private List <SectorDescriptor> GetSectorDescriptorCache()
{
var sds = new List <SectorDescriptor>();
for (int SectorIndex = 0; SectorIndex < HEADER_LENGTH && Header[SectorIndex] > 0; SectorIndex++)
{
bool density = Header[SectorIndex] >= DOUBLE_DENSITY_MASK;
int byteMultiple = density ? 1 : 2;
int offset = (Header[SectorIndex] & OFFSET_MASK) - HEADER_LENGTH_BYTES;
if (data[offset] != Floppy.IDAM)
{
continue;
}
byte trackNum = data[offset + 1 * byteMultiple];
bool sideOne = data[offset + 2 * byteMultiple] > 0;
byte sectorNum = data[offset + 3 * byteMultiple];
byte dam = 0x00;
int dataStart = 0x00;
bool deleted = false;
for (int i = offset + 7 * byteMultiple; i < offset + (7 + (density ? 43 : 30)) * byteMultiple; i += byteMultiple)
{
if (FloppyController.IsDAM(data[i], out deleted))
{
dam = data[i];
dataStart = i + byteMultiple;
break;
}
}
var sizeCode = data[offset + 4 * byteMultiple];
var dataLength = Floppy.GetDataLengthFromCode(sizeCode);
var sectorData = new byte[dataLength];
bool crcError;
bool inUse;
if (dam == 0x00)
{
crcError = true;
inUse = false;
}
else
{
inUse = !deleted;
ushort actualCrc = Lib.Crc(density ? Floppy.CRC_RESET_A1_A1_A1 : Floppy.CRC_RESET, dam);
for (int i = 0; i < dataLength; i++)
{
sectorData[i] = data[dataStart + i * byteMultiple];
actualCrc = Lib.Crc(actualCrc, sectorData[i]);
}
ushort recordedCrc = Lib.CombineBytes(data[dataStart + (dataLength + 1) * byteMultiple], data[dataStart + dataLength * byteMultiple]);
crcError = actualCrc != recordedCrc;
}
sds.Add(new SectorDescriptor(trackNum,
sectorNum,
sideOne,
density,
dam,
sectorData,
inUse,
crcError));
}
return(sds.OrderBy(s => s.SectorNumber).ToList());
}
private void SeekAddressData(byte ByteRead, OpStatus NextStatus, bool Check)
{
damBytesChecked++;
switch (opStatus)
{
case OpStatus.SeekingIDAM:
if (IndexesFound >= 5)
{
SeekError = true;
opStatus = OpStatus.NMI;
}
else
{
switch (ByteRead)
{
case Floppy.IDAM:
if (track?.HasIdamAt(TrackDataIndex, DoubleDensitySelected) ?? false)
{
readAddressIndex = 0;
ResetCRC();
crc = Lib.Crc(crc, ByteRead);
opStatus = OpStatus.ReadingAddressData;
}
idamBytesFound = 0;
break;
default:
idamBytesFound = 0;
break;
}
}
break;
case OpStatus.ReadingAddressData:
readAddressData[readAddressIndex] = ByteRead;
if (readAddressIndex == ADDRESS_DATA_CRC_HIGH_BYTE - 1)
{
// save the value before the first crc on the sector comes in
crcCalc = crc;
}
else if (readAddressIndex >= ADDRESS_DATA_CRC_LOW_BYTE)
{
damBytesChecked = 0;
crcHigh = readAddressData[ADDRESS_DATA_CRC_HIGH_BYTE];
crcLow = readAddressData[ADDRESS_DATA_CRC_LOW_BYTE];
CrcError = crcCalc != Lib.CombineBytes(crcLow, crcHigh);
var match = (TrackRegister == readAddressData[ADDRESS_DATA_TRACK_REGISTER_BYTE] &&
(!command.SideSelectVerify || (command.SideOneExpected == (readAddressData[ADDRESS_DATA_SIDE_ONE_BYTE] != 0))) &&
(SectorRegister == readAddressData[ADDRESS_DATA_SECTOR_REGISTER_BYTE]));
if (Check && !match)
{
opStatus = OpStatus.SeekingIDAM;
}
else
{
sectorLength = Floppy.GetDataLengthFromCode(readAddressData[ADDRESS_DATA_SECTOR_SIZE_BYTE]);
if (CrcError)
{
opStatus = OpStatus.SeekingIDAM;
}
else
{
opStatus = NextStatus;
}
}
}
readAddressIndex++;
break;
default:
throw new Exception();
}
}
private ushort[] RebuildHeader()
{
var header = new ushort[HEADER_LENGTH];
int headerCursor = 0;
int end = data.Length - 10;
int i = 4;
while (i < end)
{
bool density = GetDensity(i);
if (data[i] == Floppy.IDAM)
{
// is it a real IDAM? Check preceding bytes
if (density)
{
if (data[i - 1] != 0xA1 || data[i - 2] != 0xA1 || data[i - 3] != 0xA1)
{
i++;
continue;
}
}
else
{
if (data[i - 2] != 0x00)
{
i += 2;
continue;
}
}
// commit without checking address crc, since could be intentional error
header[headerCursor++] = (ushort)(i + HEADER_LENGTH_BYTES + (density ? DOUBLE_DENSITY_MASK : 0));
// now skip forward past the sector contents
// advance to length
if (density)
{
i += 4;
}
else
{
i += 8;
}
i += Floppy.GetDataLengthFromCode(data[i]) * (density ? 1 : 2);
i += 20 * (density ? 1 : 2); // filler minimum
}
else
{
if (density)
{
i++;
}
else
{
i += 2;
}
}
}
this.header = header;
return(this.header);
}