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CLK/Storage/Disk/Formats/AcornADF.cpp
2017-07-21 21:53:27 -04:00

106 lines
3.3 KiB
C++

//
// AcornADF.cpp
// Clock Signal
//
// Created by Thomas Harte on 25/09/2016.
// Copyright © 2016 Thomas Harte. All rights reserved.
//
#include "AcornADF.hpp"
#include <sys/stat.h>
#include "../Encodings/MFM.hpp"
namespace {
static const unsigned int sectors_per_track = 16;
static const unsigned int bytes_per_sector = 256;
}
using namespace Storage::Disk;
AcornADF::AcornADF(const char *file_name) :
Storage::FileHolder(file_name) {
// very loose validation: the file needs to be a multiple of 256 bytes
// and not ungainly large
if(file_stats_.st_size % bytes_per_sector) throw ErrorNotAcornADF;
if(file_stats_.st_size < 7 * bytes_per_sector) throw ErrorNotAcornADF;
// check that the initial directory's 'Hugo's are present
fseek(file_, 513, SEEK_SET);
uint8_t bytes[4];
fread(bytes, 1, 4, file_);
if(bytes[0] != 'H' || bytes[1] != 'u' || bytes[2] != 'g' || bytes[3] != 'o') throw ErrorNotAcornADF;
fseek(file_, 0x6fb, SEEK_SET);
fread(bytes, 1, 4, file_);
if(bytes[0] != 'H' || bytes[1] != 'u' || bytes[2] != 'g' || bytes[3] != 'o') throw ErrorNotAcornADF;
}
AcornADF::~AcornADF() {
flush_updates();
}
unsigned int AcornADF::get_head_position_count() {
return 80;
}
unsigned int AcornADF::get_head_count() {
return 1;
}
bool AcornADF::get_is_read_only() {
return is_read_only_;
}
long AcornADF::get_file_offset_for_position(unsigned int head, unsigned int position) {
return (position * 1 + head) * bytes_per_sector * sectors_per_track;
}
std::shared_ptr<Track> AcornADF::get_uncached_track_at_position(unsigned int head, unsigned int position) {
std::shared_ptr<Track> track;
if(head >= 2) return track;
long file_offset = get_file_offset_for_position(head, position);
fseek(file_, file_offset, SEEK_SET);
std::vector<Storage::Encodings::MFM::Sector> sectors;
for(unsigned int sector = 0; sector < sectors_per_track; sector++) {
Storage::Encodings::MFM::Sector new_sector;
new_sector.track = (uint8_t)position;
new_sector.side = (uint8_t)head;
new_sector.sector = (uint8_t)sector;
new_sector.data.resize(bytes_per_sector);
fread(&new_sector.data[0], 1, bytes_per_sector, file_);
if(feof(file_))
break;
sectors.push_back(std::move(new_sector));
}
if(sectors.size()) return Storage::Encodings::MFM::GetMFMTrackWithSectors(sectors);
return track;
}
void AcornADF::store_updated_track_at_position(unsigned int head, unsigned int position, const std::shared_ptr<Track> &track, std::mutex &file_access_mutex) {
std::vector<uint8_t> parsed_track;
Storage::Encodings::MFM::Parser parser(true, track);
for(unsigned int c = 0; c < sectors_per_track; c++) {
std::shared_ptr<Storage::Encodings::MFM::Sector> sector = parser.get_sector((uint8_t)position, (uint8_t)c);
if(sector) {
parsed_track.insert(parsed_track.end(), sector->data.begin(), sector->data.end());
} else {
// TODO: what's correct here? Warn the user that whatever has been written to the disk,
// it can no longer be stored as an SSD? If so, warn them by what route?
parsed_track.resize(parsed_track.size() + bytes_per_sector);
}
}
std::lock_guard<std::mutex> lock_guard(file_access_mutex);
long file_offset = get_file_offset_for_position(head, position);
ensure_file_is_at_least_length(file_offset);
fseek(file_, file_offset, SEEK_SET);
fwrite(parsed_track.data(), 1, parsed_track.size(), file_);
}