mbc2

src/processor/memory/rom.rs

@@ -6,7 +6,7 @@ use std::{
     str::from_utf8_unchecked,
 };
 
-use self::mbcs::{Mbc, Mbc1, Mbc3, Mbc5, None};
+use self::mbcs::{Mbc, Mbc1, Mbc2, Mbc3, Mbc5, None};
 
 mod mbcs;
 
@@ -104,6 +104,8 @@ impl Rom {
             0x01 => Box::new(Mbc1::init(data, rom_size, 0, None)),
             0x02 => Box::new(Mbc1::init(data, rom_size, ram_size, None)),
             0x03 => Box::new(Mbc1::init(data, rom_size, ram_size, Some(save_path))),
+            0x05 => Box::new(Mbc2::init(data, rom_size, None)),
+            0x06 => Box::new(Mbc2::init(data, rom_size, Some(save_path))),
             0x0F => Box::new(Mbc3::init(data, rom_size, 0, true, Some(save_path))),
             0x10 => Box::new(Mbc3::init(data, rom_size, ram_size, true, Some(save_path))),
             0x11 => Box::new(Mbc3::init(data, rom_size, 0, false, None)),

src/processor/memory/rom/mbcs.rs

@@ -1,10 +1,12 @@
 use crate::processor::memory::Address;
 
 mod mbc1;
+mod mbc2;
 mod mbc3;
 mod mbc5;
 mod none;
 pub use mbc1::Mbc1;
+pub use mbc2::Mbc2;
 pub use mbc3::Mbc3;
 pub use mbc5::Mbc5;
 pub use none::None;

src/processor/memory/rom/mbcs/mbc2.rs

@@ -0,0 +1,70 @@
+use std::path::PathBuf;
+
+use crate::processor::memory::{rom::MaybeBufferedSram, Address};
+
+use super::{rom_banks, Mbc, ROM_BANK_SIZE};
+
+pub struct Mbc2 {
+    data: Vec<u8>,
+    rom_len: usize,
+    rom_bank: u8,
+    ram: MaybeBufferedSram,
+    ram_enabled: bool,
+}
+
+impl Mbc2 {
+    pub fn init(data: Vec<u8>, rom_size: u8, save_file: Option<PathBuf>) -> Self {
+        let rom_len = rom_banks(rom_size) * ROM_BANK_SIZE;
+        let ram = MaybeBufferedSram::new(save_file, 512);
+
+        Self {
+            data,
+            rom_len,
+            rom_bank: 1,
+            ram,
+            ram_enabled: false,
+        }
+    }
+}
+
+impl Mbc for Mbc2 {
+    fn get(&self, address: Address) -> u8 {
+        match address {
+            0x0..0x4000 => self.data[address as usize],
+            0x4000..0x8000 => {
+                self.data[((address as usize - 0x4000) + (0x4000 * self.rom_bank as usize))
+                    % self.rom_len]
+            }
+            _ => panic!("passed wrong address to mbc"),
+        }
+    }
+
+    fn get_ram(&self, address: Address) -> u8 {
+        0xF0 | (0x0F & self.ram.get((address - 0xA000) as usize % 512))
+    }
+
+    fn set(&mut self, address: Address, data: u8) {
+        if address & (1 << 8) == (1 << 8) {
+            // bit 8 is set - rom bank
+            self.rom_bank = data & 0xF;
+            if self.rom_bank == 0 {
+                self.rom_bank = 1;
+            }
+        } else {
+            // bit 8 is clear - ram enable
+            self.ram_enabled = data == 0x0A;
+        }
+    }
+
+    fn set_ram(&mut self, address: Address, data: u8) {
+        self.ram.set((address - 0xA000) as usize % 512, data);
+    }
+
+    fn mbc_type(&self) -> String {
+        String::from("MBC2")
+    }
+
+    fn flush(&mut self) {
+        self.ram.flush();
+    }
+}