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CLK/Machines/Atari/2600/Cartridges/Cartridge.hpp
Thomas Harte 77ef7dc8fc Shuffles ST and 2600 into a common parent.
2019-11-09 15:31:41 -05:00

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7.7 KiB
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//
// Cartridge.h
// Clock Signal
//
// Created by Thomas Harte on 17/03/2017.
// Copyright 2017 Thomas Harte. All rights reserved.
//
#ifndef Atari2600_Cartridge_hpp
#define Atari2600_Cartridge_hpp
#include "../../../../Processors/6502/6502.hpp"
#include "../Bus.hpp"
namespace Atari2600 {
namespace Cartridge {
class BusExtender: public CPU::MOS6502::BusHandler {
public:
BusExtender(uint8_t *rom_base, std::size_t rom_size) : rom_base_(rom_base), rom_size_(rom_size) {}
void advance_cycles(int cycles) {}
protected:
uint8_t *rom_base_;
std::size_t rom_size_;
};
template<class T> class Cartridge:
public CPU::MOS6502::BusHandler,
public Bus {
public:
Cartridge(const std::vector<uint8_t> &rom) :
m6502_(*this),
rom_(rom),
bus_extender_(rom_.data(), rom.size()) {
// The above works because bus_extender_ is declared after rom_ in the instance storage list;
// consider doing something less fragile.
}
void run_for(const Cycles cycles) {
// Horizontal counter resets are used as a proxy for whether this really is an Atari 2600
// title. Random memory accesses are likely to trigger random counter resets.
horizontal_counter_resets_ = 0;
cycle_count_ = cycles;
m6502_.run_for(cycles);
}
/*!
Adjusts @c confidence_counter according to the results of the most recent run_for.
*/
void apply_confidence(Analyser::Dynamic::ConfidenceCounter &confidence_counter) {
if(cycle_count_.as_integral() < 200) return;
if(horizontal_counter_resets_ > 10)
confidence_counter.add_miss();
}
void set_reset_line(bool state) { m6502_.set_reset_line(state); }
// to satisfy CPU::MOS6502::Processor
Cycles perform_bus_operation(CPU::MOS6502::BusOperation operation, uint16_t address, uint8_t *value) {
uint8_t returnValue = 0xff;
int cycles_run_for = 3;
// this occurs as a feedback loop: the 2600 requests ready, then performs the cycles_run_for
// leap to the end of ready only once ready is signalled because on a 6502 ready doesn't take
// effect until the next read; therefore it isn't safe to assume that signalling ready immediately
// skips to the end of the line.
if(operation == CPU::MOS6502::BusOperation::Ready)
cycles_run_for = tia_.get_cycles_until_horizontal_blank(cycles_since_video_update_);
cycles_since_speaker_update_ += Cycles(cycles_run_for);
cycles_since_video_update_ += Cycles(cycles_run_for);
cycles_since_6532_update_ += Cycles(cycles_run_for / 3);
bus_extender_.advance_cycles(cycles_run_for / 3);
if(operation != CPU::MOS6502::BusOperation::Ready) {
// give the cartridge a chance to respond to the bus access
bus_extender_.perform_bus_operation(operation, address, value);
// check for a RIOT RAM access
if((address&0x1280) == 0x80) {
if(isReadOperation(operation)) {
returnValue &= mos6532_.get_ram(address);
} else {
mos6532_.set_ram(address, *value);
}
}
// check for a TIA access
if(!(address&0x1080)) {
if(isReadOperation(operation)) {
const uint16_t decodedAddress = address & 0xf;
switch(decodedAddress) {
case 0x00: // missile 0 / player collisions
case 0x01: // missile 1 / player collisions
case 0x02: // player 0 / playfield / ball collisions
case 0x03: // player 1 / playfield / ball collisions
case 0x04: // missile 0 / playfield / ball collisions
case 0x05: // missile 1 / playfield / ball collisions
case 0x06: // ball / playfield collisions
case 0x07: // player / player, missile / missile collisions
returnValue &= tia_.get_collision_flags(decodedAddress);
break;
case 0x08:
case 0x09:
case 0x0a:
case 0x0b:
// TODO: pot ports
returnValue &= 0;
break;
case 0x0c:
case 0x0d:
returnValue &= tia_input_value_[decodedAddress - 0x0c];
break;
}
} else {
const uint16_t decodedAddress = address & 0x3f;
switch(decodedAddress) {
case 0x00: update_video(); tia_.set_sync(*value & 0x02); break;
case 0x01: update_video(); tia_.set_blank(*value & 0x02); break;
case 0x02: m6502_.set_ready_line(true); break;
case 0x03:
update_video();
tia_.reset_horizontal_counter();
horizontal_counter_resets_++;
break;
// TODO: audio will now be out of synchronisation. Fix.
case 0x04:
case 0x05: update_video(); tia_.set_player_number_and_size(decodedAddress - 0x04, *value); break;
case 0x06:
case 0x07: update_video(); tia_.set_player_missile_colour(decodedAddress - 0x06, *value); break;
case 0x08: update_video(); tia_.set_playfield_ball_colour(*value); break;
case 0x09: update_video(); tia_.set_background_colour(*value); break;
case 0x0a: update_video(); tia_.set_playfield_control_and_ball_size(*value); break;
case 0x0b:
case 0x0c: update_video(); tia_.set_player_reflected(decodedAddress - 0x0b, !((*value)&8)); break;
case 0x0d:
case 0x0e:
case 0x0f: update_video(); tia_.set_playfield(decodedAddress - 0x0d, *value); break;
case 0x10:
case 0x11: update_video(); tia_.set_player_position(decodedAddress - 0x10); break;
case 0x12:
case 0x13: update_video(); tia_.set_missile_position(decodedAddress - 0x12); break;
case 0x14: update_video(); tia_.set_ball_position(); break;
case 0x1b:
case 0x1c: update_video(); tia_.set_player_graphic(decodedAddress - 0x1b, *value); break;
case 0x1d:
case 0x1e: update_video(); tia_.set_missile_enable(decodedAddress - 0x1d, (*value)&2); break;
case 0x1f: update_video(); tia_.set_ball_enable((*value)&2); break;
case 0x20:
case 0x21: update_video(); tia_.set_player_motion(decodedAddress - 0x20, *value); break;
case 0x22:
case 0x23: update_video(); tia_.set_missile_motion(decodedAddress - 0x22, *value); break;
case 0x24: update_video(); tia_.set_ball_motion(*value); break;
case 0x25:
case 0x26: tia_.set_player_delay(decodedAddress - 0x25, (*value)&1); break;
case 0x27: tia_.set_ball_delay((*value)&1); break;
case 0x28:
case 0x29: update_video(); tia_.set_missile_position_to_player(decodedAddress - 0x28, (*value)&2); break;
case 0x2a: update_video(); tia_.move(); break;
case 0x2b: update_video(); tia_.clear_motion(); break;
case 0x2c: update_video(); tia_.clear_collision_flags(); break;
case 0x15:
case 0x16: update_audio(); tia_sound_.set_control(decodedAddress - 0x15, *value); break;
case 0x17:
case 0x18: update_audio(); tia_sound_.set_divider(decodedAddress - 0x17, *value); break;
case 0x19:
case 0x1a: update_audio(); tia_sound_.set_volume(decodedAddress - 0x19, *value); break;
}
}
}
// check for a PIA access
if((address&0x1280) == 0x280) {
update_6532();
if(isReadOperation(operation)) {
returnValue &= mos6532_.get_register(address);
} else {
mos6532_.set_register(address, *value);
}
}
if(isReadOperation(operation)) {
*value &= returnValue;
}
}
if(!tia_.get_cycles_until_horizontal_blank(cycles_since_video_update_)) m6502_.set_ready_line(false);
return Cycles(cycles_run_for / 3);
}
void flush() {
update_audio();
update_video();
audio_queue_.perform();
}
protected:
CPU::MOS6502::Processor<CPU::MOS6502::Personality::P6502, Cartridge<T>, true> m6502_;
std::vector<uint8_t> rom_;
private:
T bus_extender_;
int horizontal_counter_resets_ = 0;
Cycles cycle_count_;
};
}
}
#endif /* Atari2600_Cartridge_hpp */
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