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Makes a more concrete attempt at track/sector combination.

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This commit is contained in:
Thomas Harte 2020-01-12 22:18:31 -05:00
parent 83ed36eb08
commit 2d233b6358
3 changed files with 135 additions and 226 deletions
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1
Components/1770/1770.cpp
View File

@ -336,6 +336,7 @@ void WD1770::posit_event(int new_event_type) {
READ_ID();
if(index_hole_count_ == 6) {
LOG("Nothing found to verify");
update_status([] (Status &status) {
status.seek_error = true;
});

22
Storage/Disk/DPLL/DigitalPhaseLockedLoop.hpp
View File

@ -83,7 +83,7 @@ template <typename BitHandler, size_t length_of_history = 3> class DigitalPhaseL
total_spacing_ -= offset_history_[offset_history_pointer_].spacing;
// Fill in the new fields.
const auto multiple = (new_offset + (clocks_per_bit_ >> 1)) / clocks_per_bit_;
const auto multiple = std::max((new_offset + (clocks_per_bit_ >> 1)) / clocks_per_bit_, Cycles::IntType(1));
offset_history_[offset_history_pointer_].divisor = multiple;
offset_history_[offset_history_pointer_].spacing = new_offset;
@ -94,19 +94,19 @@ template <typename BitHandler, size_t length_of_history = 3> class DigitalPhaseL
// Advance the write slot.
offset_history_pointer_ = (offset_history_pointer_ + 1) % offset_history_.size();
#ifndef NDEBUG
Cycles::IntType td = 0, ts = 0;
for(auto offset: offset_history_) {
td += offset.divisor;
ts += offset.spacing;
}
assert(ts == total_spacing_);
assert(td == total_divisor_);
#endif
// In net: use an unweighted average of the stored offsets to compute current window size,
// bucketing them by rounding to the nearest multiple of the base clocks per bit
window_length_ = total_spacing_ / total_divisor_;
#ifndef NDEBUG
bool are_all_filled = true;
for(auto offset: offset_history_) {
if(offset.spacing == 1) {
are_all_filled = false;
break;
}
}
assert(!are_all_filled || (window_length_ >= ((clocks_per_bit_ * 9) / 10) && window_length_ <= ((clocks_per_bit_ * 11) / 10)));
#endif
// Also apply a difference to phase, use a simple spring mechanism as a lowpass filter.
const auto error = new_phase - (window_length_ >> 1);

338
Storage/Disk/DiskImage/Formats/STX.cpp
View File

@ -42,17 +42,25 @@ class TrackConstructor {
std::vector<uint16_t> timing;
// Accessors.
/// @returns The byte size of this sector, according to its address mark.
uint32_t data_size() const {
return uint32_t(128 << address[3]);
}
/// @returns The byte stream this sector address would produce if a WD read track command were to observe it.
std::vector<uint8_t> get_track_address_image() const {
return track_encoding(address.begin(), address.begin() + 4, {0xa1, 0xfe});
return track_encoding(address.begin(), address.begin() + 4, {0xa1, 0xa1, 0xfe});
}
/// @returns The byte stream this sector data would produce if a WD read track command were to observe it.
std::vector<uint8_t> get_track_data_image() const {
return track_encoding(contents.begin(), contents.end(), {0xa1, 0xfb});
return track_encoding(contents.begin(), contents.end(), {0xa1, 0xa1, 0xfb});
}
private:
/// @returns The effect of encoding @c prefix followed by the bytes from @c begin to @c end as MFM data and then decoding them as if
/// observed by a WD read track command.
template <typename T> static std::vector<uint8_t> track_encoding(T begin, T end, std::initializer_list<uint8_t> prefix) {
std::vector<uint8_t> result;
result.reserve(size_t(end - begin) + prefix.size());
@ -119,57 +127,135 @@ class TrackConstructor {
// To reconcile the list of sectors with the WD get track-style track image,
// use sector bodies as definitive and refer to the track image for in-fill.
auto track_position = track_data_.begin();
const auto address_mark = {0xa1, 0xa1, 0xfe};
const auto track_mark = {0xa1, 0xa1, 0xfb};
struct Location {
enum Type {
Address, Data
} type;
std::vector<uint8_t>::const_iterator position;
const Sector &sector;
Location(Type type, std::vector<uint8_t>::const_iterator position, const Sector &sector) : type(type), position(position), sector(sector) {}
};
std::vector<Location> locations;
for(const auto &sector: sectors_) {
// Find out what the header would look like, if found in a read track.
const auto track_address = sector.get_track_address_image();
const auto track_data = sector.get_track_data_image();
{
// Find out what the address would look like, if found in a read track.
const auto track_address = sector.get_track_address_image();
// Try to locate the header within the track image.
const auto address_position = std::search(track_position, track_data_.end(), track_address.begin(), track_address.end());
const auto data_position = std::search(track_position, track_data_.end(), track_data.begin(), track_data.end());
// Try to locate the header within the track image; if it can't be found then settle for
// the next thing that looks like a header of any sort.
auto address_position = std::search(track_position, track_data_.end(), track_address.begin(), track_address.end());
if(address_position == track_data_.end()) {
address_position = std::search(track_position, track_data_.end(), address_mark.begin(), address_mark.end());
}
if(address_position == track_data_.end()) {
printf("?\n");
}
if(data_position == track_data_.end()) {
printf("??\n");
// Stop now if there's nowhere obvious to put this sector.
if(address_position == track_data_.end()) break;
locations.emplace_back(Location::Address, address_position, sector);
// Advance the track position.
track_position = address_position;
}
printf("%lu / %lu\n", address_position - track_data_.begin(), data_position - track_data_.begin());
// Do much the same thing for the data, if it exists.
if(!(sector.status & 0x10)) {
const auto track_data = sector.get_track_data_image();
// HACK: assume nothing between sectors. Crazy time!
auto data_position = std::search(track_position, track_data_.end(), track_data.begin(), track_data.end());
if(data_position == track_data_.end()) {
data_position = std::search(track_position, track_data_.end(), track_mark.begin(), track_mark.end());
}
if(data_position == track_data_.end()) break;
locations.emplace_back(Location::Data, data_position, sector);
track_position = data_position;
}
}
// Write out, being wary of potential overlapping sectors, and copying from track_data_ to fill in gaps.
auto location = locations.begin();
track_position = track_data_.begin();
while(location != locations.end()) {
// Just create an encoder if one doesn't exist. TODO: factor in data rate.
if(!encoder) {
segment.reset(new PCMSegment);
encoder = Storage::Encodings::MFM::GetMFMEncoder(segment->data);
}
// Add sector header.
encoder->add_ID_address_mark();
for(size_t c = 0; c < 6; ++c)
encoder->add_byte(sector.address[c]);
// Add a gap.
for(int c = 0; c < 12; ++c)
encoder->add_byte(0x4e);
// Add sector body.
encoder->add_data_address_mark();
for(const auto byte: sector.contents) {
encoder->add_byte(byte);
// Advance to location.position.
while(track_position != location->position) {
encoder->add_byte(*track_position);
++track_position;
}
encoder->add_crc(sector.status & 0x8); // Get the CRC wrong if required. (TODO: take from track image, if possible?)
// Add a gap.
for(int c = 0; c < 42; ++c)
encoder->add_byte(0x4e);
// Write the relevant mark and fill in a default number of bytes to write.
size_t bytes_to_write;
switch(location->type) {
default:
case Location::Address:
encoder->add_ID_address_mark();
bytes_to_write = 6;
break;
case Location::Data:
if(location->sector.status & 0x20)
encoder->add_deleted_data_address_mark();
else
encoder->add_data_address_mark();
bytes_to_write = location->sector.data_size() + 2;
break;
}
track_position += 3;
// Decide how much data to write for real; this [partially] allows for overlapping sectors.
auto next_location = location + 1;
if(next_location != locations.end()) {
bytes_to_write = std::min(bytes_to_write, size_t(next_location->position - track_position));
}
// Skip that many bytes from the underlying track image.
track_position += ssize_t(bytes_to_write);
// Write bytes.
switch(location->type) {
default:
case Location::Address:
for(size_t c = 0; c < bytes_to_write; ++c)
encoder->add_byte(location->sector.address[c]);
break;
case Location::Data: {
const auto body_bytes = std::min(bytes_to_write, size_t(location->sector.data_size()));
for(size_t c = 0; c < body_bytes; ++c)
encoder->add_byte(location->sector.contents[c]);
// Add a CRC only if it fits (TODO: crop if necessary?).
if(bytes_to_write & 127) {
encoder->add_crc((location->sector.status & 0x18) == 0x10);
}
} break;
}
// Advance location.
++location;
}
// while(segment->data.size() < track_size_ * 16) {
// encoder->add_byte(0x4e);
// }
// Write anything remaining from the track image.
while(track_position < track_data_.end()) {
encoder->add_byte(*track_position);
++track_position;
}
while(segment->data.size() < 6250 * 16) {
// Write generic padding up until the specified track size.
while(segment->data.size() < track_size_ * 16) {
encoder->add_byte(0x4e);
}
// Pad out to the minimum size a WD can actually make sense of.
// I've no idea why it's valid for tracks to be shorter than this,
// so likely I'm suffering a comprehansion deficiency.
// TODO: determine why this isn't correct (or, possibly, is).
while(segment->data.size() < 5750 * 16) {
encoder->add_byte(0x4e);
}
@ -247,10 +333,6 @@ std::shared_ptr<::Storage::Disk::Track> STX::get_track_at_position(::Storage::Di
const int track_index = (address.head * 0x80) + address.position.as_int();
if(!offset_by_track_[track_index]) return nullptr;
if(track_index == 41) {
printf("Y\n");
} else printf("N\n");
// Seek to the track (skipping the record size field).
file_.seek(offset_by_track_[track_index] + 4, SEEK_SET);
@ -258,7 +340,7 @@ std::shared_ptr<::Storage::Disk::Track> STX::get_track_at_position(::Storage::Di
const uint32_t fuzzy_size = file_.get32le();
const uint16_t sector_count = file_.get16le();
const uint16_t flags = file_.get16le();
const size_t track_length = size_t(file_.get16le() << 3); // Convert bytes to bits.
const size_t track_length = file_.get16le();
file_.seek(2, SEEK_CUR); // Skip track type; despite being named, it's apparently unused.
// If this is a trivial .ST-style sector dump, life is easy.
@ -387,178 +469,4 @@ std::shared_ptr<::Storage::Disk::Track> STX::get_track_at_position(::Storage::Di
TrackConstructor constructor(track_data, sectors, track_length, first_sync);
return constructor.get_track();
/*
* if track_data is not empty, it is what you'd see from a read track command;
* the vector of sectors will contain sectors to be written; contents will be populated,
and each individually may or may not have a fuzzy_mask and/or timing.
Also note track_length, which is the perceived length of the track, rounded to whole bytes.
*/
/* if(track_data.empty()) {
} else {
// Locate things that might be ID or data address marks; as a side effect of the way
// this is implemented, the byte_locations will be set to the first bit of apparent
// content for an ID or data mark.
struct PotentialMark {
enum class Type { ID, Data } type;
size_t byte_location;
PotentialMark(Type type, size_t byte_location) : type(type), byte_location(byte_location) {}
};
std::vector<PotentialMark> potential_marks;
{
const uint32_t id_mark = 0xa1a1fe;
const uint32_t data_mark = 0xa1a1fb;
uint32_t shifter = 0;
for(size_t c = 0; c < track_data.size(); ++c) {
shifter = ((shifter << 8) | track_data[c]) & 0xffffff;
if(shifter == id_mark) {
potential_marks.emplace_back(PotentialMark::Type::ID, c);
} else if(shifter == data_mark) {
potential_marks.emplace_back(PotentialMark::Type::Data, c);
}
}
}
// For each sector that exists, locate the correlated potential marks.
// Since sectors are now in track order, a forward walk through potential
// marks should work.
auto next_mark = potential_marks.begin();
for(auto &sector: sectors) {
if(sector.data_offset < track_data.size()) {
// The sector already tells us where its body is, so life is easy.
// Link the body to its known position, and backtrack to find the ID.
sector.track_offset_of_data = sector.data_offset;
// Search for an unconsumed data mark at this location.
auto data_search = next_mark;
while(
data_search != potential_marks.end() &&
!(data_search->type == PotentialMark::Type::Data && data_search->byte_location == sector.track_offset_of_data))
++data_search;
// Advance the potential mark consumption pointer.
next_mark = data_search + 1;
// Recede to a previous ID mark if possible.
while(data_search >= potential_marks.begin() &&
!(data_search->type == PotentialMark::Type::ID && data_search->byte_location >= sector.track_offset_of_data - 150))
--data_search;
if(data_search >= potential_marks.begin()) {
sector.track_offset_of_header = data_search->byte_location;
} else {
// Couldn't figure this one out; just make a geuss.
sector.track_offset_of_header = sector.track_offset_of_data - 50;
}
} else {
// For either approach below, the next ID is needed.
while(next_mark != potential_marks.end() && next_mark->type != PotentialMark::Type::ID)
++next_mark;
if(next_mark == potential_marks.end()) break;
// This sector's body isn't accurately represented within the read track
// image (or, at least, isn't decalred to be), so look for a suitable
// ID mark and then — if it has a body — consume the next data mark too.
if(sector.status & 0x10) {
// There's no placement information to go from, so compare by ID fields. As long
// as at least two bytes match, that'll do. Arbitrarily.
int matches = 0;
for(size_t c = 0; c < 4; ++c) {
matches += track_data[next_mark->byte_location + c] == sector.address[c];
}
if(matches >= 2) {
sector.track_offset_of_header = next_mark->byte_location;
++ next_mark;
} else {
// Desperation. The meaning of bit_position versus the track_contents is
// fairly undefined at the best of times, but seems to correlate with data
// rather than the header anyway. So, ummm...
sector.track_offset_of_header = sector.bit_position >> 3;
}
} else {
// If the next potential marks are an ID/data pair, and the stated data location is within
// 100 bytes of that encoded in the sector, take it.
auto data_mark = next_mark + 1;
if(
next_mark->type == PotentialMark::Type::ID &&
data_mark->type == PotentialMark::Type::Data &&
std::abs(int(next_mark->byte_location - (sector.bit_position >> 3))) < 100) {
sector.track_offset_of_header = next_mark->byte_location;
sector.track_offset_of_data = data_mark->byte_location;
next_mark += 2;
} else {
// Don't know. TODO?
}
}
}
}
// The game: take bytes from track_data unless or until a sector is hit.
auto next_sector = sectors.begin();
size_t bytes_consumed = 0;
std::unique_ptr<Encodings::MFM::Encoder> encoder;
std::unique_ptr<PCMSegment> segment;
while(bytes_consumed < track_length) {
// Next event is either the next sector or the end of the track. Let's see.
size_t bytes_to_consume =
((next_sector != sectors.end()) ?
next_sector->track_offset_of_header : track_length) - bytes_consumed;
// Write from bits_written to bits_written + bits_to_consume from track_data
// to an encoder. If there is no encoder right now, create one.
if(!encoder) {
segment.reset(new PCMSegment);
encoder = Encodings::MFM::GetMFMEncoder(segment->data);
}
// Output bytes up to the sector.
while(bytes_to_consume--) {
encoder->add_byte(track_data[bytes_consumed]);
++bytes_consumed;
}
// Chuck out a sector if it's time for one.
if(next_sector != sectors.end()) {
// Output header.
encoder->add_ID_address_mark(); // This is four 'bytes', but pretend it's three.
encoder->add_byte(next_sector->address[0]);
encoder->add_byte(next_sector->address[1]);
encoder->add_byte(next_sector->address[2]);
encoder->add_byte(next_sector->address[3]);
if(next_sector->address_has_crc) {
encoder->add_byte(next_sector->address[4]);
encoder->add_byte(next_sector->address[5]);
} else {
encoder->add_crc((next_sector->status & 0x18) == 0x18);
}
bytes_consumed += 9;
if(!(next_sector->status & 0x10)) {
while(bytes_consumed < next_sector->track_offset_of_data) {
encoder->add_byte(track_data[bytes_consumed]);
++bytes_consumed;
}
encoder->add_data_address_mark(); // Also four bytes, which we'll model as three.
for(const auto byte: next_sector->contents) {
encoder->add_byte(byte);
}
encoder->add_crc(next_sector->status & 0x8);
bytes_consumed += next_sector->contents.size() + 5;
}
++next_sector;
}
}
return std::make_shared<PCMTrack>(*segment);
}*/
}