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Added a parser for Oric-format MFM disks. Causing my first disk to load!

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This commit is contained in:
Thomas Harte 2016-11-26 13:40:10 +08:00
parent dcfdd73077
commit 2f86b07cfa
1 changed files with 50 additions and 11 deletions
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61
Storage/Disk/Formats/OricMFMDSK.cpp
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@ -8,6 +8,7 @@
#include "OricMFMDSK.hpp"
#include "../PCMTrack.hpp"
#include "../Encodings/MFM.hpp"
using namespace Storage::Disk;
@ -37,26 +38,64 @@ unsigned int OricMFMDSK::get_head_count()
std::shared_ptr<Track> OricMFMDSK::get_track_at_position(unsigned int head, unsigned int position)
{
long offset = 0;
long seek_offset = 0;
switch(geometry_type_)
{
case 1:
offset = (head * track_count_) + position;
seek_offset = (head * track_count_) + position;
break;
case 2:
offset = (position * track_count_ * head_count_) + head;
seek_offset = (position * track_count_ * head_count_) + head;
break;
}
fseek(file_, (offset * 6400) + 256, SEEK_SET);
// TODO: upon review, the file format actually seems to omit clock bits. So it's not an MFM capture.
// A consumer must contextually guess when an FB, FC, etc is meant to be a control mark. So turfing
// the data over directly as below isn't correct.
fseek(file_, (seek_offset * 6400) + 256, SEEK_SET);
PCMSegment segment;
segment.number_of_bits = 6250*8;
segment.data.resize(6250);
fread(segment.data.data(), 1, 6250, file_);
// The file format omits clock bits. So it's not a genuine MFM capture.
// A consumer must contextually guess when an FB, FC, etc is meant to be a control mark.
size_t track_offset = 0;
uint8_t last_header[6];
std::unique_ptr<Encodings::MFM::Encoder> encoder = Encodings::MFM::GetMFMEncoder(segment.data);
while(track_offset < 6250)
{
uint8_t next_byte = (uint8_t)fgetc(file_);
track_offset++;
switch(next_byte)
{
default:
encoder->add_byte(next_byte);
break;
case 0xfe: // an ID synchronisation
{
encoder->add_ID_address_mark();
for(int byte = 0; byte < 6; byte++)
{
last_header[byte] = (uint8_t)fgetc(file_);
encoder->add_byte(last_header[byte]);
track_offset++;
if(track_offset == 6250) break;
}
}
break;
case 0xfb: // a data synchronisation
encoder->add_data_address_mark();
for(int byte = 0; byte < (128 << last_header[3]) + 2; byte++)
{
encoder->add_byte((uint8_t)fgetc(file_));
track_offset++;
if(track_offset == 6250) break;
}
break;
}
}
segment.number_of_bits = (unsigned int)(segment.data.size() * 8);
std::shared_ptr<PCMTrack> track(new PCMTrack(segment));
return track;