RAM for cgb

src/bus.rs

@@ -1,6 +1,7 @@
 use std::ops::RangeInclusive;
 use crate::utils::join_bytes;
 use crate::rom::{ROM, load_rom};
+use crate::ram::{RAM, DMGRAM, CGBRAM, WRAM_BANK_SELECT_ADDRESS};
 use crate::ppu::{
     PPU,
     DMA_ADDRESS,
@@ -29,6 +30,7 @@ pub const HIGH_RAM: RangeInclusive<u16>                  = 0xFF80..=0xFFFE;
 pub struct Bus {
     data: [u8; 0x10000],
     pub rom: Box<dyn ROM>,
+    pub ram: Box<dyn RAM>,
     pub ppu: PPU,
     pub joypad: Joypad,
     pub timer: Timer,
@@ -51,9 +53,15 @@ impl Bus {
                 std::process::exit(1);
             },
         };
+        let info = rom.info().clone();
+        let cgb_mode = info.cgb_features() || info.cgb_only();
         let mut bus = Self {
             data: [0x00; 0x10000],
             rom,
+            ram: match cgb_mode {
+                true => Box::new(CGBRAM::new()),
+                false => Box::new(DMGRAM::new()),
+            },
             ppu: PPU::new(),
             joypad: Joypad::new(),
             timer: Timer::new(),
@@ -90,6 +98,10 @@ impl Bus {
     pub fn read(&self, address: u16) -> u8 {
         if BANK_ZERO.contains(&address) || BANK_SWITCHABLE.contains(&address)  || EXTERNAL_RAM.contains(&address) {
             return self.rom.read(address);
+        } else if WORK_RAM_1.contains(&address) || WORK_RAM_2.contains(&address) || address == WRAM_BANK_SELECT_ADDRESS {
+            return self.ram.read(address);
+        } else if ECHO_RAM.contains(&address) {
+            return self.ram.read(WORK_RAM_1.min().unwrap() + ((address - ECHO_RAM.min().unwrap()) & 0x1FFF));
         } else if address == INTERRUPT_ENABLE_ADDRESS || address == INTERRUPT_FLAG_ADDRESS {
             return self.interrupts.read(address);
         } else if VIDEO_RAM.contains(&address) {
@@ -121,17 +133,12 @@ impl Bus {
             self.rom.write(address, data);
         } else if address == INTERRUPT_ENABLE_ADDRESS || address == INTERRUPT_FLAG_ADDRESS {
             self.interrupts.write(address, data);
-        } else if WORK_RAM_1.contains(&address) || WORK_RAM_2.contains(&address) {
-            self.data[address as usize] = data;
-            // Copy to the ECHO RAM
-            if address <= 0xDDFF {
-                self.data[(ECHO_RAM.min().unwrap() + (address - WORK_RAM_1.min().unwrap())) as usize] = data;
-            }
+        } else if WORK_RAM_1.contains(&address) || WORK_RAM_2.contains(&address) || address == WRAM_BANK_SELECT_ADDRESS {
+            self.ram.write(address, data);
         } else if EXTERNAL_RAM.contains(&address) {
             self.rom.write(address, data);
         } else if ECHO_RAM.contains(&address) {
-            self.data[address as usize] = data;
-            self.data[(WORK_RAM_1.min().unwrap() + (address - ECHO_RAM.min().unwrap())) as usize] = data; // Copy to the working RAM
+            self.ram.write(WORK_RAM_1.min().unwrap() + ((address - ECHO_RAM.min().unwrap()) & 0x1FFF), data);
         } else if Timer::is_io_register(address) {
             self.timer.set_register(address, data);
         } else if Sound::is_io_register(address) {

src/lib.rs

@@ -4,6 +4,7 @@ pub mod ppu;
 pub mod timer;
 pub mod sound;
 pub mod rom;
+pub mod ram;
 pub mod bus;
 pub mod interrupts;
 pub mod joypad;

src/ram.rs

@@ -0,0 +1,80 @@
+pub const WRAM_BANK_SELECT_ADDRESS: u16 = 0xFF70;
+
+pub trait RAM {
+    fn read(&self, address: u16) -> u8;
+    fn write(&mut self, address: u16, value: u8);
+}
+
+pub struct DMGRAM {
+    data: [u8; 4096 * 2],
+}
+
+impl DMGRAM {
+    pub fn new() -> Self {
+        Self {
+            data: [0; 4096 * 2],
+        }
+    }
+}
+
+impl RAM for DMGRAM {
+    fn read(&self, address: u16) -> u8 {
+        if address == WRAM_BANK_SELECT_ADDRESS {
+            return 0xFF;
+        }
+        self.data[(address - 0xC000) as usize]
+    }
+
+    fn write(&mut self, address: u16, value: u8) {
+        if address == WRAM_BANK_SELECT_ADDRESS {
+            return;
+        }
+        self.data[(address - 0xC000) as usize] = value;
+    }
+}
+
+
+pub struct CGBRAM {
+    data: [u8; 4096 * 8],
+    bank: u8,
+
+}
+
+impl CGBRAM {
+    pub fn new() -> Self {
+        Self {
+            data: [0; 4096 * 8],
+            bank: 1,
+        }
+    }
+
+    fn switch_bank(&mut self, bank: u8) {
+        self.bank = bank;
+        if self.bank > 7 {
+            self.bank = 7;
+        } else if bank == 0 {
+            self.bank = 0;
+        }
+    }
+}
+
+impl RAM for CGBRAM {
+    fn read(&self, address: u16) -> u8 {
+        if address == WRAM_BANK_SELECT_ADDRESS {
+            return self.bank;
+        }
+        if address <= 0xCFFF {
+            return self.data[(address - 0xC000) as usize];
+        }
+        self.data[((address - 0xC000) as usize) * (self.bank as usize)]
+    }
+
+    fn write(&mut self, address: u16, value: u8) {
+        if address == WRAM_BANK_SELECT_ADDRESS {
+            return self.switch_bank(value);
+        } else if address <= 0xCFFF {
+            return self.data[(address - 0xC000) as usize] = value;
+        }
+        self.data[((address - 0xC000) as usize) * (self.bank as usize)] = value;
+    }
+}

src/rom.rs

@@ -41,6 +41,7 @@ pub fn load_rom(_filename: &str) -> std::io::Result<Box<dyn ROM>> {
         filename: "".to_string(),
         publisher: "".to_string(),
         title: "".to_string(),
+        cgb_features: false,
         cgb_only: false,
         sgb_features: false,
         has_ram: false,
@@ -150,6 +151,7 @@ pub struct ROMInfo {
     filename: String,
     publisher: String,
     title: String,
+    cgb_features: bool,
     cgb_only: bool,
     sgb_features: bool,
     has_ram: bool,
@@ -161,6 +163,14 @@ pub struct ROMInfo {
 }
 
 impl ROMInfo {
+    pub fn cgb_features(&self) -> bool {
+        self.cgb_features
+    }
+
+    pub fn cgb_only(&self) -> bool {
+        self.cgb_only
+    }
+
     pub fn set_filename(&mut self, filename: String) {
         self.filename = filename;
     }
@@ -205,6 +215,7 @@ impl ROMInfo {
             },
             publisher: "".to_string(), // TODO: Extract publisher
             title: "".to_string(), // TODO: Extract the game title
+            cgb_features: bytes[CGB_FLAG_ADDRESS as usize] == 0x80,
             cgb_only: bytes[CGB_FLAG_ADDRESS as usize] == 0xC0,
             sgb_features: bytes[SGB_FLAG_ADDRESS as usize] == 0x03,
             has_ram: match rom_type {