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Update the AES Lanier decoder to use the new architecture.

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This commit is contained in:
David Given
2019-04-28 00:47:47 +02:00
parent 00bae9fba7
commit 587f11afdc
4 changed files with 52 additions and 73 deletions
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11
doc/disk-aeslanier.md
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@@ -3,7 +3,7 @@ Disk: AES Lanier word processor
Back in 1980 Lanier released a series of very early integrated word processor
appliances, the No Problem. These were actually [rebranded AES Data Superplus
machines](http://vintagecomputers.site90.net/aes/). They wrer gigantic,
machines](http://vintagecomputers.site90.net/aes/). They were gigantic,
weighed 40kg, and one example I've found cost £13,000 in 1981 (the equivalent
of nearly £50,000 in 2018!).
@@ -17,9 +17,10 @@ indicating to the hardware where the sectors start. The encoding scheme
itself is [MMFM (aka
M2FM)](http://www.retrotechnology.com/herbs_stuff/m2fm.html), an early
attempt at double-density disk encoding which rapidly got obsoleted by the
simpler MFM. Even aside from the encoding, the format on disk was strange;
unified sector header/data records, so that the sector header (containing the
sector and track number) is actually inside the user data.
simpler MFM --- and the bytes are stored on disk _backwards_. Even aside from
the encoding, the format on disk was strange; unified sector header/data
records, so that the sector header (containing the sector and track number)
is actually inside the user data.
FluxEngine can read these, but I only have a single, fairly poor example of a
disk image, and I've had to make a lot of guesses as to the sector format
@@ -38,4 +39,4 @@ Just do:
Useful references
-----------------
* [SA800 Diskette Storage Drive - Theory Of Operations](http://www.hartetechnologies.com/manuals/Shugart/50664-1_SA800_TheorOp_May78.pdf): talks about MMFM a lot, but the Lanier machines didn't use this disk format.
* [SA800 Diskette Storage Drive - Theory Of Operations](http://www.hartetechnologies.com/manuals/Shugart/50664-1_SA800_TheorOp_May78.pdf): talks about MMFM a lot, but the Lanier machines didn't use this disk format.

9
lib/aeslanier/aeslanier.h
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@@ -3,19 +3,18 @@
#define AESLANIER_RECORD_SEPARATOR 0x55555122
#define AESLANIER_SECTOR_LENGTH 256
#define AESLANIER_RECORD_SIZE (AESLANIER_SECTOR_LENGTH + 5)
class Sector;
class Fluxmap;
class AesLanierDecoder : public AbstractSoftSectorDecoder
class AesLanierDecoder : public AbstractStatefulDecoder
{
public:
virtual ~AesLanierDecoder() {}
SectorVector decodeToSectors(
const RawRecordVector& rawRecords, unsigned physicalTrack, unsigned physicalSide);
nanoseconds_t guessClock(Fluxmap& fluxmap) const;
int recordMatcher(uint64_t fifo) const;
nanoseconds_t findSector(FluxmapReader& fmr, Track& track);
void decodeSingleSector(FluxmapReader& fmr, Track& track, Sector& sector);
};
#endif

87
lib/aeslanier/decoder.cc
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@@ -3,12 +3,15 @@
#include "aeslanier.h"
#include "crc.h"
#include "fluxmap.h"
#include "fluxmapreader.h"
#include "sector.h"
#include "bytes.h"
#include "record.h"
#include "fmt/format.h"
#include <string.h>
static const FluxPattern SECTOR_PATTERN(32, AESLANIER_RECORD_SEPARATOR);
/* This is actually M2FM, rather than MFM, but it our MFM/FM decoder copes fine with it. */
static Bytes reverse_bits(const Bytes& input)
@@ -21,63 +24,39 @@ static Bytes reverse_bits(const Bytes& input)
return output;
}
SectorVector AesLanierDecoder::decodeToSectors(const RawRecordVector& rawRecords, unsigned, unsigned)
nanoseconds_t AesLanierDecoder::findSector(FluxmapReader& fmr, Track& track)
{
std::vector<std::unique_ptr<Sector>> sectors;
return fmr.seekToPattern(SECTOR_PATTERN);
}
void AesLanierDecoder::decodeSingleSector(FluxmapReader& fmr, Track& track, Sector& sector)
{
/* Skip ID mark. */
fmr.readRawBits(16, sector.clock);
const auto& rawbits = fmr.readRawBits(AESLANIER_RECORD_SIZE*16, sector.clock);
const auto& bytes = decodeFmMfm(rawbits).slice(0, AESLANIER_RECORD_SIZE);
const auto& reversed = reverse_bits(bytes);
sector.logicalTrack = reversed[1];
sector.logicalSide = 0;
sector.logicalSector = reversed[2];
/* Check header 'checksum' (which seems far too simple to mean much). */
for (auto& rawrecord : rawRecords)
{
const auto& rawdata = rawrecord->data;
const auto& bytes = decodeFmMfm(rawdata);
const auto& reversed = reverse_bits(bytes);
uint8_t wanted = reversed[3];
uint8_t got = reversed[1] + reversed[2];
if (wanted != got)
return;
}
if (reversed.size() < 0x103)
continue;
/* Check data checksum, which also includes the header and is
* significantly better. */
unsigned track = reversed[1];
unsigned sectorid = reversed[2];
/* Basic sanity checking. */
if (track > 85)
continue;
if (sectorid > 35)
continue;
/* Check header 'checksum' (which seems far too simple to mean much). */
{
uint8_t wanted = reversed[3];
uint8_t got = reversed[1] + reversed[2];
if (wanted != got)
continue;
}
/* Check data checksum, which also includes the header and is
* significantly better. */
Bytes payload = reversed.slice(1, AESLANIER_SECTOR_LENGTH);
uint16_t wanted = reversed.reader().seek(0x101).read_le16();
uint16_t got = crc16ref(MODBUS_POLY_REF, payload);
int status = (wanted == got) ? Sector::OK : Sector::BAD_CHECKSUM;
auto sector = std::unique_ptr<Sector>(
new Sector(status, track, 0, sectorid, payload));
sectors.push_back(std::move(sector));
}
return sectors;
}
nanoseconds_t AesLanierDecoder::guessClock(Fluxmap& fluxmap) const
{
return fluxmap.guessClock() / 2;
}
int AesLanierDecoder::recordMatcher(uint64_t fifo) const
{
uint32_t masked = fifo & 0xffffffff;
if (masked == AESLANIER_RECORD_SEPARATOR)
return 16;
return 0;
sector.data = reversed.slice(1, AESLANIER_SECTOR_LENGTH);
uint16_t wanted = reversed.reader().seek(0x101).read_le16();
uint16_t got = crc16ref(MODBUS_POLY_REF, sector.data);
sector.status = (wanted == got) ? Sector::OK : Sector::BAD_CHECKSUM;
}

18
meson.build
View File

@@ -124,14 +124,14 @@ encoderlib = declare_dependency(
)
)
#aeslanierdecoderlib = declare_dependency(
# link_with:
# shared_library('aeslanierdecoderlib',
# [ 'lib/aeslanier/decoder.cc', ],
# dependencies: [fmtlib, felib, decoderlib]),
# include_directories:
# include_directories('lib/aeslanier')
#)
aeslanierdecoderlib = declare_dependency(
link_with:
shared_library('aeslanierdecoderlib',
[ 'lib/aeslanier/decoder.cc', ],
dependencies: [fmtlib, felib, decoderlib]),
include_directories:
include_directories('lib/aeslanier')
)
amigadecoderlib = declare_dependency(
link_with:
@@ -235,7 +235,7 @@ victor9kdecoderlib = declare_dependency(
executable('fe-erase', ['src/fe-erase.cc'], dependencies: [felib, writerlib])
executable('fe-inspect', ['src/fe-inspect.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib])
executable('fe-readadfs', ['src/fe-readadfs.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, ibmdecoderlib])
#executable('fe-readaeslanier', ['src/fe-readaeslanier.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, aeslanierdecoderlib])
executable('fe-readaeslanier', ['src/fe-readaeslanier.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, aeslanierdecoderlib])
executable('fe-readamiga', ['src/fe-readamiga.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, amigadecoderlib])
executable('fe-readampro', ['src/fe-readampro.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, ibmdecoderlib])
#executable('fe-readapple2', ['src/fe-readapple2.cc'], dependencies: [fmtlib, felib, decoderlib, readerlib, apple2decoderlib])