mirror of
https://github.com/TomHarte/CLK.git
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908d3b0ee5
At an initial look, I think the shift register should end up on the data bus for all odd accesses. Need to investigate more thoroughly.
265 lines
8.6 KiB
C++
265 lines
8.6 KiB
C++
//
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// DiskII.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 20/04/2018.
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// Copyright 2018 Thomas Harte. All rights reserved.
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//
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#include "DiskII.hpp"
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#include <cstdio>
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#include <cstring>
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using namespace Apple;
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namespace {
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const uint8_t input_command = 0x4; // i.e. Q6
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const uint8_t input_mode = 0x8; // i.e. Q7
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const uint8_t input_flux = 0x1;
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}
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DiskII::DiskII() :
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inputs_(input_command),
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drives_{{2045454, 300, 1}, {2045454, 300, 1}}
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{
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drives_[0].set_sleep_observer(this);
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drives_[1].set_sleep_observer(this);
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drives_[active_drive_].set_event_delegate(this);
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}
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void DiskII::set_control(Control control, bool on) {
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int previous_stepper_mask = stepper_mask_;
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switch(control) {
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case Control::P0: stepper_mask_ = (stepper_mask_ & 0xe) | (on ? 0x1 : 0x0); break;
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case Control::P1: stepper_mask_ = (stepper_mask_ & 0xd) | (on ? 0x2 : 0x0); break;
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case Control::P2: stepper_mask_ = (stepper_mask_ & 0xb) | (on ? 0x4 : 0x0); break;
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case Control::P3: stepper_mask_ = (stepper_mask_ & 0x7) | (on ? 0x8 : 0x0); break;
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case Control::Motor:
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motor_is_enabled_ = on;
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drives_[active_drive_].set_motor_on(on);
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break;
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}
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// printf("%0x: Set control %d %s\n", stepper_mask_, control, on ? "on" : "off");
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// If the stepper magnet selections have changed, and any is on, see how
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// that moves the head.
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if(previous_stepper_mask ^ stepper_mask_ && stepper_mask_) {
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// Convert from a representation of bits set to the centre of pull.
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int direction = 0;
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if(stepper_mask_&1) direction += (((stepper_position_ - 0) + 4)&7) - 4;
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if(stepper_mask_&2) direction += (((stepper_position_ - 2) + 4)&7) - 4;
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if(stepper_mask_&4) direction += (((stepper_position_ - 4) + 4)&7) - 4;
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if(stepper_mask_&8) direction += (((stepper_position_ - 6) + 4)&7) - 4;
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const int bits_set = (stepper_mask_&1) + ((stepper_mask_ >> 1)&1) + ((stepper_mask_ >> 2)&1) + ((stepper_mask_ >> 3)&1);
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direction /= bits_set;
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// Compare to the stepper position to decide whether that pulls in the current cog notch,
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// or grabs a later one.
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drives_[active_drive_].step(Storage::Disk::HeadPosition(-direction, 4));
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stepper_position_ = (stepper_position_ - direction + 8) & 7;
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}
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}
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void DiskII::set_mode(Mode mode) {
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// printf("Set mode %d\n", mode);
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inputs_ = (inputs_ & ~input_mode) | ((mode == Mode::Write) ? input_mode : 0);
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set_controller_can_sleep();
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}
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void DiskII::select_drive(int drive) {
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// printf("Select drive %d\n", drive);
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if((drive&1) == active_drive_) return;
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drives_[active_drive_].set_event_delegate(this);
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drives_[active_drive_^1].set_event_delegate(nullptr);
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drives_[active_drive_].set_motor_on(false);
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active_drive_ = drive & 1;
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drives_[active_drive_].set_motor_on(motor_is_enabled_);
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}
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void DiskII::set_data_register(uint8_t value) {
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// printf("Set data register (?)\n");
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inputs_ |= input_command;
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shift_register_ = value;
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set_controller_can_sleep();
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}
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uint8_t DiskII::get_shift_register() {
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// if(shift_register_ & 0x80) printf("[%02x] ", shift_register_);
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inputs_ &= ~input_command;
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set_controller_can_sleep();
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return shift_register_;
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}
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void DiskII::run_for(const Cycles cycles) {
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if(is_sleeping()) return;
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int integer_cycles = cycles.as_int();
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if(!controller_can_sleep_) {
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while(integer_cycles--) {
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const int address = (state_ & 0xf0) | inputs_ | ((shift_register_&0x80) >> 6);
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inputs_ |= input_flux;
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state_ = state_machine_[static_cast<std::size_t>(address)];
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switch(state_ & 0xf) {
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default: shift_register_ = 0; break; // clear
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case 0x8: break; // nop
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case 0x9: shift_register_ = static_cast<uint8_t>(shift_register_ << 1); break; // shift left, bringing in a zero
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case 0xd: shift_register_ = static_cast<uint8_t>((shift_register_ << 1) | 1); break; // shift left, bringing in a one
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case 0xa: // shift right, bringing in write protected status
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shift_register_ = (shift_register_ >> 1) | (is_write_protected() ? 0x80 : 0x00);
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// If the controller is in the sense write protect loop but the register will never change,
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// short circuit further work and return now.
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if(shift_register_ == is_write_protected() ? 0xff : 0x00) {
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if(!drive_is_sleeping_[0]) drives_[0].run_for(Cycles(integer_cycles));
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if(!drive_is_sleeping_[1]) drives_[1].run_for(Cycles(integer_cycles));
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set_controller_can_sleep();
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return;
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}
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break;
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case 0xb:
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// load data register from data bus...
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printf("TODO\n");
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// shift_register_ = data_register_;
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break; // load
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}
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// TODO: surely there's a less heavyweight solution than this?
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if(!drive_is_sleeping_[0]) drives_[0].run_for(Cycles(1));
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if(!drive_is_sleeping_[1]) drives_[1].run_for(Cycles(1));
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}
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} else {
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if(!drive_is_sleeping_[0]) drives_[0].run_for(cycles);
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if(!drive_is_sleeping_[1]) drives_[1].run_for(cycles);
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}
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set_controller_can_sleep();
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}
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void DiskII::set_controller_can_sleep() {
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// Permit the controller to sleep if it's in sense write protect mode, and the shift register
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// has already filled with the result of shifting eight times.
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controller_can_sleep_ =
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(inputs_ == (input_command | input_flux)) &&
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(shift_register_ == (is_write_protected() ? 0xff : 0x00));
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if(is_sleeping()) update_sleep_observer();
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}
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bool DiskII::is_write_protected() {
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return !!(stepper_mask_ & 2) | drives_[active_drive_].get_is_read_only();
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}
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void DiskII::set_state_machine(const std::vector<uint8_t> &state_machine) {
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/*
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An unadulterated P6 ROM read returns values with an address formed as:
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state b0, state b2, state b3, pulse, Q7, Q6, shift, state b1
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... and has the top nibble reflected. Beneath Apple Pro-DOS uses a
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different order and several of the online copies are reformatted
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into that order.
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So the code below remaps into Beneath Apple Pro-DOS order if the
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supplied state machine isn't already in that order.
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*/
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if(state_machine[0] != 0x18) {
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for(size_t source_address = 0; source_address < 256; ++source_address) {
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// Remap into Beneath Apple Pro-DOS address form.
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size_t destination_address =
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((source_address&0x80) ? 0x10 : 0x00) |
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((source_address&0x01) ? 0x20 : 0x00) |
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((source_address&0x40) ? 0x40 : 0x00) |
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((source_address&0x20) ? 0x80 : 0x00) |
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((source_address&0x10) ? 0x01 : 0x00) |
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((source_address&0x08) ? 0x08 : 0x00) |
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((source_address&0x04) ? 0x04 : 0x00) |
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((source_address&0x02) ? 0x02 : 0x00);
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uint8_t source_value = state_machine[source_address];
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// Remap into Beneath Apple Pro-DOS value form.
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source_value =
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((source_value & 0x80) ? 0x10 : 0x0) |
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((source_value & 0x40) ? 0x20 : 0x0) |
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((source_value & 0x20) ? 0x40 : 0x0) |
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((source_value & 0x10) ? 0x80 : 0x0) |
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(source_value & 0x0f);
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// Store.
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state_machine_[destination_address] = source_value;
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}
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} else {
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memcpy(&state_machine_[0], &state_machine[0], 128);
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}
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}
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void DiskII::set_disk(const std::shared_ptr<Storage::Disk::Disk> &disk, int drive) {
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drives_[drive].set_disk(disk);
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}
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void DiskII::process_event(const Storage::Disk::Track::Event &event) {
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if(event.type == Storage::Disk::Track::Event::FluxTransition) {
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inputs_ &= ~input_flux;
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set_controller_can_sleep();
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}
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}
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void DiskII::set_component_is_sleeping(Sleeper *component, bool is_sleeping) {
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drive_is_sleeping_[0] = drives_[0].is_sleeping();
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drive_is_sleeping_[1] = drives_[1].is_sleeping();
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update_sleep_observer();
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}
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bool DiskII::is_sleeping() {
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return controller_can_sleep_ && drive_is_sleeping_[0] && drive_is_sleeping_[1];
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}
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void DiskII::set_register(int address, uint8_t value) {
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trigger_address(address, value);
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}
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uint8_t DiskII::get_register(int address) {
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return trigger_address(address, 0xff);
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}
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uint8_t DiskII::trigger_address(int address, uint8_t value) {
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switch(address & 0xf) {
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default:
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case 0x0: set_control(Control::P0, false); break;
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case 0x1: set_control(Control::P0, true); break;
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case 0x2: set_control(Control::P1, false); break;
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case 0x3: set_control(Control::P1, true); break;
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case 0x4: set_control(Control::P2, false); break;
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case 0x5: set_control(Control::P2, true); break;
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case 0x6: set_control(Control::P3, false); break;
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case 0x7: set_control(Control::P3, true); break;
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case 0x8: set_control(Control::Motor, false); break;
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case 0x9: set_control(Control::Motor, true); break;
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case 0xa: select_drive(0); break;
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case 0xb: select_drive(1); break;
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case 0xc: return get_shift_register();
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case 0xd: set_data_register(value); break;
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case 0xe:
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set_mode(Mode::Read);
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return shift_register_;
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case 0xf: set_mode(Mode::Write); break;
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}
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return 0xff;
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}
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void DiskII::set_activity_observer(Activity::Observer *observer) {
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drives_[0].set_activity_observer(observer, "Drive 1", true);
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drives_[1].set_activity_observer(observer, "Drive 2", true);
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}
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