backend-infra-engineer: Pre-0.2.2 snapshot (2023)
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scawful
376
src/app/emu/snes.cc
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376
src/app/emu/snes.cc
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#include "app/emu/snes.h"
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#include <SDL_mixer.h>
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#include <cstdint>
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#include <memory>
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#include <string>
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#include <thread>
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#include "app/emu/audio/apu.h"
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#include "app/emu/audio/spc700.h"
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#include "app/emu/cpu/clock.h"
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#include "app/emu/cpu/cpu.h"
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#include "app/emu/debug/debugger.h"
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#include "app/emu/memory/memory.h"
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#include "app/emu/video/ppu.h"
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#include "app/rom.h"
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namespace yaze {
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namespace app {
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namespace emu {
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namespace {
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uint16_t GetHeaderOffset(const Memory& memory) {
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uint8_t mapMode = memory[(0x00 << 16) + 0xFFD5];
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uint16_t offset;
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switch (mapMode & 0x07) {
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case 0: // LoROM
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offset = 0x7FC0;
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break;
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case 1: // HiROM
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offset = 0xFFC0;
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break;
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case 5: // ExHiROM
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offset = 0x40;
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break;
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default:
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throw std::invalid_argument(
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"Unable to locate supported ROM mapping mode in the provided ROM "
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"file. Please try another ROM file.");
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}
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return offset;
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}
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void audio_callback(void* userdata, uint8_t* stream, int len) {
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auto* apu = static_cast<APU*>(userdata);
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auto* buffer = reinterpret_cast<int16_t*>(stream);
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for (int i = 0; i < len / 2; i++) { // Assuming 16-bit samples
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buffer[i] = apu->GetNextSample(); // This function should be implemented in
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// APU to fetch the next sample
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}
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}
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} // namespace
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ROMInfo SNES::ReadRomHeader(uint32_t offset) {
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ROMInfo romInfo;
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// Read cartridge title
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char title[22];
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for (int i = 0; i < 21; ++i) {
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title[i] = cpu_.ReadByte(offset + i);
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}
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title[21] = '\0'; // Null-terminate the string
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romInfo.title = std::string(title);
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// Read ROM speed and memory map mode
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uint8_t romSpeedAndMapMode = cpu_.ReadByte(offset + 0x15);
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romInfo.romSpeed = (ROMSpeed)(romSpeedAndMapMode & 0x07);
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romInfo.bankSize = (BankSize)((romSpeedAndMapMode >> 5) & 0x01);
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// Read ROM type
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romInfo.romType = (ROMType)cpu_.ReadByte(offset + 0x16);
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// Read ROM size
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romInfo.romSize = (ROMSize)cpu_.ReadByte(offset + 0x17);
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// Read RAM size
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romInfo.sramSize = (SRAMSize)cpu_.ReadByte(offset + 0x18);
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// Read country code
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romInfo.countryCode = (CountryCode)cpu_.ReadByte(offset + 0x19);
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// Read license
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romInfo.license = (License)cpu_.ReadByte(offset + 0x1A);
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// Read ROM version
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romInfo.version = cpu_.ReadByte(offset + 0x1B);
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// Read checksum complement
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romInfo.checksumComplement = cpu_.ReadWord(offset + 0x1E);
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// Read checksum
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romInfo.checksum = cpu_.ReadWord(offset + 0x1C);
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// Read NMI VBL vector
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romInfo.nmiVblVector = cpu_.ReadWord(offset + 0x3E);
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// Read reset vector
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romInfo.resetVector = cpu_.ReadWord(offset + 0x3C);
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return romInfo;
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}
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void SNES::Init(ROM& rom) {
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// Perform a long jump into a FastROM bank (if the ROM speed is FastROM)
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// Disable the emulation flag (switch to 65816 native mode)
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cpu_.E = 0;
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// Initialize CPU
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cpu_.Init();
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// Read the ROM header
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auto header_offset = GetHeaderOffset(memory_);
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rom_info_ = ReadRomHeader((0x00 << 16) + header_offset);
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cpu_.PB = 0x00;
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cpu_.PC = 0x8000;
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// Initialize PPU
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ppu_.Init();
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// Initialize APU
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apu_.Init();
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// Initialize SDL_Mixer to play the audio samples
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// Mix_HookMusic(audio_callback, &apu);
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// Disable interrupts and rendering
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memory_.WriteByte(0x4200, 0x00); // NMITIMEN
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memory_.WriteByte(0x420C, 0x00); // HDMAEN
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// Disable screen
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memory_.WriteByte(0x2100, 0x8F); // INIDISP
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// Fill Work-RAM with zeros using two 64KiB fixed address DMA transfers to
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// WMDATA
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// TODO: Make this load from work ram, potentially in Memory class
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std::memset((void*)memory_.ram_.data(), 0, sizeof(memory_.ram_));
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// Reset PPU registers to a known good state
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memory_.WriteByte(0x4201, 0xFF); // WRIO
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// Objects
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memory_.WriteByte(0x2101, 0x00); // OBSEL
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memory_.WriteByte(0x2102, 0x00); // OAMADDL
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memory_.WriteByte(0x2103, 0x00); // OAMADDH
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// Backgrounds
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memory_.WriteByte(0x2105, 0x00); // BGMODE
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memory_.WriteByte(0x2106, 0x00); // MOSAIC
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memory_.WriteByte(0x2107, 0x00); // BG1SC
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memory_.WriteByte(0x2108, 0x00); // BG2SC
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memory_.WriteByte(0x2109, 0x00); // BG3SC
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memory_.WriteByte(0x210A, 0x00); // BG4SC
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memory_.WriteByte(0x210B, 0x00); // BG12NBA
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memory_.WriteByte(0x210C, 0x00); // BG34NBA
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// Scroll Registers
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memory_.WriteByte(0x210D, 0x00); // BG1HOFS
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memory_.WriteByte(0x210E, 0xFF); // BG1VOFS
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memory_.WriteByte(0x210F, 0x00); // BG2HOFS
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memory_.WriteByte(0x2110, 0xFF); // BG2VOFS
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memory_.WriteByte(0x2111, 0x00); // BG3HOFS
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memory_.WriteByte(0x2112, 0xFF); // BG3VOFS
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memory_.WriteByte(0x2113, 0x00); // BG4HOFS
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memory_.WriteByte(0x2114, 0xFF); // BG4VOFS
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// VRAM Registers
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memory_.WriteByte(0x2115, 0x80); // VMAIN
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// Mode 7
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memory_.WriteByte(0x211A, 0x00); // M7SEL
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memory_.WriteByte(0x211B, 0x01); // M7A
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memory_.WriteByte(0x211C, 0x00); // M7B
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memory_.WriteByte(0x211D, 0x00); // M7C
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memory_.WriteByte(0x211E, 0x01); // M7D
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memory_.WriteByte(0x211F, 0x00); // M7X
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memory_.WriteByte(0x2120, 0x00); // M7Y
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// Windows
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memory_.WriteByte(0x2123, 0x00); // W12SEL
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memory_.WriteByte(0x2124, 0x00); // W34SEL
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memory_.WriteByte(0x2125, 0x00); // WOBJSEL
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memory_.WriteByte(0x2126, 0x00); // WH0
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memory_.WriteByte(0x2127, 0x00); // WH1
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memory_.WriteByte(0x2128, 0x00); // WH2
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memory_.WriteByte(0x2129, 0x00); // WH3
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memory_.WriteByte(0x212A, 0x00); // WBGLOG
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memory_.WriteByte(0x212B, 0x00); // WOBJLOG
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// Layer Enable
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memory_.WriteByte(0x212C, 0x00); // TM
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memory_.WriteByte(0x212D, 0x00); // TS
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memory_.WriteByte(0x212E, 0x00); // TMW
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memory_.WriteByte(0x212F, 0x00); // TSW
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// Color Math
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memory_.WriteByte(0x2130, 0x30); // CGWSEL
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memory_.WriteByte(0x2131, 0x00); // CGADSUB
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memory_.WriteByte(0x2132, 0xE0); // COLDATA
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// Misc
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memory_.WriteByte(0x2133, 0x00); // SETINI
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// Psuedo-Init
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memory_.WriteWord(0x2140, 0xBBAA);
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running_ = true;
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scanline = 0;
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}
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void SNES::Run() {
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const double targetFPS = 60.0; // 60 frames per second
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const double frame_time = 1.0 / targetFPS;
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double frame_accumulated_time = 0.0;
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auto last_time = std::chrono::high_resolution_clock::now();
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if (running_) {
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auto current_time = std::chrono::high_resolution_clock::now();
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double delta_time =
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std::chrono::duration<double>(current_time - last_time).count();
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last_time = current_time;
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frame_accumulated_time += delta_time;
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// Update the CPU
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cpu_.UpdateClock(delta_time);
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cpu_.Update(GetCpuMode());
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// Update the PPU
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ppu_.UpdateClock(delta_time);
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ppu_.Update();
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// Update the APU
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apu_.UpdateClock(delta_time);
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apu_.Update();
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if (frame_accumulated_time >= frame_time) {
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// renderer.Render();
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frame_accumulated_time -= frame_time;
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}
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HandleInput();
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}
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}
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void SNES::StepRun() {
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// Update the CPU
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cpu_.UpdateClock(0.0);
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cpu_.Update(CPU::UpdateMode::Step);
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// Update the PPU
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ppu_.UpdateClock(0.0);
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ppu_.Update();
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// Update the APU
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apu_.UpdateClock(0.0);
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apu_.Update();
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HandleInput();
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}
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// Enable NMI Interrupts
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void SNES::EnableVBlankInterrupts() {
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v_blank_flag_ = false;
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// Clear the RDNMI VBlank flag
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memory_.ReadByte(0x4210); // RDNMI
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// Enable vblank NMI interrupts and Joypad auto-read
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memory_.WriteByte(0x4200, 0x81); // NMITIMEN
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}
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// Wait until the VBlank routine has been processed
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void SNES::WaitForVBlank() {
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v_blank_flag_ = true;
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// Loop until `v_blank_flag_` is clear
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while (v_blank_flag_) {
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std::this_thread::yield();
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}
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}
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// NMI Interrupt Service Routine
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void SNES::NmiIsr() {
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// Switch to a FastROM bank (assuming NmiIsr is in bank 0x80)
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// ...
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// Push CPU registers to stack
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cpu_.PHP();
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// Reset DB and DP registers
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cpu_.DB = 0x80; // Assuming bank 0x80, can be changed to 0x00
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cpu_.D = 0;
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if (v_blank_flag_) {
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VBlankRoutine();
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// Clear `v_blank_flag_`
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v_blank_flag_ = false;
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}
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// Increment 32-bit frame_counter_
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frame_counter_++;
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// Restore CPU registers
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cpu_.PHB();
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}
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// VBlank routine
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void SNES::VBlankRoutine() {
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// Read the joypad state
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// ...
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// Update the PPU
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// ...
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// Update the APU
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// ...
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}
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void SNES::StartApuDataTransfer() {
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// 2. Setting the starting address
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const uint16_t startAddress = 0x0200;
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memory_.WriteByte(0x2142, startAddress & 0xFF); // Lower byte
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memory_.WriteByte(0x2143, startAddress >> 8); // Upper byte
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memory_.WriteByte(0x2141, 0xCC); // Any non-zero value
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memory_.WriteByte(0x2140, 0xCC); // Signal to start
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const int DATA_SIZE = 0x1000; // 4 KiB
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// 3. Sending data (simplified)
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// Assuming a buffer `audioData` containing the audio program/data
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uint8_t audioData[DATA_SIZE]; // Define DATA_SIZE and populate audioData as
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// needed
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for (int i = 0; i < DATA_SIZE; ++i) {
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memory_.WriteByte(0x2141, audioData[i]);
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memory_.WriteByte(0x2140, i & 0xFF);
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while (memory_.ReadByte(0x2140) != (i & 0xFF))
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; // Wait for acknowledgment
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}
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// 4. Running the SPC700 program
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memory_.WriteByte(0x2142, startAddress & 0xFF); // Lower byte
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memory_.WriteByte(0x2143, startAddress >> 8); // Upper byte
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memory_.WriteByte(0x2141, 0x00); // Zero to start the program
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memory_.WriteByte(0x2140, 0xCE); // Increment by 2
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while (memory_.ReadByte(0x2140) != 0xCE)
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; // Wait for acknowledgment
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}
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void SNES::HandleInput() {
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// ...
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}
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void SNES::SaveState(const std::string& path) {
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// ...
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}
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void SNES::LoadState(const std::string& path) {
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// ...
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}
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} // namespace emu
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} // namespace app
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} // namespace yaze
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