1
0
mirror of https://github.com/TomHarte/CLK.git synced 2024-12-01 11:49:58 +00:00
CLK/Analyser/Static/FAT12/StaticAnalyser.cpp
2023-12-10 22:17:23 -05:00

101 lines
3.9 KiB
C++

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