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Allow split decoders (into sector record and data record).

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This commit is contained in:
David Given
2019-04-19 00:55:01 +02:00
parent b158692a3a
commit 5f8e0c846c
18 changed files with 375 additions and 194 deletions
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122
lib/macintosh/decoder.cc
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@@ -12,7 +12,8 @@
#include <string.h>
#include <algorithm>
const FluxPattern SECTOR_ID_PATTERN(16, 0xd5aa);
const FluxPattern SECTOR_RECORD_PATTERN(24, MAC_SECTOR_RECORD);
const FluxPatterns SECTOR_OR_DATA_RECORD_PATTERN(24, { MAC_SECTOR_RECORD, MAC_DATA_RECORD });
static int decode_data_gcr(uint8_t gcr)
{
@@ -122,72 +123,57 @@ uint8_t decode_side(uint8_t side)
return !!(side & 0x40);
}
void MacintoshDecoder::decodeToSectors(Track& track)
nanoseconds_t MacintoshDecoder::findSector(FluxmapReader& fmr, Track& track)
{
Sector sector;
sector.physicalSide = track.physicalSide;
sector.physicalTrack = track.physicalTrack;
RawRecord record;
FluxmapReader fmr(*track.fluxmap);
bool headerIsValid = false;
for (;;)
{
nanoseconds_t clockPeriod = fmr.seekToPattern(SECTOR_ID_PATTERN);
if (fmr.eof() || !clockPeriod)
break;
sector.clock = record.clock = clockPeriod;
sector.position = record.position = fmr.tellNs();
Bytes idbytes = toBytes(fmr.readRawBits(24, clockPeriod)).slice(0, 3);
record.bytes.clear().writer() += idbytes;
switch (idbytes.reader().read_be24())
{
case MAC_SECTOR_RECORD:
{
auto header = toBytes(fmr.readRawBits(7*8, clockPeriod))
.slice(0, 7);
record.bytes.writer().seekToEnd() += header;
uint8_t encodedTrack = decode_data_gcr(header[0]);
if (encodedTrack != (track.physicalTrack & 0x3f))
break;
uint8_t encodedSector = decode_data_gcr(header[1]);
uint8_t encodedSide = decode_data_gcr(header[2]);
uint8_t formatByte = decode_data_gcr(header[3]);
uint8_t wantedsum = decode_data_gcr(header[4]);
uint8_t gotsum = (encodedTrack ^ encodedSector ^ encodedSide ^ formatByte) & 0x3f;
headerIsValid = (wantedsum == gotsum);
sector.logicalTrack = track.physicalTrack;
sector.logicalSide = decode_side(encodedSide);
sector.logicalSector = encodedSector;
break;
}
case MAC_DATA_RECORD:
{
if (!headerIsValid)
break;
headerIsValid = false;
fmr.readRawBits(8, clockPeriod); /* skip spare byte */
auto inputbuffer = toBytes(fmr.readRawBits(MAC_ENCODED_SECTOR_LENGTH*8, clockPeriod))
.slice(0, MAC_ENCODED_SECTOR_LENGTH);
record.bytes.writer().seekToEnd() += inputbuffer;
for (unsigned i=0; i<inputbuffer.size(); i++)
inputbuffer[i] = decode_data_gcr(inputbuffer[i]);
sector.status = Sector::BAD_CHECKSUM;
sector.data = decode_crazy_data(inputbuffer, sector.status);
track.sectors.push_back(sector);
break;
}
}
track.rawrecords.push_back(record);
}
return fmr.seekToPattern(SECTOR_RECORD_PATTERN);
}
nanoseconds_t MacintoshDecoder::findData(FluxmapReader& fmr, Track& track)
{
return fmr.seekToPattern(SECTOR_OR_DATA_RECORD_PATTERN);
}
void MacintoshDecoder::decodeHeader(FluxmapReader& fmr, Track& track, Sector& sector)
{
/* Skip ID (as we know it's a MAC_SECTOR_RECORD). */
fmr.readRawBits(24, sector.clock);
/* Read header. */
auto header = toBytes(fmr.readRawBits(7*8, sector.clock)).slice(0, 7);
uint8_t encodedTrack = decode_data_gcr(header[0]);
if (encodedTrack != (track.physicalTrack & 0x3f))
return;
uint8_t encodedSector = decode_data_gcr(header[1]);
uint8_t encodedSide = decode_data_gcr(header[2]);
uint8_t formatByte = decode_data_gcr(header[3]);
uint8_t wantedsum = decode_data_gcr(header[4]);
sector.logicalTrack = track.physicalTrack;
sector.logicalSide = decode_side(encodedSide);
sector.logicalSector = encodedSector;
uint8_t gotsum = (encodedTrack ^ encodedSector ^ encodedSide ^ formatByte) & 0x3f;
if (wantedsum == gotsum)
sector.status = Sector::DATA_MISSING; /* unintuitive but correct */
}
void MacintoshDecoder::decodeData(FluxmapReader& fmr, Track& track, Sector& sector)
{
auto id = toBytes(fmr.readRawBits(24, sector.clock)).reader().read_be24();
if (id != MAC_DATA_RECORD)
return;
/* Read data. */
fmr.readRawBits(8, sector.clock); /* skip spare byte */
auto inputbuffer = toBytes(fmr.readRawBits(MAC_ENCODED_SECTOR_LENGTH*8, sector.clock))
.slice(0, MAC_ENCODED_SECTOR_LENGTH);
for (unsigned i=0; i<inputbuffer.size(); i++)
inputbuffer[i] = decode_data_gcr(inputbuffer[i]);
sector.status = Sector::BAD_CHECKSUM;
sector.data = decode_crazy_data(inputbuffer, sector.status);
}