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88 lines
2.3 KiB
C++
88 lines
2.3 KiB
C++
//
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// 2MG.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 23/11/2020.
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// Copyright © 2020 Thomas Harte. All rights reserved.
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//
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#include "2MG.hpp"
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#include "MacintoshIMG.hpp"
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#include <cstring>
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using namespace Storage::Disk;
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DiskImageHolderBase *Disk2MG::open(const std::string &file_name) {
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FileHolder file(file_name);
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// Check the signature.
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if(!file.check_signature("2IMG")) throw Error::InvalidFormat;
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// Grab the creator, potential to fix the data size momentarily.
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const auto creator = file.read(4);
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// Grab the header size, version number and image format.
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const uint16_t header_size = file.get16le();
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const uint16_t version = file.get16le();
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const uint32_t format = file.get32le();
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const uint32_t flags = file.get32le();
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// Skip the number of ProDOS blocks; this is surely implicit from the data size?
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file.seek(4, SEEK_CUR);
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// Get the offset and size of the disk image data.
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const uint32_t data_start = file.get32le();
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uint32_t data_size = file.get32le();
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// Correct for the Sweet 16 emulator, which writes broken 2MGs.
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if(!data_size && !memcmp(creator.data(), "WOOF", 4)) {
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data_size = uint32_t(file.stats().st_size - header_size);
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}
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// Skipped:
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//
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// four bytes, offset to comment
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// four bytes, length of comment
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// four bytes, offset to creator-specific data
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// four bytes, length of creator-specific data
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//
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// (all of which relate to optional appendages).
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// Validate.
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if(header_size < 0x40 || header_size >= file.stats().st_size) {
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throw Error::InvalidFormat;
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}
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if(version > 1) {
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throw Error::InvalidFormat;
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}
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// TODO: based on format, instantiate a suitable disk image.
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switch(format) {
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default: throw Error::InvalidFormat;
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case 0:
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// TODO: DOS 3.3 sector order.
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break;
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case 1:
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// ProDOS order, which could still mean Macintosh-style or Apple II-style. Try them both.
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try {
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return new DiskImageHolder<Storage::Disk::MacintoshIMG>(file_name, MacintoshIMG::FixedType::GCR, data_start, data_size);
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} catch(...) {}
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// TODO: Apple II-style.
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break;
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case 2:
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// TODO: NIB data (yuck!).
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break;
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}
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// So: maybe extend FileHolder to handle hiding the header before instantiating
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// a proper holder? Probably more valid than having each actual disk class do
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// its own range logic?
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(void)flags;
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throw Error::InvalidFormat;
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return nullptr;
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}
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