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169 lines
4.7 KiB
C++
169 lines
4.7 KiB
C++
//
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// MFMDiskController.cpp
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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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#include "MFMDiskController.hpp"
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#include "../Encodings/MFM/Constants.hpp"
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using namespace Storage::Disk;
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MFMController::MFMController(Cycles clock_rate) :
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Storage::Disk::Controller(clock_rate),
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shifter_(&crc_generator_) {
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}
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void MFMController::process_index_hole() {
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posit_event(static_cast<int>(Event::IndexHole));
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}
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void MFMController::process_write_completed() {
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posit_event(static_cast<int>(Event::DataWritten));
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}
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void MFMController::set_is_double_density(bool is_double_density) {
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is_double_density_ = is_double_density;
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Storage::Time bit_length;
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bit_length.length = 1;
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bit_length.clock_rate = is_double_density ? 500000 : 250000;
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set_expected_bit_length(bit_length);
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shifter_.set_is_double_density(is_double_density);
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}
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bool MFMController::get_is_double_density() {
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return is_double_density_;
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}
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void MFMController::set_data_mode(DataMode mode) {
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data_mode_ = mode;
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shifter_.set_should_obey_syncs(mode == DataMode::Scanning);
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}
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MFMController::Token MFMController::get_latest_token() {
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return latest_token_;
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}
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CRC::CCITT &MFMController::get_crc_generator() {
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return crc_generator_;
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}
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void MFMController::process_input_bit(int value) {
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if(data_mode_ == DataMode::Writing) return;
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shifter_.add_input_bit(value);
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switch(shifter_.get_token()) {
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case Encodings::MFM::Shifter::Token::None:
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return;
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case Encodings::MFM::Shifter::Token::Index:
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latest_token_.type = Token::Index;
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break;
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case Encodings::MFM::Shifter::Token::ID:
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latest_token_.type = Token::ID;
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break;
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case Encodings::MFM::Shifter::Token::Data:
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latest_token_.type = Token::Data;
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break;
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case Encodings::MFM::Shifter::Token::DeletedData:
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latest_token_.type = Token::DeletedData;
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break;
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case Encodings::MFM::Shifter::Token::Sync:
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latest_token_.type = Token::Sync;
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break;
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case Encodings::MFM::Shifter::Token::Byte:
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latest_token_.type = Token::Byte;
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break;
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}
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latest_token_.byte_value = shifter_.get_byte();
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posit_event(int(Event::Token));
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}
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void MFMController::write_bit(int bit) {
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if(is_double_density_) {
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get_drive().write_bit(!bit && !last_bit_);
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get_drive().write_bit(!!bit);
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last_bit_ = bit;
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} else {
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get_drive().write_bit(true);
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get_drive().write_bit(!!bit);
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}
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}
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void MFMController::write_byte(uint8_t byte) {
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for(int c = 0; c < 8; c++) write_bit((byte << c)&0x80);
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crc_generator_.add(byte);
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}
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void MFMController::write_raw_short(uint16_t value) {
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for(int c = 0; c < 16; c++) {
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get_drive().write_bit(!!((value << c)&0x8000));
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}
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}
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void MFMController::write_crc() {
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uint16_t crc = get_crc_generator().get_value();
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write_byte(crc >> 8);
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write_byte(crc & 0xff);
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}
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void MFMController::write_n_bytes(int quantity, uint8_t value) {
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while(quantity--) write_byte(value);
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}
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void MFMController::write_id_joiner() {
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if(get_is_double_density()) {
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write_n_bytes(12, 0x00);
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for(int c = 0; c < 3; c++) write_raw_short(Storage::Encodings::MFM::MFMSync);
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get_crc_generator().set_value(Storage::Encodings::MFM::MFMPostSyncCRCValue);
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write_byte(Storage::Encodings::MFM::IDAddressByte);
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} else {
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write_n_bytes(6, 0x00);
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get_crc_generator().reset();
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write_raw_short(Storage::Encodings::MFM::FMIDAddressMark);
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}
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}
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void MFMController::write_id_data_joiner(bool is_deleted, bool skip_first_gap) {
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if(get_is_double_density()) {
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if(!skip_first_gap) write_n_bytes(22, 0x4e);
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write_n_bytes(12, 0x00);
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for(int c = 0; c < 3; c++) write_raw_short(Storage::Encodings::MFM::MFMSync);
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get_crc_generator().set_value(Storage::Encodings::MFM::MFMPostSyncCRCValue);
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write_byte(is_deleted ? Storage::Encodings::MFM::DeletedDataAddressByte : Storage::Encodings::MFM::DataAddressByte);
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} else {
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if(!skip_first_gap) write_n_bytes(11, 0xff);
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write_n_bytes(6, 0x00);
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get_crc_generator().reset();
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get_crc_generator().add(is_deleted ? Storage::Encodings::MFM::DeletedDataAddressByte : Storage::Encodings::MFM::DataAddressByte);
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write_raw_short(is_deleted ? Storage::Encodings::MFM::FMDeletedDataAddressMark : Storage::Encodings::MFM::FMDataAddressMark);
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}
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}
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void MFMController::write_post_data_gap() {
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if(get_is_double_density()) {
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write_n_bytes(54, 0x4e);
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} else {
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write_n_bytes(27, 0xff);
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}
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}
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void MFMController::write_start_of_track() {
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if(get_is_double_density()) {
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write_n_bytes(80, 0x4e);
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write_n_bytes(12, 0x00);
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for(int c = 0; c < 3; c++) write_raw_short(Storage::Encodings::MFM::MFMIndexSync);
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write_byte(Storage::Encodings::MFM::IndexAddressByte);
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write_n_bytes(50, 0x4e);
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} else {
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write_n_bytes(40, 0xff);
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write_n_bytes(6, 0x00);
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write_raw_short(Storage::Encodings::MFM::FMIndexAddressMark);
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write_n_bytes(26, 0xff);
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}
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}
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