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122 lines
3.3 KiB
C++
122 lines
3.3 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 "../../../../NumberTheory/CRC.hpp"
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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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const char signature[8] = {
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'W', 'O', 'Z', '1',
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static_cast<char>(0xff), 0x0a, 0x0d, 0x0a
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};
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if(!file_.check_signature(signature, 8)) throw Error::InvalidFormat;
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// Check the file's CRC32, instead of skipping it.
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const uint32_t crc = file_.get32le();
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CRC::CRC32 crc_generator;
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while(true) {
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uint8_t next = file_.get8();
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if(file_.eof()) break;
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crc_generator.add(next);
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}
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if(crc != crc_generator.get_value()) {
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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() + static_cast<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 != 1) 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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/* 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: Cretor; a UTF-8 string.
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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; if this track is defined to be unformatted, return no track.
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const int table_position = address.head * (is_3_5_disk_ ? 80 : 160) + (is_3_5_disk_ ? address.position.as_int() : address.position.as_quarter());
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if(track_map_[table_position] == 0xff) return NoSuchTrack;
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// Seek to the real track.
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return tracks_offset_ + track_map_[table_position] * 6656;
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}
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std::shared_ptr<Track> WOZ::get_track_at_position(Track::Address address) {
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long offset = file_offset(address);
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if(offset == NoSuchTrack) return nullptr;
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// Seek to the real track.
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PCMSegment track_contents;
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{
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std::lock_guard<std::mutex> lock_guard(file_.get_file_access_mutex());
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file_.seek(offset, SEEK_SET);
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// In WOZ 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.data = file_.read(6646);
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track_contents.data.resize(file_.get16le());
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track_contents.number_of_bits = file_.get16le();
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}
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return std::shared_ptr<PCMTrack>(new PCMTrack(track_contents));
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}
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