update readme, remove todo! from bus and display registers

README.md

@@ -2,13 +2,15 @@
 Work in progress experimental SNES emulator written in Rust.
 
 ## Resources
-* https://softpixel.com/~cwright/sianse/docs/65816NFO.HTM
-* https://ersanio.gitbook.io/assembly-for-the-snes
-* https://wiki.superfamicom.org
-* https://snesdev.mesen.ca/wiki/index.php
-* https://problemkaputt.de/fullsnes.htm
-* BCD addition and substraction: https://ehaskins.com/2018-01-30%20Z80%20DAA/
-* 65816 programming manual: https://www.nesdev.org/w/images/default/7/76/Programmanual.pdf
+* SNES General:
+    * https://wiki.superfamicom.org
+    * https://snesdev.mesen.ca/wiki/index.php
+    * https://problemkaputt.de/fullsnes.htm
+* 65816 CPU:
+    * https://softpixel.com/~cwright/sianse/docs/65816NFO.HTM
+    * https://ersanio.gitbook.io/assembly-for-the-snes
+    * 65816 programming manual: https://www.nesdev.org/w/images/default/7/76/Programmanual.pdf
+    * BCD addition and substraction: https://ehaskins.com/2018-01-30%20Z80%20DAA/
 * Test ROMs
     * PeterLemon's test ROMs: https://github.com/PeterLemon/SNES
 * Retro Game Mechanics Explained SNES playlists:

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;

snes-frontend/src/main.rs

@@ -217,7 +217,7 @@ fn main() {
                                 if let Some(path) = FileDialog::new()
                                     .pick_file()
                                 {
-                                    match emulator.rom.load(&String::from(path.to_str().unwrap())) {
+                                    match emulator.bus.rom.load(&String::from(path.to_str().unwrap())) {
                                         Ok(_) => {
                                             state.emulation.is_paused = false;
                                         },
@@ -289,6 +289,24 @@ fn main() {
                                 )
                             }
                         }
+
+                        if state.debug_options.show_cpu_registers {
+                            let window = imgui::Window::new("CPU Registers");
+                            window
+                                .size([150.0, 200.0], Condition::FirstUseEver)
+                                .build(&ui, || {
+                                    ui.text(format!("SP:        | {:#06X}",   emulator.cpu.registers.sp));
+                                    ui.text(format!("X:         | {:#06X}",   emulator.cpu.registers.x));
+                                    ui.text(format!("Y:         | {:#06X}",   emulator.cpu.registers.y));
+                                    ui.text(format!("A:         | {:#06X}",   emulator.cpu.registers.a));
+                                    ui.text(format!("P:         |   {:#04X}", emulator.cpu.registers.p));
+                                    ui.text(format!("D:         | {:#06X}",   emulator.cpu.registers.d));
+                                    ui.text(format!("PBR:       |   {:#04X}", emulator.cpu.registers.pbr));
+                                    ui.text(format!("DBR:       |   {:#04X}", emulator.cpu.registers.dbr));
+                                    ui.text(format!("PC:        | {:#06X}",   emulator.cpu.registers.pc));
+                                    ui.text(format!("EMU MODE:  |  {}",       emulator.cpu.registers.emulation_mode));
+                                });
+                        }
                     }
 
                     // Actually run the emulation