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217 lines
7.7 KiB
C++
217 lines
7.7 KiB
C++
//
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// Cartridge.h
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// Clock Signal
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//
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// Created by Thomas Harte on 17/03/2017.
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// Copyright © 2017 Thomas Harte. All rights reserved.
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//
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#ifndef Atari2600_Cartridge_hpp
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#define Atari2600_Cartridge_hpp
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#include "../../Processors/6502/CPU6502.hpp"
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namespace Atari2600 {
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class Bus {
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public:
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Bus() :
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tia_input_value_{0xff, 0xff},
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cycles_since_speaker_update_(0),
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cycles_since_video_update_(0),
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cycles_since_6532_update_(0) {}
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virtual void run_for_cycles(int number_of_cycles) = 0;
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virtual void set_reset_line(bool state) = 0;
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// the RIOT, TIA and speaker
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PIA mos6532_;
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std::shared_ptr<TIA> tia_;
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std::shared_ptr<Speaker> speaker_;
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// joystick state
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uint8_t tia_input_value_[2];
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protected:
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// speaker backlog accumlation counter
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unsigned int cycles_since_speaker_update_;
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inline void update_audio() {
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unsigned int audio_cycles = cycles_since_speaker_update_ / 114;
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cycles_since_speaker_update_ %= 114;
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speaker_->run_for_cycles(audio_cycles);
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}
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// video backlog accumulation counter
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unsigned int cycles_since_video_update_;
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inline void update_video() {
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tia_->run_for_cycles((int)cycles_since_video_update_);
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cycles_since_video_update_ = 0;
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}
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// RIOT backlog accumulation counter
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unsigned int cycles_since_6532_update_;
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inline void update_6532() {
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mos6532_.run_for_cycles(cycles_since_6532_update_);
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cycles_since_6532_update_ = 0;
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}
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};
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template<class T> class Cartridge:
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public CPU6502::Processor<Cartridge<T>>,
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public Bus {
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public:
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Cartridge(const std::vector<uint8_t> &rom) :
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rom_(rom) {}
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void run_for_cycles(int number_of_cycles) { CPU6502::Processor<Cartridge<T>>::run_for_cycles(number_of_cycles); }
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void set_reset_line(bool state) { CPU6502::Processor<Cartridge<T>>::set_reset_line(state); }
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// to satisfy CPU6502::Processor
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unsigned int perform_bus_operation(CPU6502::BusOperation operation, uint16_t address, uint8_t *value) {
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uint8_t returnValue = 0xff;
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unsigned int cycles_run_for = 3;
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// this occurs as a feedback loop — the 2600 requests ready, then performs the cycles_run_for
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// leap to the end of ready only once ready is signalled — because on a 6502 ready doesn't take
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// effect until the next read; therefore it isn't safe to assume that signalling ready immediately
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// skips to the end of the line.
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if(operation == CPU6502::BusOperation::Ready)
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cycles_run_for = (unsigned int)tia_->get_cycles_until_horizontal_blank(cycles_since_video_update_);
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cycles_since_speaker_update_ += cycles_run_for;
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cycles_since_video_update_ += cycles_run_for;
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cycles_since_6532_update_ += (cycles_run_for / 3);
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if(operation != CPU6502::BusOperation::Ready) {
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// give the cartridge a chance to respond to the bus access
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static_cast<T *>(this)->perform_bus_operation(operation, address, value);
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// check for a RIOT RAM access
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if((address&0x1280) == 0x80) {
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if(isReadOperation(operation)) {
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returnValue &= mos6532_.get_ram(address);
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} else {
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mos6532_.set_ram(address, *value);
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}
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}
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// check for a TIA access
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if(!(address&0x1080)) {
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if(isReadOperation(operation)) {
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const uint16_t decodedAddress = address & 0xf;
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switch(decodedAddress) {
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case 0x00: // missile 0 / player collisions
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case 0x01: // missile 1 / player collisions
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case 0x02: // player 0 / playfield / ball collisions
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case 0x03: // player 1 / playfield / ball collisions
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case 0x04: // missile 0 / playfield / ball collisions
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case 0x05: // missile 1 / playfield / ball collisions
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case 0x06: // ball / playfield collisions
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case 0x07: // player / player, missile / missile collisions
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returnValue &= tia_->get_collision_flags(decodedAddress);
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break;
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case 0x08:
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case 0x09:
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case 0x0a:
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case 0x0b:
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// TODO: pot ports
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returnValue &= 0;
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break;
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case 0x0c:
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case 0x0d:
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returnValue &= tia_input_value_[decodedAddress - 0x0c];
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break;
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}
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} else {
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const uint16_t decodedAddress = address & 0x3f;
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switch(decodedAddress) {
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case 0x00: update_video(); tia_->set_sync(*value & 0x02); break;
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case 0x01: update_video(); tia_->set_blank(*value & 0x02); break;
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case 0x02: CPU6502::Processor<Cartridge<T>>::set_ready_line(true); break;
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case 0x03: update_video(); tia_->reset_horizontal_counter(); break;
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// TODO: audio will now be out of synchronisation — fix
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case 0x04:
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case 0x05: update_video(); tia_->set_player_number_and_size(decodedAddress - 0x04, *value); break;
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case 0x06:
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case 0x07: update_video(); tia_->set_player_missile_colour(decodedAddress - 0x06, *value); break;
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case 0x08: update_video(); tia_->set_playfield_ball_colour(*value); break;
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case 0x09: update_video(); tia_->set_background_colour(*value); break;
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case 0x0a: update_video(); tia_->set_playfield_control_and_ball_size(*value); break;
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case 0x0b:
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case 0x0c: update_video(); tia_->set_player_reflected(decodedAddress - 0x0b, !((*value)&8)); break;
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case 0x0d:
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case 0x0e:
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case 0x0f: update_video(); tia_->set_playfield(decodedAddress - 0x0d, *value); break;
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case 0x10:
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case 0x11: update_video(); tia_->set_player_position(decodedAddress - 0x10); break;
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case 0x12:
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case 0x13: update_video(); tia_->set_missile_position(decodedAddress - 0x12); break;
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case 0x14: update_video(); tia_->set_ball_position(); break;
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case 0x1b:
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case 0x1c: update_video(); tia_->set_player_graphic(decodedAddress - 0x1b, *value); break;
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case 0x1d:
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case 0x1e: update_video(); tia_->set_missile_enable(decodedAddress - 0x1d, (*value)&2); break;
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case 0x1f: update_video(); tia_->set_ball_enable((*value)&2); break;
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case 0x20:
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case 0x21: update_video(); tia_->set_player_motion(decodedAddress - 0x20, *value); break;
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case 0x22:
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case 0x23: update_video(); tia_->set_missile_motion(decodedAddress - 0x22, *value); break;
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case 0x24: update_video(); tia_->set_ball_motion(*value); break;
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case 0x25:
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case 0x26: tia_->set_player_delay(decodedAddress - 0x25, (*value)&1); break;
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case 0x27: tia_->set_ball_delay((*value)&1); break;
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case 0x28:
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case 0x29: update_video(); tia_->set_missile_position_to_player(decodedAddress - 0x28, (*value)&2); break;
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case 0x2a: update_video(); tia_->move(); break;
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case 0x2b: update_video(); tia_->clear_motion(); break;
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case 0x2c: update_video(); tia_->clear_collision_flags(); break;
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case 0x15:
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case 0x16: update_audio(); speaker_->set_control(decodedAddress - 0x15, *value); break;
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case 0x17:
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case 0x18: update_audio(); speaker_->set_divider(decodedAddress - 0x17, *value); break;
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case 0x19:
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case 0x1a: update_audio(); speaker_->set_volume(decodedAddress - 0x19, *value); break;
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}
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}
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}
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// check for a PIA access
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if((address&0x1280) == 0x280) {
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update_6532();
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if(isReadOperation(operation)) {
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returnValue &= mos6532_.get_register(address);
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} else {
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mos6532_.set_register(address, *value);
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}
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}
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if(isReadOperation(operation)) {
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*value &= returnValue;
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}
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}
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if(!tia_->get_cycles_until_horizontal_blank(cycles_since_video_update_)) CPU6502::Processor<Cartridge<T>>::set_ready_line(false);
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return cycles_run_for / 3;
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}
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void synchronise() {
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update_audio();
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update_video();
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speaker_->flush();
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}
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protected:
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std::vector<uint8_t> rom_;
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};
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}
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#endif /* Atari2600_Cartridge_hpp */
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