoMBC),
-            MBCKind::MBC1 => Box::new(MBC1::new(ram_info, rom_info)),
-            MBCKind::MBC1WithBattery => Box::new(MBC1::new(ram_info, rom_info)), // TODO: Implement Saving
-            MBCKind::MBC3 => Box::new(MBC3::new(ram_size)),
-            MBCKind::MBC3WithBattery => Box::new(MBC3::new(ram_size)), // TODO: Implement Saving
-            MBCKind::MBC5 => Box::new(MBC5::new(ram_size)),
-            MBCKind::MBC5WithBattery => Box::new(MBC5::new(ram_size)), // TDO: Implement Saving
+            MBCKind::MBC1 => Box::new(MBC1::new(ram_size, rom_size)),
+            MBCKind::MBC1WithBattery => Box::new(MBC1::new(ram_size, rom_size)), // TODO: Implement Saving
+            MBCKind::MBC3 => Box::new(MBC3::new(ram_cap)),
+            MBCKind::MBC3WithBattery => Box::new(MBC3::new(ram_cap)), // TODO: Implement Saving
+            MBCKind::MBC5 => Box::new(MBC5::new(ram_cap, rom_cap)),
+            MBCKind::MBC5WithBattery => Box::new(MBC5::new(ram_cap, rom_cap)), // TDO: Implement Saving
         }
     }
 
@@ -68,12 +69,12 @@ impl Cartridge {
         self.title.as_deref()
     }
 
-    fn detect_ram_info(memory: &[u8]) -> RamInfo {
+    fn detect_ram_info(memory: &[u8]) -> RamSize {
         let id = memory[RAM_SIZE_ADDRESS];
         id.into()
     }
 
-    fn detect_rom_info(memory: &[u8]) -> RomInfo {
+    fn detect_rom_info(memory: &[u8]) -> RomSize {
         let id = dbg!(memory[ROM_SIZE_ADDRESS]);
         id.into()
     }
@@ -114,17 +115,17 @@ struct MBC1 {
     /// 2-bit number
     ram_bank: u8,
     mode: bool,
-    ram_size: RamInfo,
+    ram_size: RamSize,
     memory: Vec<u8>,
-    rom_size: RomInfo,
+    rom_size: RomSize,
     mem_enabled: bool,
 }
 
 impl MBC1 {
-    fn new(ram_size: RamInfo, rom_size: RomInfo) -> Self {
+    fn new(ram_size: RamSize, rom_size: RomSize) -> Self {
         Self {
             rom_bank: 0x01,
-            memory: vec![0; ram_size.size() as usize],
+            memory: vec![0; ram_size.capacity() as usize],
             ram_size,
             rom_size,
             ram_bank: Default::default(),
@@ -134,7 +135,7 @@ impl MBC1 {
     }
 
     fn zero_bank(&self) -> u8 {
-        use RomInfo::*;
+        use RomSize::*;
 
         match self.rom_size {
             None | Four | Eight | Sixteen | ThirtyTwo => 0x00,
@@ -145,7 +146,7 @@ impl MBC1 {
     }
 
     fn _mbcm_zero_bank(&self) -> u8 {
-        use RomInfo::*;
+        use RomSize::*;
 
         match self.rom_size {
             None | Four | Eight | Sixteen | ThirtyTwo => 0x00,
@@ -156,7 +157,7 @@ impl MBC1 {
     }
 
     fn high_bank(&self) -> u8 {
-        use RomInfo::*;
+        use RomSize::*;
 
         let base = self.rom_bank & self.rom_size_mask();
 
@@ -169,7 +170,7 @@ impl MBC1 {
     }
 
     fn rom_size_mask(&self) -> u8 {
-        use RomInfo::*;
+        use RomSize::*;
 
         match self.rom_size {
             None => 0b00000001,
@@ -182,10 +183,10 @@ impl MBC1 {
     }
 
     fn ram_addr(&self, addr: u16) -> u16 {
-        use RamInfo::*;
+        use RamSize::*;
 
         match self.ram_size {
-            Unused | One => (addr - 0xA000) % self.ram_size.size() as u16,
+            Unused | One => (addr - 0xA000) % self.ram_size.capacity() as u16,
             Four => {
                 if self.mode {
                     0x2000 * self.ram_bank as u16 + (addr - 0xA000)
@@ -270,9 +271,9 @@ struct MBC3 {
 }
 
 impl MBC3 {
-    fn new(ram_size: usize) -> Self {
+    fn new(ram_cap: usize) -> Self {
         Self {
-            memory: vec![0; ram_size],
+            memory: vec![0; ram_cap],
             rom_bank: Default::default(),
             ram_bank: Default::default(),
             devs_enabled: Default::default(),
@@ -352,19 +353,26 @@ struct MBC5 {
     /// 4-bit number
     ram_bank: u8,
 
+    rom_cap: usize,
+
     memory: Vec<u8>,
     mem_enabled: bool,
 }
 
 impl MBC5 {
-    fn new(ram_size: usize) -> Self {
+    fn new(ram_cap: usize, rom_cap: usize) -> Self {
         Self {
             rom_bank: 0x01,
-            memory: vec![0; ram_size],
+            memory: vec![0; ram_cap],
+            rom_cap,
             ram_bank: Default::default(),
             mem_enabled: Default::default(),
         }
     }
+
+    fn bank_addr(&self, addr: u16) -> usize {
+        (0x4000 * self.rom_bank as usize + (addr as usize - 0x4000)) % self.rom_cap
+    }
 }
 
 impl MBCIo for MBC5 {
@@ -373,9 +381,7 @@ impl MBCIo for MBC5 {
 
         match addr {
             0x0000..=0x3FFF => Address(addr as usize),
-            0x4000..=0x7FFF => {
-                Address(0x4000u16.wrapping_mul(self.rom_bank) as usize + (addr as usize - 0x4000))
-            }
+            0x4000..=0x7FFF => Address(self.bank_addr(addr)),
             0xA000..=0xBFFF if self.mem_enabled => {
                 Value(self.memory[0x2000 * self.ram_bank as usize + (addr as usize - 0xA000)])
             }
@@ -441,7 +447,7 @@ impl Default for MBCKind {
 }
 
 #[derive(Debug, Clone, Copy)]
-enum RamInfo {
+enum RamSize {
     None = 0x00,
     Unused = 0x01,
     One = 0x02,
@@ -450,9 +456,9 @@ enum RamInfo {
     Eight = 0x05,
 }
 
-impl RamInfo {
-    fn size(&self) -> usize {
-        use RamInfo::*;
+impl RamSize {
+    fn capacity(&self) -> usize {
+        use RamSize::*;
 
         match *self {
             None => 0,
@@ -465,15 +471,15 @@ impl RamInfo {
     }
 }
 
-impl Default for RamInfo {
+impl Default for RamSize {
     fn default() -> Self {
         Self::None
     }
 }
 
-impl From<u8> for RamInfo {
+impl From<u8> for RamSize {
     fn from(byte: u8) -> Self {
-        use RamInfo::*;
+        use RamSize::*;
 
         match byte {
             0x00 => None,
@@ -488,7 +494,7 @@ impl From<u8> for RamInfo {
 }
 
 #[derive(Debug, Clone, Copy)]
-enum RomInfo {
+enum RomSize {
     None = 0x00,              // 32KB (also called Two)
     Four = 0x01,              // 64KB
     Eight = 0x02,             // 128KB
@@ -503,10 +509,10 @@ enum RomInfo {
     NinetySix = 0x54,         // 1.5MB
 }
 
-impl RomInfo {
+impl RomSize {
     // https://hacktix.github.io/GBEDG/mbcs/#rom-size
-    fn size(&self) -> u32 {
-        use RomInfo::*;
+    fn capacity(&self) -> usize {
+        use RomSize::*;
 
         match self {
             SeventyTwo => 0x120000,
@@ -517,9 +523,9 @@ impl RomInfo {
     }
 }
 
-impl From<u8> for RomInfo {
+impl From<u8> for RomSize {
     fn from(byte: u8) -> Self {
-        use RomInfo::*;
+        use RomSize::*;
 
         match byte {
             0x00 => None,