fluxengine/lib/imagereader/d88imagereader.cc

#include "globals.h"
#include "flags.h"
#include "sector.h"
#include "imagereader/imagereader.h"
#include "image.h"
#include "proto.h"
#include "lib/config.pb.h"
#include "imagereader/imagereaderimpl.h"
#include "fmt/format.h"
#include <algorithm>
#include <iostream>
#include <fstream>

// reader based on this partial documentation of the D88 format:
// https://www.pc98.org/project/doc/d88.html

class D88ImageReader : public ImageReader
{
public:
	D88ImageReader(const ImageReaderProto& config):
		ImageReader(config)
	{}

	std::unique_ptr<Image> readImage()
	{
        std::ifstream inputFile(_config.filename(), std::ios::in | std::ios::binary);
        if (!inputFile.is_open())
            Error() << "cannot open input file";

        Bytes header(0x24); // read first entry of track table as well
        inputFile.read((char*) header.begin(), header.size());

        // the DIM header technically has a bit field for sectors present,
        // however it is currently ignored by this reader

        std::string diskName = header.slice(0, 0x16);

        if (diskName[0])
            std::cout << "D88: disk name: " << diskName << "\n";

        ByteReader headerReader(header);

        // media flag indicates media density, currently unused
        char mediaFlag = headerReader.seek(0x1b).read_8();

        inputFile.seekg( 0, std::ios::end );
        int fileSize = inputFile.tellg();

        int diskSize = headerReader.seek(0x1c).read_le32();

        if (diskSize > fileSize)
            std::cout << "D88: found multiple disk images. Only using first\n";

        int trackTableEnd = headerReader.seek(0x20).read_le32();
        int trackTableSize = trackTableEnd - 0x20;

        Bytes trackTable(trackTableSize);
        inputFile.seekg(0x20);
        inputFile.read((char*) trackTable.begin(), trackTable.size());
        ByteReader trackTableReader(trackTable);

        if (config.encoder().format_case() != EncoderProto::FormatCase::FORMAT_NOT_SET)
            std::cout << "D88: overriding configured format";

        auto ibm = config.mutable_encoder()->mutable_ibm();
        config.mutable_cylinders()->set_end(0);

        std::unique_ptr<Image> image(new Image);
        for (int track = 0; track < trackTableSize / 4; track++)
        {
            int trackOffset = trackTableReader.seek(track * 4).read_le32();
            if (trackOffset == 0) continue;

            int currentTrackOffset = trackOffset;
            int currentTrackCylinder = -1;
            int currentSectorsInTrack = 0xffff; // don't know # of sectors until we read the first one
            int trackSectorSize = -1;
            int trackMfm = -1;

            auto trackdata = ibm->add_trackdata();
            trackdata->set_clock_rate_khz(500);
            trackdata->set_track_length_ms(167);
            auto sectors = trackdata->mutable_sectors();

            for (int sectorInTrack = 0; sectorInTrack < currentSectorsInTrack; sectorInTrack++){
                Bytes sectorHeader(0x10);
                inputFile.read((char*) sectorHeader.begin(), sectorHeader.size());
                ByteReader sectorHeaderReader(sectorHeader);
                int cylinder = sectorHeaderReader.seek(0).read_8();
                int head = sectorHeaderReader.seek(1).read_8();
                int sectorId = sectorHeaderReader.seek(2).read_8();
                int sectorSize = 128 << sectorHeaderReader.seek(3).read_8();
                int sectorsInTrack = sectorHeaderReader.seek(4).read_le16();
                int fm = sectorHeaderReader.seek(6).read_8();
                int ddam = sectorHeaderReader.seek(7).read_8();
                int fddStatusCode = sectorHeaderReader.seek(8).read_8();
                int rpm = sectorHeaderReader.seek(13).read_8();
                // D88 provides much more sector information that is currently ignored
                if (ddam != 0)
                    Error() << "D88: nonzero ddam currently unsupported";
                if (rpm != 0)
                    Error() << "D88: 1.44MB 300rpm formats currently unsupported";
                if (fddStatusCode != 0)
                    Error() << "D88: nonzero fdd status codes are currently unsupported";
                if (currentSectorsInTrack == 0xffff) {
                    currentSectorsInTrack = sectorsInTrack;
                } else if (currentSectorsInTrack != sectorsInTrack) {
                    Error() << "D88: mismatched number of sectors in track";
                }
                if (currentTrackCylinder < 0) {
                    currentTrackCylinder = cylinder;
                } else if (currentTrackCylinder != cylinder) {
                    Error() << "D88: all sectors in a track must belong to the same cylinder";
                }
                if (trackSectorSize < 0) {
                    trackSectorSize = sectorSize;
                    // this is the first sector we've read, use it settings for per-track data
                    trackdata->set_cylinder(cylinder);
                    trackdata->set_head(head);
                    trackdata->set_sector_size(sectorSize);
                    trackdata->set_use_fm(fm);
                    if (fm) {
                        trackdata->set_gap_fill_byte(0xffff);
                        trackdata->set_idam_byte(0xf57e);
                        trackdata->set_dam_byte(0xf56f);
                    }
                    // create timings to approximately match N88-BASIC
                    if (sectorSize <= 128) {
                        trackdata->set_gap0(0x1b);
                        trackdata->set_gap2(0x09);
                        trackdata->set_gap3(0x1b);
                    } else if (sectorSize <= 256) {
                        trackdata->set_gap0(0x36);
                        trackdata->set_gap3(0x36);
                    }
                } else if (trackSectorSize != sectorSize) {
                    Error() << "D88: multiple sector sizes per track are currently unsupported";
                }
                Bytes data(sectorSize);
                inputFile.read((char*) data.begin(), data.size());
                const auto& sector = image->put(cylinder, head, sectorId);
                sector->status = Sector::OK;
                sector->logicalTrack = cylinder;
                sector->physicalCylinder = cylinder;
                sector->logicalSide = sector->physicalHead = head;
                sector->logicalSector = sectorId;
                sector->data = data;

                sectors->add_sector(sectorId);
                if (config.cylinders().end() < cylinder)
                    config.mutable_cylinders()->set_end(cylinder);
            }
        }

        image->calculateSize();
        const Geometry& geometry = image->getGeometry();
        std::cout << fmt::format("D88: read {} tracks, {} sides\n",
                        geometry.numTracks, geometry.numSides);
        return image;
    }

};

std::unique_ptr<ImageReader> ImageReader::createD88ImageReader(
	const ImageReaderProto& config)
{
    return std::unique_ptr<ImageReader>(new D88ImageReader(config));
}