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59 lines
1.9 KiB
C++
59 lines
1.9 KiB
C++
#include "globals.h"
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#include "fluxmap.h"
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#include "decoders/fluxmapreader.h"
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#include "protocol.h"
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#include "record.h"
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#include "decoders/decoders.h"
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#include "sector.h"
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#include "amiga.h"
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#include "bytes.h"
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#include "fmt/format.h"
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#include <string.h>
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#include <algorithm>
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/*
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* Amiga disks use MFM but it's not quite the same as IBM MFM. They only use
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* a single type of record with a different marker byte.
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*
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* See the big comment in the IBM MFM decoder for the gruesome details of how
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* MFM works.
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*/
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static const FluxPattern SECTOR_PATTERN(48, AMIGA_SECTOR_RECORD);
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AbstractDecoder::RecordType AmigaDecoder::advanceToNextRecord()
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{
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_sector->clock = _fmr->seekToPattern(SECTOR_PATTERN);
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if (_fmr->eof() || !_sector->clock)
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return UNKNOWN_RECORD;
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return SECTOR_RECORD;
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}
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void AmigaDecoder::decodeSectorRecord()
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{
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const auto& rawbits = readRawBits(AMIGA_RECORD_SIZE*16);
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const auto& rawbytes = toBytes(rawbits).slice(0, AMIGA_RECORD_SIZE*2);
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const auto& bytes = decodeFmMfm(rawbits).slice(0, AMIGA_RECORD_SIZE);
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const uint8_t* ptr = bytes.begin() + 3;
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Bytes header = amigaDeinterleave(ptr, 4);
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Bytes recoveryinfo = amigaDeinterleave(ptr, 16);
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_sector->logicalTrack = header[1] >> 1;
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_sector->logicalSide = header[1] & 1;
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_sector->logicalSector = header[2];
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uint32_t wantedheaderchecksum = amigaDeinterleave(ptr, 4).reader().read_be32();
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uint32_t gotheaderchecksum = amigaChecksum(rawbytes.slice(6, 40));
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if (gotheaderchecksum != wantedheaderchecksum)
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return;
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uint32_t wanteddatachecksum = amigaDeinterleave(ptr, 4).reader().read_be32();
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uint32_t gotdatachecksum = amigaChecksum(rawbytes.slice(62, 1024));
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_sector->data.clear();
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_sector->data.writer().append(amigaDeinterleave(ptr, 512)).append(recoveryinfo);
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_sector->status = (gotdatachecksum == wanteddatachecksum) ? Sector::OK : Sector::BAD_CHECKSUM;
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}
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