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CLK/Storage/Disk/DiskImage/Formats/WOZ.cpp
2020-07-24 21:56:20 -04:00

227 lines
6.7 KiB
C++

//
// WOZ.cpp
// Clock Signal
//
// Created by Thomas Harte on 23/04/2018.
// Copyright 2018 Thomas Harte. All rights reserved.
//
#include "WOZ.hpp"
#include "../../Track/PCMTrack.hpp"
#include "../../Track/TrackSerialiser.hpp"
#include <cstring>
using namespace Storage::Disk;
WOZ::WOZ(const std::string &file_name) :
file_(file_name) {
constexpr const char signature1[8] = {
'W', 'O', 'Z', '1',
char(0xff), 0x0a, 0x0d, 0x0a
};
constexpr const char signature2[8] = {
'W', 'O', 'Z', '2',
char(0xff), 0x0a, 0x0d, 0x0a
};
const bool isWoz1 = file_.check_signature(signature1, 8);
file_.seek(0, SEEK_SET);
const bool isWoz2 = file_.check_signature(signature2, 8);
if(!isWoz1 && !isWoz2) throw Error::InvalidFormat;
type_ = isWoz2 ? Type::WOZ2 : Type::WOZ1;
// Get the file's CRC32.
const uint32_t crc = file_.get32le();
// Get the collection of all data that contributes to the CRC.
post_crc_contents_ = file_.read(size_t(file_.stats().st_size - 12));
// Test the CRC.
const uint32_t computed_crc = crc_generator.compute_crc(post_crc_contents_);
if(crc != computed_crc) {
throw Error::InvalidFormat;
}
// Retreat to the first byte after the CRC.
file_.seek(12, SEEK_SET);
// Parse all chunks up front.
bool has_tmap = false;
while(true) {
const uint32_t chunk_id = file_.get32le();
const uint32_t chunk_size = file_.get32le();
if(file_.eof()) break;
long end_of_chunk = file_.tell() + long(chunk_size);
#define CK(str) (str[0] | (str[1] << 8) | (str[2] << 16) | (str[3] << 24))
switch(chunk_id) {
case CK("INFO"): {
const uint8_t version = file_.get8();
if(version > 2) break;
is_3_5_disk_ = file_.get8() == 2;
is_read_only_ = file_.get8() == 1;
/*
Ignored:
1 byte: Synchronized; 1 = Cross track sync was used during imaging.
1 byte: Cleaned; 1 = MC3470 fake bits have been removed.
32 bytes: Creator; a UTF-8 string.
And, if version 2, following the creator:
1 byte number of disk sides
1 byte boot sector format
1 byte optimal bit timing
2 bytes compatible hardware
2 bytes minimum required RAM
2 bytes largest track
*/
} break;
case CK("TMAP"): {
file_.read(track_map_, 160);
has_tmap = true;
} break;
case CK("TRKS"): {
tracks_offset_ = file_.tell();
} break;
// TODO: parse META chunks.
default:
break;
}
#undef CK
file_.seek(end_of_chunk, SEEK_SET);
}
if(tracks_offset_ == -1 || !has_tmap) throw Error::InvalidFormat;
}
HeadPosition WOZ::get_maximum_head_position() {
return is_3_5_disk_ ? HeadPosition(80) : HeadPosition(160, 4);
}
int WOZ::get_head_count() {
return is_3_5_disk_ ? 2 : 1;
}
long WOZ::file_offset(Track::Address address) {
// Calculate table position.
int table_position;
if(!is_3_5_disk_) {
table_position = address.head * 160 + address.position.as_quarter();
} else {
if(type_ == Type::WOZ1) {
table_position = address.head * 80 + address.position.as_int();
} else {
table_position = address.head + (address.position.as_int() * 2);
}
}
// Check that this track actually exists.
if(track_map_[table_position] == 0xff) {
return NoSuchTrack;
}
// Seek to the real track.
switch(type_) {
case Type::WOZ1: return tracks_offset_ + track_map_[table_position] * 6656;
default:
case Type::WOZ2: return tracks_offset_ + track_map_[table_position] * 8;
}
}
bool WOZ::tracks_differ(Track::Address lhs, Track::Address rhs) {
const long offset1 = file_offset(lhs);
const long offset2 = file_offset(rhs);
return offset1 != offset2;
}
std::shared_ptr<Track> WOZ::get_track_at_position(Track::Address address) {
const long offset = file_offset(address);
if(offset == NoSuchTrack) {
return nullptr;
}
// Seek to the real track.
std::vector<uint8_t> track_contents;
size_t number_of_bits;
{
std::lock_guard lock_guard(file_.get_file_access_mutex());
file_.seek(offset, SEEK_SET);
switch(type_) {
case Type::WOZ1:
// In WOZ 1, a track is up to 6646 bytes of data, followed by a two-byte record of the
// number of bytes that actually had data in them, then a two-byte count of the number
// of bits that were used. Other information follows but is not intended for emulation.
track_contents = file_.read(6646);
file_.seek(2, SEEK_CUR);
number_of_bits = std::min(file_.get16le(), uint16_t(6646*8));
break;
default:
case Type::WOZ2: {
// In WOZ 2 an extra level of indirection allows for variable track sizes.
const uint16_t starting_block = file_.get16le();
file_.seek(2, SEEK_CUR); // Skip the block count; the amount of data to read is implied by the number of bits.
number_of_bits = file_.get32le();
file_.seek(starting_block * 512, SEEK_SET);
track_contents = file_.read((number_of_bits + 7) >> 3);
} break;
}
}
return std::make_shared<PCMTrack>(PCMSegment(number_of_bits, track_contents));
}
void WOZ::set_tracks(const std::map<Track::Address, std::shared_ptr<Track>> &tracks) {
if(type_ == Type::WOZ2) return;
for(const auto &pair: tracks) {
// Decode the track and store, patching into the post_crc_contents_.
auto segment = Storage::Disk::track_serialisation(*pair.second, Storage::Time(1, 50000));
auto offset = size_t(file_offset(pair.first) - 12);
std::vector<uint8_t> segment_bytes = segment.byte_data();
memcpy(&post_crc_contents_[offset - 12], segment_bytes.data(), segment_bytes.size());
// Write number of bytes and number of bits.
post_crc_contents_[offset + 6646] = uint8_t(segment.data.size() >> 3);
post_crc_contents_[offset + 6647] = uint8_t(segment.data.size() >> 11);
post_crc_contents_[offset + 6648] = uint8_t(segment.data.size());
post_crc_contents_[offset + 6649] = uint8_t(segment.data.size() >> 8);
// Set no splice information now provided, since it's been lost if ever it was known.
post_crc_contents_[offset + 6650] = 0xff;
post_crc_contents_[offset + 6651] = 0xff;
}
// Calculate the new CRC.
const uint32_t crc = crc_generator.compute_crc(post_crc_contents_);
// Grab the file lock, then write the CRC, then just dump the entire file buffer.
std::lock_guard lock_guard(file_.get_file_access_mutex());
file_.seek(8, SEEK_SET);
file_.put_le(crc);
file_.write(post_crc_contents_);
}
bool WOZ::get_is_read_only() {
/*
There is an unintended issue with the disk code that sites above here: it doesn't understand the idea
of multiple addresses mapping to the same track, yet it maintains a cache of track contents. Therefore
if a WOZ is written to, what's written will magically be exactly 1/4 track wide, not affecting its
neighbours. I've made WOZs readonly until I can correct that issue.
*/
return true;
// return file_.get_is_known_read_only() || is_read_only_ || type_ == Type::WOZ2; // WOZ 2 disks are currently read only.
}