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https://github.com/davidgiven/fluxengine.git
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85 lines
2.6 KiB
C++
85 lines
2.6 KiB
C++
#include "lib/globals.h"
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#include "lib/fluxmap.h"
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#include "lib/decoders/fluxmapreader.h"
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#include "protocol.h"
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#include "lib/decoders/decoders.h"
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#include "lib/sector.h"
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#include "amiga.h"
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#include "lib/bytes.h"
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#include "fmt/format.h"
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#include "lib/decoders/decoders.pb.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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class AmigaDecoder : public Decoder
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{
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public:
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AmigaDecoder(const DecoderProto& config):
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Decoder(config),
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_config(config.amiga())
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{
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}
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nanoseconds_t advanceToNextRecord() override
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{
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return seekToPattern(SECTOR_PATTERN);
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}
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void decodeSectorRecord() override
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{
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if (readRaw48() != AMIGA_SECTOR_RECORD)
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return;
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const auto& rawbits = readRawBits(AMIGA_RECORD_SIZE * 16);
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if (rawbits.size() < (AMIGA_RECORD_SIZE * 16))
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return;
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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();
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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 =
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amigaDeinterleave(ptr, 4).reader().read_be32();
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uint32_t gotheaderchecksum = amigaChecksum(rawbytes.slice(0, 40));
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if (gotheaderchecksum != wantedheaderchecksum)
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return;
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uint32_t wanteddatachecksum =
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amigaDeinterleave(ptr, 4).reader().read_be32();
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uint32_t gotdatachecksum = amigaChecksum(rawbytes.slice(56, 1024));
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Bytes data;
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data.writer().append(amigaDeinterleave(ptr, 512)).append(recoveryinfo);
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_sector->data = data;
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_sector->status = (gotdatachecksum == wanteddatachecksum)
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? Sector::OK
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: Sector::BAD_CHECKSUM;
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}
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private:
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const AmigaDecoderProto& _config;
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nanoseconds_t _clock;
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};
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std::unique_ptr<Decoder> createAmigaDecoder(const DecoderProto& config)
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{
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return std::unique_ptr<Decoder>(new AmigaDecoder(config));
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}
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