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CLK/Machines/Enterprise/Enterprise.cpp

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//
// Enterprise.cpp
// Clock Signal
//
// Created by Thomas Harte on 10/06/2021.
// Copyright © 2021 Thomas Harte. All rights reserved.
//
#include "Enterprise.hpp"
#include "Dave.hpp"
#include "EXDos.hpp"
#include "Keyboard.hpp"
#include "Nick.hpp"
#include "../MachineTypes.hpp"
#include "../../Analyser/Static/Enterprise/Target.hpp"
#include "../../ClockReceiver/JustInTime.hpp"
#include "../../Outputs/Speaker/Implementation/LowpassSpeaker.hpp"
#include "../../Processors/Z80/Z80.hpp"
namespace Enterprise {
/*
Notes to self on timing:
Nick divides each line into 57 windows; each window lasts 16 cycles and dedicates the
first 10 of those to VRAM accesses, leaving the final six for a Z80 video RAM access
if one has been requested.
The Z80 has a separate, asynchronous 4Mhz clock. That's that.
The documentation is also very forward in emphasising that Nick generates phaselocked
(i.e. in-phase) PAL video.
So: 57*16 = 912 cycles/line.
A standard PAL line lasts 64µs and during that time outputs 283.7516 colour cycles.
I shall _guess_ that the Enterprise stretches each line to 284 colour cycles rather than
reducing it to 283.
Therefore 912 cycles occurs in 284/283.7516 * 64 µs.
So one line = 181760000 / 2837516 µs = 45440000 / 709379 µs
=> one cycle = 45440000 / 709379*912 = 45440000 / 646953648 = 2840000 / 40434603 µs
=> clock rate of 40434603 / 2840000 Mhz
And, therefore, the ratio to a 4Mhz Z80 clock is:
40434603 / (2840000 * 4)
= 40434603 / 11360000
i.e. roughly 3.55 Nick cycles per Z80 cycle.
If that's true then the 6-cycle window is around 1.69 Z80 cycles long. Given that the Z80
clock in an Enterprise can be stopped in half-cycle increments only, the Z80 can only be
guaranteed to have around a 1.19 cycle minimum for its actual access. I'm therefore further
postulating that the clock stoppage takes place so as to align the final cycle of a relevant
access over the available window.
*/
template <bool has_disk_controller> class ConcreteMachine:
public Activity::Source,
public CPU::Z80::BusHandler,
public Machine,
public MachineTypes::AudioProducer,
public MachineTypes::MappedKeyboardMachine,
public MachineTypes::MediaTarget,
public MachineTypes::ScanProducer,
public MachineTypes::TimedMachine {
private:
constexpr uint8_t min_ram_slot(const Analyser::Static::Enterprise::Target &target) {
size_t ram_size = 128*1024;
switch(target.model) {
case Analyser::Static::Enterprise::Target::Model::Enterprise64: ram_size = 64*1024; break;
case Analyser::Static::Enterprise::Target::Model::Enterprise128: ram_size = 128*1024; break;
case Analyser::Static::Enterprise::Target::Model::Enterprise256: ram_size = 256*1024; break;
}
return uint8_t(0x100 - ram_size / 0x4000);
}
public:
ConcreteMachine([[maybe_unused]] const Analyser::Static::Enterprise::Target &target, const ROMMachine::ROMFetcher &rom_fetcher) :
min_ram_slot_(min_ram_slot(target)),
z80_(*this),
nick_(ram_.end() - 65536),
dave_audio_(audio_queue_),
speaker_(dave_audio_) {
// Request a clock of 4Mhz; this'll be mapped upwards for Nick and Dave elsewhere.
set_clock_rate(4'000'000);
ROM::Request request;
using Target = Analyser::Static::Enterprise::Target;
// Pick one or more EXOS ROMs.
switch(target.exos_version) {
case Target::EXOSVersion::v10: request = request && ROM::Request(ROM::Name::EnterpriseEXOS10); break;
case Target::EXOSVersion::v20: request = request && ROM::Request(ROM::Name::EnterpriseEXOS20); break;
case Target::EXOSVersion::v21: request = request && ROM::Request(ROM::Name::EnterpriseEXOS21); break;
case Target::EXOSVersion::v23: request = request && ROM::Request(ROM::Name::EnterpriseEXOS23); break;
case Target::EXOSVersion::Any:
request =
request && (
ROM::Request(ROM::Name::EnterpriseEXOS10) || ROM::Request(ROM::Name::EnterpriseEXOS20) ||
ROM::Request(ROM::Name::EnterpriseEXOS21) || ROM::Request(ROM::Name::EnterpriseEXOS23)
);
break;
default: break;
}
// Similarly pick one or more BASIC ROMs.
switch(target.basic_version) {
case Target::BASICVersion::v10:
request = request && (
ROM::Request(ROM::Name::EnterpriseBASIC10) ||
(ROM::Request(ROM::Name::EnterpriseBASIC10Part1) && ROM::Request(ROM::Name::EnterpriseBASIC10Part2))
);
break;
case Target::BASICVersion::v11:
request = request && (
ROM::Request(ROM::Name::EnterpriseBASIC11) ||
ROM::Request(ROM::Name::EnterpriseBASIC11Suffixed)
);
case Target::BASICVersion::v21:
request = request && ROM::Request(ROM::Name::EnterpriseBASIC21);
break;
case Target::BASICVersion::Any:
request =
request && (
ROM::Request(ROM::Name::EnterpriseBASIC10) ||
(ROM::Request(ROM::Name::EnterpriseBASIC10Part1) && ROM::Request(ROM::Name::EnterpriseBASIC10Part2)) ||
ROM::Request(ROM::Name::EnterpriseBASIC11) ||
ROM::Request(ROM::Name::EnterpriseBASIC21)
);
break;
default: break;
}
// Possibly add in a DOS.
switch(target.dos) {
case Target::DOS::EXDOS: request = request && ROM::Request(ROM::Name::EnterpriseEXDOS); break;
default: break;
}
// Get and validate ROMs.
auto roms = rom_fetcher(request);
if(!request.validate(roms)) {
throw ROMMachine::Error::MissingROMs;
}
// Extract the appropriate EXOS ROM.
exos_.fill(0xff);
for(const auto rom_name: { ROM::Name::EnterpriseEXOS10, ROM::Name::EnterpriseEXOS20, ROM::Name::EnterpriseEXOS21, ROM::Name::EnterpriseEXOS23 }) {
const auto exos = roms.find(rom_name);
if(exos != roms.end()) {
memcpy(exos_.data(), exos->second.data(), std::min(exos_.size(), exos->second.size()));
break;
}
}
// Extract the appropriate BASIC ROM[s] (if any).
basic_.fill(0xff);
bool has_basic = false;
for(const auto rom_name: { ROM::Name::EnterpriseBASIC10, ROM::Name::EnterpriseBASIC11, ROM::Name::EnterpriseBASIC11Suffixed, ROM::Name::EnterpriseBASIC21 }) {
const auto basic = roms.find(rom_name);
if(basic != roms.end()) {
memcpy(basic_.data(), basic->second.data(), std::min(basic_.size(), basic->second.size()));
has_basic = true;
break;
}
}
if(!has_basic) {
const auto basic1 = roms.find(ROM::Name::EnterpriseBASIC10Part1);
const auto basic2 = roms.find(ROM::Name::EnterpriseBASIC10Part2);
if(basic1 != roms.end() && basic2 != roms.end()) {
memcpy(&basic_[0x0000], basic1->second.data(), std::min(size_t(8192), basic1->second.size()));
memcpy(&basic_[0x2000], basic2->second.data(), std::min(size_t(8192), basic2->second.size()));
}
}
// Extract the appropriate DOS ROMs.
epdos_rom_.fill(0xff);
const auto epdos = roms.find(ROM::Name::EnterpriseEPDOS);
if(epdos != roms.end()) {
memcpy(epdos_rom_.data(), epdos->second.data(), std::min(epdos_rom_.size(), epdos->second.size()));
}
exdos_rom_.fill(0xff);
const auto exdos = roms.find(ROM::Name::EnterpriseEXDOS);
if(exdos != roms.end()) {
memcpy(exdos_rom_.data(), exdos->second.data(), std::min(exdos_rom_.size(), exdos->second.size()));
}
// Seed key state.
clear_all_keys();
// Take a reasonable guess at the initial memory configuration:
// put EXOS into the first bank since this is a Z80 and therefore
// starts from address 0; the third instruction in EXOS is a jump
// to $c02e so it's reasonable to assume EXOS is in the highest bank
// too, and it appears to act correctly if it's the first 16kb that's
// in the highest bank. From there I guess: all banks are initialised
// to 0.
page<0>(0x00);
page<1>(0x00);
page<2>(0x00);
page<3>(0x00);
// Set up audio.
speaker_.set_input_rate(250000.0f); // TODO: a bigger number, and respect the programmable divider.
// Pass on any media.
insert_media(target.media);
}
~ConcreteMachine() {
audio_queue_.flush();
}
// MARK: - Z80::BusHandler.
forceinline void advance_nick(HalfCycles duration) {
if(nick_ += duration) {
const auto nick = nick_.last_valid();
const bool nick_interrupt_line = nick->get_interrupt_line();
if(nick_interrupt_line && !previous_nick_interrupt_line_) {
set_interrupts(uint8_t(Dave::Interrupt::Nick), nick_.last_sequence_point_overrun());
}
previous_nick_interrupt_line_ = nick_interrupt_line;
}
}
forceinline HalfCycles perform_machine_cycle(const CPU::Z80::PartialMachineCycle &cycle) {
using PartialMachineCycle = CPU::Z80::PartialMachineCycle;
const uint16_t address = cycle.address ? *cycle.address : 0x0000;
// Calculate an access penalty, if applicable.
//
// Rule applied here, which is slightly inferred:
//
// Non-video reads and writes are delayed by exactly a cycle or not delayed at all,
// depending on the programmer's configuration of Dave.
//
// Video reads and writes, and Nick port accesses, are delayed so that the last
// clock cycle of the machine cycle falls wholly inside the designated Z80 access
// window, per Nick.
//
// The switch statement below just attempts to implement that logic.
//
HalfCycles penalty;
switch(cycle.operation) {
default: break;
// For non-video pauses, insert during the initial part of the bus cycle.
case CPU::Z80::PartialMachineCycle::ReadStart:
case CPU::Z80::PartialMachineCycle::WriteStart:
if(!is_video_[address >> 14] && wait_mode_ == WaitMode::OnAllAccesses) {
penalty = HalfCycles(2);
}
break;
case CPU::Z80::PartialMachineCycle::ReadOpcodeStart:
if(!is_video_[address >> 14] && wait_mode_ != WaitMode::None) {
penalty = HalfCycles(2);
} else {
// Query Nick for the amount of delay that would occur with one cycle left
// in this read opcode.
const auto delay_time = nick_.time_since_flush(HalfCycles(2));
const auto delay = nick_.last_valid()->get_time_until_z80_slot(delay_time);
penalty = nick_.back_map(delay, delay_time);
}
break;
// Video pauses: insert right at the end of the bus cycle.
case CPU::Z80::PartialMachineCycle::Write:
// Ensure all video that should have been collected prior to
// this write has been.
if(is_video_[address >> 14]) {
nick_.flush();
}
[[fallthrough]];
case CPU::Z80::PartialMachineCycle::Read:
if(is_video_[address >> 14]) {
// Get delay, in Nick cycles, for a Z80 access that occurs in 0.5
// cycles from now (i.e. with one cycle left to run).
const auto delay_time = nick_.time_since_flush(HalfCycles(1));
const auto delay = nick_.last_valid()->get_time_until_z80_slot(delay_time);
penalty = nick_.back_map(delay, delay_time);
}
break;
case CPU::Z80::PartialMachineCycle::Input:
case CPU::Z80::PartialMachineCycle::Output: {
if((address & 0xf0) == 0x80) {
// Get delay, in Nick cycles, for a Z80 access that occurs in 0.5
// cycles from now (i.e. with one cycle left to run).
const auto delay_time = nick_.time_since_flush(HalfCycles(1));
const auto delay = nick_.last_valid()->get_time_until_z80_slot(delay_time);
penalty = nick_.back_map(delay, delay_time);
}
}
}
const HalfCycles full_length = cycle.length + penalty;
time_since_audio_update_ += full_length;
advance_nick(full_length);
if(dave_timer_ += full_length) {
set_interrupts(dave_timer_.last_valid()->get_new_interrupts(), dave_timer_.last_sequence_point_overrun());
}
// The WD/etc runs at a nominal 8Mhz.
if constexpr (has_disk_controller) {
exdos_.run_for(Cycles(full_length.as_integral()));
}
switch(cycle.operation) {
default: break;
case CPU::Z80::PartialMachineCycle::Input:
switch(address & 0xff) {
default:
printf("Unhandled input: %04x\n", address);
// assert(false);
*cycle.value = 0xff;
break;
case 0x10: case 0x11: case 0x12: case 0x13:
case 0x14: case 0x15: case 0x16: case 0x17:
*cycle.value = exdos_.read(address);
break;
case 0x18: case 0x19: case 0x1a: case 0x1b:
case 0x1c: case 0x1d: case 0x1e: case 0x1f:
*cycle.value = exdos_.get_control_register();
break;
case 0xb0: *cycle.value = pages_[0]; break;
case 0xb1: *cycle.value = pages_[1]; break;
case 0xb2: *cycle.value = pages_[2]; break;
case 0xb3: *cycle.value = pages_[3]; break;
case 0xb4:
*cycle.value = interrupt_mask_ | interrupt_state_;
break;
case 0xb5:
if(active_key_line_ < key_lines_.size()) {
*cycle.value = key_lines_[active_key_line_];
} else {
*cycle.value = 0xff;
}
break;
case 0xb6:
// TODO: joystick input.
*cycle.value = 0xff;
break;
}
break;
case CPU::Z80::PartialMachineCycle::Output:
switch(address & 0xff) {
default:
printf("Unhandled output: %04x\n", address);
// assert(false);
break;
case 0x10: case 0x11: case 0x12: case 0x13:
case 0x14: case 0x15: case 0x16: case 0x17:
exdos_.write(address, *cycle.value);
break;
case 0x18: case 0x19: case 0x1a: case 0x1b:
case 0x1c: case 0x1d: case 0x1e: case 0x1f:
exdos_.set_control_register(*cycle.value);
break;
case 0x80: case 0x81: case 0x82: case 0x83:
case 0x84: case 0x85: case 0x86: case 0x87:
case 0x88: case 0x89: case 0x8a: case 0x8b:
case 0x8c: case 0x8d: case 0x8e: case 0x8f:
nick_->write(address, *cycle.value);
break;
case 0xb0: page<0>(*cycle.value); break;
case 0xb1: page<1>(*cycle.value); break;
case 0xb2: page<2>(*cycle.value); break;
case 0xb3: page<3>(*cycle.value); break;
case 0xa0: case 0xa1: case 0xa2: case 0xa3:
case 0xa4: case 0xa5: case 0xa6: case 0xa7:
case 0xa8: case 0xa9: case 0xaa: case 0xab:
case 0xac: case 0xad: case 0xae: case 0xaf:
update_audio();
dave_audio_.write(address, *cycle.value);
dave_timer_->write(address, *cycle.value);
break;
case 0xb4:
interrupt_mask_ = *cycle.value & 0x55;
interrupt_state_ &= ~*cycle.value;
update_interrupts();
if(interrupt_mask_ & 0x45) {
printf("Unimplemented interrupts requested: %02x\n", interrupt_mask_ & 0x45);
}
break;
case 0xb5:
active_key_line_ = *cycle.value & 0xf;
// TODO: printer strobe, type sound, REM switches.
break;
case 0xb6:
printf("TODO: printer output %02x\n", *cycle.value);
break;
case 0xbf:
printf("TODO: Dave sysconfig %02x\n", *cycle.value);
switch((*cycle.value >> 2)&3) {
default: wait_mode_ = WaitMode::None; break;
case 0: wait_mode_ = WaitMode::OnAllAccesses; break;
case 1: wait_mode_ = WaitMode::OnM1; break;
}
break;
}
break;
case CPU::Z80::PartialMachineCycle::Read:
case CPU::Z80::PartialMachineCycle::ReadOpcode:
if(read_pointers_[address >> 14]) {
*cycle.value = read_pointers_[address >> 14][address];
} else {
*cycle.value = 0xff;
}
break;
case CPU::Z80::PartialMachineCycle::Write:
if(write_pointers_[address >> 14]) {
write_pointers_[address >> 14][address] = *cycle.value;
}
break;
}
return penalty;
}
void flush() {
nick_.flush();
update_audio();
audio_queue_.perform();
}
private:
// MARK: - Memory layout
std::array<uint8_t, 256 * 1024> ram_{};
std::array<uint8_t, 64 * 1024> exos_;
std::array<uint8_t, 16 * 1024> basic_;
std::array<uint8_t, 16 * 1024> exdos_rom_;
std::array<uint8_t, 32 * 1024> epdos_rom_;
const uint8_t min_ram_slot_;
const uint8_t *read_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
uint8_t *write_pointers_[4] = {nullptr, nullptr, nullptr, nullptr};
uint8_t pages_[4] = {0x80, 0x80, 0x80, 0x80};
template <size_t slot> void page(uint8_t offset) {
pages_[slot] = offset;
#define Map(location, source) \
if(offset >= location && offset < location + source.size() / 0x4000) { \
page<slot>(&source[(offset - location) * 0x4000], nullptr); \
is_video_[slot] = false; \
return; \
}
Map(0, exos_);
Map(16, basic_);
Map(32, exdos_rom_);
Map(48, epdos_rom_);
#undef Map
// Of whatever size of RAM I've declared above, use only the final portion.
// This correlated with Nick always having been handed the final 64kb and,
// at least while the RAM is the first thing declared above, does a little
// to benefit data locality. Albeit not in a useful sense.
if(offset >= min_ram_slot_) {
const auto ram_floor = 4194304 - ram_.size();
const size_t address = offset * 0x4000 - ram_floor;
is_video_[slot] = offset >= 0xfc; // TODO: this hard-codes a 64kb video assumption.
page<slot>(&ram_[address], &ram_[address]);
return;
}
page<slot>(nullptr, nullptr);
}
template <size_t slot> void page(const uint8_t *read, uint8_t *write) {
read_pointers_[slot] = read ? read - (slot * 0x4000) : nullptr;
write_pointers_[slot] = write ? write - (slot * 0x4000) : nullptr;
}
// MARK: - Memory Timing
// The wait mode affects all memory accesses _outside of the video area_.
enum class WaitMode {
None,
OnM1,
OnAllAccesses
} wait_mode_ = WaitMode::None;
bool is_video_[4]{};
// MARK: - ScanProducer
void set_scan_target(Outputs::Display::ScanTarget *scan_target) override {
nick_.last_valid()->set_scan_target(scan_target);
}
Outputs::Display::ScanStatus get_scaled_scan_status() const override {
return nick_.last_valid()->get_scaled_scan_status();
}
// MARK: - AudioProducer
Outputs::Speaker::Speaker *get_speaker() final {
return &speaker_;
}
// MARK: - TimedMachine
void run_for(const Cycles cycles) override {
z80_.run_for(cycles);
}
// MARK: - KeyboardMachine
Enterprise::KeyboardMapper keyboard_mapper_;
KeyboardMapper *get_keyboard_mapper() final {
return &keyboard_mapper_;
}
uint8_t active_key_line_ = 0;
std::array<uint8_t, 10> key_lines_;
void set_key_state(uint16_t key, bool is_pressed) final {
if(is_pressed) {
key_lines_[key >> 8] &= ~uint8_t(key);
} else {
key_lines_[key >> 8] |= uint8_t(key);
}
}
void clear_all_keys() final {
key_lines_.fill(0xff);
}
// MARK: - MediaTarget
bool insert_media(const Analyser::Static::Media &media) final {
if constexpr (has_disk_controller) {
if(!media.disks.empty()) {
exdos_.set_disk(media.disks.front(), 0);
}
}
return true;
}
// MARK: - Interrupts
uint8_t interrupt_mask_ = 0x00, interrupt_state_ = 0x00;
void set_interrupts(uint8_t mask, HalfCycles offset = HalfCycles(0)) {
interrupt_state_ |= uint8_t(mask);
update_interrupts(offset);
}
void update_interrupts(HalfCycles offset = HalfCycles(0)) {
z80_.set_interrupt_line((interrupt_state_ >> 1) & interrupt_mask_, offset);
}
// MARK: - Chips.
CPU::Z80::Processor<ConcreteMachine, false, false> z80_;
JustInTimeActor<Nick, HalfCycles, 40434603, 11360000> nick_;
bool previous_nick_interrupt_line_ = false;
// Cf. timing guesses above.
Concurrency::DeferringAsyncTaskQueue audio_queue_;
Dave::Audio dave_audio_;
Outputs::Speaker::LowpassSpeaker<Dave::Audio> speaker_;
HalfCycles time_since_audio_update_;
// The following two should both use the same divider.
JustInTimeActor<Dave::TimedInterruptSource, HalfCycles, 1, 16> dave_timer_;
inline void update_audio() {
// TODO: divide by only 8, letting Dave divide itself by a further 2 or 3
// as per its own register.
speaker_.run_for(audio_queue_, time_since_audio_update_.divide_cycles(Cycles(16)));
}
// MARK: - EXDos card.
EXDos exdos_;
// MARK: - Activity Source
void set_activity_observer(Activity::Observer *observer) final {
if constexpr (has_disk_controller) {
exdos_.set_activity_observer(observer);
}
}
};
}
using namespace Enterprise;
Machine *Machine::Enterprise(const Analyser::Static::Target *target, const ROMMachine::ROMFetcher &rom_fetcher) {
using Target = Analyser::Static::Enterprise::Target;
const Target *const enterprise_target = dynamic_cast<const Target *>(target);
if(enterprise_target->dos == Target::DOS::None)
return new Enterprise::ConcreteMachine<false>(*enterprise_target, rom_fetcher);
else
return new Enterprise::ConcreteMachine<true>(*enterprise_target, rom_fetcher);
}
Machine::~Machine() {}
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