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295 lines
8.7 KiB
C++
295 lines
8.7 KiB
C++
//
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// ADB.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 31/10/2020.
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// Copyright © 2020 Thomas Harte. All rights reserved.
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//
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#include "ADB.hpp"
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#include <cassert>
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#include <cstdio>
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#include <iostream>
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// TEST.
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#include "../../../InstructionSets/M50740/Parser.hpp"
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#include "../../../InstructionSets/Disassembler.hpp"
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#define LOG_PREFIX "[ADB GLU] "
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#include "../../../Outputs/Log.hpp"
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using namespace Apple::IIgs::ADB;
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namespace {
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// Flags affecting the CPU-visible status register.
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enum class CPUFlags: uint8_t {
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MouseDataFull = 0x80,
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MouseInterruptEnabled = 0x40,
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CommandDataIsValid = 0x20,
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CommandDataInterruptEnabled = 0x10,
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KeyboardDataFull = 0x08,
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KeyboardDataInterruptEnabled = 0x04,
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MouseXIsAvailable = 0x02,
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CommandRegisterFull = 0x01,
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};
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// Flags affecting the microcontroller-visible register.
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enum class MicrocontrollerFlags: uint8_t {
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CommandRegisterFull = 0x40,
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};
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}
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GLU::GLU() :
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executor_(*this),
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bus_(HalfCycles(1'789'772)),
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controller_id_(bus_.add_device()),
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mouse_(bus_),
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keyboard_(bus_) {}
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// MARK: - External interface.
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uint8_t GLU::get_keyboard_data() {
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// The classic Apple II serial keyboard register:
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// b7: key strobe.
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// b6–b0: ASCII code.
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return (registers_[0] & 0x7f) | ((status_ & uint8_t(CPUFlags::KeyboardDataFull)) ? 0x80 : 0x00);
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}
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void GLU::clear_key_strobe() {
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// Clears the key strobe of the classic Apple II serial keyboard register.
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status_ &= ~uint8_t(CPUFlags::KeyboardDataFull);
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}
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uint8_t GLU::get_any_key_down() {
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// The Apple IIe check-for-any-key-down bit.
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return registers_[5];
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}
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uint8_t GLU::get_mouse_data() {
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// Alternates between returning x and y values.
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//
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// b7: 1 = button is up; 0 = button is down.
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// b6: delta sign bit; 1 = negative.
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// b5–b0: mouse delta.
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const uint8_t result = registers_[visible_mouse_register_];
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if(visible_mouse_register_ == 3) {
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status_ &= ~uint8_t(CPUFlags::MouseDataFull);
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}
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// Spelt out at tedious length because Clang has trust issues.
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static constexpr int first_register = 2;
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static constexpr int second_register = 3;
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static constexpr int flip_mask = first_register ^ second_register;
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visible_mouse_register_ ^= flip_mask;
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return result;
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}
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uint8_t GLU::get_modifier_status() {
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// b7: 1 = command key pressed; 0 = not.
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// b6: option key.
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// b5: 1 = modifier key latch has been updated, no key has been pressed; 0 = not.
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// b4: any numeric keypad key.
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// b3: a key is down.
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// b2: caps lock is pressed.
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// b1: control key.
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// b0: shift key.
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return registers_[6];
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}
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uint8_t GLU::get_data() {
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// b0–2: number of data bytes to be returned.
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// b3: 1 = a valid service request is pending; 0 = no request pending.
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// b4: 1 = control, command and delete keys have been pressed simultaneously; 0 = they haven't.
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// b5: 1 = control, command and reset have all been pressed together; 0 = they haven't.
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// b6: 1 = ADB controller encountered an error and reset itself; 0 = no error.
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// b7: 1 = ADB has received a response from the addressed ADB device; 0 = no respone.
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status_ &= ~uint8_t(CPUFlags::CommandDataIsValid);
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return registers_[7];
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}
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uint8_t GLU::get_status() {
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// b7: 1 = mouse data register is full; 0 = empty.
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// b6: 1 = mouse interrupt is enabled.
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// b5: 1 = command/data has valid data.
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// b4: 1 = command/data interrupt is enabled.
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// b3: 1 = keyboard data is full.
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// b2: 1 = keyboard data interrupt is enabled.
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// b1: 1 = mouse x-data is available; 0 = y.
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// b0: 1 = command register is full (set when command is written); 0 = empty (cleared when data is read).
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return status_ | ((visible_mouse_register_ == 2) ? 0 : uint8_t(CPUFlags::MouseXIsAvailable));
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}
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void GLU::set_status(uint8_t status) {
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// This permits only the interrupt flags to be set.
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constexpr uint8_t interrupt_flags =
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uint8_t(CPUFlags::MouseInterruptEnabled) |
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uint8_t(CPUFlags::CommandDataInterruptEnabled) |
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uint8_t(CPUFlags::KeyboardDataInterruptEnabled);
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status_ = (status_ & ~interrupt_flags) | (status & interrupt_flags);
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}
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void GLU::set_command(uint8_t command) {
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registers_[1] = command;
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registers_[4] |= uint8_t(MicrocontrollerFlags::CommandRegisterFull);
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status_ |= uint8_t(CPUFlags::CommandRegisterFull);
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}
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// MARK: - Setup and run.
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void GLU::set_microcontroller_rom(const std::vector<uint8_t> &rom) {
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executor_.set_rom(rom);
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// TEST invocation.
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/* InstructionSet::Disassembler<InstructionSet::M50740::Parser, 0x1fff, InstructionSet::M50740::Instruction, uint8_t, uint16_t> disassembler;
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disassembler.disassemble(rom.data(), 0x1000, uint16_t(rom.size()), 0x1000);
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const auto instructions = disassembler.instructions();
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const auto entry_points = disassembler.entry_points();
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for(const auto &pair : instructions) {
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std::cout << std::hex << pair.first << "\t\t";
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if(entry_points.find(pair.first) != entry_points.end()) {
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std::cout << "L" << pair.first << "\t";
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} else {
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std::cout << "\t\t";
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}
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std::cout << operation_name(pair.second.operation) << " ";
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std::cout << address(pair.second.addressing_mode, &rom[pair.first - 0x1000], pair.first);
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std::cout << std::endl;
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}*/
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}
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void GLU::run_for(Cycles cycles) {
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executor_.run_for(cycles);
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}
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// MARK: - M50470 port handler
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void GLU::set_port_output(int port, uint8_t value) {
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switch(port) {
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case 0:
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register_latch_ = value;
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break;
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case 1:
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// printf("Keyboard write: %02x???\n", value);
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break;
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case 2: {
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// printf("ADB data line input: %d???\n", value >> 7);
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// printf("IIe keyboard reset line: %d\n", (value >> 6)&1);
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// printf("IIgs reset line: %d\n", (value >> 5)&1);
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// printf("GLU strobe: %d\n", (value >> 4)&1);
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// printf("Select GLU register: %d [%02x]\n", value & 0xf, value);
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register_address_ = value & 0xf;
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// This is an ugly hack, I think. Per Neil Parker's Inside the Apple IIGS ADB Controller
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// http://nparker.llx.com/a2/adb.html#external:
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//
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// The protocol for reading an ADB GLU register is as follows:
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//
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// 1. Put the register number of the ADB GLU register in port P2 bits 0-3.
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// 2. Clear bit 4 of port P2, read the data from P0, and set bit 4 of P0.
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//
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// The protocol for writing a GLU register is similar:
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//
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// 1. Write the register number to port P2 bits 0-3.
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// 2. Write the data to port P0.
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// 3. Configure port P0 for output by writing $FF to $E1.
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// 4. Clear bit 4 of P2, and immediately set it again.
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// 5. Configure port P0 for input by writing 0 to $E1.
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//
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// ---
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//
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// I tried: linking a read or write to rising or falling edges of the strobe.
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// Including with hysteresis as per the "immediately" (which, in practice, seems
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// to mean "in the very next instruction", i.e. 5 cycles later). That didn't seem
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// properly to differentiate.
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//
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// So I'm focussing on the "configure port P0 for output" bit. Which I don't see
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// would be visible here unless it is actually an exposed signal, which is unlikely.
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//
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// Ergo: ugly. HACK.
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const bool strobe = value & 0x10;
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if(strobe != register_strobe_) {
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register_strobe_ = strobe;
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if(!register_strobe_) {
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if(executor_.get_output_mask(0)) {
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registers_[register_address_] = register_latch_;
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switch(register_address_) {
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default: break;
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case 0: status_ |= uint8_t(CPUFlags::KeyboardDataFull); break;
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case 2:
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case 3:
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status_ |= uint8_t(CPUFlags::MouseDataFull);
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visible_mouse_register_ = 2;
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break;
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case 7: status_ |= uint8_t(CPUFlags::CommandDataIsValid); break;
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}
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} else {
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register_latch_ = registers_[register_address_];
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switch(register_address_) {
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default: break;
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case 1:
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registers_[4] &= ~uint8_t(MicrocontrollerFlags::CommandRegisterFull);
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status_ &= ~uint8_t(CPUFlags::CommandRegisterFull);
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break;
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}
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}
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}
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}
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} break;
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case 3:
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if(modifier_state_ != (value & 0x30)) {
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modifier_state_ = value & 0x30;
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LOG("Modifier state: " << int(value & 0x30));
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}
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// Output is inverted respective to input; the microcontroller
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// sets a value of '1' in order to pull the ADB bus low.
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bus_.set_device_output(controller_id_, !(value & 0x08));
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break;
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default: assert(false);
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}
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}
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bool GLU::get_command_button() const {
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return modifier_state_ & 0x20;
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}
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bool GLU::get_option_button() const {
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return modifier_state_ & 0x10;
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}
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uint8_t GLU::get_port_input(int port) {
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switch(port) {
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case 0: return register_latch_;
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case 1:
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// printf("IIe keyboard read\n");
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return 0x06;
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case 2:
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// printf("ADB data line input, etc\n");
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return bus_.get_state() ? 0x80 : 0x00;
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case 3:
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// printf("ADB data line output, etc\n");
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return 0x00;
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default: assert(false);
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}
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return 0xff;
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}
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void GLU::run_ports_for(Cycles cycles) {
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bus_.run_for(cycles);
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}
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void GLU::set_vertical_blank(bool is_blank) {
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vertical_blank_ = is_blank;
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executor_.set_interrupt_line(is_blank);
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}
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