quickerNES/source/emuInstance.hpp

#pragma once

#include <core/Nes_Emu.h>
#include <core/Nes_State.h>
#include <string>
#include <utils.hpp> 
#include "sha1/sha1.hpp"

#define _LOW_MEM_SIZE 0x800
#define _HIGH_MEM_SIZE 0x2000
#define _NAMETABLES_MEM_SIZE 0x1000

class EmuInstance
{
 public:

 typedef uint8_t inputType;

 // Deleting default constructors
 EmuInstance() = delete;
 EmuInstance(EmuInstance& e) = delete;
 ~EmuInstance() = default;

 EmuInstance(const std::string& romFilePath, const std::string& stateFilePath)
 {
  // Creating new emulator
  _nes = new Nes_Emu;

  // Loading ROM
  std::string romData;
  bool status = loadStringFromFile(romData, romFilePath.c_str());
  if (status == false) EXIT_WITH_ERROR("Could not find/read state file: %s\n", romFilePath.c_str());

  // Calculating ROM hash value
  _romSHA1String = SHA1::GetHash((uint8_t*)romData.data(), romData.size());

  // Loading the rom into the emulator
  Mem_File_Reader romReader(romData.data(), (int)romData.size());
  Auto_File_Reader romFile(romReader);
  auto result = _nes->load_ines(romFile);
  if (result != 0) EXIT_WITH_ERROR("Could not initialize emulator with rom file: %s\n", romFilePath.c_str());

  // Getting state size to use
  _stateSize = getStateSizeImpl();

  // Loading state file, if specified
  if (stateFilePath != "") loadStateFile(stateFilePath);
 }

 uint8_t* getLowMem() { return _nes->low_mem(); };
 uint8_t* getNametableMem() { return _nes->nametable_mem(); };
 uint8_t* getHighMem() { return _nes->high_mem();};
 const uint8_t* getChrMem() { return _nes->chr_mem();};
 size_t getChrMemSize() { return _nes->chr_size();};

 const std::string getRomSHA1() const { return _romSHA1String; }; 

 void loadStateFile(const std::string& stateFilePath) 
 {
  // Loading state data
  std::string stateData;
  bool status = loadStringFromFile(stateData, stateFilePath.c_str());
  if (status == false) EXIT_WITH_ERROR("Could not find/read state file: %s\n", stateFilePath.c_str());
  Mem_File_Reader stateReader(stateData.data(), (int)stateData.size());
  Auto_File_Reader stateFile(stateReader);

  // Loading state data into state object
  Nes_State state;
  state.read(stateFile);

  // Loading state object into the emulator
  _nes->load_state(state);
 }

 inline size_t getStateSize() const { return _stateSize; }

 inline hash_t getStateHash() 
 {
  MetroHash128 hash;

  uint8_t stateData[_stateSize];
  serializeState(stateData);

  hash.Update(getLowMem(), _LOW_MEM_SIZE);
  hash.Update(getHighMem(), _HIGH_MEM_SIZE);
  hash.Update(getNametableMem(), _NAMETABLES_MEM_SIZE);
  hash.Update(getChrMem(), getChrMemSize());

  hash_t result;
  hash.Finalize(reinterpret_cast<uint8_t *>(&result));
  return result;
 }

 void saveStateFile(const std::string& stateFilePath) const 
 {
  std::string stateData;
  stateData.resize(_stateSize);
  serializeState((uint8_t*)stateData.data());
  saveStringToFile(stateData, stateFilePath.c_str());
 }

 void serializeState(uint8_t* state) const 
 {
  Mem_Writer w(state, _stateSize, 0);
  Auto_File_Writer a(w);
  _nes->save_state(a);
 }

 void deserializeState(const uint8_t* state) 
 {
  Mem_File_Reader r(state, _stateSize);
  Auto_File_Reader a(r);
  _nes->load_state(a);
 }

 // Controller input bits
 // 0 - A / 1
 // 1 - B / 2
 // 2 - Select / 4
 // 3 - Start / 8
 // 4 - Up / 16
 // 5 - Down / 32
 // 6 - Left / 64
 // 7 - Right / 128

 // Move Format:
 // RLDUTSBA
 // ........

 static inline inputType moveStringToCode(const std::string& move)
 {
  inputType moveCode = 0;

  for (size_t i = 0; i < move.size(); i++) switch(move[i])
  {
    case 'U': moveCode |= 0b00010000; break;
    case 'D': moveCode |= 0b00100000; break;
    case 'L': moveCode |= 0b01000000; break;
    case 'R': moveCode |= 0b10000000; break;
    case 'S': moveCode |= 0b00001000; break;
    case 's': moveCode |= 0b00000100; break;
    case 'B': moveCode |= 0b00000010; break;
    case 'A': moveCode |= 0b00000001; break;
    case 'r': break;
    case '.': break;
    case '|': break;
    default: EXIT_WITH_ERROR("Move provided cannot be parsed: '%s', unrecognized character: '%c'\n", move.c_str(), move[i]);
  }

  return moveCode;
 }

 static inline std::string moveCodeToString(const inputType move)
 {
#ifndef _NES_PLAYER_2
  std::string moveString = "|..|";
#else
  std::string moveString = "|..|........|";
#endif

  if (move & 0b00010000) moveString += 'U'; else moveString += '.';
  if (move & 0b00100000) moveString += 'D'; else moveString += '.';
  if (move & 0b01000000) moveString += 'L'; else moveString += '.';
  if (move & 0b10000000) moveString += 'R'; else moveString += '.';
  if (move & 0b00001000) moveString += 'S'; else moveString += '.';
  if (move & 0b00000100) moveString += 's'; else moveString += '.';
  if (move & 0b00000010) moveString += 'B'; else moveString += '.';
  if (move & 0b00000001) moveString += 'A'; else moveString += '.';

  moveString += "|";
  return moveString;
 }

 void advanceState(const std::string& move)
 {
  if (move.find("r") != std::string::npos) _nes->reset(false); 

  advanceState(moveStringToCode(move), 0);
 }

 void advanceState(const inputType controller1, const inputType controller2) 
 {
  _nes->emulate_frame(controller1, controller2);
 }

 Nes_Emu* getInternalEmulator() const { return _nes; }

 private:

 inline size_t getStateSizeImpl() const
 {
  // Using dry writer to just obtain the state size
  Dry_Writer w;
  Auto_File_Writer a(w);
  _nes->save_state(a);
  return w.size();
 }

 // Emulator instance
 Nes_Emu* _nes;

 // State size for the given rom
 size_t _stateSize;

 // SHA1 rom hash 
 std::string _romSHA1String;

};