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The F85 decoder has been ported to work with the new architecture (works rather

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better, too).
This commit is contained in:
David Given
2019-04-19 18:19:11 +02:00
parent 3a531c0889
commit eefecc87fe
4 changed files with 66 additions and 70 deletions
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3
doc/disk-durangof85.md
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@@ -15,7 +15,8 @@ it for the following photo...
<img src="durangof85.jpg" style="max-width: 60%" alt="A Durango F85, held precariously">
</div>
...and even then, only for a few seconds.
...and even then, they had to airbrush out the tendons in her neck from the
effort!
It used 5.25 soft-sectored disks storing an impressive-for-those-days
480kBish on a side, using a proprietary 4-in-5 GCR encoding. They used 77

101
lib/f85/decoder.cc
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@@ -1,5 +1,6 @@
#include "globals.h"
#include "fluxmap.h"
#include "fluxmapreader.h"
#include "protocol.h"
#include "record.h"
#include "decoders.h"
@@ -11,6 +12,9 @@
#include <string.h>
#include <algorithm>
const FluxPattern SECTOR_RECORD_PATTERN(24, F85_SECTOR_RECORD);
const FluxPatterns SECTOR_OR_DATA_RECORD_PATTERN(24, { F85_SECTOR_RECORD, F85_DATA_RECORD });
static int decode_data_gcr(uint8_t gcr)
{
switch (gcr)
@@ -47,62 +51,51 @@ static Bytes decode(const std::vector<bool>& bits)
return output;
}
SectorVector DurangoF85Decoder::decodeToSectors(const RawRecordVector& rawRecords, unsigned, unsigned)
nanoseconds_t DurangoF85Decoder::findSector(FluxmapReader& fmr, Track& track)
{
std::vector<std::unique_ptr<Sector>> sectors;
unsigned nextSector;
unsigned nextTrack;
bool headerIsValid = false;
for (auto& rawrecord : rawRecords)
{
const auto& rawdata = rawrecord->data;
const auto& bytes = decode(rawdata);
if (bytes.size() < 4)
continue;
switch (bytes[0])
{
case 0xce: /* sector record */
{
headerIsValid = false;
nextSector = bytes[3];
nextTrack = bytes[1];
uint16_t wantChecksum = bytes.reader().seek(5).read_be16();
uint16_t gotChecksum = crc16(CCITT_POLY, 0xef21, bytes.slice(1, 4));
headerIsValid = (wantChecksum == gotChecksum);
break;
}
case 0xcb: /* data record */
{
if (!headerIsValid)
break;
if (bytes.size() < (F85_SECTOR_LENGTH + 3))
continue;
const auto& payload = bytes.slice(1, F85_SECTOR_LENGTH);
uint16_t wantChecksum = bytes.reader().seek(F85_SECTOR_LENGTH+1).read_be16();
uint16_t gotChecksum = crc16(CCITT_POLY, 0xbf84, payload);
int status = (wantChecksum == gotChecksum) ? Sector::OK : Sector::BAD_CHECKSUM;
auto sector = std::unique_ptr<Sector>(
new Sector(status, nextTrack, 0, nextSector, payload));
sectors.push_back(std::move(sector));
break;
}
}
}
return sectors;
return fmr.seekToPattern(SECTOR_RECORD_PATTERN);
}
int DurangoF85Decoder::recordMatcher(uint64_t fifo) const
nanoseconds_t DurangoF85Decoder::findData(FluxmapReader& fmr, Track& track)
{
uint32_t masked = fifo & 0xffff;
if (masked == F85_RECORD_SEPARATOR)
return 6;
return 0;
return fmr.seekToPattern(SECTOR_OR_DATA_RECORD_PATTERN);
}
void DurangoF85Decoder::decodeHeader(FluxmapReader& fmr, Track& track, Sector& sector)
{
/* Skip sync bits and ID byte. */
fmr.readRawBits(24, sector.clock);
/* Read header. */
const auto& bytes = decode(fmr.readRawBits(6*10, sector.clock));
sector.logicalSector = bytes[2];
sector.logicalSide = 0;
sector.logicalTrack = bytes[0];
uint16_t wantChecksum = bytes.reader().seek(4).read_be16();
uint16_t gotChecksum = crc16(CCITT_POLY, 0xef21, bytes.slice(0, 4));
if (wantChecksum == gotChecksum)
sector.status = Sector::DATA_MISSING; /* unintuitive but correct */
}
void DurangoF85Decoder::decodeData(FluxmapReader& fmr, Track& track, Sector& sector)
{
/* Skip sync bits and check ID byte. */
fmr.readRawBits(14, sector.clock);
uint8_t idbyte = decode(fmr.readRawBits(10, sector.clock)).slice(0, 1)[0];
if (idbyte != 0xcb)
return;
const auto& bytes = decode(fmr.readRawBits((F85_SECTOR_LENGTH+3)*10, sector.clock))
.slice(0, F85_SECTOR_LENGTH+3);
ByteReader br(bytes);
sector.data = br.read(F85_SECTOR_LENGTH);
uint16_t wantChecksum = br.read_be16();
uint16_t gotChecksum = crc16(CCITT_POLY, 0xbf84, sector.data);
sector.status = (wantChecksum == gotChecksum) ? Sector::OK : Sector::BAD_CHECKSUM;
}

12
lib/f85/f85.h
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@@ -1,20 +1,22 @@
#ifndef F85_H
#define F85_H
#define F85_RECORD_SEPARATOR 0xfffc
#define F85_SECTOR_RECORD 0xffffce /* 1111 1111 1111 1111 1100 1110 */
#define F85_DATA_RECORD 0xffffcb /* 1111 1111 1111 1111 1100 1101 */
#define F85_SECTOR_LENGTH 512
class Sector;
class Fluxmap;
class DurangoF85Decoder : public AbstractSoftSectorDecoder
class DurangoF85Decoder : public AbstractSplitDecoder
{
public:
virtual ~DurangoF85Decoder() {}
SectorVector decodeToSectors(
const RawRecordVector& rawRecords, unsigned physicalTrack, unsigned physicalSide);
int recordMatcher(uint64_t fifo) const;
nanoseconds_t findSector(FluxmapReader& fmr, Track& track) override;
nanoseconds_t findData(FluxmapReader& fmr, Track& track) override;
void decodeHeader(FluxmapReader& fmr, Track& track, Sector& sector) override;
void decodeData(FluxmapReader& fmr, Track& track, Sector& sector) override;
};
#endif

20
meson.build
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@@ -177,15 +177,15 @@ encoderlib = declare_dependency(
# include_directories:
# include_directories('lib/c64')
#)
#
#f85decoderlib = declare_dependency(
# link_with:
# shared_library('f85decoderlib',
# [ 'lib/f85/decoder.cc', ],
# dependencies: [fmtlib, felib, decoderlib]),
# include_directories:
# include_directories('lib/f85')
#)
f85decoderlib = declare_dependency(
link_with:
shared_library('f85decoderlib',
[ 'lib/f85/decoder.cc', ],
dependencies: [fmtlib, felib, decoderlib]),
include_directories:
include_directories('lib/f85')
)
fb100decoderlib = declare_dependency(
link_with:
@@ -242,7 +242,7 @@ executable('fe-inspect', ['src/fe-inspect.cc'], dependencies
#executable('fe-readbrother', ['src/fe-readbrother.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, brotherdecoderlib])
#executable('fe-readc64', ['src/fe-readc64.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, c64decoderlib])
#executable('fe-readdfs', ['src/fe-readdfs.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, ibmdecoderlib])
#executable('fe-readf85', ['src/fe-readf85.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, f85decoderlib])
executable('fe-readf85', ['src/fe-readf85.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, f85decoderlib])
executable('fe-readfb100', ['src/fe-readfb100.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, fb100decoderlib])
#executable('fe-readibm', ['src/fe-readibm.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, ibmdecoderlib])
executable('fe-readmac', ['src/fe-readmac.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, macdecoderlib])