Add mapper 474

src/nes/cartridge/mapper.cc

@@ -98,6 +98,7 @@ Mapper::Mapper(
 #include "mappers/mapper_004.h"
 #include "mappers/mapper_007.h"
 #include "mappers/mapper_009.h"
+#include "mappers/mapper_474.h"
 
 Mapper* Mapper::Factory(const ROM_File* rom_file) {
   if (rom_file == nullptr)
@@ -111,6 +112,7 @@ Mapper* Mapper::Factory(const ROM_File* rom_file) {
   case 4: return new Mapper_004(*rom_file);
   case 7: return new Mapper_007(*rom_file);
   case 9: return new Mapper_009(*rom_file);
+  case 474: return new Mapper_474(*rom_file);
   }
 
   return nullptr;

src/nes/cartridge/mappers/mapper_474.cc

@@ -0,0 +1,52 @@
+#include "mapper_474.h"
+
+#include <cassert>
+#include <cstdio>
+
+Mapper_474::Mapper_474(const ROM_File& rom_file)
+  : Mapper(474, "NROM-383", rom_file, 0x4000, 0x2000)
+  , prg_ram(0x2000)
+{
+  this->mirror_mode = rom_file.meta.mirror_mode;
+  this->has_battery = rom_file.meta.has_battery;
+}
+
+// reading has no side-effects
+u8 Mapper_474::read(u16 addr) { return this->peek(addr); }
+u8 Mapper_474::peek(u16 addr) const {
+  // Wired to the PPU MMU
+  if (in_range(addr, 0x0000, 0x1FFF)) return this->chr_mem->peek(addr);
+
+  // Wired to the CPU MMU
+
+  // submapper 3 has_battery must be true
+  if (in_range(addr, 0x4020, 0x5FFF)) return this->has_battery ?
+    this->prg_ram.peek(addr - 0x4000) :
+    this->prg_extra->peek(addr - 0x4000);
+  if (in_range(addr, 0x6000, 0x7FFF)) return this->prg_extra->peek(addr - 0x4000);
+  if (in_range(addr, 0x8000, 0xBFFF)) return this->prg_lo->peek(addr - 0x8000);
+  if (in_range(addr, 0xC000, 0xFFFF)) return this->prg_hi->peek(addr - 0xC000);
+
+  assert(false);
+  return 0;
+}
+
+void Mapper_474::write(u16 addr, u8 val) {
+  // Since there is potentially CHR RAM, try to write to it (if in range)
+  if (in_range(addr, 0x0000, 0x1FFF)) {
+    this->chr_mem->write(addr, val);
+  }
+  else if (in_range(addr, 0x4020, 0x5FFF)) {
+    if (this->has_battery) {
+      this->prg_ram.write(addr - 0x4000, val);
+    }
+  }
+}
+
+void Mapper_474::update_banks() {
+  this->prg_extra = &this->get_prg_bank(0);
+  this->prg_lo = &this->get_prg_bank(1);
+  this->prg_hi = &this->get_prg_bank(2);
+
+  this->chr_mem = &this->get_chr_bank(0);
+}

src/nes/cartridge/mappers/mapper_474.h

@@ -0,0 +1,45 @@
+#pragma once
+
+#include "nes/generic/ram/ram.h"
+#include "nes/generic/rom/rom.h"
+#include "common/util.h"
+#include "../mapper.h"
+
+#include "common/serializable.h"
+
+// https://www.nesdev.org/wiki/NES_2.0_Mapper_474
+class Mapper_474 final : public Mapper {
+private:
+  // CPU Memory Space
+  RAM  prg_ram; // 0x4020 ... 0x5FFF - Fixed RAM (only submapper 3)
+  ROM* prg_extra; // 0x4020 ... 0x7FFF - Fixed
+  ROM* prg_lo; // 0x8000 ... 0xBFFF - Fixed
+  ROM* prg_hi; // 0xC000 ... 0xFFFF - Fixed
+
+  // PPU Memory Space
+  Memory* chr_mem; // 0x0000 ... 0x1FFF - Fixed
+
+  Mirroring::Type mirror_mode;
+  bool has_battery;
+
+  SERIALIZE_PARENT(Mapper)
+    SERIALIZE_START(1, "Mapper_474")
+    SERIALIZE_POD(mirror_mode)
+    SERIALIZE_END(1)
+
+    void update_banks() override;
+
+  // Nothing to reset...
+  void reset() override {}
+
+public:
+  Mapper_474(const ROM_File& rom_file);
+
+  // <Memory>
+  u8 read(u16 addr)       override;
+  u8 peek(u16 addr) const override;
+  void write(u16 addr, u8 val) override;
+  // <Memory/>
+
+  Mirroring::Type mirroring() const override { return this->mirror_mode; };
+};

src/nes/cartridge/parse_rom.cc

@@ -79,7 +79,14 @@ static ROM_File* parseROM_iNES(const u8* data, uint data_len) {
   if (rf->meta.is_VS)
     fprintf(stderr, "[File Parsing][iNES] This is a VS ROM\n");
 
-  rf->meta.mapper = data[6] >> 4 | (data[7] & 0xFF00);
+  if (is_NES2)
+  {
+    rf->meta.mapper = data[6] >> 4 | (data[7] & 0xF0) | ((data[8] & 0xF) << 8);
+  }
+  else
+  {
+    rf->meta.mapper = data[6] >> 4 | (data[7] & 0xF0);
+  }
 
   fprintf(stderr, "[File Parsing][iNES] Mapper: %d\n", rf->meta.mapper);
 

src/nes/cartridge/rom_file.h

@@ -14,7 +14,7 @@ struct ROM_File {
   struct { // ROM metadata
     Mirroring::Type mirror_mode;
 
-    u8 mapper;
+    u16 mapper;
 
     bool has_battery; // Has battery backed SRAM at 0x6000 - 0x7FFF
     bool has_trainer; // Has 512 byte trainer at 0x7000 - 0x71FF