first draft of ppu

Author: Duckulus

src/cpu.rs

@@ -1,8 +1,10 @@
-use crate::memory_map::MemoryMap;
+use cpu_memory::CpuMemory;
 use std::fmt;
 use std::thread::sleep;
 use std::time::Duration;
 
+pub mod cpu_memory;
+
 const STATUS_NEGATIVE_BIT: u32 = 7;
 const STATUS_OVERFLOW_BIT: u32 = 6;
 const STATUS_IGNORED_BIT: u32 = 5;
@@ -156,7 +158,7 @@ impl Default for CpuOptions {
 pub struct Cpu {
     options: CpuOptions,
     registers: Registers,
-    memory: MemoryMap,
+    memory: CpuMemory,
     clock_speed: u32,
 }
 
@@ -1291,7 +1293,7 @@ impl Cpu {
 }
 
 impl Cpu {
-    pub fn new(options: CpuOptions, memory: MemoryMap, clock_speed: u32) -> Self {
+    pub fn new(options: CpuOptions, memory: CpuMemory, clock_speed: u32) -> Self {
         Self {
             options,
             registers: Registers::new(memory.reset_vector()),
@@ -1300,7 +1302,7 @@ impl Cpu {
         }
     }
 
-    pub fn with_nes_options(memory: MemoryMap, clock_speed: u32) -> Self {
+    pub fn with_nes_options(memory: CpuMemory, clock_speed: u32) -> Self {
         Self {
             options: NES_CPU_OPTIONS,
             registers: Registers::new(memory.reset_vector()),
@@ -1512,16 +1514,16 @@ impl Cpu {
 
 #[cfg(test)]
 mod test {
-    use crate::cpu::{Cpu, CpuOptions};
-    use crate::memory_map::MemoryMap;
+    use crate::cpu::Cpu;
+    use crate::cpu::cpu_memory::CpuMemory;
     use crate::nes_rom::NesRom;
     use std::fs::File;
     use std::io::{BufRead, BufReader};
 
     #[test]
     fn nestest() {
         let rom = NesRom::read_from_file("./vendor/nestest/nestest.nes").unwrap();
-        let memory_map = MemoryMap::new(rom);
+        let memory_map = CpuMemory::new(rom);
         let mut cpu = Cpu::with_nes_options(memory_map, 1 << 16);
         cpu.registers.pc = 0xC000;
         cpu.registers.p = 0x24;

src/memory_map.rs src/cpu/cpu_memory.rssrc/memory_map.rs renamed to src/cpu/cpu_memory.rs

@@ -1,13 +1,13 @@
 use crate::nes_rom::NesRom;
 use crate::ram::Ram;
 
-pub struct MemoryMap {
+pub struct CpuMemory {
     sram: Ram,
     rom: NesRom,
     prg_ram: Ram
 }
 
-impl MemoryMap {
+impl CpuMemory {
     pub fn new(rom: NesRom) -> Self {
         Self {
             sram: Ram::new(0x8000),

src/main.rs

@@ -1,23 +1,23 @@
 mod cpu;
-mod memory_map;
 mod nes_rom;
 mod ram;
+mod ppu;
 
-use crate::memory_map::MemoryMap;
+use cpu::cpu_memory::CpuMemory;
 use crate::nes_rom::NesRom;
 use cpu::Cpu;
 
 fn main() -> Result<(), anyhow::Error> {
     println!("Starting Emulator!");
 
-    let rom = NesRom::read_from_file("./nestest.nes")?;
+    let rom = NesRom::read_from_file("./vendor/nestest/nestest.nes")?;
     println!("{rom:#?}");
 
-    let memory_map = MemoryMap::new(rom);
+    let memory_map = CpuMemory::new(rom);
     println!("Entry point: {:#X}", memory_map.reset_vector());
 
     let mut cpu = Cpu::with_nes_options(memory_map, 1 << 16);
-    cpu.run();
+    // cpu.run();
 
     Ok(())
 }

src/nes_rom.rs

@@ -3,12 +3,12 @@ use std::io::Read;
 use std::fmt;
 
 #[derive(Debug)]
-pub enum NametableArrangement {
+pub enum NametableMirroring {
     Vertical,
     Horizontal,
 }
 
-impl NametableArrangement {
+impl NametableMirroring {
     fn from_bit(value: u8) -> Self {
         match value {
             0 => Self::Vertical,
@@ -45,7 +45,7 @@ pub struct NesRom {
     trainer: Option<[u8; TRAINER_SIZE]>,
     mapper: u8,
     alt_nametable: bool,
-    nametable_arrangement: NametableArrangement,
+    nametable_arrangement: NametableMirroring,
     battery_backed_prg_ram: bool,
     prg_ram_size: u8,
     tv_system: TvSystem,
@@ -60,7 +60,7 @@ impl fmt::Debug for NesRom {
             _has_trainer: bool,
             _mapper: &'a u8,
             _alt_nametable: &'a bool,
-            _nametable_arrangement: &'a NametableArrangement,
+            _nametable_arrangement: &'a NametableMirroring,
             _battery_backed_prg_ram: &'a bool,
             _prg_ram_size: &'a u8,
             _tv_system: &'a TvSystem,
@@ -111,7 +111,7 @@ impl NesRom {
         let flags7 = header[7];
         let mapper = (flags7 & 0xF0) | (flags6 >> 4);
         let alt_nametable = (flags6 >> 3) & 1 == 1;
-        let nametable_arrangement = NametableArrangement::from_bit(flags6 & 1);
+        let nametable_arrangement = NametableMirroring::from_bit(flags6 & 1);
         let has_trainer = (flags6 >> 2) & 1 == 1;
         let battery_backed_prg_ram = (flags6 >> 1) & 1 == 1;
         let prg_ram_size = header[8];

src/ppu.rs

@@ -0,0 +1,89 @@
+use crate::nes_rom::NametableMirroring;
+use crate::ppu::ppu_memory::PpuMemory;
+
+mod ppu_memory;
+
+struct PpuAddr {
+    hi: u8,
+    lo: u8,
+    is_hi: bool,
+}
+
+impl PpuAddr {
+    fn new() -> Self {
+        Self {
+            hi: 0,
+            lo: 0,
+            is_hi: true,
+        }
+    }
+
+    fn set(&mut self, value: u8) {
+        if self.is_hi {
+            self.hi = value;
+        } else {
+            self.lo = value;
+        }
+
+        self.is_hi = !self.is_hi;
+    }
+
+    fn get_addr(&self) -> u16 {
+        const PPU_ADDR_MASK: u16 = 0x3FFF;
+        ((self.hi as u16) << 8 | (self.lo as u16)) & PPU_ADDR_MASK
+    }
+
+    fn increment_addr(&mut self, amount: u16) {
+        //TODO
+    }
+}
+
+const PPU_CTRL_NAMETABLE_MASK: u8 = 0x3;
+const PPU_VRAM_ADD_INCREMENT_BIT: u8 = 2;
+const PPU_SPRITE_PATTERN_ADDR_BIT: u8 = 3;
+const PPU_BACKRGROUND_ADDR_BIT: u8 = 4;
+const PPU_SPRITE_SIZE_BIT: u8 = 5;
+const PPU_MASTER_SLAVE_SELECT_BIT: u8 = 6;
+const PPU_VBLANK_NMI_BIT: u8 = 7;
+
+struct PpuRegisters {
+    ctrl: u8,
+    mask: u8,
+    status: u8,
+    oam_addr: u8,
+    oam_data: u8,
+    scroll: u8,
+    addr: PpuAddr,
+    data_buffer: u8,
+    oam_dma: u8,
+}
+
+impl PpuRegisters {
+    pub fn new() -> Self {
+        Self {
+            ctrl: 0,
+            mask: 0,
+            status: 0,
+            oam_addr: 0,
+            oam_data: 0,
+            scroll: 0,
+            addr: PpuAddr::new(),
+            data_buffer: 0,
+            oam_dma: 0,
+        }
+    }
+}
+
+pub struct Ppu {
+    registers: PpuRegisters,
+    memory: PpuMemory,
+}
+
+impl Ppu {
+    pub fn new(chr_rom: Vec<u8>, mirroring: NametableMirroring) -> Self {
+        Self {
+            registers: PpuRegisters::new(),
+            memory: PpuMemory::new(chr_rom, mirroring),
+        }
+    }
+}

src/ppu/ppu_memory.rs

@@ -0,0 +1,24 @@
+use crate::nes_rom::NametableMirroring;
+
+pub struct PpuMemory {
+    chr_rom: Vec<u8>,
+    mirroring: NametableMirroring,
+}
+
+impl PpuMemory {
+    pub fn new(chr_rom: Vec<u8>, mirroring: NametableMirroring) -> Self {
+        Self { chr_rom, mirroring }
+    }
+
+    fn read(&self, addr: u16) -> u8 {
+        if addr < 0x2000 {
+            self.chr_rom[addr as usize]
+        } else {
+            unimplemented!()
+        }
+    }
+
+    fn write(&mut self, addr: u16, data: u8) {
+        unimplemented!();
+    }
+}