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CLK/Storage/Disk/Controller/MFMDiskController.cpp

169 lines
4.6 KiB
C++

//
// MFMDiskController.cpp
// Clock Signal
//
// Created by Thomas Harte on 05/08/2017.
// Copyright 2017 Thomas Harte. All rights reserved.
//
#include "MFMDiskController.hpp"
#include "../Encodings/MFM/Constants.hpp"
using namespace Storage::Disk;
MFMController::MFMController(Cycles clock_rate) :
Storage::Disk::Controller(clock_rate),
shifter_(&crc_generator_) {
}
void MFMController::process_index_hole() {
posit_event(int(Event::IndexHole));
}
void MFMController::process_write_completed() {
posit_event(int(Event::DataWritten));
}
void MFMController::set_is_double_density(bool is_double_density) {
is_double_density_ = is_double_density;
Storage::Time bit_length;
bit_length.length = 1;
bit_length.clock_rate = is_double_density ? 500000 : 250000;
set_expected_bit_length(bit_length);
shifter_.set_is_double_density(is_double_density);
}
bool MFMController::get_is_double_density() {
return is_double_density_;
}
void MFMController::set_data_mode(DataMode mode) {
data_mode_ = mode;
shifter_.set_should_obey_syncs(mode == DataMode::Scanning);
}
MFMController::Token MFMController::get_latest_token() {
return latest_token_;
}
CRC::CCITT &MFMController::get_crc_generator() {
return crc_generator_;
}
void MFMController::process_input_bit(int value) {
if(data_mode_ == DataMode::Writing) return;
shifter_.add_input_bit(value);
switch(shifter_.get_token()) {
case Encodings::MFM::Shifter::Token::None:
return;
case Encodings::MFM::Shifter::Token::Index:
latest_token_.type = Token::Index;
break;
case Encodings::MFM::Shifter::Token::ID:
latest_token_.type = Token::ID;
break;
case Encodings::MFM::Shifter::Token::Data:
latest_token_.type = Token::Data;
break;
case Encodings::MFM::Shifter::Token::DeletedData:
latest_token_.type = Token::DeletedData;
break;
case Encodings::MFM::Shifter::Token::Sync:
latest_token_.type = Token::Sync;
break;
case Encodings::MFM::Shifter::Token::Byte:
latest_token_.type = Token::Byte;
break;
}
latest_token_.byte_value = shifter_.get_byte();
posit_event(int(Event::Token));
}
void MFMController::write_bit(int bit) {
if(is_double_density_) {
get_drive().write_bit(!bit && !last_bit_);
get_drive().write_bit(!!bit);
last_bit_ = bit;
} else {
get_drive().write_bit(true);
get_drive().write_bit(!!bit);
}
}
void MFMController::write_byte(uint8_t byte) {
for(int c = 0; c < 8; c++) write_bit((byte << c)&0x80);
crc_generator_.add(byte);
}
void MFMController::write_raw_short(uint16_t value) {
for(int c = 0; c < 16; c++) {
get_drive().write_bit(!!((value << c)&0x8000));
}
}
void MFMController::write_crc() {
uint16_t crc = get_crc_generator().get_value();
write_byte(crc >> 8);
write_byte(crc & 0xff);
}
void MFMController::write_n_bytes(int quantity, uint8_t value) {
while(quantity--) write_byte(value);
}
void MFMController::write_id_joiner() {
if(get_is_double_density()) {
write_n_bytes(12, 0x00);
for(int c = 0; c < 3; c++) write_raw_short(Storage::Encodings::MFM::MFMSync);
get_crc_generator().set_value(Storage::Encodings::MFM::MFMPostSyncCRCValue);
write_byte(Storage::Encodings::MFM::IDAddressByte);
} else {
write_n_bytes(6, 0x00);
get_crc_generator().reset();
write_raw_short(Storage::Encodings::MFM::FMIDAddressMark);
}
}
void MFMController::write_id_data_joiner(bool is_deleted, bool skip_first_gap) {
if(get_is_double_density()) {
if(!skip_first_gap) write_n_bytes(22, 0x4e);
write_n_bytes(12, 0x00);
for(int c = 0; c < 3; c++) write_raw_short(Storage::Encodings::MFM::MFMSync);
get_crc_generator().set_value(Storage::Encodings::MFM::MFMPostSyncCRCValue);
write_byte(is_deleted ? Storage::Encodings::MFM::DeletedDataAddressByte : Storage::Encodings::MFM::DataAddressByte);
} else {
if(!skip_first_gap) write_n_bytes(11, 0xff);
write_n_bytes(6, 0x00);
get_crc_generator().reset();
get_crc_generator().add(is_deleted ? Storage::Encodings::MFM::DeletedDataAddressByte : Storage::Encodings::MFM::DataAddressByte);
write_raw_short(is_deleted ? Storage::Encodings::MFM::FMDeletedDataAddressMark : Storage::Encodings::MFM::FMDataAddressMark);
}
}
void MFMController::write_post_data_gap() {
if(get_is_double_density()) {
write_n_bytes(54, 0x4e);
} else {
write_n_bytes(27, 0xff);
}
}
void MFMController::write_start_of_track() {
if(get_is_double_density()) {
write_n_bytes(80, 0x4e);
write_n_bytes(12, 0x00);
for(int c = 0; c < 3; c++) write_raw_short(Storage::Encodings::MFM::MFMIndexSync);
write_byte(Storage::Encodings::MFM::IndexAddressByte);
write_n_bytes(50, 0x4e);
} else {
write_n_bytes(40, 0xff);
write_n_bytes(6, 0x00);
write_raw_short(Storage::Encodings::MFM::FMIndexAddressMark);
write_n_bytes(26, 0xff);
}
}