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CLK/Storage/Disk/DiskImage/Formats/2MG.cpp
2021-02-16 22:51:57 -05:00

88 lines
2.3 KiB
C++

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