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114 lines
3.2 KiB
C++
114 lines
3.2 KiB
C++
//
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// SSD.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 18/09/2016.
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// Copyright © 2016 Thomas Harte. All rights reserved.
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//
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#include "SSD.hpp"
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#include <sys/stat.h>
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#include "../Encodings/MFM.hpp"
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using namespace Storage::Disk;
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SSD::SSD(const char *file_name) :
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Storage::FileHolder(file_name)
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{
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// very loose validation: the file needs to be a multiple of 256 bytes
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// and not ungainly large
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if(file_stats_.st_size & 255) throw ErrorNotSSD;
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if(file_stats_.st_size < 512) throw ErrorNotSSD;
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if(file_stats_.st_size > 800*256) throw ErrorNotSSD;
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// this has two heads if the suffix is .dsd, one if it's .ssd
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head_count_ = (tolower(file_name[strlen(file_name) - 3]) == 'd') ? 2 : 1;
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track_count_ = (unsigned int)(file_stats_.st_size / (256 * 10));
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if(track_count_ < 40) track_count_ = 40;
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else if(track_count_ < 80) track_count_ = 80;
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}
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SSD::~SSD()
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{
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flush_updates();
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}
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unsigned int SSD::get_head_position_count()
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{
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return track_count_;
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}
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unsigned int SSD::get_head_count()
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{
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return head_count_;
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}
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bool SSD::get_is_read_only()
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{
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return is_read_only_;
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}
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long SSD::get_file_offset_for_position(unsigned int head, unsigned int position)
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{
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return (position * head_count_ + head) * 256 * 10;
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}
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std::shared_ptr<Track> SSD::get_uncached_track_at_position(unsigned int head, unsigned int position)
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{
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std::shared_ptr<Track> track;
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if(head >= head_count_) return track;
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fseek(file_, get_file_offset_for_position(head, position), SEEK_SET);
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std::vector<Storage::Encodings::MFM::Sector> sectors;
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for(int sector = 0; sector < 10; sector++)
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{
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Storage::Encodings::MFM::Sector new_sector;
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new_sector.track = (uint8_t)position;
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new_sector.side = 0;
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new_sector.sector = (uint8_t)sector;
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new_sector.data.resize(256);
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fread(new_sector.data.data(), 1, 256, file_);
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// zero out if this wasn't present in the disk image; it's still appropriate to put a sector
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// on disk because one will have been placed during formatting, but there's no reason to leak
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// information from outside the emulated machine's world
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if(feof(file_)) memset(new_sector.data.data(), 0, 256);
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sectors.push_back(std::move(new_sector));
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}
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if(sectors.size()) return Storage::Encodings::MFM::GetFMTrackWithSectors(sectors);
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return track;
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}
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void SSD::store_updated_track_at_position(unsigned int head, unsigned int position, const std::shared_ptr<Track> &track, std::mutex &file_access_mutex)
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{
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std::vector<uint8_t> parsed_track;
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Storage::Encodings::MFM::Parser parser(false, track);
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for(unsigned int c = 0; c < 10; c++)
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{
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std::shared_ptr<Storage::Encodings::MFM::Sector> sector = parser.get_sector((uint8_t)position, (uint8_t)c);
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if(sector)
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{
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parsed_track.insert(parsed_track.end(), sector->data.begin(), sector->data.end());
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}
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else
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{
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// TODO: what's correct here? Warn the user that whatever has been written to the disk,
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// it can no longer be stored as an SSD? If so, warn them by what route?
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parsed_track.resize(parsed_track.size() + 256);
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}
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}
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std::lock_guard<std::mutex> lock_guard(file_access_mutex);
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long file_offset = get_file_offset_for_position(head, position);
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ensure_file_is_at_least_length(file_offset);
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fseek(file_, file_offset, SEEK_SET);
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fwrite(parsed_track.data(), 1, parsed_track.size(), file_);
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}
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