Files
fluxengine/arch/victor9k/decoder.cc
dg 4ab66afca0 Split the encoder's use of clock and bitcell, as for FM/MFM they're different
things; make the FM/MFM decoders use twice the bitcell for the clock.
2021-12-06 23:18:31 +00:00

125 lines
3.1 KiB
C++

#include "globals.h"
#include "fluxmap.h"
#include "decoders/fluxmapreader.h"
#include "protocol.h"
#include "decoders/decoders.h"
#include "sector.h"
#include "victor9k.h"
#include "crc.h"
#include "bytes.h"
#include "fmt/format.h"
#include <string.h>
#include <algorithm>
const FluxPattern SECTOR_RECORD_PATTERN(32, VICTOR9K_SECTOR_RECORD);
const FluxPattern DATA_RECORD_PATTERN(32, VICTOR9K_DATA_RECORD);
const FluxMatchers ANY_RECORD_PATTERN({ &SECTOR_RECORD_PATTERN, &DATA_RECORD_PATTERN });
static int decode_data_gcr(uint8_t gcr)
{
switch (gcr)
{
#define GCR_ENTRY(gcr, data) \
case gcr: return data;
#include "data_gcr.h"
#undef GCR_ENTRY
}
return -1;
}
static Bytes decode(const std::vector<bool>& bits)
{
Bytes output;
ByteWriter bw(output);
BitWriter bitw(bw);
auto ii = bits.begin();
while (ii != bits.end())
{
uint8_t inputfifo = 0;
for (size_t i=0; i<5; i++)
{
if (ii == bits.end())
break;
inputfifo = (inputfifo<<1) | *ii++;
}
uint8_t decoded = decode_data_gcr(inputfifo);
bitw.push(decoded, 4);
}
bitw.flush();
return output;
}
class Victor9kDecoder : public AbstractDecoder
{
public:
Victor9kDecoder(const DecoderProto& config):
AbstractDecoder(config)
{}
RecordType advanceToNextRecord()
{
const FluxMatcher* matcher = nullptr;
_sector->clock = _sector->bitcell = _fmr->seekToPattern(ANY_RECORD_PATTERN, matcher);
if (matcher == &SECTOR_RECORD_PATTERN)
return SECTOR_RECORD;
if (matcher == &DATA_RECORD_PATTERN)
return DATA_RECORD;
return UNKNOWN_RECORD;
}
void decodeSectorRecord()
{
/* Skip the sync marker bit. */
readRawBits(22);
/* Read header. */
auto bytes = decode(readRawBits(4*10)).slice(0, 4);
uint8_t rawTrack = bytes[1];
_sector->logicalSector = bytes[2];
uint8_t gotChecksum = bytes[3];
_sector->logicalTrack = rawTrack & 0x7f;
_sector->logicalSide = rawTrack >> 7;
uint8_t wantChecksum = bytes[1] + bytes[2];
if ((_sector->logicalSector > 20) || (_sector->logicalTrack > 85) || (_sector->logicalSide > 1))
return;
if (wantChecksum == gotChecksum)
_sector->status = Sector::DATA_MISSING; /* unintuitive but correct */
}
void decodeDataRecord()
{
/* Skip the sync marker bit. */
readRawBits(22);
/* Read data. */
auto bytes = decode(readRawBits((VICTOR9K_SECTOR_LENGTH+5)*10))
.slice(0, VICTOR9K_SECTOR_LENGTH+5);
ByteReader br(bytes);
/* Check that this is actually a data record. */
if (br.read_8() != 8)
return;
_sector->data = br.read(VICTOR9K_SECTOR_LENGTH);
uint16_t gotChecksum = sumBytes(_sector->data);
uint16_t wantChecksum = br.read_le16();
_sector->status = (gotChecksum == wantChecksum) ? Sector::OK : Sector::BAD_CHECKSUM;
}
};
std::unique_ptr<AbstractDecoder> createVictor9kDecoder(const DecoderProto& config)
{
return std::unique_ptr<AbstractDecoder>(new Victor9kDecoder(config));
}