mirror of
https://github.com/davidgiven/fluxengine.git
synced 2025-10-24 11:11:02 -07:00
91 lines
2.9 KiB
C++
91 lines
2.9 KiB
C++
#include "lib/core/globals.h"
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#include "lib/decoders/decoders.h"
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#include "arch/agat/agat.h"
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#include "lib/core/crc.h"
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#include "lib/data/fluxmap.h"
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#include "lib/data/fluxmapreader.h"
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#include "lib/data/fluxpattern.h"
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#include "lib/data/sector.h"
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#include "lib/core/bytes.h"
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#include "fmt/format.h"
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#include <string.h>
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// clang-format off
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/*
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* data: X X X X X X X X X - - X - X - X - X X - X - X - = 0xff956a
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* flux: 01 01 01 01 01 01 01 01 01 00 10 01 00 01 00 01 00 01 01 00 01 00 01 00 = 0x555549111444
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*
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* data: X X X X X X X X - X X - X - X - X - - X - X - X = 0xff6a95
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* flux: 01 01 01 01 01 01 01 01 00 01 01 00 01 00 01 00 01 00 10 01 00 01 00 01 = 0x555514444911
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*
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* Each pattern is prefixed with this one:
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*
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* data: - - - X - - X - = 0x12
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* flux: (10) 10 10 10 01 00 10 01 00 = 0xa924
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* magic: (10) 10 00 10 01 00 10 01 00 = 0x8924
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* ^
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*
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* This seems to be generated by emitting A4 in MFM and then a single 0 bit to
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* shift it out of phase, so the data bits become clock bits and vice versa.
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*
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* X - X - - X - - = 0xA4
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* 0100010010010010 = MFM encoded
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* 1000100100100100 = with trailing zero
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* - - - X - - X - = effective bitstream = 0x12
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*/
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// clang-format on
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static const FluxPattern SECTOR_PATTERN(64, SECTOR_ID);
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static const FluxPattern DATA_PATTERN(64, DATA_ID);
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static const FluxMatchers ALL_PATTERNS = {&SECTOR_PATTERN, &DATA_PATTERN};
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class AgatDecoder : public Decoder
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{
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public:
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AgatDecoder(const DecoderProto& config): Decoder(config) {}
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nanoseconds_t advanceToNextRecord() override
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{
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return seekToPattern(ALL_PATTERNS);
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}
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void decodeSectorRecord() override
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{
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if (readRaw64() != SECTOR_ID)
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return;
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auto bytes = decodeFmMfm(readRawBits(64)).slice(0, 4);
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if (bytes[3] != 0x5a)
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return;
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_sector->logicalTrack = bytes[1] >> 1;
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_sector->logicalSector = bytes[2];
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_sector->logicalSide = bytes[1] & 1;
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_sector->status = Sector::DATA_MISSING; /* unintuitive but correct */
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}
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void decodeDataRecord() override
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{
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if (readRaw64() != DATA_ID)
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return;
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Bytes bytes = decodeFmMfm(readRawBits((AGAT_SECTOR_SIZE + 2) * 16))
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.slice(0, AGAT_SECTOR_SIZE + 2);
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if (bytes[AGAT_SECTOR_SIZE + 1] != 0x5a)
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return;
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_sector->data = bytes.slice(0, AGAT_SECTOR_SIZE);
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uint8_t wantChecksum = bytes[AGAT_SECTOR_SIZE];
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uint8_t gotChecksum = agatChecksum(_sector->data);
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_sector->status =
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(wantChecksum == gotChecksum) ? Sector::OK : Sector::BAD_CHECKSUM;
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}
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};
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std::unique_ptr<Decoder> createAgatDecoder(const DecoderProto& config)
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{
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return std::unique_ptr<Decoder>(new AgatDecoder(config));
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}
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