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76 lines
2.1 KiB
C++
76 lines
2.1 KiB
C++
//
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// DMK.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 08/01/2018.
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// Copyright © 2018 Thomas Harte. All rights reserved.
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//
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#include "DMK.hpp"
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using namespace Storage::Disk;
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DMK::DMK(const char *file_name) :
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file_(file_name) {
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// Determine whether this DMK represents a read-only disk (whether intentionally,
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// or by virtue of placement).
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uint8_t read_only_byte = file_.get8();
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if(read_only_byte != 0x00 && read_only_byte != 0xff) throw ErrorNotDMK;
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is_read_only_ = (read_only_byte == 0xff) || file_.get_is_known_read_only();
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// Read track count and size.
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head_position_count_ = static_cast<int>(file_.get8());
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track_length_ = static_cast<long>(file_.get16le());
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// Track length must be at least 0x80, as that's the size of the IDAM
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// table before track contents.
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if(track_length_ < 0x80) throw ErrorNotDMK;
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// Read the file flags and apply them.
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uint8_t flags = file_.get8();
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head_count_ = 2 - ((flags & 0x10) >> 4);
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head_position_count_ /= head_count_;
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is_purely_single_density_ = !!(flags & 0x40);
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// Skip to the end of the header and check that this is
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// "in the emulator's native format".
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file_.seek(0xc, SEEK_SET);
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uint32_t format = file_.get32le();
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if(format) throw ErrorNotDMK;
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}
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int DMK::get_head_position_count() {
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return head_position_count_;
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}
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int DMK::get_head_count() {
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return head_count_;
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}
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bool DMK::get_is_read_only() {
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return is_read_only_;
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}
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long DMK::get_file_offset_for_position(Track::Address address) {
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return (address.head*head_count_ + address.position) * track_length_ + 16;
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}
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std::shared_ptr<::Storage::Disk::Track> DMK::get_track_at_position(::Storage::Disk::Track::Address address) {
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file_.seek(get_file_offset_for_position(address), SEEK_SET);
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uint16_t idam_locations[64];
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std::size_t index = 0;
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for(std::size_t c = 0; c < sizeof(idam_locations); ++c) {
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idam_locations[index] = file_.get16le();
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if((idam_locations[index] & 0x7fff) >= 128) {
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index++;
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}
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}
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// `index` is now the final (sensical) entry in the IDAM location table.
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// TODO: parse track contents.
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printf("number of IDAMs: %d", index);
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return nullptr;
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}
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