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106 lines
3.9 KiB
C++
106 lines
3.9 KiB
C++
//
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// StaticAnalyser.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 05/12/2023.
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// Copyright 2023 Thomas Harte. All rights reserved.
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//
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#include "StaticAnalyser.hpp"
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#include "../Enterprise/StaticAnalyser.hpp"
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#include "../PCCompatible/StaticAnalyser.hpp"
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#include "../../../Storage/Disk/Track/TrackSerialiser.hpp"
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#include "../../../Storage/Disk/Encodings/MFM/Constants.hpp"
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#include "../../../Storage/Disk/Encodings/MFM/SegmentParser.hpp"
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Analyser::Static::TargetList Analyser::Static::FAT12::GetTargets(
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const Media &media,
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const std::string &file_name,
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TargetPlatform::IntType platforms
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) {
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// This analyser can comprehend disks only.
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if(media.disks.empty()) return {};
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auto &disk = media.disks.front();
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TargetList targets;
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// Total list of potential platforms is:
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//
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// * the Enterprise (and, by extension, CP/M-targetted software);
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// * the Atari ST;
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// * the MSX (ditto on CP/M); and
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// * the PC.
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//
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// (though the MSX and Atari ST don't currently call in here for now)
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// If the disk image is very small or large, map it to the PC. That's the only option old enough
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// to have used 5.25" media.
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if(disk->get_maximum_head_position() <= Storage::Disk::HeadPosition(40)) {
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return Analyser::Static::PCCompatible::GetTargets(media, file_name, platforms);
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}
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// Attempt to grab MFM track 0, sector 1: the boot sector.
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const auto track_zero =
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disk->get_track_at_position(Storage::Disk::Track::Address(0, Storage::Disk::HeadPosition(0)));
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const auto sector_map = Storage::Encodings::MFM::sectors_from_segment(
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Storage::Disk::track_serialisation(
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*track_zero,
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Storage::Encodings::MFM::MFMBitLength
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), Storage::Encodings::MFM::Density::Double);
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// If no sectors were found, assume this disk was either single density or high density, which both imply the PC.
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if(sector_map.empty() || sector_map.size() > 10) {
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return Analyser::Static::PCCompatible::GetTargets(media, file_name, platforms);
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}
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const Storage::Encodings::MFM::Sector *boot_sector = nullptr;
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for(const auto &pair: sector_map) {
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if(pair.second.address.sector == 1) {
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boot_sector = &pair.second;
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break;
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}
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}
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// This shouldn't technically be possible since the disk has been identified as FAT12, but be safe.
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if(!boot_sector) {
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return {};
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}
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// Check for key phrases that imply a PC disk.
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const auto &sample = boot_sector->samples[0];
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const std::vector<std::string> pc_strings = {
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// MS-DOS strings.
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"MSDOS",
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"Non-System disk or disk error",
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// DOS Plus strings.
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"Insert a SYSTEM disk",
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};
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for(const auto &string: pc_strings) {
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if(
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std::search(sample.begin(), sample.end(), string.begin(), string.end()) != sample.end()
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) {
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return Analyser::Static::PCCompatible::GetTargets(media, file_name, platforms);
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}
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}
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// TODO: look for a COM, EXE or BAT, inspect. AUTOEXEC.BAT and/or CONFIG.SYS could be either PC or MSX.
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// Disassembling the boot sector doesn't necessarily work, as several Enterprise titles out there in the wild seem
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// to have been created by WINIMAGE which adds an x86 PC-style boot sector.
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// Enterprise notes: EXOS files all start with a 16-byte header which should begin with a 0 and then have a type
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// byte that will be 0xa or lower; cf http://epbas.lgb.hu/readme.html
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//
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// Some disks commonly passed around as Enterprise software are actually CP/M software, expecting IS-DOS (the CP/M
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// clone) to be present. It's certainly possible the same could be true of MSX disks and MSX-DOS. So analysing COM
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// files probably means searching for CALL 5s and/or INT 21hs, if not a more rigorous disassembly.
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//
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// I have not been able to locate a copy of IS-DOS so there's probably not much that can be done here; perhaps I
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// could redirect to an MSX2 with MSX-DOS2? Though it'd be nicer if I had a machine that was pure CP/M.
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// Being unable to prove that this is a PC disk, throw it to the Enterprise.
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return Analyser::Static::Enterprise::GetTargets(media, file_name, platforms);
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}
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