FdcGcr.cpp - emulators/yapesdl - Rivoreo Source Code Repositories

 /*

   Here we emulate low-level disk drive mechanics.

   The bit rate is not a function of spindle motor speed (as is the bit
   density, in bits/inch).  The bit rate is:

   Tracks 1 to 17       4,000,000/13
   Tracks 18 to 24      4,000,000/14
   Tracks 25 to 30      4,000,000/15
   Tracks 31 to 35      4,000,000/16

   These table gives us the number of gcr bits that rotated per tick * 4

   Tracks over 35 are not properly emulated...

 */
 #include <memory.h>
 #include <string.h>
 #include <stdio.h>
 #include "FdcGcr.h"

 const unsigned int NUM_SYNC=5;
 // this should be speed zone dependent
 const unsigned int GCR_SECTOR_GAP_LENGTH = 6; // in VICE it's 6?!
 							// SYNC Header Gap SYNC Data Gap
 const unsigned int GCR_SECTOR_SIZE = NUM_SYNC+10+9+NUM_SYNC+325+GCR_SECTOR_GAP_LENGTH;
 // Maximum track size is +3% of the theoretical value of max. bit rate (7928)
 const unsigned int GCR_MAX_TRACK_SIZE = 4000000 / 8 / 13 / 5 * 10307 / 10000;//GCR_SECTOR_SIZE * 21;
 // Total GCR encoded data size
 const unsigned int GCR_DISK_SIZE = GCR_MAX_TRACK_SIZE * MAX_NUM_TRACKS;

 // Nr of sectors on each track
 const unsigned int d64NumOfSectors[MAX_NUM_TRACKS+1] = {
 	0,
 	21,21,21,21,21,21,21,21,21,21,21,21,21,21,21,21,21, // 1-17
 	19,19,19,19,19,19,19, // 18-24
 	18,18,18,18,18,18, // 25-30
 	17,17,17,17,17, // 30-35
 	// extra
 	17,17,17,17,17,17 // 36-41
 };

 // Pointer offset vector to tracks and sectors in d64 file
 const unsigned int d64SectorOffset[MAX_NUM_TRACKS+1] = {
 	0,
 	0,21,42,63,84,105,126,147,168,189,210,231,252,273,294,315,336,
 	357,376,395,414,433,452,471,
 	490,508,526,544,562,580,
 	598,615,632,649,666,
 	// extra tracks
 	683,700,717,734,751,768
 };

 const struct {
 	unsigned char error_code;
 	char error_desc[40];
 } job_codes[] = {
 	{0 , "N/A"},
 	{0 , "No error, sector ok."},
 	{20, "Header block not found."},
 	{21, "No sync character."},
 	{22, "Data block not present."},
 	{23, "Checksum error in data block."},
 	{24, "N/A"},
 	{25, "N/A"},
 	{26, "N/A"},
 	{27, "Checksum error in header block."},
 	{28, "N/A"},
 	{29, "Disk ID mismatch."}
 };

 const unsigned int speed_zone[MAX_NUM_TRACKS+1] = {
 	0,
 	3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3, // 1-17
 	2,2,2,2,2,2,2, // 18-24
 	1,1,1,1,1,1, // 25-30
 	0,0,0,0,0, // 30-35
 	// extra
 	0,0,0,0,0,0 // 36-41
 };

 unsigned int FdcGcr::sectorSize[MAX_NUM_TRACKS+1];

 FdcGcr::FdcGcr()
 {
 	setId("FDC8");
 	diskImageHandle = NULL;

 	gcrData = gcrPtr = gcrTrackBegin = new unsigned char[GCR_DISK_SIZE];
 	gcrTrackEnd = gcrTrackBegin + GCR_MAX_TRACK_SIZE;
 	currentHalfTrack = 2;

 	isDiskInserted = false;
 	motorSpinning = false;
 	isDiskCorrupted = false;
 	gcrCurrentBitcount = 0;
 	spinFactor = 2;
 	gcrCurrentBitRate = spinFactor * 16;
 	writeMode = false;
 	for (unsigned int i = 1; i<=MAX_NUM_TRACKS; i++ ) {
 		// 300 rotation per min, 5 per sec
 		sectorSize[i] = 4000000 / (16 - speed_zone[i]) / 8 / 5;
 	}
 	NrOfTracks = 35;
 }

 FdcGcr::~FdcGcr()
 {
 	closeDiskImage();
 	isDiskInserted = false;
 	if (gcrData)
 		delete[] gcrData;
 }

 void FdcGcr::dumpState()
 {
 	unsigned int tmp;

 	saveVar(imageName, sizeof(imageName));
 	saveVar(&imageType, sizeof(imageType));
 	saveVar(&NrOfTracks, sizeof(NrOfTracks));
 	saveVar(&NrOfSectors, sizeof(NrOfSectors));
 	saveVar(&gcrCurrentBitcount, sizeof(gcrCurrentBitcount));
 	saveVar(&gcrCurrentBitRate, sizeof(gcrCurrentBitRate));
 	saveVar(&currentHalfTrack, sizeof(currentHalfTrack));
 	saveVar(gcrData, GCR_DISK_SIZE);
 	tmp = (unsigned int) (gcrPtr - gcrData);
 	saveVar(&tmp, sizeof(tmp));
 	tmp = (unsigned int)(gcrTrackBegin - gcrData);
 	saveVar(&tmp, sizeof(tmp));
 	tmp = (unsigned int)(gcrTrackEnd - gcrData);
 	saveVar(&tmp, sizeof(tmp));
 	saveVar(&byteLatched, sizeof(byteLatched));
 	saveVar(&byteWritten, sizeof(byteWritten));
 	saveVar(&byteReady, sizeof(byteReady));
 	saveVar(&byteReadyEdge, sizeof(byteReadyEdge));
 	saveVar(&motorSpinning, sizeof(motorSpinning));
 	saveVar(&isDiskInserted, sizeof(isDiskInserted));
 	saveVar(&isImageWriteProtected, sizeof(isImageWriteProtected));
 	saveVar(&isDiskSwapped, sizeof(isDiskSwapped));
 	saveVar(&isDiskCorrupted, sizeof(isDiskCorrupted));
 	saveVar(&isImageChanged, sizeof(isImageChanged));
 	saveVar(&writeMode, sizeof(writeMode));
 	saveVar(&spinFactor, sizeof(spinFactor));
 }

 void FdcGcr::readState()
 {
 	unsigned int tmp;

 	// close old image
 	closeDiskImage();

 	readVar(imageName, sizeof(imageName));
 	readVar(&imageType, sizeof(imageType));
 	readVar(&NrOfTracks, sizeof(NrOfTracks));
 	readVar(&NrOfSectors, sizeof(NrOfSectors));
 	readVar(&gcrCurrentBitcount, sizeof(gcrCurrentBitcount));
 	readVar(&gcrCurrentBitRate, sizeof(gcrCurrentBitRate));
 	readVar(&currentHalfTrack, sizeof(currentHalfTrack));
 	readVar(gcrData, GCR_DISK_SIZE);
 	readVar(&tmp, sizeof(tmp));
 	gcrPtr = tmp + gcrData;
 	readVar(&tmp, sizeof(tmp));
 	gcrTrackBegin = tmp + gcrData;
 	readVar(&tmp, sizeof(tmp));
 	gcrTrackEnd = tmp + gcrData;
 	readVar(&byteLatched, sizeof(byteLatched));
 	readVar(&byteWritten, sizeof(byteWritten));
 	readVar(&byteReady, sizeof(byteReady));
 	readVar(&byteReadyEdge, sizeof(byteReadyEdge));
 	readVar(&motorSpinning, sizeof(motorSpinning));
 	readVar(&isDiskInserted, sizeof(isDiskInserted));
 	readVar(&isImageWriteProtected, sizeof(isImageWriteProtected));
 	readVar(&isDiskSwapped, sizeof(isDiskSwapped));
 	readVar(&isDiskCorrupted, sizeof(isDiskCorrupted));
 	readVar(&isImageChanged, sizeof(isImageChanged));
 	readVar(&writeMode, sizeof(writeMode));
 	readVar(&spinFactor, sizeof(spinFactor));
 }

 void FdcGcr::openDiskImage(char *filepath)
 {
 	closeDiskImage();
 	attachD64file(filepath);
 	imageType = DISK_D64;
 	strcpy(imageName, filepath);
 }

 void FdcGcr::reset()
 {
 	gcrCurrentBitcount = 0;
 	writeMode = false;
 }

 void FdcGcr::closeDiskImage()
 {
 	if (diskImageHandle != NULL) {
 		fflush(diskImageHandle);
 		fclose(diskImageHandle);
 		diskImageHandle = NULL;
 	}
 	// check if images has changed and save
 	if (isDiskInserted && !isDiskCorrupted && isImageChanged) {
 		if(DISK_D64 == imageType)
 			gcr2disk();
 	}
 	strcpy(imageName, "");
 	// Clear GCR buffer with gaps to avoid read errors later
 	memset(gcrData, 0x55, GCR_DISK_SIZE);

 	isDiskInserted = false;
 }

 void FdcGcr::attachD64file(char *filepath)
 {
 	unsigned long size;
 	unsigned char magic[4];
 	unsigned char bam[256];

 	// Try opening the file as R/W, then for read only if it failed
 	isImageWriteProtected = false;
 	diskImageHandle = fopen(filepath, "rb+");
 	if (diskImageHandle == NULL) {
 		isImageWriteProtected = true;
 		diskImageHandle = fopen(filepath, "rb");
 	}
 	if (diskImageHandle != NULL) {

 		fseek(diskImageHandle, 0, SEEK_END);
 		size = ftell(diskImageHandle);
 		// Check length
 		if ( (size < MIN_d64NumOfSectors * 256) || (size > MAX_d64NumOfSectors * 257) ) {
 			fclose(diskImageHandle);
 			diskImageHandle = NULL;
 			isDiskInserted = false;
 			return;
 		}

 		switch (size) {
 		    case 174848:
           	case 175531:
           	    NrOfTracks = 35;
           	    break;
 		    case (683+1*17)*256:
           	case (683+1*17)*256 + 683 + 17:
           	    NrOfTracks = 36;
 		    	break;
 		    case (683+2*17)*256:
           	case (683+2*17)*256 + 683 + 17*2:
           	    NrOfTracks = 37;
 		    	break;
 		    case (683+3*17)*256:
           	case (683+3*17)*256 + 683 + 17*3:
           	    NrOfTracks = 38;
 		    	break;
 		    case (683+4*17)*256:
           	case (683+4*17)*256 + 683 + 17*4:
           	    NrOfTracks = 39;
 		    	break;
 		    case (683+5*17)*256:
           	case (683+5*17)*256 + 683 + 17*5:
           	    NrOfTracks = 40;
 		    	break;
   			default:
   			    NrOfTracks = 35;
   			    break;
 		}
 //		Log::write(_T("Number of tracks: %i.\n"), NrOfTracks);
 		NrOfSectors = d64SectorOffset[NrOfTracks+1];
 	//	Log::write(_T("Number of sectors: %i.\n"), NrOfSectors);

 		// x64 image?
 		fseek(diskImageHandle, 0, SEEK_SET);
 		fread(&magic, 4, 1, diskImageHandle);
 		if (magic[0] == 0x43 && magic[1] == 0x15 && magic[2] == 0x41 && magic[3] == 0x64)
 			diskImageHeaderSize = 64;
 		else
 			diskImageHeaderSize = 0;

 		// Preset error info (all sectors no error)
 		memset(diskErrorInfo, 1, sizeof(diskErrorInfo));

 		// Load sector error info from .d64 file, if available
 		if (!diskImageHeaderSize && size == NrOfSectors * 257) {
 //			Log::write(_T("Sector error info found.\n"));
 			fseek(diskImageHandle, NrOfSectors * 256, SEEK_SET);
 			fread(&diskErrorInfo, NrOfSectors, 1, diskImageHandle);
 		}

 		// Read BAM and get ID
 		if (!readSector(18, 0, bam)) {
 			isDiskCorrupted = true;
 		} else {
 			id1 = bam[162];
 			id2 = bam[163];
 			// Create GCR encoded disk data from image
 			disk2gcr();
 			// indicate that the disk is present
 			isDiskInserted = true;
 			isImageChanged = false;
 			isDiskCorrupted = false;
 			isDiskSwapped = true;
 		}
 		return;
 	}
 	isDiskInserted = false;
 }

 bool FdcGcr::readSector(int track, int sector, unsigned char *buffer)
 {
 	int offset;

 	// Convert track/sector to byte offset in file
 	if ((offset = offsetFromTS(track, sector)) < 0)
 		return false;

 	fseek(diskImageHandle, offset + diskImageHeaderSize, SEEK_SET);

 	size_t r = fread(buffer, 1, 256, diskImageHandle);
 	return r == 256;
 }

 void FdcGcr::trackSector(unsigned int &track, unsigned int &sector)
 {
 	track = ((currentHalfTrack >> 1));
 	sector = (unsigned int) ((gcrPtr - gcrTrackBegin) / GCR_SECTOR_SIZE);
 }

 /*
    Convert track/sector to offset
 */

 unsigned int FdcGcr::secnumFromTS(unsigned int track, unsigned int sector)
 {
 	return d64SectorOffset[track] + sector;
 }

 int FdcGcr::offsetFromTS(unsigned int track, unsigned int sector)
 {
 	if ((track < 1) || (track > MAX_NUM_TRACKS) || (sector >= d64NumOfSectors[track]))
 		return -1;

 	return (d64SectorOffset[track] + sector) << 8;
 }

 /*
    Convert between 4 bytes and 5 GCR encoded bytes
 */
 const unsigned int tblEncodeToGCR[16] = {
 	0x0A, 0x0B, 0x12, 0x13, 0x0E, 0x0F, 0x16, 0x17,
 	0x09, 0x19, 0x1A, 0x1B, 0x0D, 0x1D, 0x1E, 0x15
 };

 const unsigned int tblDecodeFromGCR[32] = {
 	0, 0, 0, 0, 0, 0, 0, 0,  0, 8, 0, 1, 0,12, 4, 5,
     0, 0, 2, 3, 0,15, 6, 7,  0, 9,10,11, 0,13,14, 0
 };

 void FdcGcr::gcrConv4bytesTo5(unsigned char *from, unsigned char *to)
 {
 	unsigned int g;

 	g = (tblEncodeToGCR[*from >> 4] << 5) | tblEncodeToGCR[*from & 15];
 	*to++ = g >> 2;
 	*to = (g << 6) & 0xC0;
 	from++;

 	g = (tblEncodeToGCR[*from >> 4] << 5) | tblEncodeToGCR[*from & 15];
 	*to++ |= (g >> 4) & 0x3F;
 	*to = (g << 4) & 0xF0;
 	from++;

 	g = (tblEncodeToGCR[*from >> 4] << 5) | tblEncodeToGCR[*from & 15];
 	*to++ |= (g >> 6) & 0x0F;
 	*to = (g << 2) & 0xFC;
 	from++;

 	g = (tblEncodeToGCR[*from >> 4] << 5) | tblEncodeToGCR[*from & 15];
 	*to++ |= (g >> 8) & 0x03;
 	*to = (unsigned char) g;
 }

 void FdcGcr::gcrConv5bytesTo4(unsigned char *buffer, unsigned char *ptr)
 {
     unsigned int i;
     unsigned char gcr_bytes[8];

     gcr_bytes[0] = (*buffer)>>3;
     gcr_bytes[1] =((*buffer++)&0x07)<<2;
     gcr_bytes[1] |=(*buffer)>>6;
     gcr_bytes[2] =((*buffer)&0x3E)>>1;
     gcr_bytes[3] =((*buffer++)&0x01)<<4;
     gcr_bytes[3]|=((*buffer)&0xF0)>>4;
     gcr_bytes[4] =((*buffer++)&0x0F)<<1;
     gcr_bytes[4] |=(*buffer)>>7;
     gcr_bytes[5] =((*buffer)&0x7C)>>2;
     gcr_bytes[6] =((*buffer++)&0x03)<<3;
     gcr_bytes[6]|=((*buffer)&0xE0)>>5;
     gcr_bytes[7] = (*buffer)&0x1F;

     for (i = 0; i < 4; i++, ptr++) {
         *ptr = tblDecodeFromGCR[gcr_bytes[2 * i]] << 4;
         *ptr |= tblDecodeFromGCR[gcr_bytes[2 * i + 1]];
     }
 }

 void FdcGcr::sector2gcr(int track, int sector)
 {
 	unsigned char block[256];
 	unsigned char buf[4], headerID1;
 /*
 	This formula did not work with Nibble hack em
 	unsigned char *p = gcrData + (track-1) * GCR_MAX_TRACK_SIZE +
 		sector * sectorSize[track] / d64NumOfSectors[track];
 */
 	unsigned char *p = gcrData + (track-1) * GCR_MAX_TRACK_SIZE + sector * GCR_SECTOR_SIZE;
 	//Log::write("Track %02i, sector %02i at offset %04i.\n", track, sector, p - gcrData );
 	readSector(track, sector, block);

 	const unsigned char errCode = job_codes[ diskErrorInfo[d64SectorOffset[track]+sector]].error_code;
 	const unsigned char syncByte = errCode == 21 ? 0x55 : 0xFF;

 	headerID1 = (errCode == 29) ? id1^0xFF : id1;
 	// Create GCR header
 	memset( p, syncByte, NUM_SYNC);	// Header SYNC bytes
 	p += NUM_SYNC;
     buf[0] = (errCode == 20) ? 0xFF : 0x08;	// Header mark
 	buf[1] = sector ^ track ^ id2 ^ headerID1; // Checksum
 	buf[2] = sector;
 	buf[3] = track;

     if (errCode == 27)
         buf[1] ^= 0xFF;

 	gcrConv4bytesTo5(buf, p);
 	buf[0] = id2;
 	buf[1] = headerID1;
 	buf[2] = buf[3] = 0x0f;
 	gcrConv4bytesTo5(buf, p+5);
 	p += 10;
 	memset(p, 0x55, 9);		// Header gap
 	p += 9;

 	// Create GCR data
 	unsigned char sum;
 	memset( p, syncByte, NUM_SYNC);	// Data SYNC bytes
 	p += NUM_SYNC;

 	buf[0] = errCode == 22 ? 0xFF : 0x07; // Data mark
 	sum = buf[1] = block[0];
 	sum ^= buf[2] = block[1];
 	sum ^= buf[3] = block[2];
 	gcrConv4bytesTo5(buf, p);
 	p += 5;
 	for (int i=3; i<255; i+=4) {
 		sum ^= buf[0] = block[i];
 		sum ^= buf[1] = block[i+1];
 		sum ^= buf[2] = block[i+2];
 		sum ^= buf[3] = block[i+3];
 		gcrConv4bytesTo5(buf, p);
 		p += 5;
 	}
 	sum ^= buf[0] = block[255];
 	if (errCode == 23) sum ^= 0xFF;
 	buf[1] = sum;	// Checksum
 	// These bytes are needed to have a multiple of four bytes
 	buf[2] = 0;
 	buf[3] = 0;
 	gcrConv4bytesTo5(buf, p);
 	p += 5;

 	memset(p, 0x55, GCR_SECTOR_GAP_LENGTH);	// Gap before next sector
 	//p += GCR_SECTOR_GAP_LENGTH;
 }

 void FdcGcr::gcr2sector(unsigned char *buffer, unsigned char *p,
                                unsigned char *trackStart,
                                unsigned char *trackEnd)
 {
     unsigned int	i, j;
     unsigned char	*offset = p;
     unsigned char	gcrBufferPtr[5];

     for ( i=0; i<65; i++) {
         for ( j=0; j<5; j++) {
             gcrBufferPtr[j] = *offset++;
             if (offset == trackEnd)
                 offset = trackStart;
         }
         gcrConv5bytesTo4(gcrBufferPtr, buffer);
         buffer += 4;
     }
 }

 void FdcGcr::dumpGcr(unsigned char *p)
 {
 	FILE *gcrdump = NULL;
 	char dumpName[512];

 	sprintf(dumpName, "GCRDUMP%s.BIN", imageName);
 	gcrdump = fopen(dumpName, "wb");
 	if (!gcrdump)
         return;
 	for (unsigned int i = 0; i < GCR_MAX_TRACK_SIZE * 35; i++)
 		fputc( *p++, gcrdump );
 	fclose( gcrdump );
 }

 void FdcGcr::disk2gcr(void)
 {
 	// Convert all tracks and sectors
 	for ( unsigned int track=1; track<=NrOfTracks; track++)
 		for( unsigned int sector=0; sector<d64NumOfSectors[track]; sector++)
 			sector2gcr(track, sector);
 #if 0
 	dumpGcr(gcrData);
 #endif
 }

 unsigned char *FdcGcr::getSectorHeaderOffset(unsigned int track, unsigned int sector,
 										unsigned char *trackStart, unsigned char *trackEnd)
 {
     unsigned char *offset = trackStart;
     unsigned char gcr_header[5], header_data[4];
 	bool wrap_around = false;
     int nr_of_syncs_found = 0;

 	while ((offset < trackEnd) && !wrap_around) {
 		while (*offset != 0xFF) {
 			offset++;
 			if (offset >= trackEnd) {
 				if (wrap_around) {
 //					Log::write(_T("GCR error: no synch found.\n"));
 					dumpGcr(gcrData);
 					return NULL;
 				} else {
 					wrap_around = true;
 					offset = trackStart;
 				}
 			}
 		}
 		while (*offset == 0xFF) {
 			offset++;
 			if (offset == trackEnd) {
 				offset = trackStart;
 				wrap_around = true;
 			}
 			// more sync than size is found?
 			if( (trackEnd - trackStart) <= ++nr_of_syncs_found ) {
 //				Log::write(_T("GCR error: too many synch bytes found.\n"));
 				return NULL;
 			}
         }
         for (unsigned int i = 0; i < 5; i++) {
             gcr_header[i] = *(offset++);
             if (offset >= trackEnd) {
                 offset = trackStart;
                 wrap_around = true;
             }
         }
         gcrConv5bytesTo4(gcr_header, header_data);
         if (header_data[0] == 0x08 && header_data[2] == sector && header_data[3] == track)
 			return offset;
     }
     return NULL;
 }

 void FdcGcr::gcr2disk(void)
 {
 	FILE			*d64dump;
 	char			new_d64_file[266];
 	unsigned char	*offset;
 	unsigned char	sector_buffer[260];

 	strcpy( new_d64_file, imageName);

 	d64dump = fopen( const_cast<char*> (new_d64_file), "wb");
 	if (!d64dump)
 		return;

 	// Convert all tracks and sectors
 	for ( unsigned int track = 1; track<=NrOfTracks; track ++) { // NUM_TRACKS

 		unsigned char *trackStart	= gcrData + (track - 1) * GCR_MAX_TRACK_SIZE;
 		unsigned char *trackEnd	= trackStart + sectorSize[track];
 		//offset = trackStart;

 		for ( unsigned int sec = 0; sec<d64NumOfSectors[track]; sec++) {
 			offset = getSectorHeaderOffset( track, sec, trackStart, trackEnd);

 			if ( NULL == offset ) {
 //				Log::write(_T("Error dumping gcr data (illegal pointer) at track: %i, sector: %i.\n"),
 //					track, sec);
 				isDiskCorrupted = true;
 				fclose(d64dump);
 				return;
 			}

 			int header = 0;
 			// seek data header
 			while (*offset != 0xFF) {
 				offset++;
 				if (offset == trackEnd)
 					offset = trackStart;
 				header++;
 				if (header >= 10000) {
 //					Log::write(_T("Error dumping gcr data (no header) at track: %i, sector: %i.\n"),
 //						track, sec);
 					isDiskCorrupted = true;
 					fclose(d64dump);
 					return;
 				}
 			}
 			// seek sector data
 			bool fullyRotated = false;
 			while (*offset == 0xFF && !fullyRotated) { // data mark (0x07) in GCR (0x55)
 				offset++;
 				if (offset == trackEnd) {
 					if (!fullyRotated) {
 						offset = trackStart;
 						fullyRotated = true;
 					} else {
 	//					Log::write(_T("Error dumping gcr data (no data mark) at track: %i, sector: %i.\n"),
 				//			track, sec);
 						isDiskCorrupted = true;
 					}
 				}
 			}
 			// convert to 260 bytes
 			gcr2sector( sector_buffer, offset, trackStart, trackEnd);
 			if (sector_buffer[0] != 0x07) {
 				isDiskCorrupted = true;
 				//fclose(d64dump);
 				//return;
 //				Log::write(_T("Warning: head of buffer not data mark at track: %i, sector %i, file offset: %i.\n"),
 //					track, sec, ftell(d64dump));
 			}
 			// write one sector
 			fwrite( &(sector_buffer[1]), 256, 1, d64dump);
 		}
 	}
 	fclose(d64dump);
 }

 // Move R/W head inwards (towards higher tracks)
 void FdcGcr::moveHeadIn(void)
 {
 	unsigned long newGCRoffset;

 	if (currentHalfTrack >= NrOfTracks*2) {
 //		fprintf(stderr, "Drive head moved over highest track of current image.");
 		if (currentHalfTrack == MAX_NUM_TRACKS*2) {
 //			fprintf(sdterr, (_T("Attempt to move drive head over track 41."));
 			return;
 		}
 		NrOfTracks = currentHalfTrack >> 1;
 	}
 	// Note actual position within the old track...
 	newGCRoffset = (unsigned long)(gcrPtr - gcrTrackBegin) * sectorSize[(currentHalfTrack+1) >> 1]
 		/ sectorSize[(currentHalfTrack) >> 1] ;

 	currentHalfTrack++;

 	gcrTrackBegin = gcrData + ((currentHalfTrack >> 1) - 1) * GCR_MAX_TRACK_SIZE;
 	gcrTrackEnd = gcrTrackBegin + sectorSize[currentHalfTrack >> 1];

 	gcrPtr = gcrTrackBegin + newGCRoffset;
 }

 // Move R/W head outwards (towards lower tracks)
 void FdcGcr::moveHeadOut(void)
 {
 	unsigned long newGCRoffset;

 	if (currentHalfTrack == 2)
 		return;

 	// Note actual position within the old track...
 	newGCRoffset = (unsigned long) (gcrPtr - gcrTrackBegin) * sectorSize[(currentHalfTrack-1) >> 1]
 		/ sectorSize[(currentHalfTrack) >> 1];

 	currentHalfTrack--;

 	gcrTrackBegin = gcrData + ((currentHalfTrack >> 1) - 1) * GCR_MAX_TRACK_SIZE;
 	gcrTrackEnd = gcrTrackBegin + sectorSize[currentHalfTrack >> 1];

 	gcrPtr = gcrTrackBegin + newGCRoffset;
 }
	/*

	Here we emulate low-level disk drive mechanics.

	The bit rate is not a function of spindle motor speed (as is the bit
	density, in bits/inch). The bit rate is:

	Tracks 1 to 17 4,000,000/13
	Tracks 18 to 24 4,000,000/14
	Tracks 25 to 30 4,000,000/15
	Tracks 31 to 35 4,000,000/16

	These table gives us the number of gcr bits that rotated per tick * 4

	Tracks over 35 are not properly emulated...

	*/
	#include <memory.h>
	#include <string.h>
	#include <stdio.h>
	#include "FdcGcr.h"

	const unsigned int NUM_SYNC=5;
	// this should be speed zone dependent
	const unsigned int GCR_SECTOR_GAP_LENGTH = 6; // in VICE it's 6?!
	// SYNC Header Gap SYNC Data Gap
	const unsigned int GCR_SECTOR_SIZE = NUM_SYNC+10+9+NUM_SYNC+325+GCR_SECTOR_GAP_LENGTH;
	// Maximum track size is +3% of the theoretical value of max. bit rate (7928)
	const unsigned int GCR_MAX_TRACK_SIZE = 4000000 / 8 / 13 / 5 * 10307 / 10000;//GCR_SECTOR_SIZE * 21;
	// Total GCR encoded data size
	const unsigned int GCR_DISK_SIZE = GCR_MAX_TRACK_SIZE * MAX_NUM_TRACKS;

	// Nr of sectors on each track
	const unsigned int d64NumOfSectors[MAX_NUM_TRACKS+1] = {
	0,
	21,21,21,21,21,21,21,21,21,21,21,21,21,21,21,21,21, // 1-17
	19,19,19,19,19,19,19, // 18-24
	18,18,18,18,18,18, // 25-30
	17,17,17,17,17, // 30-35
	// extra
	17,17,17,17,17,17 // 36-41
	};

	// Pointer offset vector to tracks and sectors in d64 file
	const unsigned int d64SectorOffset[MAX_NUM_TRACKS+1] = {
	0,
	0,21,42,63,84,105,126,147,168,189,210,231,252,273,294,315,336,
	357,376,395,414,433,452,471,
	490,508,526,544,562,580,
	598,615,632,649,666,
	// extra tracks
	683,700,717,734,751,768
	};

	const struct {
	unsigned char error_code;
	char error_desc[40];
	} job_codes[] = {
	{0 , "N/A"},
	{0 , "No error, sector ok."},
	{20, "Header block not found."},
	{21, "No sync character."},
	{22, "Data block not present."},
	{23, "Checksum error in data block."},
	{24, "N/A"},
	{25, "N/A"},
	{26, "N/A"},
	{27, "Checksum error in header block."},
	{28, "N/A"},
	{29, "Disk ID mismatch."}
	};

	const unsigned int speed_zone[MAX_NUM_TRACKS+1] = {
	0,
	3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3, // 1-17
	2,2,2,2,2,2,2, // 18-24
	1,1,1,1,1,1, // 25-30
	0,0,0,0,0, // 30-35
	// extra
	0,0,0,0,0,0 // 36-41
	};

	unsigned int FdcGcr::sectorSize[MAX_NUM_TRACKS+1];

	FdcGcr::FdcGcr()
	{
	setId("FDC8");
	diskImageHandle = NULL;

	gcrData = gcrPtr = gcrTrackBegin = new unsigned char[GCR_DISK_SIZE];
	gcrTrackEnd = gcrTrackBegin + GCR_MAX_TRACK_SIZE;
	currentHalfTrack = 2;

	isDiskInserted = false;
	motorSpinning = false;
	isDiskCorrupted = false;
	gcrCurrentBitcount = 0;
	spinFactor = 2;
	gcrCurrentBitRate = spinFactor * 16;
	writeMode = false;
	for (unsigned int i = 1; i<=MAX_NUM_TRACKS; i++ ) {
	// 300 rotation per min, 5 per sec
	sectorSize[i] = 4000000 / (16 - speed_zone[i]) / 8 / 5;
	}
	NrOfTracks = 35;
	}

	FdcGcr::~FdcGcr()
	{
	closeDiskImage();
	isDiskInserted = false;
	if (gcrData)
	delete[] gcrData;
	}

	void FdcGcr::dumpState()
	{
	unsigned int tmp;

	saveVar(imageName, sizeof(imageName));
	saveVar(&imageType, sizeof(imageType));
	saveVar(&NrOfTracks, sizeof(NrOfTracks));
	saveVar(&NrOfSectors, sizeof(NrOfSectors));
	saveVar(&gcrCurrentBitcount, sizeof(gcrCurrentBitcount));
	saveVar(&gcrCurrentBitRate, sizeof(gcrCurrentBitRate));
	saveVar(&currentHalfTrack, sizeof(currentHalfTrack));
	saveVar(gcrData, GCR_DISK_SIZE);
	tmp = (unsigned int) (gcrPtr - gcrData);
	saveVar(&tmp, sizeof(tmp));
	tmp = (unsigned int)(gcrTrackBegin - gcrData);
	saveVar(&tmp, sizeof(tmp));
	tmp = (unsigned int)(gcrTrackEnd - gcrData);
	saveVar(&tmp, sizeof(tmp));
	saveVar(&byteLatched, sizeof(byteLatched));
	saveVar(&byteWritten, sizeof(byteWritten));
	saveVar(&byteReady, sizeof(byteReady));
	saveVar(&byteReadyEdge, sizeof(byteReadyEdge));
	saveVar(&motorSpinning, sizeof(motorSpinning));
	saveVar(&isDiskInserted, sizeof(isDiskInserted));
	saveVar(&isImageWriteProtected, sizeof(isImageWriteProtected));
	saveVar(&isDiskSwapped, sizeof(isDiskSwapped));
	saveVar(&isDiskCorrupted, sizeof(isDiskCorrupted));
	saveVar(&isImageChanged, sizeof(isImageChanged));
	saveVar(&writeMode, sizeof(writeMode));
	saveVar(&spinFactor, sizeof(spinFactor));
	}

	void FdcGcr::readState()
	{
	unsigned int tmp;

	// close old image
	closeDiskImage();

	readVar(imageName, sizeof(imageName));
	readVar(&imageType, sizeof(imageType));
	readVar(&NrOfTracks, sizeof(NrOfTracks));
	readVar(&NrOfSectors, sizeof(NrOfSectors));
	readVar(&gcrCurrentBitcount, sizeof(gcrCurrentBitcount));
	readVar(&gcrCurrentBitRate, sizeof(gcrCurrentBitRate));
	readVar(&currentHalfTrack, sizeof(currentHalfTrack));
	readVar(gcrData, GCR_DISK_SIZE);
	readVar(&tmp, sizeof(tmp));
	gcrPtr = tmp + gcrData;
	readVar(&tmp, sizeof(tmp));
	gcrTrackBegin = tmp + gcrData;
	readVar(&tmp, sizeof(tmp));
	gcrTrackEnd = tmp + gcrData;
	readVar(&byteLatched, sizeof(byteLatched));
	readVar(&byteWritten, sizeof(byteWritten));
	readVar(&byteReady, sizeof(byteReady));
	readVar(&byteReadyEdge, sizeof(byteReadyEdge));
	readVar(&motorSpinning, sizeof(motorSpinning));
	readVar(&isDiskInserted, sizeof(isDiskInserted));
	readVar(&isImageWriteProtected, sizeof(isImageWriteProtected));
	readVar(&isDiskSwapped, sizeof(isDiskSwapped));
	readVar(&isDiskCorrupted, sizeof(isDiskCorrupted));
	readVar(&isImageChanged, sizeof(isImageChanged));
	readVar(&writeMode, sizeof(writeMode));
	readVar(&spinFactor, sizeof(spinFactor));
	}

	void FdcGcr::openDiskImage(char *filepath)
	{
	closeDiskImage();
	attachD64file(filepath);
	imageType = DISK_D64;
	strcpy(imageName, filepath);
	}

	void FdcGcr::reset()
	{
	gcrCurrentBitcount = 0;
	writeMode = false;
	}

	void FdcGcr::closeDiskImage()
	{
	if (diskImageHandle != NULL) {
	fflush(diskImageHandle);
	fclose(diskImageHandle);
	diskImageHandle = NULL;
	}
	// check if images has changed and save
	if (isDiskInserted && !isDiskCorrupted && isImageChanged) {
	if(DISK_D64 == imageType)
	gcr2disk();
	}
	strcpy(imageName, "");
	// Clear GCR buffer with gaps to avoid read errors later
	memset(gcrData, 0x55, GCR_DISK_SIZE);

	isDiskInserted = false;
	}

	void FdcGcr::attachD64file(char *filepath)
	{
	unsigned long size;
	unsigned char magic[4];
	unsigned char bam[256];

	// Try opening the file as R/W, then for read only if it failed
	isImageWriteProtected = false;
	diskImageHandle = fopen(filepath, "rb+");
	if (diskImageHandle == NULL) {
	isImageWriteProtected = true;
	diskImageHandle = fopen(filepath, "rb");
	}
	if (diskImageHandle != NULL) {

	fseek(diskImageHandle, 0, SEEK_END);
	size = ftell(diskImageHandle);
	// Check length
	if ( (size < MIN_d64NumOfSectors * 256) \|\| (size > MAX_d64NumOfSectors * 257) ) {
	fclose(diskImageHandle);
	diskImageHandle = NULL;
	isDiskInserted = false;
	return;
	}

	switch (size) {
	case 174848:
	case 175531:
	NrOfTracks = 35;
	break;
	case (683+117)256:
	case (683+117)256 + 683 + 17:
	NrOfTracks = 36;
	break;
	case (683+217)256:
	case (683+217)256 + 683 + 17*2:
	NrOfTracks = 37;
	break;
	case (683+317)256:
	case (683+317)256 + 683 + 17*3:
	NrOfTracks = 38;
	break;
	case (683+417)256:
	case (683+417)256 + 683 + 17*4:
	NrOfTracks = 39;
	break;
	case (683+517)256:
	case (683+517)256 + 683 + 17*5:
	NrOfTracks = 40;
	break;
	default:
	NrOfTracks = 35;
	break;
	}
	// Log::write(_T("Number of tracks: %i.\n"), NrOfTracks);
	NrOfSectors = d64SectorOffset[NrOfTracks+1];
	// Log::write(_T("Number of sectors: %i.\n"), NrOfSectors);

	// x64 image?
	fseek(diskImageHandle, 0, SEEK_SET);
	fread(&magic, 4, 1, diskImageHandle);
	if (magic[0] == 0x43 && magic[1] == 0x15 && magic[2] == 0x41 && magic[3] == 0x64)
	diskImageHeaderSize = 64;
	else
	diskImageHeaderSize = 0;

	// Preset error info (all sectors no error)
	memset(diskErrorInfo, 1, sizeof(diskErrorInfo));

	// Load sector error info from .d64 file, if available
	if (!diskImageHeaderSize && size == NrOfSectors * 257) {
	// Log::write(_T("Sector error info found.\n"));
	fseek(diskImageHandle, NrOfSectors * 256, SEEK_SET);
	fread(&diskErrorInfo, NrOfSectors, 1, diskImageHandle);
	}

	// Read BAM and get ID
	if (!readSector(18, 0, bam)) {
	isDiskCorrupted = true;
	} else {
	id1 = bam[162];
	id2 = bam[163];
	// Create GCR encoded disk data from image
	disk2gcr();
	// indicate that the disk is present
	isDiskInserted = true;
	isImageChanged = false;
	isDiskCorrupted = false;
	isDiskSwapped = true;
	}
	return;
	}
	isDiskInserted = false;
	}

	bool FdcGcr::readSector(int track, int sector, unsigned char *buffer)
	{
	int offset;

	// Convert track/sector to byte offset in file
	if ((offset = offsetFromTS(track, sector)) < 0)
	return false;

	fseek(diskImageHandle, offset + diskImageHeaderSize, SEEK_SET);

	size_t r = fread(buffer, 1, 256, diskImageHandle);
	return r == 256;
	}

	void FdcGcr::trackSector(unsigned int &track, unsigned int &sector)
	{
	track = ((currentHalfTrack >> 1));
	sector = (unsigned int) ((gcrPtr - gcrTrackBegin) / GCR_SECTOR_SIZE);
	}

	/*
	Convert track/sector to offset
	*/

	unsigned int FdcGcr::secnumFromTS(unsigned int track, unsigned int sector)
	{
	return d64SectorOffset[track] + sector;
	}

	int FdcGcr::offsetFromTS(unsigned int track, unsigned int sector)
	{
	if ((track < 1) \|\| (track > MAX_NUM_TRACKS) \|\| (sector >= d64NumOfSectors[track]))
	return -1;

	return (d64SectorOffset[track] + sector) << 8;
	}

	/*
	Convert between 4 bytes and 5 GCR encoded bytes
	*/
	const unsigned int tblEncodeToGCR[16] = {
	0x0A, 0x0B, 0x12, 0x13, 0x0E, 0x0F, 0x16, 0x17,
	0x09, 0x19, 0x1A, 0x1B, 0x0D, 0x1D, 0x1E, 0x15
	};

	const unsigned int tblDecodeFromGCR[32] = {
	0, 0, 0, 0, 0, 0, 0, 0, 0, 8, 0, 1, 0,12, 4, 5,
	0, 0, 2, 3, 0,15, 6, 7, 0, 9,10,11, 0,13,14, 0
	};

	void FdcGcr::gcrConv4bytesTo5(unsigned char from, unsigned char to)
	{
	unsigned int g;

	g = (tblEncodeToGCR[from >> 4] << 5) \| tblEncodeToGCR[from & 15];
	*to++ = g >> 2;
	*to = (g << 6) & 0xC0;
	from++;

	g = (tblEncodeToGCR[from >> 4] << 5) \| tblEncodeToGCR[from & 15];
	*to++ \|= (g >> 4) & 0x3F;
	*to = (g << 4) & 0xF0;
	from++;

	g = (tblEncodeToGCR[from >> 4] << 5) \| tblEncodeToGCR[from & 15];
	*to++ \|= (g >> 6) & 0x0F;
	*to = (g << 2) & 0xFC;
	from++;

	g = (tblEncodeToGCR[from >> 4] << 5) \| tblEncodeToGCR[from & 15];
	*to++ \|= (g >> 8) & 0x03;
	*to = (unsigned char) g;
	}

	void FdcGcr::gcrConv5bytesTo4(unsigned char buffer, unsigned char ptr)
	{
	unsigned int i;
	unsigned char gcr_bytes[8];

	gcr_bytes[0] = (*buffer)>>3;
	gcr_bytes[1] =((*buffer++)&0x07)<<2;
	gcr_bytes[1] \|=(*buffer)>>6;
	gcr_bytes[2] =((*buffer)&0x3E)>>1;
	gcr_bytes[3] =((*buffer++)&0x01)<<4;
	gcr_bytes[3]\|=((*buffer)&0xF0)>>4;
	gcr_bytes[4] =((*buffer++)&0x0F)<<1;
	gcr_bytes[4] \|=(*buffer)>>7;
	gcr_bytes[5] =((*buffer)&0x7C)>>2;
	gcr_bytes[6] =((*buffer++)&0x03)<<3;
	gcr_bytes[6]\|=((*buffer)&0xE0)>>5;
	gcr_bytes[7] = (*buffer)&0x1F;

	for (i = 0; i < 4; i++, ptr++) {
	ptr = tblDecodeFromGCR[gcr_bytes[2 i]] << 4;
	ptr \|= tblDecodeFromGCR[gcr_bytes[2 i + 1]];
	}
	}

	void FdcGcr::sector2gcr(int track, int sector)
	{
	unsigned char block[256];
	unsigned char buf[4], headerID1;
	/*
	This formula did not work with Nibble hack em
	unsigned char p = gcrData + (track-1) GCR_MAX_TRACK_SIZE +
	sector * sectorSize[track] / d64NumOfSectors[track];
	*/
	unsigned char p = gcrData + (track-1) GCR_MAX_TRACK_SIZE + sector * GCR_SECTOR_SIZE;
	//Log::write("Track %02i, sector %02i at offset %04i.\n", track, sector, p - gcrData );
	readSector(track, sector, block);

	const unsigned char errCode = job_codes[ diskErrorInfo[d64SectorOffset[track]+sector]].error_code;
	const unsigned char syncByte = errCode == 21 ? 0x55 : 0xFF;

	headerID1 = (errCode == 29) ? id1^0xFF : id1;
	// Create GCR header
	memset( p, syncByte, NUM_SYNC); // Header SYNC bytes
	p += NUM_SYNC;
	buf[0] = (errCode == 20) ? 0xFF : 0x08; // Header mark
	buf[1] = sector ^ track ^ id2 ^ headerID1; // Checksum
	buf[2] = sector;
	buf[3] = track;

	if (errCode == 27)
	buf[1] ^= 0xFF;

	gcrConv4bytesTo5(buf, p);
	buf[0] = id2;
	buf[1] = headerID1;
	buf[2] = buf[3] = 0x0f;
	gcrConv4bytesTo5(buf, p+5);
	p += 10;
	memset(p, 0x55, 9); // Header gap
	p += 9;

	// Create GCR data
	unsigned char sum;
	memset( p, syncByte, NUM_SYNC); // Data SYNC bytes
	p += NUM_SYNC;

	buf[0] = errCode == 22 ? 0xFF : 0x07; // Data mark
	sum = buf[1] = block[0];
	sum ^= buf[2] = block[1];
	sum ^= buf[3] = block[2];
	gcrConv4bytesTo5(buf, p);
	p += 5;
	for (int i=3; i<255; i+=4) {
	sum ^= buf[0] = block[i];
	sum ^= buf[1] = block[i+1];
	sum ^= buf[2] = block[i+2];
	sum ^= buf[3] = block[i+3];
	gcrConv4bytesTo5(buf, p);
	p += 5;
	}
	sum ^= buf[0] = block[255];
	if (errCode == 23) sum ^= 0xFF;
	buf[1] = sum; // Checksum
	// These bytes are needed to have a multiple of four bytes
	buf[2] = 0;
	buf[3] = 0;
	gcrConv4bytesTo5(buf, p);
	p += 5;

	memset(p, 0x55, GCR_SECTOR_GAP_LENGTH); // Gap before next sector
	//p += GCR_SECTOR_GAP_LENGTH;
	}

	void FdcGcr::gcr2sector(unsigned char buffer, unsigned char p,
	unsigned char *trackStart,
	unsigned char *trackEnd)
	{
	unsigned int i, j;
	unsigned char *offset = p;
	unsigned char gcrBufferPtr[5];

	for ( i=0; i<65; i++) {
	for ( j=0; j<5; j++) {
	gcrBufferPtr[j] = *offset++;
	if (offset == trackEnd)
	offset = trackStart;
	}
	gcrConv5bytesTo4(gcrBufferPtr, buffer);
	buffer += 4;
	}
	}

	void FdcGcr::dumpGcr(unsigned char *p)
	{
	FILE *gcrdump = NULL;
	char dumpName[512];

	sprintf(dumpName, "GCRDUMP%s.BIN", imageName);
	gcrdump = fopen(dumpName, "wb");
	if (!gcrdump)
	return;
	for (unsigned int i = 0; i < GCR_MAX_TRACK_SIZE * 35; i++)
	fputc( *p++, gcrdump );
	fclose( gcrdump );
	}

	void FdcGcr::disk2gcr(void)
	{
	// Convert all tracks and sectors
	for ( unsigned int track=1; track<=NrOfTracks; track++)
	for( unsigned int sector=0; sector<d64NumOfSectors[track]; sector++)
	sector2gcr(track, sector);
	#if 0
	dumpGcr(gcrData);
	#endif
	}

	unsigned char *FdcGcr::getSectorHeaderOffset(unsigned int track, unsigned int sector,
	unsigned char trackStart, unsigned char trackEnd)
	{
	unsigned char *offset = trackStart;
	unsigned char gcr_header[5], header_data[4];
	bool wrap_around = false;
	int nr_of_syncs_found = 0;

	while ((offset < trackEnd) && !wrap_around) {
	while (*offset != 0xFF) {
	offset++;
	if (offset >= trackEnd) {
	if (wrap_around) {
	// Log::write(_T("GCR error: no synch found.\n"));
	dumpGcr(gcrData);
	return NULL;
	} else {
	wrap_around = true;
	offset = trackStart;
	}
	}
	}
	while (*offset == 0xFF) {
	offset++;
	if (offset == trackEnd) {
	offset = trackStart;
	wrap_around = true;
	}
	// more sync than size is found?
	if( (trackEnd - trackStart) <= ++nr_of_syncs_found ) {
	// Log::write(_T("GCR error: too many synch bytes found.\n"));
	return NULL;
	}
	}
	for (unsigned int i = 0; i < 5; i++) {
	gcr_header[i] = *(offset++);
	if (offset >= trackEnd) {
	offset = trackStart;
	wrap_around = true;
	}
	}
	gcrConv5bytesTo4(gcr_header, header_data);
	if (header_data[0] == 0x08 && header_data[2] == sector && header_data[3] == track)
	return offset;
	}
	return NULL;
	}

	void FdcGcr::gcr2disk(void)
	{
	FILE *d64dump;
	char new_d64_file[266];
	unsigned char *offset;
	unsigned char sector_buffer[260];

	strcpy( new_d64_file, imageName);

	d64dump = fopen( const_cast<char*> (new_d64_file), "wb");
	if (!d64dump)
	return;

	// Convert all tracks and sectors
	for ( unsigned int track = 1; track<=NrOfTracks; track ++) { // NUM_TRACKS

	unsigned char trackStart = gcrData + (track - 1) GCR_MAX_TRACK_SIZE;
	unsigned char *trackEnd = trackStart + sectorSize[track];
	//offset = trackStart;

	for ( unsigned int sec = 0; sec<d64NumOfSectors[track]; sec++) {
	offset = getSectorHeaderOffset( track, sec, trackStart, trackEnd);

	if ( NULL == offset ) {
	// Log::write(_T("Error dumping gcr data (illegal pointer) at track: %i, sector: %i.\n"),
	// track, sec);
	isDiskCorrupted = true;
	fclose(d64dump);
	return;
	}

	int header = 0;
	// seek data header
	while (*offset != 0xFF) {
	offset++;
	if (offset == trackEnd)
	offset = trackStart;
	header++;
	if (header >= 10000) {
	// Log::write(_T("Error dumping gcr data (no header) at track: %i, sector: %i.\n"),
	// track, sec);
	isDiskCorrupted = true;
	fclose(d64dump);
	return;
	}
	}
	// seek sector data
	bool fullyRotated = false;
	while (*offset == 0xFF && !fullyRotated) { // data mark (0x07) in GCR (0x55)
	offset++;
	if (offset == trackEnd) {
	if (!fullyRotated) {
	offset = trackStart;
	fullyRotated = true;
	} else {
	// Log::write(_T("Error dumping gcr data (no data mark) at track: %i, sector: %i.\n"),
	// track, sec);
	isDiskCorrupted = true;
	}
	}
	}
	// convert to 260 bytes
	gcr2sector( sector_buffer, offset, trackStart, trackEnd);
	if (sector_buffer[0] != 0x07) {
	isDiskCorrupted = true;
	//fclose(d64dump);
	//return;
	// Log::write(_T("Warning: head of buffer not data mark at track: %i, sector %i, file offset: %i.\n"),
	// track, sec, ftell(d64dump));
	}
	// write one sector
	fwrite( &(sector_buffer[1]), 256, 1, d64dump);
	}
	}
	fclose(d64dump);
	}

	// Move R/W head inwards (towards higher tracks)
	void FdcGcr::moveHeadIn(void)
	{
	unsigned long newGCRoffset;

	if (currentHalfTrack >= NrOfTracks*2) {
	// fprintf(stderr, "Drive head moved over highest track of current image.");
	if (currentHalfTrack == MAX_NUM_TRACKS*2) {
	// fprintf(sdterr, (_T("Attempt to move drive head over track 41."));
	return;
	}
	NrOfTracks = currentHalfTrack >> 1;
	}
	// Note actual position within the old track...
	newGCRoffset = (unsigned long)(gcrPtr - gcrTrackBegin) * sectorSize[(currentHalfTrack+1) >> 1]
	/ sectorSize[(currentHalfTrack) >> 1] ;

	currentHalfTrack++;

	gcrTrackBegin = gcrData + ((currentHalfTrack >> 1) - 1) * GCR_MAX_TRACK_SIZE;
	gcrTrackEnd = gcrTrackBegin + sectorSize[currentHalfTrack >> 1];

	gcrPtr = gcrTrackBegin + newGCRoffset;
	}

	// Move R/W head outwards (towards lower tracks)
	void FdcGcr::moveHeadOut(void)
	{
	unsigned long newGCRoffset;

	if (currentHalfTrack == 2)
	return;

	// Note actual position within the old track...
	newGCRoffset = (unsigned long) (gcrPtr - gcrTrackBegin) * sectorSize[(currentHalfTrack-1) >> 1]
	/ sectorSize[(currentHalfTrack) >> 1];

	currentHalfTrack--;

	gcrTrackBegin = gcrData + ((currentHalfTrack >> 1) - 1) * GCR_MAX_TRACK_SIZE;
	gcrTrackEnd = gcrTrackBegin + sectorSize[currentHalfTrack >> 1];

	gcrPtr = gcrTrackBegin + newGCRoffset;
	}