Method decodeSectorRecord

arch/northstar/decoder.cc:141–178

    }

    void decodeSectorRecord() override
    {
        uint64_t id = toBytes(readRawBits(64)).reader().read_be64();
        unsigned recordSize, payloadSize, headerSize;

        if (id == MFM_ID)
        {
            recordSize = NORTHSTAR_ENCODED_SECTOR_SIZE_DD;
            payloadSize = NORTHSTAR_PAYLOAD_SIZE_DD;
            headerSize = NORTHSTAR_HEADER_SIZE_DD;
        }
        else
        {
            recordSize = NORTHSTAR_ENCODED_SECTOR_SIZE_SD;
            payloadSize = NORTHSTAR_PAYLOAD_SIZE_SD;
            headerSize = NORTHSTAR_HEADER_SIZE_SD;
        }

        auto rawbits = readRawBits(recordSize * 16);
        auto bytes = decodeFmMfm(rawbits).slice(0, recordSize);
        ByteReader br(bytes);

        _sector->logicalHead = _ltl->logicalHead;
        _sector->logicalSector = _hardSectorId;
        _sector->logicalCylinder = _ltl->logicalCylinder;

        if (headerSize == NORTHSTAR_HEADER_SIZE_DD)
        {
            br.read_8(); /* MFM second Sync char, usually 0xFB */
        }

        _sector->data = br.read(payloadSize);
        uint8_t wantChecksum = br.read_8();
        uint8_t gotChecksum =
            northstarChecksum(bytes.slice(headerSize - 1, payloadSize));
        _sector->status =
            (wantChecksum == gotChecksum) ? Sector::OK : Sector::BAD_CHECKSUM;
    }

private:
    const NorthstarDecoderProto& _config;