51 lines
1.4 KiB
C++
51 lines
1.4 KiB
C++
//
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// FD.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 04/04/2026.
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// Copyright © 2026 Thomas Harte. All rights reserved.
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//
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#include "FD.hpp"
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namespace {
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// Per https://en.wikipedia.org/wiki/List_of_floppy_disk_formats the Thomson
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// uses 16 256-byte sectors per track.
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constexpr int tracks_per_side = 40;
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constexpr int sectors_per_track = 16;
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constexpr int sector_size = 1;
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constexpr int bytes_per_track = sectors_per_track * (128 << sector_size);
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constexpr int bytes_per_side = tracks_per_side * bytes_per_track;
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}
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using namespace Storage::Disk;
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FD::FD(const std::string &file_name) : MFMSectorDump(file_name) {
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// Disk has two heads if the suffix is .dsd or if it's too large to be an SSD.
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const bool is_double_sided = file_.stats().st_size > bytes_per_side;
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if(
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file_.stats().st_size != bytes_per_side &&
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file_.stats().st_size != bytes_per_side * 2
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) throw Error::InvalidFormat;
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head_count_ = is_double_sided ? 2 : 1;
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set_geometry(sectors_per_track, sector_size, 1, Encodings::MFM::Density::Double);
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}
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HeadPosition FD::maximum_head_position() const {
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return HeadPosition(tracks_per_side);
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}
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int FD::head_count() const {
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return head_count_;
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}
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long FD::get_file_offset_for_position(const Track::Address address) const {
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// TODO: RESOLVE GUESS HERE.
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// Guess is that data is interleaved.
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return (address.position.as_int() * head_count_ + address.head) * bytes_per_track;
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}
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