mirror of
https://github.com/davidgiven/fluxengine.git
synced 2025-10-31 11:17:01 -07:00
87 lines
2.1 KiB
C++
87 lines
2.1 KiB
C++
#include "globals.h"
|
|
#include "decoders/decoders.h"
|
|
#include "mx/mx.h"
|
|
#include "crc.h"
|
|
#include "fluxmap.h"
|
|
#include "decoders/fluxmapreader.h"
|
|
#include "sector.h"
|
|
#include <string.h>
|
|
|
|
const int SECTOR_SIZE = 256;
|
|
|
|
/*
|
|
* MX disks are a bunch of sectors glued together with no gaps or sync markers,
|
|
* following a single beginning-of-track synchronisation and identification
|
|
* sequence.
|
|
*/
|
|
|
|
/* FM beginning of track marker:
|
|
* 0 0 f 3 decoded nibbles
|
|
* 0 0 0 0 0 0 0 0 1 1 1 1 0 0 1 1
|
|
* 1010 1010 1010 1010 1111 1111 1010 1111
|
|
* a a a a f f a f encoded nibbles
|
|
*/
|
|
const FluxPattern ID_PATTERN(32, 0xaaaaffaf);
|
|
|
|
class MxDecoder : public AbstractDecoder
|
|
{
|
|
public:
|
|
MxDecoder(const DecoderProto& config):
|
|
AbstractDecoder(config)
|
|
{}
|
|
|
|
void beginTrack() override
|
|
{
|
|
_clock = _sector->clock = seekToPattern(ID_PATTERN);
|
|
_currentSector = 0;
|
|
}
|
|
|
|
nanoseconds_t advanceToNextRecord() override
|
|
{
|
|
if (_currentSector == 11)
|
|
{
|
|
/* That was the last sector on the disk. */
|
|
return 0;
|
|
}
|
|
else
|
|
return _clock;
|
|
}
|
|
|
|
void decodeSectorRecord() override
|
|
{
|
|
/* Skip the ID pattern and track word, which is only present on the
|
|
* first sector. We don't trust the track word because some driver
|
|
* don't write it correctly. */
|
|
|
|
if (_currentSector == 0)
|
|
readRawBits(64);
|
|
|
|
auto bits = readRawBits((SECTOR_SIZE+2)*16);
|
|
auto bytes = decodeFmMfm(bits).slice(0, SECTOR_SIZE+2);
|
|
|
|
uint16_t gotChecksum = 0;
|
|
ByteReader br(bytes);
|
|
for (int i=0; i<(SECTOR_SIZE/2); i++)
|
|
gotChecksum += br.read_be16();
|
|
uint16_t wantChecksum = br.read_be16();
|
|
|
|
_sector->logicalTrack = _sector->physicalCylinder;
|
|
_sector->logicalSide = _sector->physicalHead;
|
|
_sector->logicalSector = _currentSector;
|
|
_sector->data = bytes.slice(0, SECTOR_SIZE).swab();
|
|
_sector->status = (gotChecksum == wantChecksum) ? Sector::OK : Sector::BAD_CHECKSUM;
|
|
_currentSector++;
|
|
}
|
|
|
|
private:
|
|
nanoseconds_t _clock;
|
|
int _currentSector;
|
|
};
|
|
|
|
std::unique_ptr<AbstractDecoder> createMxDecoder(const DecoderProto& config)
|
|
{
|
|
return std::unique_ptr<AbstractDecoder>(new MxDecoder(config));
|
|
}
|
|
|
|
|