starting refactor of mapper

src/cartridge/mmc1.rs

@@ -0,0 +1,28 @@
+use super::{Cartridge, Mapper, Mirror};
+
+pub struct Mmc1 {
+    cart: Cartridge,
+    step: u8,
+    shift_register: u8,
+    prg_low_bank: usize,
+    prg_high_bank: usize,
+    chr_low_bank: usize,
+    chr_high_bank: usize,
+    mirroring: Mirror,
+}
+
+impl Mmc1 {
+    fn new(cart: Cartridge) -> Self {
+        Mmc1
+    }
+}
+
+impl Mapper for Mmc1 {
+    fn read(&mut self, address: usize) -> u8 {
+        0
+    }
+
+    fn write(&mut self, address: usize, value: u8) {
+
+    }
+}

src/cartridge/mod.rs

@@ -1,8 +1,19 @@
-mod mappers;
+mod nrom;
 
-use mappers::get_mapper_funcs;
 use std::io::Read;
 
+pub trait Mapper {
+    fn read(&mut self, address: usize) -> u8;
+    fn write(&mut self, address: usize, value: u8);
+}
+
+pub enum Mirror {
+    LowBank,
+    HighBank,
+    Horizontal,
+    Vertical,
+}
+
 // To avoid separate read and write functions for every mapper, the mapper functions returns a reference to the CPU or PPU's own
 // byte of memory, which the calling method can dereference to read or set the value.
 pub type CpuMapperFunc = fn(&mut crate::cpu::Cpu, usize, bool) -> Option<&mut u8>;

src/cartridge/nrom.rs

@@ -1,3 +1,9 @@
+use super::Cartridge;
+
+pub struct Nrom {
+    cart: Cartridge,
+}
+
 
 pub fn nrom_cpu(cpu: &mut crate::cpu::Cpu, address: usize, writing: bool) -> Option<&mut u8> {
     // PRG-ROM, not -RAM

src/cpu/mod.rs

@@ -2,6 +2,10 @@ mod addressing_modes;
 mod opcodes;
 mod utility;
 
+use std::cell::RefCell;
+use std::rc::Rc;
+use crate::cartridge::Mapper;
+
 // RAM locations
 const STACK_OFFSET: usize = 0x100;
 const NMI_VECTOR: usize = 0xFFFA;
@@ -70,8 +74,9 @@ pub struct Cpu {
     mode_table: Vec<Mode>,
 
     // cartridge data
-    pub prg_rom: Vec<Vec<u8>>, // one 16 KiB chunk for each specified in iNES header
-    mapper_func: crate::cartridge::CpuMapperFunc,
+    mapper: Rc<RefCell<dyn Mapper>>,
+    // pub prg_rom: Vec<Vec<u8>>, // one 16 KiB chunk for each specified in iNES header
+    // mapper_func: crate::cartridge::CpuMapperFunc,
 
     // ppu
     pub ppu: super::Ppu,
@@ -86,7 +91,7 @@ pub struct Cpu {
 }
 
 impl Cpu {
-    pub fn new(cart: &super::Cartridge, ppu: super::Ppu, apu: super::Apu) -> Self {
+    pub fn new(mapper: Rc<RefCell<dyn Mapper>>, ppu: super::Ppu, apu: super::Apu) -> Self {
         let mut cpu = Cpu{
             mem: vec![0; 0x2000],
             A: 0, X: 0, Y: 0,
@@ -95,8 +100,9 @@ impl Cpu {
             P: 0x24, // TODO: change this back to 0x34? nestest.nes ROM has it as 0x24 at start.
             clock: 0,
             delay: 0,
-            prg_rom: cart.prg_rom.clone(),
-            mapper_func: cart.cpu_mapper_func,
+            mapper: mapper,
+            // prg_rom: cart.prg_rom.clone(),
+            // mapper_func: cart.cpu_mapper_func,
             ppu: ppu,
             apu: apu,
             strobe: 0,

src/main.rs

@@ -124,7 +124,8 @@ fn main() -> Result<(), String> {
 
 TODO:
 - common mappers
-- DMC audio channel, high- and low-pass filters, refactor envelope
+- untangle CPU and PPU
+- DMC audio channel, high- and low-pass filters, refactor envelope, fix static
 - name audio variables (dividers, counters, etc.) more consistently
 - battery-backed RAM solution
 - GUI? drag and drop ROMs?

src/ppu/mod.rs

@@ -2,6 +2,10 @@ mod cpu_registers;
 mod rendering;
 mod memory;
 
+use std::cell::RefCell;
+use std::rc::Rc;
+use crate::cartridge::Mapper;
+
 pub struct Ppu {
     line_cycle: usize, // x coordinate
     scanline:   usize, // y coordinate
@@ -14,9 +18,10 @@ pub struct Ppu {
     w: u8, // First or second write toggle (1 bit)
 
     // Cartridge things
-    pub pattern_tables: Vec<Vec<u8>>, // CHR-ROM, one 8 KiB chunk for each specified in iNES header
-    mapper_func: crate::cartridge::PpuMapperFunc,
-    mirroring: u8, // 0: horizontal, 1: vertical
+    pub mapper: Rc<RefCell<dyn Mapper>>,
+    // pub pattern_tables: Vec<Vec<u8>>, // CHR-ROM, one 8 KiB chunk for each specified in iNES header
+    // mapper_func: crate::cartridge::PpuMapperFunc,
+    // mirroring: u8, // 0: horizontal, 1: vertical
 
     // Each nametable byte is a reference to the start of an 8-byte sequence in the pattern table.
     // That sequence represents an 8x8 tile, from top row to bottom.
@@ -85,7 +90,7 @@ pub struct Ppu {
 }
 
 impl Ppu {
-    pub fn new(cart: &super::Cartridge) -> Self {
+    pub fn new(mapper: Rc<RefCell<dyn Mapper>>) -> Self {
         Ppu {
             line_cycle:                    0,
             scanline:                      0,
@@ -94,14 +99,15 @@ impl Ppu {
             t:                             0,
             x:                             0,
             w:                             0,
-            pattern_tables:                cart.chr_rom.clone(),
-            mapper_func:                   cart.ppu_mapper_func,
-            mirroring:                     cart.mirroring,
+            mapper:                        mapper,
+            // pattern_tables:                cart.chr_rom.clone(),
+            // mapper_func:                   cart.ppu_mapper_func,
+            // mirroring:                     cart.mirroring,
             nametable_0:                   vec![0u8; 0x0400],
             nametable_1:                   vec![0u8; 0x0400],
             nametable_2:                   vec![0u8; 0x0400],
             nametable_3:                   vec![0u8; 0x0400],
-            palette_ram:           vec![0u8; 0x0020],
+            palette_ram:                   vec![0u8; 0x0020],
             background_pattern_sr_low:     0,
             background_pattern_sr_high:    0,
             nametable_byte:                0,