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Implements read-only MSA support.

This commit is contained in:
Thomas Harte 2019-10-03 22:41:20 -04:00
parent 8b397626bf
commit 345b32d6e3
5 changed files with 79 additions and 5 deletions

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@ -386,6 +386,8 @@
<string>Owner</string>
<key>LSTypeIsPackage</key>
<false/>
<key>NSDocumentClass</key>
<string>$(PRODUCT_MODULE_NAME).MachineDocument</string>
</dict>
<dict>
<key>CFBundleTypeExtensions</key>
@ -406,6 +408,8 @@
<string>Owner</string>
<key>LSTypeIsPackage</key>
<false/>
<key>NSDocumentClass</key>
<string>$(PRODUCT_MODULE_NAME).MachineDocument</string>
</dict>
<dict>
<key>CFBundleTypeExtensions</key>

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@ -8,16 +8,77 @@
#include "MSA.hpp"
#include "Utility/ImplicitSectors.hpp"
using namespace Storage::Disk;
MSA::MSA(const std::string &file_name) :
file_(file_name) {
const auto signature = file_.get16be();
if(signature != 0x0e0f) throw Error::InvalidFormat;
sectors_per_track_ = file_.get16be();
sides_ = 1 + file_.get16be();
starting_track_ = file_.get16be();
ending_track_ = file_.get16be();
// Create the uncompressed track list.
while(true) {
const auto data_length = file_.get16be();
if(file_.eof()) break;
if(data_length == sectors_per_track_ * 512) {
// This is an uncompressed track.
uncompressed_tracks_.push_back(file_.read(data_length));
} else {
// This is an RLE-compressed track.
std::vector<uint8_t> track;
track.reserve(sectors_per_track_ * 512);
uint16_t pointer = 0;
while(pointer < data_length) {
const auto byte = file_.get8();
// Compression scheme: if the byte E5 is encountered, an RLE run follows.
// An RLE run is encoded as the byte to repeat plus a 16-bit repeat count.
if(byte != 0xe5) {
track.push_back(byte);
++pointer;
continue;
}
pointer += 4;
if(pointer > data_length) break;
const auto value = file_.get8();
auto count = file_.get16be();
while(count--) {
track.push_back(value);
}
}
if(pointer != data_length || track.size() != sectors_per_track_ * 512) throw Error::InvalidFormat;
uncompressed_tracks_.push_back(std::move(track));
}
}
if(uncompressed_tracks_.size() != (ending_track_ - starting_track_ + 1)*sides_) throw Error::InvalidFormat;
}
std::shared_ptr<::Storage::Disk::Track> MSA::get_track_at_position(::Storage::Disk::Track::Address address) {
return nullptr;
if(address.head >= sides_) return nullptr;
const auto position = address.position.as_int();
if(position < starting_track_) return nullptr;
if(position >= ending_track_) return nullptr;
const auto &track = uncompressed_tracks_[size_t(position) * size_t(sides_) + size_t(address.head)];
return track_for_sectors(track.data(), sectors_per_track_, uint8_t(position), uint8_t(address.head), 0, 2, true);
}
HeadPosition MSA::get_maximum_head_position() {
return HeadPosition(10);
return HeadPosition(ending_track_);
}
int MSA::get_head_count() {
return sides_;
}

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@ -12,6 +12,8 @@
#include "../DiskImage.hpp"
#include "../../../FileHolder.hpp"
#include <vector>
namespace Storage {
namespace Disk {
@ -25,10 +27,17 @@ class MSA final: public DiskImage {
// Implemented to satisfy @c DiskImage.
HeadPosition get_maximum_head_position() override;
int get_head_count() override;
std::shared_ptr<::Storage::Disk::Track> get_track_at_position(::Storage::Disk::Track::Address address) override;
private:
FileHolder file_;
uint16_t sectors_per_track_;
uint16_t sides_;
uint16_t starting_track_;
uint16_t ending_track_;
std::vector<std::vector<uint8_t>> uncompressed_tracks_;
};

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@ -18,7 +18,7 @@
using namespace Storage::Disk;
std::shared_ptr<Track> Storage::Disk::track_for_sectors(uint8_t *const source, int number_of_sectors, uint8_t track, uint8_t side, uint8_t first_sector, uint8_t size, bool is_double_density) {
std::shared_ptr<Track> Storage::Disk::track_for_sectors(const uint8_t *const source, int number_of_sectors, uint8_t track, uint8_t side, uint8_t first_sector, uint8_t size, bool is_double_density) {
std::vector<Storage::Encodings::MFM::Sector> sectors;
off_t byte_size = static_cast<off_t>(128 << size);

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@ -16,8 +16,8 @@
namespace Storage {
namespace Disk {
std::shared_ptr<Track> track_for_sectors(uint8_t *const source, int number_of_sectors, uint8_t track, uint8_t side, uint8_t first_sector, uint8_t size, bool is_double_density);
void decode_sectors(Track &track, uint8_t *const destination, uint8_t first_sector, uint8_t last_sector, uint8_t sector_size, bool is_double_density);
std::shared_ptr<Track> track_for_sectors(const uint8_t *source, int number_of_sectors, uint8_t track, uint8_t side, uint8_t first_sector, uint8_t size, bool is_double_density);
void decode_sectors(Track &track, uint8_t *destination, uint8_t first_sector, uint8_t last_sector, uint8_t sector_size, bool is_double_density);
}
}