116 lines
2.9 KiB
C
116 lines
2.9 KiB
C
//
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// Created by william on 10/15/23.
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//
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#include <assert.h>
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#include "log.h"
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#include "memory.h"
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#include "../include/rom.h"
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#include "cpu.h"
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#define RAM_SIZE 0x0800
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#define RAM_MAX_ADDR 0x2000
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#define PPU_MAX_ADDR 0x4000
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#define APU_MAX_ADDR 0x4020
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#define UNMAPPED_MAX_ADDR 0x6000
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#define CARTRIDGE_RAM_MAX_ADDR 0x8000
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#define MEM_ADDR_MAX 0xffff
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byte ram[RAM_SIZE];
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byte *mem_get_ptr(address addr) {
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assert(addr <= RAM_MAX_ADDR);
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if (addr < RAM_MAX_ADDR) {
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address ram_addr = addr % RAM_SIZE; // There is four mirror of RAM
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return &ram[ram_addr];
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}
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// Only supported for RAM
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assert(false);
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}
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byte mem_get_byte(address addr) {
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assert(addr <= MEM_ADDR_MAX);
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if (addr < RAM_MAX_ADDR) {
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address ram_addr = addr % RAM_SIZE;
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return ram[ram_addr];
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} else if (addr < PPU_MAX_ADDR) {
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address relative_addr = addr - RAM_MAX_ADDR;
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byte ppu_reg = relative_addr % 8;
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return ppu_read_reg(ppu_reg);
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} else if (addr < APU_MAX_ADDR) {
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// TODO NES API and I/O registers
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return 0;
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} else if (addr < UNMAPPED_MAX_ADDR) {
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// Unmapped
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assert(false);
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} else if (addr < CARTRIDGE_RAM_MAX_ADDR) {
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// TODO Cartridge RAM
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return 0;
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} else {
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address rom_addr = addr - CARTRIDGE_RAM_MAX_ADDR;
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Mapper *mapper = system_get_mapper();
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return *(mapper->mem_read(rom_addr));
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}
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}
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word mem_get_word(address addr) {
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assert(addr <= MEM_ADDR_MAX - 1);
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byte data1;
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byte data2;
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if (addr < RAM_MAX_ADDR - 1) {
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address ram_addr = addr % RAM_SIZE;
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data1 = ram[ram_addr];
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data2 = ram[ram_addr + 1];
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} else if (addr < UNMAPPED_MAX_ADDR) {
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// Unsupported
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assert(false);
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} else if (addr < CARTRIDGE_RAM_MAX_ADDR) {
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// TODO Cartridge RAM
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return 0;
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} else {
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address rom_addr = addr - CARTRIDGE_RAM_MAX_ADDR;
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Mapper *mapper = system_get_mapper();
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byte *location = mapper->mem_read(rom_addr);
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data1 = *location;
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data2 = *(location + 1);
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}
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return data1 + (data2 << 8);
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}
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void mem_set_byte(address addr, byte data) {
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assert(addr < MEM_ADDR_MAX);
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if (addr < RAM_MAX_ADDR) {
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address ram_addr = addr % RAM_SIZE;
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ram[ram_addr] = data;
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} else if (addr < PPU_MAX_ADDR) {
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address relative_addr = addr - RAM_MAX_ADDR;
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byte ppu_reg = relative_addr % 8;
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ppu_write_reg(ppu_reg, data);
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} else if (addr == PPU_REGISTER_OAM_DMA_ADDR) {
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ppu_write_oamaddr(data);
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// Writing to this address triggers an upload to the PPU memory
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cpu_trigger_oam_dma();
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} else if (addr < APU_MAX_ADDR) {
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// TODO NES API and I/O registers
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} else if (addr < UNMAPPED_MAX_ADDR) {
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// Unmapped
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assert(false);
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} else if (addr < CARTRIDGE_RAM_MAX_ADDR) {
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// TODO Cartridge RAM
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} else {
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// ROM is read-only
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assert(false);
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}
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} |