Fix memory mapping

CMakeLists.txt

@@ -11,7 +11,7 @@ add_subdirectory(cpu)
 add_subdirectory(ppu)
 add_subdirectory(mappers)
 add_subdirectory(rom)
-add_subdirectory(debugger)
+#add_subdirectory(debugger)
 add_subdirectory(utils)
 add_subdirectory(gui)
 
@@ -29,7 +29,7 @@ set(SOURCE main.c system.c)
 
 add_executable(nes_emulator ${HEADERS} ${SOURCE})
 
-target_link_libraries(nes_emulator nes_cpu nes_ppu nes_mappers nes_rom nes_debugger nes_utils nes_gui log.c)
+target_link_libraries(nes_emulator nes_cpu nes_ppu nes_mappers nes_rom nes_utils nes_gui log.c)
 target_include_directories(nes_emulator PUBLIC
         "${PROJECT_BINARY_DIR}"
         ${EXTRA_INCLUDES})

cpu/cpu.c

@@ -64,7 +64,7 @@ void cpu_process_nmi() {
 }
 
 void oam_dma_upload() {
-    byte page_high_addr = *ppu_get_state()->oam_dma_register;    // TODO
+    byte page_high_addr = ppu_get_state()->oam_dma_register;    // TODO
     address page_addr = ((address) page_high_addr) << 8;
     byte n = 0xff;
 

cpu/memory.c

@@ -8,62 +8,107 @@
 #include "../include/rom.h"
 #include "cpu.h"
 
+
+#define RAM_SIZE 0x0800
 #define RAM_MAX_ADDR 0x2000
-#define RAM_BANK_SIZE 0x800
 #define PPU_MAX_ADDR 0x4000
-#define PPU_BANK_SIZE 0x8
 #define APU_MAX_ADDR 0x4020
-#define MAX_ADDR 0xffff
+#define UNMAPPED_MAX_ADDR 0x6000
+#define CARTRIDGE_RAM_MAX_ADDR 0x8000
+#define MEM_ADDR_MAX 0xffff
 
 byte ram[RAM_SIZE];
 
-byte mem_get_byte(address addr) {
-    assert(addr <= MAX_ADDR);
-
-    if (addr >= RAM_MAX_ADDR && addr < PPU_MAX_ADDR) {
-        byte reg = (addr - RAM_MAX_ADDR) % PPU_BANK_SIZE;
-        return ppu_read_reg(reg);
-    }
-
-    return ram[addr];
-}
-
 byte *mem_get_ptr(address addr) {
-    assert(addr <= MAX_ADDR);
+    assert(addr <= RAM_MAX_ADDR);
 
-    return &ram[addr];
+    if (addr < RAM_MAX_ADDR) {
+        address ram_addr = addr % RAM_SIZE;   // There is four mirror of RAM
+        return &ram[ram_addr];
+    }
+
+    // Only supported for RAM
+    assert(false);
+}
+
+byte mem_get_byte(address addr) {
+    assert(addr <= MEM_ADDR_MAX);
+
+    if (addr < RAM_MAX_ADDR) {
+        address ram_addr = addr % RAM_SIZE;
+        return ram[ram_addr];
+    } else if (addr < PPU_MAX_ADDR) {
+        address relative_addr = addr - RAM_MAX_ADDR;
+        byte ppu_reg = relative_addr % 8;
+        return ppu_read_reg(ppu_reg);
+    } else if (addr < APU_MAX_ADDR) {
+        // TODO NES API and I/O registers
+        return 0;
+    } else if (addr < UNMAPPED_MAX_ADDR) {
+        // Unmapped
+        assert(false);
+    } else if (addr < CARTRIDGE_RAM_MAX_ADDR) {
+        // TODO Cartridge RAM
+        return 0;
+    } else {
+        address rom_addr = addr - CARTRIDGE_RAM_MAX_ADDR;
+
+        Mapper *mapper = system_get_mapper();
+        return *(mapper->mem_read(rom_addr));
+    }
 }
 
 word mem_get_word(address addr) {
-    assert(addr < MAX_ADDR);
+    assert(addr <= MEM_ADDR_MAX - 1);
 
-    word word = ram[addr];
-    word += ram[addr + 1] << 8;    // Little endian
-    return word;
+    byte data1;
+    byte data2;
+
+    if (addr < RAM_MAX_ADDR - 1) {
+        address ram_addr = addr % RAM_SIZE;
+        data1 = ram[ram_addr];
+        data2 = ram[ram_addr + 1];
+    } else if (addr < UNMAPPED_MAX_ADDR) {
+        // Unsupported
+        assert(false);
+    } else if (addr < CARTRIDGE_RAM_MAX_ADDR) {
+        // TODO Cartridge RAM
+        return 0;
+    } else {
+        address rom_addr = addr - CARTRIDGE_RAM_MAX_ADDR;
+
+        Mapper *mapper = system_get_mapper();
+        byte *location = mapper->mem_read(rom_addr);
+
+        data1 = *location;
+        data2 = *(location + 1);
     }
 
-void mem_set_byte(address addr, byte byte) {
-    assert(addr < MAX_ADDR);
+    return data1 + (data2 << 8);
+}
 
-    log_trace("Writing '%02x' to address 0x%04x", byte, addr);
+void mem_set_byte(address addr, byte data) {
+    assert(addr < MEM_ADDR_MAX);
 
     if (addr < RAM_MAX_ADDR) {
-        address init_ram_addr = addr % RAM_BANK_SIZE;
-
-        // The value must also be cloned in the three mirrors
-        for (int i = 0; i < 4; i++) {
-            address ram_addr = init_ram_addr + RAM_BANK_SIZE * i;
-            ram[ram_addr] = byte;
-        }
+        address ram_addr = addr % RAM_SIZE;
+        ram[ram_addr] = data;
     } else if (addr < PPU_MAX_ADDR) {
-        address reg_addr = (addr - RAM_MAX_ADDR) % PPU_BANK_SIZE;
-        ppu_write_reg(reg_addr, byte);
-    } else {
-        ram[addr] = byte;
-
-        if (addr == PPU_REGISTER_OAM_DMA_ADDR) {
+        address relative_addr = addr - RAM_MAX_ADDR;
+        byte ppu_reg = relative_addr % 8;
+        ppu_write_reg(ppu_reg, data);
+    } else if (addr == PPU_REGISTER_OAM_DMA_ADDR) {
         // Writing to this address triggers an upload to the PPU memory
         cpu_trigger_oam_dma();
-        }
+    } else if (addr < APU_MAX_ADDR) {
+        // TODO NES API and I/O registers
+    } else if (addr < UNMAPPED_MAX_ADDR) {
+        // Unmapped
+        assert(false);
+    } else if (addr < CARTRIDGE_RAM_MAX_ADDR) {
+        // TODO Cartridge RAM
+    } else {
+        // ROM is read-only
+        assert(false);
     }
 }

cpu/memory.h

@@ -37,8 +37,8 @@ word mem_get_word(address addr);
  * Sets a byte in a system's memory.
  *
  * @param addr The address to set
- * @param value The value to set
+ * @param data The data to set
  */
-void mem_set_byte(address addr, byte value);
+void mem_set_byte(address addr, byte data);
 
 #endif //NESEMULATOR_MEMORY_H

include/ppu.h

@@ -5,7 +5,6 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include "types.h"
-#include "../ppu/memory.h"
 
 #ifndef NESEMULATOR_PPU_H
 #define NESEMULATOR_PPU_H
@@ -61,11 +60,18 @@ typedef struct ppu_memory {
     byte *palette;
 } PPUMemory;
 
+typedef struct ppu_tile_fetch {
+    byte nametable;
+    byte attribute_table;
+    byte pattern_table_tile_low;
+    byte pattern_table_tile_high;
+} PPUTileFetch;
+
 typedef struct ppu {
     PPUMemory memory;
 
-    byte *registers;
-    byte *oam_dma_register;
+    byte registers[8];
+    byte oam_dma_register;
     byte vram[PPU_VRAM_SIZE];
     byte oam[PPU_OAM_SIZE];
     bool odd_frame;
@@ -90,8 +96,7 @@ PPU *ppu_get_state();
  *
  * @param ppu
  */
-void ppu_init(byte *registers_ram, byte *oam_dma_register);
-void ppu_uninit();
+void ppu_init();
 
 /**
  * Cycles the PPU.

include/rom.h

@@ -19,7 +19,7 @@ typedef struct {
     bool nametable_mirrored;
 
     byte *prg_rom;
-    int prg_rom_size;
+    unsigned int prg_rom_size;
 
     byte *chr_rom;
 } Rom;

include/types.h

@@ -5,14 +5,14 @@
 #ifndef NESEMULATOR_TYPES_H
 #define NESEMULATOR_TYPES_H
 
-#define RAM_SIZE 0xffff
-#define VRAM_SIZE 0x4000
+//#define RAM_SIZE 0xffff
+//#define VRAM_SIZE 0x4000
 
 typedef unsigned char byte;
 typedef unsigned short address;
 typedef unsigned short word;
 
 //typedef byte ram[RAM_SIZE];
-typedef byte vram[VRAM_SIZE];
+//typedef byte vram[VRAM_SIZE];
 
 #endif //NESEMULATOR_TYPES_H

main.c

@@ -27,7 +27,7 @@ int main() {
     log_set_level(LOG_INFO);
 
     system_init();
-    char *rom_path = "../test_roms/dk_japan.nes";
+    char *rom_path = "../test_roms/dk_jp.nes";
 
     if (!rom_load(rom_path)) {
         system_uninit();

mappers/nrom.c

@@ -2,23 +2,17 @@
 #include "../include/rom.h"
 #include "../cpu/memory.h"
 
-#define SIMPLE_MAPPER_PRG_START_ADDR 0x8000
 #define PRG_BANK_SIZE 0x4000    // 16Kb
 
 byte *nrom_mem_read(address addr) {
-    if (addr >= SIMPLE_MAPPER_PRG_START_ADDR) {
     Rom *rom = rom_get();
-        address relative_addr = addr - SIMPLE_MAPPER_PRG_START_ADDR;
 
     if (addr < PRG_BANK_SIZE || rom->prg_rom_size > PRG_BANK_SIZE) {
-            return &rom->prg_rom[relative_addr];
+        return &rom->prg_rom[addr];
     }
 
     // The second bank is mirrored
-        return &rom->prg_rom[relative_addr - PRG_BANK_SIZE];
-    }
-
-    return NULL;
+    return &rom->prg_rom[addr - PRG_BANK_SIZE];
 }
 
 byte *nrom_ppu_read(address addr) {

ppu/CMakeLists.txt

@@ -1,7 +1,5 @@
-set(HEADERS pattern_table.h ppu.h palette.h
-        memory.h)
-set(SOURCE pattern_table.c ppu.c palette.c
-        memory.c)
+set(HEADERS pattern_table.h ppu.h palette.h)
+set(SOURCE pattern_table.c ppu.c palette.c)
 
 add_library(nes_ppu ${SOURCE} ${HEADERS})
 

ppu/memory.c

@@ -1,48 +0,0 @@
-//
-// Created by william on 5/17/24.
-//
-
-#include <assert.h>
-#include "memory.h"
-
-void ppu_vram_fetch(PPUVramFetch *fetch, address addr) {
-    assert(addr < VRAM_SIZE);
-
-    if (fetch->finished) {
-        fetch->finished = false;
-        return;
-    }
-
-    fetch->data = *fetch->vram[addr];
-    fetch->finished = true;
-}
-
-void ppu_tile_fetch(PPUTileFetch *fetch, address addr) {
-    if (fetch->fetch_cycle >= 8) {
-        fetch->fetch_cycle = 0;
-    }
-
-    if (fetch->fetch_cycle % 2 == 0) {
-        // First cycle of a memory fetch
-        ppu_vram_fetch(&fetch->vram_fetch, addr + (fetch->fetch_cycle / 2));
-    } else {
-        // Second cycle of a fetch, the data should be available
-        byte data = fetch->vram_fetch.data;
-        switch (fetch->fetch_cycle) {
-            case 1:
-                fetch->nametable = data;
-                break;
-            case 3:
-                fetch->attribute_table = data;
-                break;
-            case 5:
-                fetch->pattern_table_tile_low = data;
-                break;
-            case 7:
-                fetch->pattern_table_tile_high = data;
-                break;
-            default:
-                assert(false);
-        }
-    }
-}

ppu/memory.h

@@ -1,28 +0,0 @@
-//
-// Created by william on 5/17/24.
-//
-
-#include <stdbool.h>
-#include "../include/types.h"
-
-#ifndef NES_EMULATOR_MEMORY_H
-#define NES_EMULATOR_MEMORY_H
-
-typedef struct ppu_vram_fetch {
-    vram *vram;
-    byte data;
-    bool finished;
-} PPUVramFetch;
-
-typedef struct ppu_tile_fetch {
-    byte nametable;
-    byte attribute_table;
-    byte pattern_table_tile_low;
-    byte pattern_table_tile_high;
-} PPUTileFetch;
-
-void ppu_vram_fetch(PPUVramFetch *fetch, address addr);
-
-void ppu_tile_fetch(PPUTileFetch *fetch, address addr);
-
-#endif //NES_EMULATOR_MEMORY_H

ppu/ppu.c

@@ -29,12 +29,8 @@
 
 PPU ppu_state;
 
-void ppu_init(byte *registers_ram, byte *oam_dma_register) {
+void ppu_init() {
     memset(&ppu_state, 0, sizeof(PPU));
-
-    ppu_state.oam_dma_register = oam_dma_register;
-    ppu_state.registers = registers_ram;
-    memset(&ppu_state.registers, 0, 8);
 }
 
 PPU *ppu_get_state() {
@@ -62,24 +58,24 @@ void ppu_visible_frame(unsigned int cycle) {
     if (cycle == 0) {
         // Idle...
     } else if (cycle <= 256) {
-        byte tile_fetch_cycle = (cycle - 1) % 8;
-        switch (tile_fetch_cycle) {
-            case 1:
-                ppu_state.tile_fetch.nametable = ppu_read(ppu_state.ppu_address);
-                break;
-            case 3:
-                ppu_state.tile_fetch.attribute_table = ppu_read(ppu_state.ppu_address);
-                break;
-            case 5:
-                ppu_state.tile_fetch.pattern_table_tile_low = ppu_read(ppu_state.ppu_address);
-                break;
-            case 7:
-                ppu_state.tile_fetch.pattern_table_tile_high = ppu_read(ppu_state.ppu_address);
-                ppu_state.ppu_address++;
-                break;
-            default:
-                break;
-        }
+//        byte tile_fetch_cycle = (cycle - 1) % 8;
+//        switch (tile_fetch_cycle) {
+//            case 1:
+//                ppu_state.tile_fetch.nametable = ppu_read(ppu_state.ppu_address);
+//                break;
+//            case 3:
+//                ppu_state.tile_fetch.attribute_table = ppu_read(ppu_state.ppu_address);
+//                break;
+//            case 5:
+//                ppu_state.tile_fetch.pattern_table_tile_low = ppu_read(ppu_state.ppu_address);
+//                break;
+//            case 7:
+//                ppu_state.tile_fetch.pattern_table_tile_high = ppu_read(ppu_state.ppu_address);
+//                ppu_state.ppu_address++;
+//                break;
+//            default:
+//                break;
+//        }
     } else if (cycle <= 320) {
         // OAMADDR is cleared on sprite loading for pre-render and visible lines
         ppu_write_reg(PPU_REGISTER_OAM_ADDR, 0);
@@ -180,15 +176,6 @@ byte ppu_read_reg(byte reg) {
     return ppu_state.registers[reg];
 }
 
-void ppu_write_reg_ram(byte reg, byte data) {
-    byte *ppu_ram = mem_get_ptr(PPU_RAM_BASE_ADDR);
-
-    for (int i = 0; i < PPU_RAM_BANK_COUNT; i++) {
-        byte ram_offset = (i * PPU_RAM_BANK_SIZE) + reg;
-        *(ppu_ram + ram_offset) = data;
-    }
-}
-
 void ppu_write_reg(byte reg, byte data) {
     ppu_state.registers[reg] = data;
 
@@ -234,7 +221,7 @@ void ppu_write_reg(byte reg, byte data) {
         ppu_write_reg(PPU_REGISTER_OAM_ADDR, oam_addr + 1);
     }
 
-    ppu_write_reg_ram(reg, data);
+    ppu_state.registers[reg] = data;
 }
 
 byte ppu_read(address addr) {

rom/ines.c

@@ -59,7 +59,7 @@ typedef struct {
     struct INesHeaderFlags flags;
 } INesHeader;
 
-bool rom_is_ines(const char header[16]) {
+bool rom_is_ines(const byte header[16]) {
     return header[0] == 'N' && header[1] == 'E' && header[2] == 'S';
 }
 
@@ -139,8 +139,6 @@ bool rom_ines_read_prg_rom(FILE *file, INesHeader *header, Rom *rom) {
         return false;
     }
 
-    system_get_mapper()->post_prg_load(header->prg_rom_size);
-
     return true;
 }
 

rom/rom.c

@@ -21,14 +21,13 @@ bool rom_load(char *path) {
         return false;
     }
 
-    char header_buffer[ROM_HEADER_SIZE] = {0};
-    size_t read_size = fread(header_buffer, sizeof(char), ROM_HEADER_SIZE, file);
+    size_t read_size = fread(&rom.header, sizeof(byte), ROM_HEADER_SIZE, file);
     if (read_size < ROM_HEADER_SIZE) {
         log_error("Failed to read ROM");
         return false;
     }
 
-    if (!rom_is_ines(header_buffer)) {
+    if (!rom_is_ines(rom.header)) {
         log_error("Only iNes ROMs are supported");
         return false;
     }

system.c

@@ -13,11 +13,8 @@
 System current_sys;
 
 void system_init() {
-    byte *registers_base_addr = mem_get_ptr(PPU_REGISTERS_BASE_ADDR);
-    byte *oam_dma_register = mem_get_ptr(PPU_REGISTER_OAM_DMA_ADDR);
-
     cpu_init();
-    ppu_init(registers_base_addr, oam_dma_register);
+    ppu_init();
 
     current_sys.mapper = get_mapper(MAPPER_TYPE_SIMPLE);
     current_sys.cycle_count = 7;
@@ -41,7 +38,6 @@ void system_next_frame() {
 }
 
 void system_uninit() {
-    ppu_uninit();
 }
 
 unsigned int system_get_cycles() {