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CLK/Machines/Sinclair/ZX8081/ZX8081.cpp

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//
// ZX8081.cpp
// Clock Signal
//
// Created by Thomas Harte on 04/06/2017.
// Copyright 2017 Thomas Harte. All rights reserved.
//
#include "ZX8081.hpp"
#include "../../MachineTypes.hpp"
#include "../../../Components/AY38910/AY38910.hpp"
#include "../../../Processors/Z80/Z80.hpp"
#include "../../../Storage/Tape/Tape.hpp"
#include "../../../Storage/Tape/Parsers/ZX8081.hpp"
#include "../../../ClockReceiver/ForceInline.hpp"
#include "../../Utility/MemoryFuzzer.hpp"
#include "../../Utility/Typer.hpp"
#include "../../../Outputs/Speaker/Implementation/LowpassSpeaker.hpp"
#include "../../../Analyser/Static/ZX8081/Target.hpp"
#include "../Keyboard/Keyboard.hpp"
#include "Video.hpp"
#include <cstdint>
#include <cstring>
#include <memory>
#include <vector>
namespace {
// The clock rate is 3.25Mhz.
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constexpr unsigned int ZX8081ClockRate = 3250000;
}
// TODO:
// Quiksilva sound support:
// 7FFFh.W PSG index
// 7FFEh.R/W PSG data
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namespace Sinclair {
namespace ZX8081 {
enum ROMType: uint8_t {
ZX80 = 0, ZX81
};
using CharacterMapper = Sinclair::ZX::Keyboard::CharacterMapper;
template<bool is_zx81> class ConcreteMachine:
public MachineTypes::TimedMachine,
public MachineTypes::ScanProducer,
public MachineTypes::AudioProducer,
public MachineTypes::MediaTarget,
public MachineTypes::MappedKeyboardMachine,
public Configurable::Device,
public Utility::TypeRecipient<CharacterMapper>,
public CPU::Z80::BusHandler,
public Machine {
public:
ConcreteMachine(const Analyser::Static::ZX8081::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
Utility::TypeRecipient<CharacterMapper>(keyboard_machine()),
z80_(*this),
keyboard_(keyboard_machine()),
keyboard_mapper_(keyboard_machine()),
tape_player_(ZX8081ClockRate),
ay_(GI::AY38910::Personality::AY38910, audio_queue_),
speaker_(ay_) {
set_clock_rate(ZX8081ClockRate);
speaker_.set_input_rate(float(ZX8081ClockRate) / 2.0f);
const bool use_zx81_rom = target.is_ZX81 || target.ZX80_uses_ZX81_ROM;
const ROM::Name rom_name = use_zx81_rom ? ROM::Name::ZX81 : ROM::Name::ZX80;
const ROM::Request request(rom_name);
auto roms = rom_fetcher(request);
if(!request.validate(roms)) {
throw ROMMachine::Error::MissingROMs;
}
rom_ = std::move(roms.find(rom_name)->second);
rom_mask_ = uint16_t(rom_.size() - 1);
switch(target.memory_model) {
case Analyser::Static::ZX8081::Target::MemoryModel::Unexpanded:
ram_.resize(1024);
ram_base_ = 16384;
ram_mask_ = 1023;
break;
case Analyser::Static::ZX8081::Target::MemoryModel::SixteenKB:
ram_.resize(16384);
ram_base_ = 16384;
ram_mask_ = 16383;
break;
case Analyser::Static::ZX8081::Target::MemoryModel::SixtyFourKB:
ram_.resize(65536);
ram_base_ = 8192;
ram_mask_ = 65535;
break;
}
Memory::Fuzz(ram_);
// Ensure valid initial key state.
clear_all_keys();
if(!target.loading_command.empty()) {
type_string(target.loading_command);
should_autorun_ = true;
}
insert_media(target.media);
}
~ConcreteMachine() {
audio_queue_.flush();
}
forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
const HalfCycles previous_counter = horizontal_counter_;
horizontal_counter_ += cycle.length;
time_since_ay_update_ += cycle.length;
if(previous_counter < vsync_start_ && horizontal_counter_ >= vsync_start_) {
video_.run_for(vsync_start_ - previous_counter);
set_hsync(true);
line_counter_ = (line_counter_ + 1) & 7;
if(nmi_is_enabled_) {
z80_.set_non_maskable_interrupt_line(true);
}
video_.run_for(horizontal_counter_ - vsync_start_);
} else if(previous_counter < vsync_end_ && horizontal_counter_ >= vsync_end_) {
video_.run_for(vsync_end_ - previous_counter);
set_hsync(false);
if(nmi_is_enabled_) {
z80_.set_non_maskable_interrupt_line(false);
z80_.set_wait_line(false);
}
video_.run_for(horizontal_counter_ - vsync_end_);
} else {
video_.run_for(cycle.length);
}
if constexpr (is_zx81) horizontal_counter_ %= HalfCycles(Cycles(207));
if(!tape_advance_delay_) {
tape_player_.run_for(cycle.length);
} else {
tape_advance_delay_ = std::max(tape_advance_delay_ - cycle.length, HalfCycles(0));
}
if(nmi_is_enabled_ && !z80_.get_halt_line() && z80_.get_non_maskable_interrupt_line()) {
z80_.set_wait_line(true);
}
if(!cycle.is_terminal()) {
return Cycles(0);
}
const uint16_t address = cycle.address ? *cycle.address : 0;
bool is_opcode_read = false;
switch(cycle.operation) {
case CPU::Z80::PartialMachineCycle::Output:
if(!nmi_is_enabled_) {
line_counter_ = 0;
set_vsync(false);
}
if(!(address & 2)) nmi_is_enabled_ = false;
if(!(address & 1)) nmi_is_enabled_ = is_zx81;
if(is_zx81 && !nmi_is_enabled_) z80_.set_wait_line(false);
// The below emulates the ZonX AY expansion device.
if constexpr (is_zx81) {
if((address&0xef) == 0xcf) {
ay_set_register(*cycle.value);
} else if((address&0xef) == 0x0f) {
ay_set_data(*cycle.value);
}
}
break;
case CPU::Z80::PartialMachineCycle::Input: {
uint8_t value = 0xff;
if(!(address&1)) {
if(!nmi_is_enabled_) set_vsync(true);
value &= keyboard_.read(address);
value &= ~(tape_player_.get_input() ? 0x00 : 0x80);
}
// The below emulates the ZonX AY expansion device.
if constexpr (is_zx81) {
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if((address&0xef) == 0xcf) {
value &= ay_read_data();
}
}
*cycle.value = value;
} break;
case CPU::Z80::PartialMachineCycle::Interrupt:
// resetting event is M1 and IOREQ both simultaneously having leading edges;
// that happens 2 cycles before the end of INTACK. So the timer was reset and
// now has advanced twice.
horizontal_counter_ = HalfCycles(2);
*cycle.value = 0xff;
break;
case CPU::Z80::PartialMachineCycle::Refresh:
// The ZX80 and 81 signal an interrupt while refresh is active and bit 6 of the refresh
// address is low. The Z80 signals a refresh, providing the refresh address during the
// final two cycles of an opcode fetch. Therefore communicate a transient signalling
// of the IRQ line if necessary.
if(!(address & 0x40)) {
z80_.set_interrupt_line(true, Cycles(-2));
z80_.set_interrupt_line(false);
}
if(has_latched_video_byte_) {
std::size_t char_address = size_t((address & 0xfe00) | ((latched_video_byte_ & 0x3f) << 3) | line_counter_);
const uint8_t mask = (latched_video_byte_ & 0x80) ? 0x00 : 0xff;
if(char_address < ram_base_) {
latched_video_byte_ = rom_[char_address & rom_mask_] ^ mask;
} else {
latched_video_byte_ = ram_[address & ram_mask_] ^ mask;
}
video_.output_byte(latched_video_byte_);
has_latched_video_byte_ = false;
}
break;
case CPU::Z80::PartialMachineCycle::ReadOpcode:
// Check for use of the fast tape hack.
if(use_fast_tape_hack_ && address == tape_trap_address_) {
const uint64_t prior_offset = tape_player_.get_tape()->get_offset();
const int next_byte = parser_.get_next_byte(tape_player_.get_tape());
if(next_byte != -1) {
const uint16_t hl = z80_.get_value_of_register(CPU::Z80::Register::HL);
ram_[hl & ram_mask_] = uint8_t(next_byte);
*cycle.value = 0x00;
z80_.set_value_of_register(CPU::Z80::Register::ProgramCounter, tape_return_address_ - 1);
// Assume that having read one byte quickly, we're probably going to be asked to read
// another shortly. Therefore, temporarily disable the tape motor for 1000 cycles in order
// to avoid fighting with real time. This is a stop-gap fix.
tape_advance_delay_ = 1000;
return 0;
} else {
tape_player_.get_tape()->set_offset(prior_offset);
}
}
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if(should_autorun_ && address == finished_load_address_) {
type_string(is_zx81 ? "r \n" : "r\n "); // Spaces here are not especially scientific; they merely ensure sufficient pauses for both the ZX80 and 81, empirically.
should_autorun_ = false;
}
// Check for automatic tape control.
if(use_automatic_tape_motor_control_) {
tape_player_.set_motor_control((address >= automatic_tape_motor_start_address_) && (address < automatic_tape_motor_end_address_));
}
is_opcode_read = true;
[[fallthrough]];
case CPU::Z80::PartialMachineCycle::Read:
if(address < ram_base_) {
*cycle.value = rom_[address & rom_mask_];
} else {
const uint8_t value = ram_[address & ram_mask_];
// If this is an M1 cycle reading from above the 32kb mark and HALT is not
// currently active, latch for video output and return a NOP. Otherwise,
// just return the value as read.
if(is_opcode_read && address&0x8000 && !(value & 0x40) && !z80_.get_halt_line()) {
latched_video_byte_ = value;
has_latched_video_byte_ = true;
*cycle.value = 0;
} else *cycle.value = value;
}
break;
case CPU::Z80::PartialMachineCycle::Write:
if(address >= ram_base_) {
ram_[address & ram_mask_] = *cycle.value;
}
break;
default: break;
}
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if(typer_) typer_->run_for(cycle.length);
return HalfCycles(0);
}
forceinline void flush() {
video_.flush();
if constexpr (is_zx81) {
update_audio();
audio_queue_.perform();
}
}
void set_scan_target(Outputs::Display::ScanTarget *scan_target) final {
video_.set_scan_target(scan_target);
}
Outputs::Display::ScanStatus get_scaled_scan_status() const final {
return video_.get_scaled_scan_status();
}
Outputs::Speaker::Speaker *get_speaker() final {
return is_zx81 ? &speaker_ : nullptr;
}
void run_for(const Cycles cycles) final {
z80_.run_for(cycles);
}
bool insert_media(const Analyser::Static::Media &media) final {
if(!media.tapes.empty()) {
tape_player_.set_tape(media.tapes.front());
}
set_use_fast_tape();
return !media.tapes.empty();
}
void type_string(const std::string &string) final {
Utility::TypeRecipient<CharacterMapper>::add_typer(string);
}
bool can_type(char c) const final {
return Utility::TypeRecipient<CharacterMapper>::can_type(c);
}
// MARK: - Keyboard
void set_key_state(uint16_t key, bool is_pressed) final {
keyboard_.set_key_state(key, is_pressed);
}
void clear_all_keys() final {
keyboard_.clear_all_keys();
}
static constexpr Sinclair::ZX::Keyboard::Machine keyboard_machine() {
return is_zx81 ? Sinclair::ZX::Keyboard::Machine::ZX81 : Sinclair::ZX::Keyboard::Machine::ZX80;
}
// MARK: - Tape control
void set_use_automatic_tape_motor_control(bool enabled) {
use_automatic_tape_motor_control_ = enabled;
if(!enabled) {
tape_player_.set_motor_control(false);
}
}
void set_tape_is_playing(bool is_playing) final {
tape_player_.set_motor_control(is_playing);
}
bool get_tape_is_playing() final {
return tape_player_.get_motor_control();
}
// MARK: - Typer timing
HalfCycles get_typer_delay(const std::string &) const final {
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return z80_.get_is_resetting() ? Cycles(7'000'000) : Cycles(0);
}
HalfCycles get_typer_frequency() const final {
return Cycles(146'250);
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}
KeyboardMapper *get_keyboard_mapper() final {
return &keyboard_mapper_;
}
// MARK: - Configuration options.
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std::unique_ptr<Reflection::Struct> get_options() final {
auto options = std::make_unique<Options>(Configurable::OptionsType::UserFriendly); // OptionsType is arbitrary, but not optional.
options->automatic_tape_motor_control = use_automatic_tape_motor_control_;
options->quickload = allow_fast_tape_hack_;
return options;
}
void set_options(const std::unique_ptr<Reflection::Struct> &str) {
const auto options = dynamic_cast<Options *>(str.get());
set_use_automatic_tape_motor_control(options->automatic_tape_motor_control);
allow_fast_tape_hack_ = options->quickload;
set_use_fast_tape();
}
private:
CPU::Z80::Processor<ConcreteMachine, false, is_zx81> z80_;
Video video_;
// If fast tape loading is enabled then the PC will be trapped at tape_trap_address_;
// the emulator will then do a high-level reinterpretation of the standard ZX80/81 reading
// of a single byte, and the next thing executed will be at tape_return_address_;
static constexpr uint16_t tape_trap_address_ = is_zx81 ? 0x37c : 0x220;
static constexpr uint16_t tape_return_address_ = is_zx81 ? 0x380 : 0x248;
// If automatic tape motor control is enabled then the tape will be permitted to play any time
// the program counter is >= automatic_tape_motor_start_address_ and < automatic_tape_motor_end_address_.
static constexpr uint16_t automatic_tape_motor_start_address_ = is_zx81 ? 0x340 : 0x206;
static constexpr uint16_t automatic_tape_motor_end_address_ = is_zx81 ? 0x3c3 : 0x24d;
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// When automatically loading, if the PC gets to the finished_load_address_ in order to print 0/0
// (so it's anything that indicates that loading completed, but the program did not autorun) then the
// emulator will automatically RUN whatever has been loaded.
static constexpr uint16_t finished_load_address_ = is_zx81 ?
0x6d1 : // ZX81: this is the routine that prints 0/0 (i.e. success).
0x203; // ZX80: this is the JR that exits the ZX80's LOAD and returns to MAIN-EXEC.
bool should_autorun_ = false;
std::vector<uint8_t> ram_;
uint16_t ram_mask_, ram_base_;
std::vector<uint8_t> rom_;
uint16_t rom_mask_;
bool vsync_ = false, hsync_ = false;
int line_counter_ = 0;
Sinclair::ZX::Keyboard::Keyboard keyboard_;
Sinclair::ZX::Keyboard::KeyboardMapper keyboard_mapper_;
HalfClockReceiver<Storage::Tape::BinaryTapePlayer> tape_player_;
Storage::Tape::ZX8081::Parser parser_;
bool nmi_is_enabled_ = false;
static constexpr auto vsync_start_ = is_zx81 ? HalfCycles(32) : HalfCycles(26);
static constexpr auto vsync_end_ = is_zx81 ? HalfCycles(64) : HalfCycles(66);
HalfCycles horizontal_counter_;
uint8_t latched_video_byte_ = 0;
bool has_latched_video_byte_ = false;
bool use_fast_tape_hack_ = false;
bool allow_fast_tape_hack_ = false;
void set_use_fast_tape() {
use_fast_tape_hack_ = allow_fast_tape_hack_ && tape_player_.has_tape();
}
bool use_automatic_tape_motor_control_ = true;
HalfCycles tape_advance_delay_ = 0;
// MARK: - Video
inline void set_vsync(bool sync) {
vsync_ = sync;
update_sync();
}
inline void set_hsync(bool sync) {
hsync_ = sync;
update_sync();
}
inline void update_sync() {
video_.set_sync(vsync_ || hsync_);
}
// MARK: - Audio
Concurrency::DeferringAsyncTaskQueue audio_queue_;
using AY = GI::AY38910::AY38910<false>;
AY ay_;
Outputs::Speaker::PullLowpass<AY> speaker_;
HalfCycles time_since_ay_update_;
inline void ay_set_register(uint8_t value) {
update_audio();
GI::AY38910::Utility::select_register(ay_, value);
}
inline void ay_set_data(uint8_t value) {
update_audio();
GI::AY38910::Utility::write_data(ay_, value);
}
inline uint8_t ay_read_data() {
update_audio();
return GI::AY38910::Utility::read(ay_);
}
inline void update_audio() {
speaker_.run_for(audio_queue_, time_since_ay_update_.divide_cycles(Cycles(2)));
}
};
}
}
using namespace Sinclair::ZX8081;
// See header; constructs and returns an instance of the ZX80 or 81.
Machine *Machine::ZX8081(const Analyser::Static::Target *target, const ROMMachine::ROMFetcher &rom_fetcher) {
const auto zx_target = dynamic_cast<const Analyser::Static::ZX8081::Target *>(target);
// Instantiate the correct type of machine.
if(zx_target->is_ZX81) return new ConcreteMachine<true>(*zx_target, rom_fetcher);
else return new ConcreteMachine<false>(*zx_target, rom_fetcher);
}
Machine::~Machine() {}