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Advances to being able to cope with STXs with no special features whatsoever.

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Well, other than perhaps a broken data CRC. Fuzzy bits, timing differences and the stuff between sectors are all currently absent.
This commit is contained in:
Thomas Harte 2020-01-09 21:03:01 -05:00
parent 985b36da73
commit b4befd57a9
1 changed files with 172 additions and 109 deletions
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207
Storage/Disk/DiskImage/Formats/STX.cpp
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@ -24,6 +24,79 @@ namespace {
class TrackConstructor {
public:
constexpr static uint16_t NoFirstOffset = std::numeric_limits<uint16_t>::max();
struct Sector {
// Records explicitly present in the sector table.
uint32_t data_offset = 0;
size_t bit_position = 0;
uint16_t data_duration = 0;
uint8_t address[6] = {0, 0, 0, 0, 0, 0};
uint8_t status = 0;
// Other facts that will either be supplied by the STX or which
// will be empty.
std::vector<uint8_t> fuzzy_mask;
std::vector<uint8_t> contents;
std::vector<uint16_t> timing;
// Accessors.
uint32_t data_size() {
return uint32_t(128 << address[3]);
}
// std::vector<uint8_t> get_track_header_image() {
//
// }
};
TrackConstructor(const std::vector<uint8_t> &track_data, const std::vector<Sector> &sectors, size_t track_size, uint16_t first_sync) :
track_data_(track_data), sectors_(sectors), track_size_(track_size), first_sync_(first_sync) {
}
std::shared_ptr<PCMTrack> get_track() {
std::unique_ptr<Storage::Encodings::MFM::Encoder> encoder;
std::unique_ptr<PCMSegment> segment;
// 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.
for(const auto &sector: sectors_) {
// HACK: assume nothing between sectors. Crazy time!
if(!encoder) {
segment.reset(new PCMSegment);
encoder = Storage::Encodings::MFM::GetMFMEncoder(segment->data);
}
// Add sector header.
encoder->add_ID_address_mark();
for(int 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);
}
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);
}
return std::make_shared<PCMTrack>(*segment);
}
private:
const std::vector<uint8_t> &track_data_;
const std::vector<Sector> &sectors_;
const size_t track_size_;
const uint16_t first_sync_;
};
@ -107,32 +180,11 @@ std::shared_ptr<::Storage::Disk::Track> STX::get_track_at_position(::Storage::Di
}
// Grab sector records, if provided.
struct Sector {
// Records explicitly present in the sector table.
uint32_t data_offset = 0;
size_t bit_position = 0;
uint16_t data_duration = 0;
uint8_t address[6] = {0, 0, 0, 0, 0, 0};
uint8_t status = 0;
std::vector<TrackConstructor::Sector> sectors;
std::vector<uint8_t> track_data;
uint16_t first_sync = TrackConstructor::NoFirstOffset;
// Other facts that will either be supplied by the STX or which
// will be empty.
std::vector<uint8_t> fuzzy_mask;
std::vector<uint8_t> contents;
// Information accumulated locally during processing.
bool address_has_crc = true;
size_t track_offset_of_header = 0;
size_t track_offset_of_data = 0;
// Accessors.
uint32_t data_size() {
return uint32_t(128 << address[3]);
}
};
std::vector<Sector> sectors;
if(flags & 1) {
// Read sector records first.
// Sector records come first.
for(uint16_t c = 0; c < sector_count; ++c) {
sectors.emplace_back();
sectors.back().data_offset = file_.get32le();
@ -143,7 +195,7 @@ std::shared_ptr<::Storage::Disk::Track> STX::get_track_at_position(::Storage::Di
file_.seek(1, SEEK_CUR);
}
// Now read fuzzy masks, if available.
// If fuzzy masks are specified, attach them to their corresponding sectors.
if(fuzzy_size) {
uint32_t fuzzy_bytes_read = 0;
for(auto &sector: sectors) {
@ -165,56 +217,29 @@ std::shared_ptr<::Storage::Disk::Track> STX::get_track_at_position(::Storage::Di
// But, just in case, check and possibly skip some.
file_.seek(long(fuzzy_size) - fuzzy_bytes_read, SEEK_CUR);
}
} else {
// No sector records, so there should be no fuzzy records.
// Skip the supplied size, just in case.
file_.seek(fuzzy_size, SEEK_CUR);
}
// From here: there's either a track image or there isn't.
//
// If there is then it may or may not contain the sector bodies.
// The sectors themselves will be the guide — if they have
// offsets within the track image then that's that; if it's
// outside then that implies extra sector contents.
//
// If there isn't a track image at all then either the sectors
// were explicit or they're completely implicit, like an ST file.
// There may or may not be a track image. Grab it if so.
// Grab the read-track-esque track contents, if available.
std::vector<uint8_t> track_data;
long sector_start = file_.tell();
if(flags & 0x40) {
// Bit 6 => there is a track to read;
// bit
if(flags & 0x80) {
const uint16_t first_sync = file_.get16le();
first_sync = file_.get16le();
const uint16_t image_size = file_.get16le();
track_data = file_.read(image_size);
// TODO: and encode... ignoring sector contents?
(void)first_sync;
} else {
const uint16_t image_size = file_.get16le();
track_data = file_.read(image_size);
}
}
// Grab all sector contents.
if(sectors.empty()) {
// No explicit sectors were given, so create the implied sort.
for(int c = 0; c < sector_count; ++c) {
sectors.emplace_back();
sectors.back().address[0] = uint8_t(address.position.as_int()); // Track.
sectors.back().address[1] = uint8_t(address.head); // Head.
sectors.back().address[2] = uint8_t(c + 1); // Sector.
sectors.back().address[3] = uint8_t(c + 1); // Size.
sectors.back().address_has_crc = false;
sectors.back().contents = file_.read(512);
sectors.back().bit_position = size_t(c); // For the sake of ordering only.
}
} else {
// Grab sector contents.
long end_of_data = file_.tell();
for(auto &sector: sectors) {
// If the FDC record-not-found flag is set, there's no sector body to find.
// Otherwise there's a sector body in the file somewhere.
if(!(sector.status & 0x10)) {
file_.seek(sector.data_offset + sector_start, SEEK_SET);
sector.contents = file_.read(sector.data_size());
@ -222,16 +247,60 @@ std::shared_ptr<::Storage::Disk::Track> STX::get_track_at_position(::Storage::Di
}
}
file_.seek(end_of_data, SEEK_SET);
// Grab timing info if available.
file_.seek(4, SEEK_CUR); // Skip the timing descriptor, as it includes no new information.
for(auto &sector: sectors) {
// Skip any sector with no intra-sector bit width variation.
if(!(sector.status&1)) continue;
const auto timing_record_size = sector.data_size() >> 4; // Use one entry per 16 bytes.
sector.timing.resize(timing_record_size);
if(!is_new_format_) {
// Generate timing records for Macrodos/Speedlock.
// Timing is specified in quarters. Which might or might not be
// quantities of 128 bytes, who knows?
for(size_t c = 0; c < timing_record_size; ++c) {
if(c < (timing_record_size >> 2)) {
sector.timing[c] = 127;
} else if(c < ((timing_record_size*2) >> 2)) {
sector.timing[c] = 133;
} else if(c < ((timing_record_size*3) >> 2)) {
sector.timing[c] = 121;
} else {
sector.timing[c] = 127;
}
}
// Check for timing info.
if(is_new_format_) {
// Do something, do something, else, else.
continue;
}
// This is going to be a new-format record.
for(size_t c = 0; c < timing_record_size; ++c) {
sector.timing[c] = file_.get16be(); // These values are big endian, unlike the rest of the file.
}
}
// Sort the sectors by starting position. It's perfectly possible that they're always
// sorted in STX but, again, the reverse-engineered documentation doesn't make the
// promise, so that's that.
std::sort(sectors.begin(), sectors.end(),
[] (TrackConstructor::Sector &lhs, TrackConstructor::Sector &rhs) {
return lhs.bit_position < rhs.bit_position;
});
/*
Having reached here:
Having reached here, the actual stuff of parsing the file structure should be done.
So hand off to the TrackConstructor.
*/
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.
@ -239,12 +308,7 @@ std::shared_ptr<::Storage::Disk::Track> STX::get_track_at_position(::Storage::Di
Also note track_length, which is the perceived length of the track, rounded to whole bytes.
*/
// Sort the sectors by starting position. It's perfectly possible that they're always
// sorted in STX but, again, the reverse-engineered documentation doesn't make the
// promise, so that's that.
std::sort(sectors.begin(), sectors.end(), [] (Sector &lhs, Sector &rhs) { return lhs.bit_position < rhs.bit_position; });
if(track_data.empty()) {
/* if(track_data.empty()) {
} else {
// Locate things that might be ID or data address marks; as a side effect of the way
@ -407,7 +471,6 @@ std::shared_ptr<::Storage::Disk::Track> STX::get_track_at_position(::Storage::Di
}
return std::make_shared<PCMTrack>(*segment);
}
}*/
return nullptr;
}