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CLK/Storage/Disk/DiskImage/Formats/OricMFMDSK.cpp

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//
// OricMFMDSK.cpp
// Clock Signal
//
// Created by Thomas Harte on 21/11/2016.
// Copyright 2016 Thomas Harte. All rights reserved.
//
#include "OricMFMDSK.hpp"
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#include "../../Encodings/MFM/Constants.hpp"
#include "../../Encodings/MFM/Shifter.hpp"
#include "../../Encodings/MFM/Encoder.hpp"
#include "../../Track/PCMTrack.hpp"
#include "../../Track/TrackSerialiser.hpp"
using namespace Storage::Disk;
OricMFMDSK::OricMFMDSK(const std::string &file_name) :
file_(file_name) {
if(!file_.check_signature("MFM_DISK"))
throw Error::InvalidFormat;
head_count_ = file_.get32le();
track_count_ = file_.get32le();
geometry_type_ = file_.get32le();
if(geometry_type_ < 1 || geometry_type_ > 2)
throw Error::InvalidFormat;
}
HeadPosition OricMFMDSK::get_maximum_head_position() {
return HeadPosition(static_cast<int>(track_count_));
}
int OricMFMDSK::get_head_count() {
return static_cast<int>(head_count_);
}
long OricMFMDSK::get_file_offset_for_position(Track::Address address) {
int seek_offset = 0;
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switch(geometry_type_) {
case 1:
seek_offset = address.head * static_cast<int>(track_count_) + address.position.as_int();
break;
case 2:
seek_offset = address.position.as_int() * static_cast<int>(track_count_ * head_count_) + address.head;
break;
}
return static_cast<long>(seek_offset) * 6400 + 256;
}
std::shared_ptr<Track> OricMFMDSK::get_track_at_position(Track::Address address) {
PCMSegment segment;
{
std::lock_guard<std::mutex> lock_guard(file_.get_file_access_mutex());
file_.seek(get_file_offset_for_position(address), SEEK_SET);
// The file format omits clock bits. So it's not a genuine MFM capture.
// A consumer must contextually guess when an FB, FC, etc is meant to be a control mark.
std::size_t track_offset = 0;
uint8_t last_header[6] = {0, 0, 0, 0, 0, 0};
std::unique_ptr<Encodings::MFM::Encoder> encoder = Encodings::MFM::GetMFMEncoder(segment.data);
bool did_sync = false;
while(track_offset < 6250) {
uint8_t next_byte = file_.get8();
track_offset++;
switch(next_byte) {
default: {
encoder->add_byte(next_byte);
if(did_sync) {
switch(next_byte) {
default: break;
case 0xfe:
for(int byte = 0; byte < 6; byte++) {
last_header[byte] = file_.get8();
encoder->add_byte(last_header[byte]);
++track_offset;
if(track_offset == 6250) break;
}
break;
case 0xfb:
for(int byte = 0; byte < (128 << last_header[3]) + 2; byte++) {
encoder->add_byte(file_.get8());
++track_offset;
// Special exception: don't interrupt a sector body if it seems to
// be about to run over the end of the track. It seems like BD-500
// disks break the usual 6250-byte rule, pushing out to just less
// than 6400 bytes total.
if(track_offset == 6400) break;
}
break;
}
}
did_sync = false;
}
break;
case 0xa1: // a synchronisation mark that implies a sector or header coming
encoder->output_short(Storage::Encodings::MFM::MFMSync);
did_sync = true;
break;
case 0xc2: // an 'ordinary' synchronisation mark
encoder->output_short(Storage::Encodings::MFM::MFMIndexSync);
break;
}
}
}
return std::make_shared<PCMTrack>(segment);
}
void OricMFMDSK::set_tracks(const std::map<Track::Address, std::shared_ptr<Track>> &tracks) {
for(const auto &track : tracks) {
PCMSegment segment = Storage::Disk::track_serialisation(*track.second, Storage::Encodings::MFM::MFMBitLength);
Storage::Encodings::MFM::Shifter shifter;
shifter.set_is_double_density(true);
shifter.set_should_obey_syncs(true);
std::vector<uint8_t> parsed_track;
int size = 0;
int offset = 0;
bool capture_size = false;
for(const auto bit : segment.data) {
shifter.add_input_bit(bit ? 1 : 0);
if(shifter.get_token() == Storage::Encodings::MFM::Shifter::Token::None) continue;
parsed_track.push_back(shifter.get_byte());
if(offset) {
offset--;
if(!offset) {
shifter.set_should_obey_syncs(true);
}
if(capture_size && offset == 2) {
size = parsed_track.back();
capture_size = false;
}
}
if( shifter.get_token() == Storage::Encodings::MFM::Shifter::Token::Data ||
shifter.get_token() == Storage::Encodings::MFM::Shifter::Token::DeletedData) {
offset = 128 << size;
shifter.set_should_obey_syncs(false);
}
if(shifter.get_token() == Storage::Encodings::MFM::Shifter::Token::ID) {
offset = 6;
shifter.set_should_obey_syncs(false);
capture_size = true;
}
}
long file_offset = get_file_offset_for_position(track.first);
std::lock_guard<std::mutex> lock_guard(file_.get_file_access_mutex());
file_.seek(file_offset, SEEK_SET);
std::size_t track_size = std::min(static_cast<std::size_t>(6400), parsed_track.size());
file_.write(parsed_track.data(), track_size);
}
}
bool OricMFMDSK::get_is_read_only() {
return file_.get_is_known_read_only();
}