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