update readme, remove todo! from bus and display registers

snes-core/src/cpu/bus.rs

@@ -1,8 +1,13 @@
 use crate::ppu::PPU;
+use crate::cpu::internal_registers::InternalRegisters;
+use crate::rom::ROM;
+use crate::rom::lo_rom::LoROM;
 
 pub struct Bus {
     wram: [u8; 0x10000],
     pub ppu: PPU,
+    pub rom: Box<dyn ROM>,
+    pub internal_registers: InternalRegisters,
 }
 
 #[derive(PartialEq, Debug)]
@@ -19,6 +24,8 @@ impl Bus {
         Self {
             wram: [0; 0x10000],
             ppu: PPU::new(),
+            rom: Box::new(LoROM::new()),
+            internal_registers: InternalRegisters::new(),
         }
     }
 
@@ -54,7 +61,9 @@ impl Bus {
         match section {
             MemoryMap::WRAM => self.read_wram(address),
             MemoryMap::PPU => self.ppu.registers.read(address as u16),
-            _ => todo!("Implement other memory sections. Address: {:#08X}", address),
+            MemoryMap::CPU => self.internal_registers.read(address as u16),
+            MemoryMap::Joypad => 0x00,  // TODO: Placeholder
+            MemoryMap::Cartridge => self.rom.read(address),
         }
     }
 
@@ -63,7 +72,9 @@ impl Bus {
         match section {
             MemoryMap::WRAM => self.write_wram(address, value),
             MemoryMap::PPU => self.ppu.registers.write(address as u16, value),
-            _ => todo!("Implement other memory sections. Address: {:#08X}", address),
+            MemoryMap::CPU => self.internal_registers.write(address as u16, value),
+            MemoryMap::Joypad => {},  // TODO: Placeholder
+            MemoryMap::Cartridge => self.rom.write(address, value),
         }
     }
 }

snes-core/src/cpu/internal_registers.rs

@@ -0,0 +1,24 @@
+pub const INTERNAL_REGISTERS_ADDRESS: u16 = 0x4200;
+
+pub struct InternalRegisters {
+    _registers: [u8; 32],
+}
+
+impl InternalRegisters {
+    pub fn new() -> Self {
+        Self {
+            _registers: [0; 32],
+        }
+    }
+
+    pub fn read(&self, _address: u16) -> u8 {
+        // TODO: Placeholder
+        // self.registers[(address - INTERNAL_REGISTERS_ADDRESS) as usize]
+        0x00
+    }
+
+    pub fn write(&mut self, _address: u16, _value: u8) {
+        // TODO: Placeholder
+        // self.registers[(address - INTERNAL_REGISTERS_ADDRESS) as usize] = value;
+    }
+}

snes-core/src/cpu/mod.rs

@@ -4,3 +4,4 @@ pub mod bus;
 pub mod registers;
 pub mod instructions;
 pub mod cycles;
+pub mod internal_registers;