mirror of https://github.com/TomHarte/CLK.git
136 lines
3.3 KiB
C++
136 lines
3.3 KiB
C++
//
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// i8272.hpp
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// Clock Signal
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//
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// Created by Thomas Harte on 05/08/2017.
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// Copyright 2017 Thomas Harte. All rights reserved.
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//
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#pragma once
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#include "CommandDecoder.hpp"
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#include "Status.hpp"
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#include "../../Storage/Disk/Controller/MFMDiskController.hpp"
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#include <cstdint>
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#include <memory>
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#include <vector>
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namespace Intel::i8272 {
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class BusHandler {
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public:
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virtual ~BusHandler() {}
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virtual void set_dma_data_request([[maybe_unused]] bool drq) {}
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virtual void set_interrupt([[maybe_unused]] bool irq) {}
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};
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class i8272 : public Storage::Disk::MFMController {
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public:
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i8272(BusHandler &bus_handler, Cycles clock_rate);
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void run_for(Cycles);
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void set_data_input(uint8_t value);
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uint8_t get_data_output();
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void write(int address, uint8_t value);
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uint8_t read(int address);
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void set_dma_acknowledge(bool dack);
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void set_terminal_count(bool tc);
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ClockingHint::Preference preferred_clocking() const final;
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protected:
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virtual void select_drive(int number) = 0;
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private:
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// The bus handler, for interrupt and DMA-driven usage. [TODO]
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BusHandler &bus_handler_;
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std::unique_ptr<BusHandler> allocated_bus_handler_;
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// Status registers.
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Status status_;
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// The incoming command.
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CommandDecoder command_;
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// A buffer to accumulate the result.
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std::vector<uint8_t> result_stack_;
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uint8_t input_ = 0;
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bool has_input_ = false;
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bool expects_input_ = false;
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// Event stream: the 8272-specific events, plus the current event state.
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enum class Event8272: int {
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CommandByte = (1 << 3),
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Timer = (1 << 4),
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ResultEmpty = (1 << 5),
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NoLongerReady = (1 << 6)
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};
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void posit_event(int type) final;
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int interesting_event_mask_ = int(Event8272::CommandByte);
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int resume_point_ = 0;
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bool is_access_command_ = false;
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// The counter used for ::Timer events.
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Cycles::IntType delay_time_ = 0;
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// The connected drives.
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struct Drive {
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uint8_t head_position = 0;
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// Seeking: persistent state.
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enum Phase {
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NotSeeking,
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Seeking,
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CompletedSeeking
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} phase = NotSeeking;
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bool did_seek = false;
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bool seek_failed = false;
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// Seeking: transient state.
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Cycles::IntType step_rate_counter = 0;
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int steps_taken = 0;
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int target_head_position = 0; // either an actual number, or -1 to indicate to step until track zero
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// Head state.
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Cycles::IntType head_unload_delay[2] = {0, 0};
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bool head_is_loaded[2] = {false, false};
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} drives_[4];
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int drives_seeking_ = 0;
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/// @returns @c true if the selected drive, which is number @c drive, can stop seeking.
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bool seek_is_satisfied(int drive);
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// User-supplied parameters; as per the specify command.
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int step_rate_time_ = 1;
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int head_unload_time_ = 1;
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int head_load_time_ = 1;
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bool dma_mode_ = false;
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bool is_executing_ = false;
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// A count of head unload timers currently running.
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int head_timers_running_ = 0;
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// Transient storage and counters used while reading the disk.
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uint8_t header_[6] = {0, 0, 0, 0, 0, 0};
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int distance_into_section_ = 0;
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int index_hole_count_ = 0, index_hole_limit_ = 0;
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// Keeps track of the drive and head in use during commands.
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int active_drive_ = 0;
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int active_head_ = 0;
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// Internal registers.
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uint8_t cylinder_ = 0, head_ = 0, sector_ = 0, size_ = 0;
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// Master switch on not performing any work.
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bool is_sleeping_ = false;
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};
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}
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