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295 lines
8.1 KiB
C++
295 lines
8.1 KiB
C++
//
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// Keyboard.h
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// Clock Signal
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//
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// Created by Thomas Harte on 08/05/2019.
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// Copyright © 2019 Thomas Harte. All rights reserved.
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//
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#ifndef Apple_Macintosh_Keyboard_hpp
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#define Apple_Macintosh_Keyboard_hpp
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#include "../../KeyboardMachine.hpp"
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#include <mutex>
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#include <vector>
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namespace Apple {
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namespace Macintosh {
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class Keyboard {
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public:
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void set_input(bool data) {
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switch(mode_) {
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case Mode::Waiting:
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/*
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"Only the computer can initiate communication over the keyboard lines. When the computer and keyboard
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are turned on, the computer is in charge of the keyboard interface and the keyboard is passive. The
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computer signals that it is ready to begin communication by pulling the Keyboard Data line low."
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*/
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if(!data) {
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mode_ = Mode::AcceptingCommand;
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phase_ = 0;
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command_ = 0;
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}
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break;
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case Mode::AcceptingCommand:
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/* Note value, so that it can be latched upon a clock transition. */
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data_input_ = data;
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break;
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case Mode::AwaitingEndOfCommand:
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/*
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The last bit of the command leaves the Keyboard Data line low; the computer then indicates that it is ready
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to receive the keyboard's response by setting the Keyboard Data line high.
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*/
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if(data) {
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mode_ = Mode::PerformingCommand;
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phase_ = 0;
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}
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break;
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default:
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case Mode::SendingResponse:
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/* This line isn't currently an input; do nothing. */
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break;
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}
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}
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bool get_clock() {
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return clock_output_;
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}
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bool get_data() {
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return !!(response_ & 0x80);
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}
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/*!
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The keyboard expects ~10 µs-frequency ticks, i.e. a clock rate of just around 100 kHz.
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*/
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void run_for(HalfCycles cycle) {
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switch(mode_) {
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default:
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case Mode::Waiting: return;
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case Mode::AcceptingCommand: {
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/*
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"When the computer is sending data to the keyboard, the keyboard transmits eight cycles of 400 µS each (180 µS low,
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220 µS high) on the Keyboard Clock line. On the falling edge of each keyboard clock cycle, the Macintosh Plus places
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a data bit on the data line and holds it there for 400 µS. The keyboard reads the data bit 80 µS after the rising edge
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of the Keyboard Clock signal."
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*/
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const auto offset = phase_ % 40;
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clock_output_ = offset >= 18;
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if(offset == 26) {
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command_ = (command_ << 1) | (data_input_ ? 1 : 0);
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}
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++phase_;
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if(phase_ == 8*40) {
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mode_ = Mode::AwaitingEndOfCommand;
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phase_ = 0;
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clock_output_ = false;
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}
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} break;
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case Mode::AwaitingEndOfCommand:
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// Time out if the end-of-command seems not to be forthcoming.
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// This is an elaboration on my part; a guess.
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++phase_;
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if(phase_ == 1000) {
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clock_output_ = false;
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mode_ = Mode::Waiting;
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phase_ = 0;
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}
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return;
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case Mode::PerformingCommand: {
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response_ = perform_command(command_);
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// Inquiry has a 0.25-second timeout; everything else is instant.
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++phase_;
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if(phase_ == 25000 || command_ != 0x10 || response_ != 0x7b) {
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mode_ = Mode::SendingResponse;
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phase_ = 0;
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}
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} break;
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case Mode::SendingResponse: {
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/*
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"When sending data to the computer, the keyboard transmits eight cycles of 330 µS each (160 µS low, 170 µS high)
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on the normally high Keyboard Clock line. It places a data bit on the data line 40 µS before the falling edge of each
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clock cycle and maintains it for 330 µS. The VIA in the computer latches the data bit into its shift register on the
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rising edge of the Keyboard Clock signal."
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*/
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const auto offset = phase_ % 33;
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clock_output_ = offset >= 16;
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if(offset == 29) {
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response_ <<= 1;
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}
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++phase_;
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if(phase_ == 8*33) {
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clock_output_ = false;
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mode_ = Mode::Waiting;
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phase_ = 0;
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}
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} break;
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}
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}
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void enqueue_key_state(uint16_t key, bool is_pressed) {
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// Front insert; messages will be pop_back'd.
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std::lock_guard<decltype(key_queue_mutex_)> lock(key_queue_mutex_);
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// Keys on the keypad are preceded by a $79 keycode; in the internal naming scheme
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// they are indicated by having bit 8 set. So add the $79 prefix if required.
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if(key & 0x100) {
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key_queue_.insert(key_queue_.begin(), 0x79);
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}
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key_queue_.insert(key_queue_.begin(), (is_pressed ? 0x00 : 0x80) | uint8_t(key));
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}
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private:
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int perform_command(int command) {
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switch(command) {
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case 0x10: // Inquiry.
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case 0x14: { // Instant.
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std::lock_guard<decltype(key_queue_mutex_)> lock(key_queue_mutex_);
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if(!key_queue_.empty()) {
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const auto new_message = key_queue_.back();
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key_queue_.pop_back();
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return new_message;
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}
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} break;
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case 0x16: // Model number.
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return
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0x01 | // b0: always 1
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(1 << 1) | // keyboard model number
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(1 << 4); // next device number
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// (b7 not set => no next device)
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case 0x36: // Test
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return 0x7d; // 0x7d = ACK, 0x77 = not ACK.
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}
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return 0x7b; // No key transition.
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}
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enum class Mode {
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Waiting,
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AcceptingCommand,
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AwaitingEndOfCommand,
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SendingResponse,
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PerformingCommand
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} mode_ = Mode::Waiting;
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int phase_ = 0;
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int command_ = 0;
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int response_ = 0;
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bool data_input_ = false;
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bool clock_output_ = false;
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// TODO: improve this very, very simple implementation.
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std::mutex key_queue_mutex_;
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std::vector<uint8_t> key_queue_;
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};
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/*!
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Provides a mapping from idiomatic PC keys to Macintosh keys.
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*/
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class KeyboardMapper: public KeyboardMachine::MappedMachine::KeyboardMapper {
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uint16_t mapped_key_for_key(Inputs::Keyboard::Key key) override {
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using Key = Inputs::Keyboard::Key;
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switch(key) {
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default: return KeyboardMachine::MappedMachine::KeyNotMapped;
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/*
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See p284 of the Apple Guide to the Macintosh Family Hardware
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for documentation of the mapping below.
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*/
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case Key::BackTick: return 0x65;
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case Key::k1: return 0x25;
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case Key::k2: return 0x27;
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case Key::k3: return 0x29;
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case Key::k4: return 0x2b;
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case Key::k5: return 0x2f;
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case Key::k6: return 0x2d;
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case Key::k7: return 0x35;
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case Key::k8: return 0x39;
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case Key::k9: return 0x33;
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case Key::k0: return 0x3b;
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case Key::Hyphen: return 0x37;
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case Key::Equals: return 0x31;
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case Key::BackSpace: return 0x67;
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case Key::Tab: return 0x61;
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case Key::Q: return 0x19;
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case Key::W: return 0x1b;
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case Key::E: return 0x1d;
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case Key::R: return 0x1f;
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case Key::T: return 0x23;
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case Key::Y: return 0x21;
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case Key::U: return 0x41;
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case Key::I: return 0x45;
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case Key::O: return 0x3f;
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case Key::P: return 0x47;
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case Key::OpenSquareBracket: return 0x43;
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case Key::CloseSquareBracket: return 0x3d;
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case Key::CapsLock: return 0x73;
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case Key::A: return 0x01;
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case Key::S: return 0x03;
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case Key::D: return 0x05;
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case Key::F: return 0x07;
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case Key::G: return 0x0b;
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case Key::H: return 0x09;
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case Key::J: return 0x4d;
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case Key::K: return 0x51;
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case Key::L: return 0x4b;
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case Key::Semicolon: return 0x53;
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case Key::Quote: return 0x4f;
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case Key::Enter: return 0x49;
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case Key::LeftShift: return 0x71;
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case Key::Z: return 0x0d;
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case Key::X: return 0x0f;
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case Key::C: return 0x11;
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case Key::V: return 0x13;
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case Key::B: return 0x17;
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case Key::N: return 0x5b;
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case Key::M: return 0x5d;
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case Key::Comma: return 0x57;
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case Key::FullStop: return 0x5f;
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case Key::ForwardSlash: return 0x59;
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case Key::RightShift: return 0x71;
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case Key::Left: return 0x100 | 0x0d;
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case Key::Right: return 0x100 | 0x05;
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case Key::Up: return 0x100 | 0x1b;
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case Key::Down: return 0x100 | 0x11;
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case Key::LeftOption:
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case Key::RightOption: return 0x75;
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case Key::LeftMeta:
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case Key::RightMeta: return 0x6f;
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case Key::Space: return 0x63;
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case Key::BackSlash: return 0x55;
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/* TODO: the numeric keypad. */
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}
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}
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};
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}
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}
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#endif /* Apple_Macintosh_Keyboard_hpp */
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