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503 lines
14 KiB
C++
503 lines
14 KiB
C++
//
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// ZXSpectrum.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 17/03/2021.
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// Copyright © 2021 Thomas Harte. All rights reserved.
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//
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#include "ZXSpectrum.hpp"
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#include "Video.hpp"
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#define LOG_PREFIX "[Spectrum] "
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#include "../../MachineTypes.hpp"
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#include "../../../Processors/Z80/Z80.hpp"
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#include "../../../Components/AudioToggle/AudioToggle.hpp"
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#include "../../../Components/AY38910/AY38910.hpp"
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#include "../../../Outputs/Log.hpp"
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#include "../../../Outputs/Speaker/Implementation/CompoundSource.hpp"
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#include "../../../Outputs/Speaker/Implementation/LowpassSpeaker.hpp"
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#include "../../../Outputs/Speaker/Implementation/SampleSource.hpp"
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#include "../../../Analyser/Static/ZXSpectrum/Target.hpp"
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#include "../../Utility/MemoryFuzzer.hpp"
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#include "../../../ClockReceiver/JustInTime.hpp"
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#include "../Keyboard/Keyboard.hpp"
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#include <array>
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namespace Sinclair {
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namespace ZXSpectrum {
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using Model = Analyser::Static::ZXSpectrum::Target::Model;
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template<Model model> class ConcreteMachine:
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public Configurable::Device,
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public Machine,
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public MachineTypes::AudioProducer,
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public MachineTypes::MappedKeyboardMachine,
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public MachineTypes::MediaTarget,
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public MachineTypes::ScanProducer,
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public MachineTypes::TimedMachine,
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public CPU::Z80::BusHandler {
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public:
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ConcreteMachine(const Analyser::Static::ZXSpectrum::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
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z80_(*this),
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ay_(GI::AY38910::Personality::AY38910, audio_queue_),
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audio_toggle_(audio_queue_),
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mixer_(ay_, audio_toggle_),
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speaker_(mixer_),
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keyboard_(Sinclair::ZX::Keyboard::Machine::ZXSpectrum),
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keyboard_mapper_(Sinclair::ZX::Keyboard::Machine::ZXSpectrum),
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tape_player_(clock_rate() * 2)
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{
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set_clock_rate(clock_rate());
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speaker_.set_input_rate(float(clock_rate()) / 2.0f);
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// With only the +2a and +3 currently supported, the +3 ROM is always
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// the one required.
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const auto roms =
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rom_fetcher({ {"ZXSpectrum", "the +2a/+3 ROM", "plus3.rom", 64 * 1024, 0x96e3c17a} });
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if(!roms[0]) throw ROMMachine::Error::MissingROMs;
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memcpy(rom_.data(), roms[0]->data(), std::min(rom_.size(), roms[0]->size()));
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// Set up initial memory map.
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update_memory_map();
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Memory::Fuzz(ram_);
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// Insert media.
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insert_media(target.media);
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}
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~ConcreteMachine() {
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audio_queue_.flush();
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}
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static constexpr unsigned int clock_rate() {
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// constexpr unsigned int ClockRate = 3'500'000;
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constexpr unsigned int Plus3ClockRate = 3'546'875; // See notes below; this is a guess.
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// Notes on timing for the +2a and +3:
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//
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// Standard PAL produces 283.7516 colour cycles per line, each line being 64µs.
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// The oft-quoted 3.5469 Mhz would seem to imply 227.0016 clock cycles per line.
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// Since those Spectrums actually produce 228 cycles per line, but software like
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// Chromatrons seems to assume a fixed phase relationship, I guess that the real
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// clock speed is whatever gives:
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//
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// 228 / [cycles per line] * 283.7516 = [an integer].
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//
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// i.e. 228 * 283.7516 = [an integer] * [cycles per line], such that cycles per line ~= 227
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// ... which would imply that 'an integer' is probably 285, i.e.
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//
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// 228 / [cycles per line] * 283.7516 = 285
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// => 227.00128 = [cycles per line]
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// => clock rate = 3.546895 Mhz?
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//
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// That is... unless I'm mistaken about the PAL colour subcarrier and it's actually 283.75,
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// which would give exactly 227 cycles/line and therefore 3.546875 Mhz.
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//
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// A real TV would be likely to accept either, I guess. But it does seem like
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// the Spectrum is a PAL machine with a fixed colour phase relationship. For
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// this emulator's world, that's a first!
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return Plus3ClockRate;
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}
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// MARK: - TimedMachine
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void run_for(const Cycles cycles) override {
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z80_.run_for(cycles);
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}
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void flush() {
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video_.flush();
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update_audio();
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audio_queue_.perform();
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}
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// MARK: - ScanProducer
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void set_scan_target(Outputs::Display::ScanTarget *scan_target) override {
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video_->set_scan_target(scan_target);
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}
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Outputs::Display::ScanStatus get_scaled_scan_status() const override {
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return video_->get_scaled_scan_status();
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}
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void set_display_type(Outputs::Display::DisplayType display_type) override {
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video_->set_display_type(display_type);
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}
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// MARK: - BusHandler
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forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
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// Ignore all but terminal cycles.
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// TODO: I doubt this is correct for timing.
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if(!cycle.is_terminal()) {
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advance(cycle.length);
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return HalfCycles(0);
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}
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HalfCycles delay(0);
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uint16_t address = cycle.address ? *cycle.address : 0x0000;
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using PartialMachineCycle = CPU::Z80::PartialMachineCycle;
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switch(cycle.operation) {
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default: break;
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case PartialMachineCycle::ReadOpcode:
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case PartialMachineCycle::Read:
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// Apply contention if necessary.
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if(is_contended_[address >> 14]) {
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delay = video_.last_valid()->access_delay(video_.time_since_flush());
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}
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*cycle.value = read_pointers_[address >> 14][address];
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break;
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case PartialMachineCycle::Write:
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// Apply contention if necessary.
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// For now this causes a video sync up every time any contended area is written to.
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// TODO: flush only upon a video-area write.
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if(is_contended_[address >> 14]) {
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delay = video_->access_delay(HalfCycles(0));
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}
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write_pointers_[address >> 14][address] = *cycle.value;
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break;
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case PartialMachineCycle::Output:
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// Test for port FE.
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if(!(address&1)) {
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update_audio();
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audio_toggle_.set_output(*cycle.value & 0x10);
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video_->set_border_colour(*cycle.value & 7);
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// b0–b2: border colour
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// b3: enable tape input (?)
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// b4: tape and speaker output
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}
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// Test for classic 128kb paging.
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// if(!(address&0x8002)) {
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// }
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// Test for +2a/+3 paging.
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// if((address & 0xc002) == 0x4000) {
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// }
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switch(address) {
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default: break;
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case 0x1ffd:
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// Write to +2a/+3 paging register.
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port1ffd_ = *cycle.value;
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update_memory_map();
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break;
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case 0x7ffd:
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// Write to classic 128kb paging register.
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disable_paging_ |= *cycle.value & 0x20;
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port7ffd_ = *cycle.value;
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update_memory_map();
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break;
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case 0xfffd:
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// Select AY register.
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update_audio();
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GI::AY38910::Utility::select_register(ay_, *cycle.value);
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break;
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case 0xbffd:
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// Write to AY register.
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update_audio();
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GI::AY38910::Utility::write_data(ay_, *cycle.value);
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break;
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}
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break;
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case PartialMachineCycle::Input:
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*cycle.value = 0xff;
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if(!(address&1)) {
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// Port FE:
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//
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// address b8+: mask of keyboard lines to select
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// result: b0–b4: mask of keys pressed
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// b6: tape input
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*cycle.value &= keyboard_.read(address);
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*cycle.value &= tape_player_.get_input() ? 0xbf : 0xff;
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// If this read is within 200 cycles of the previous,
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// count it as an adjacent hit; if 20 of those have
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// occurred then start the tape motor.
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if(use_automatic_tape_motor_control_) {
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if(cycles_since_tape_input_read_ < HalfCycles(400)) {
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++recent_tape_hits_;
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if(recent_tape_hits_ == 20) {
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tape_player_.set_motor_control(true);
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}
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} else {
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recent_tape_hits_ = 0;
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}
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cycles_since_tape_input_read_ = HalfCycles(0);
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}
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}
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switch(address) {
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default: break;
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case 0xfffd:
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// Read from AY register.
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update_audio();
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*cycle.value &= GI::AY38910::Utility::read_data(ay_);
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break;
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}
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break;
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}
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advance(cycle.length + delay);
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return delay;
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}
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private:
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void advance(HalfCycles duration) {
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time_since_audio_update_ += duration;
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video_ += duration;
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if(video_.did_flush()) {
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z80_.set_interrupt_line(video_.last_valid()->get_interrupt_line());
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}
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// TODO: sleeping support here.
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tape_player_.run_for(duration.as_integral());
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// Update automatic tape motor control, if enabled; if it's been
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// 3 seconds since software last possibly polled the tape, stop it.
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if(use_automatic_tape_motor_control_ && cycles_since_tape_input_read_ < HalfCycles(clock_rate() * 6)) {
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cycles_since_tape_input_read_ += duration;
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if(cycles_since_tape_input_read_ >= HalfCycles(clock_rate() * 6)) {
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tape_player_.set_motor_control(false);
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recent_tape_hits_ = 0;
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}
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}
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}
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public:
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// MARK: - Typer
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// HalfCycles get_typer_delay(const std::string &) const final {
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// return z80_.get_is_resetting() ? Cycles(7'000'000) : Cycles(0);
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// }
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//
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// HalfCycles get_typer_frequency() const final {
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// return Cycles(146'250);
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// }
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KeyboardMapper *get_keyboard_mapper() override {
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return &keyboard_mapper_;
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}
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// MARK: - Keyboard
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void set_key_state(uint16_t key, bool is_pressed) override {
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keyboard_.set_key_state(key, is_pressed);
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}
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void clear_all_keys() override {
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keyboard_.clear_all_keys();
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}
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// MARK: - MediaTarget.
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bool insert_media(const Analyser::Static::Media &media) override {
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// If there are any tapes supplied, use the first of them.
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if(!media.tapes.empty()) {
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tape_player_.set_tape(media.tapes.front());
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}
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return !media.tapes.empty();
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}
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// MARK: - Tape control
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void set_use_automatic_tape_motor_control(bool enabled) {
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use_automatic_tape_motor_control_ = enabled;
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if(!enabled) {
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tape_player_.set_motor_control(false);
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}
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}
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void set_tape_is_playing(bool is_playing) final {
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tape_player_.set_motor_control(is_playing);
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}
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bool get_tape_is_playing() final {
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return tape_player_.get_motor_control();
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}
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// MARK: - Configuration options.
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std::unique_ptr<Reflection::Struct> get_options() override {
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auto options = std::make_unique<Options>(Configurable::OptionsType::UserFriendly); // OptionsType is arbitrary, but not optional.
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options->automatic_tape_motor_control = use_automatic_tape_motor_control_;
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options->quickload = allow_fast_tape_hack_;
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return options;
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}
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void set_options(const std::unique_ptr<Reflection::Struct> &str) override {
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const auto options = dynamic_cast<Options *>(str.get());
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set_video_signal_configurable(options->output);
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set_use_automatic_tape_motor_control(options->automatic_tape_motor_control);
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allow_fast_tape_hack_ = options->quickload;
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set_use_fast_tape();
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}
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// MARK: - AudioProducer.
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Outputs::Speaker::Speaker *get_speaker() override {
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return &speaker_;
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}
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private:
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CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
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// MARK: - Memory.
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std::array<uint8_t, 64*1024> rom_;
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std::array<uint8_t, 128*1024> ram_;
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std::array<uint8_t, 16*1024> scratch_;
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const uint8_t *read_pointers_[4];
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uint8_t *write_pointers_[4];
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bool is_contended_[4];
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uint8_t port1ffd_ = 0;
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uint8_t port7ffd_ = 0;
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bool disable_paging_ = false;
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void update_memory_map() {
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// If paging is permanently disabled, don't react.
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if(disable_paging_) {
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return;
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}
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// Set the proper video base pointer.
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video_->set_video_source(&ram_[((port7ffd_ & 0x08) ? 7 : 5) * 16384]);
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if(port1ffd_ & 1) {
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// "Special paging mode", i.e. one of four fixed
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// RAM configurations, port 7ffd doesn't matter.
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switch(port1ffd_ & 0x6) {
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default:
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case 0x00:
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set_memory(0, &ram_[0 * 16384], &ram_[0 * 16384], false);
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set_memory(1, &ram_[1 * 16384], &ram_[1 * 16384], false);
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set_memory(2, &ram_[2 * 16384], &ram_[2 * 16384], false);
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set_memory(3, &ram_[3 * 16384], &ram_[3 * 16384], false);
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break;
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case 0x02:
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set_memory(0, &ram_[4 * 16384], &ram_[4 * 16384], true);
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set_memory(1, &ram_[5 * 16384], &ram_[5 * 16384], true);
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set_memory(2, &ram_[6 * 16384], &ram_[6 * 16384], true);
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set_memory(3, &ram_[7 * 16384], &ram_[7 * 16384], true);
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break;
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case 0x04:
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set_memory(0, &ram_[4 * 16384], &ram_[4 * 16384], true);
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set_memory(1, &ram_[5 * 16384], &ram_[5 * 16384], true);
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set_memory(2, &ram_[6 * 16384], &ram_[6 * 16384], true);
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set_memory(3, &ram_[3 * 16384], &ram_[3 * 16384], false);
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break;
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case 0x06:
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set_memory(0, &ram_[4 * 16384], &ram_[4 * 16384], true);
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set_memory(1, &ram_[7 * 16384], &ram_[7 * 16384], true);
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set_memory(2, &ram_[6 * 16384], &ram_[6 * 16384], true);
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set_memory(3, &ram_[3 * 16384], &ram_[3 * 16384], false);
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break;
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}
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return;
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}
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// Apply standard 128kb-esque mapping (albeit with extra ROM to pick from).
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const auto rom = &rom_[ (((port1ffd_ >> 1) & 2) | ((port7ffd_ >> 4) & 1)) * 16384];
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set_memory(0, rom, nullptr, false);
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set_memory(1, &ram_[5 * 16384], &ram_[5 * 16384], true);
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set_memory(2, &ram_[2 * 16384], &ram_[2 * 16384], false);
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const auto high_ram = &ram_[(port7ffd_ & 7) * 16384];
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set_memory(3, high_ram, high_ram, (port7ffd_ & 7) >= 4);
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}
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void set_memory(int bank, const uint8_t *read, uint8_t *write, bool is_contended) {
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is_contended_[bank] = is_contended;
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read_pointers_[bank] = read - bank*16384;
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write_pointers_[bank] = (write ? write : scratch_.data()) - bank*16384;
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}
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// MARK: - Audio.
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Concurrency::DeferringAsyncTaskQueue audio_queue_;
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GI::AY38910::AY38910<false> ay_;
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Audio::Toggle audio_toggle_;
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Outputs::Speaker::CompoundSource<GI::AY38910::AY38910<false>, Audio::Toggle> mixer_;
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Outputs::Speaker::LowpassSpeaker<Outputs::Speaker::CompoundSource<GI::AY38910::AY38910<false>, Audio::Toggle>> speaker_;
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HalfCycles time_since_audio_update_;
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void update_audio() {
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speaker_.run_for(audio_queue_, time_since_audio_update_.divide_cycles(Cycles(2)));
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}
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// MARK: - Video.
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static constexpr VideoTiming video_timing = VideoTiming::Plus3;
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JustInTimeActor<Video<video_timing>> video_;
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// MARK: - Keyboard.
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Sinclair::ZX::Keyboard::Keyboard keyboard_;
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Sinclair::ZX::Keyboard::KeyboardMapper keyboard_mapper_;
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// MARK: - Tape and disc.
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Storage::Tape::BinaryTapePlayer tape_player_;
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bool use_automatic_tape_motor_control_ = true;
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HalfCycles cycles_since_tape_input_read_;
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int recent_tape_hits_ = 0;
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bool allow_fast_tape_hack_ = false;
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void set_use_fast_tape() {
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// TODO.
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}
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};
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}
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}
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using namespace Sinclair::ZXSpectrum;
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Machine *Machine::ZXSpectrum(const Analyser::Static::Target *target, const ROMMachine::ROMFetcher &rom_fetcher) {
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const auto zx_target = dynamic_cast<const Analyser::Static::ZXSpectrum::Target *>(target);
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switch(zx_target->model) {
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case Model::Plus2a: return new ConcreteMachine<Model::Plus2a>(*zx_target, rom_fetcher);
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case Model::Plus3: return new ConcreteMachine<Model::Plus3>(*zx_target, rom_fetcher);
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}
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return nullptr;
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}
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Machine::~Machine() {}
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