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87 lines
2.1 KiB
C++
87 lines
2.1 KiB
C++
//
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// HFE.cpp
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// Clock Signal
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//
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// Created by Thomas Harte on 17/08/2017.
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// Copyright © 2017 Thomas Harte. All rights reserved.
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//
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#include "HFE.hpp"
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#include "../PCMTrack.hpp"
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using namespace Storage::Disk;
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HFE::HFE(const char *file_name) :
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Storage::FileHolder(file_name) {
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if(!check_signature("HXCPICFE", 8)) throw ErrorNotHFE;
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if(fgetc(file_)) throw ErrorNotHFE;
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track_count_ = (unsigned int)fgetc(file_);
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head_count_ = (unsigned int)fgetc(file_);
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fseek(file_, 7, SEEK_CUR);
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track_list_offset_ = (long)fgetc16le() << 9;
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}
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HFE::~HFE() {
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}
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unsigned int HFE::get_head_position_count() {
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return track_count_;
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}
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unsigned int HFE::get_head_count() {
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return head_count_;
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}
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bool HFE::get_is_read_only() {
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return true;
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}
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std::shared_ptr<Track> HFE::get_uncached_track_at_position(unsigned int head, unsigned int position) {
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// Get track position and length from the lookup table; data is then always interleaved
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// based on an assumption of two heads.
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fseek(file_, track_list_offset_ + position * 4, SEEK_SET);
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long track_offset = (long)fgetc16le() << 9;
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uint16_t track_length = fgetc16le();
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fseek(file_, track_offset, SEEK_SET);
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if(head) fseek(file_, 256, SEEK_CUR);
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PCMSegment segment;
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uint16_t side_length = track_length / 2;
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segment.data.resize(side_length);
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segment.number_of_bits = side_length * 8;
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uint16_t c = 0;
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while(c < side_length) {
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uint16_t length = (uint16_t)std::min(256, side_length - c);
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fread(&segment.data[c], 1, length, file_);
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c += length;
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fseek(file_, 256, SEEK_CUR);
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}
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// Flip bytes; HFE's preference is that the least-significant bit
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// is serialised first, but PCMTrack posts the most-significant first.
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for(size_t i = 0; i < segment.data.size(); i++) {
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uint8_t original = segment.data[i];
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uint8_t flipped_byte =
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(uint8_t)(
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((original & 0x01) << 7) |
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((original & 0x02) << 5) |
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((original & 0x04) << 3) |
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((original & 0x08) << 1) |
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((original & 0x10) >> 1) |
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((original & 0x20) >> 3) |
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((original & 0x40) >> 5) |
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((original & 0x80) >> 7)
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);
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segment.data[i] = flipped_byte;
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}
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std::shared_ptr<Track> track(new PCMTrack(segment));
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return track;
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}
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