public void WriteRecord(bool binary, byte[] mrecord)
{
TapeConverter.ToTape(binary, mrecord, out byte[] trecord);
if (p7bflag)
{
trecord[0] |= 0x80;
f.Write(trecord, 0, trecord.Length);
}
else
{
byte[] len = BitConverter.GetBytes(trecord.Length);
if (!BitConverter.IsLittleEndian)
{
Array.Reverse(len);
}
f.Write(len, 0, 4);
f.Write(trecord, 0, (int)trecord.Length);
f.Write(len, 0, 4);
}
}
public int ReadRecord(out bool binary, out byte[] mrecord) /* reads a record as array of 6-bit value from tape-file, retun -1:end of input file 0: EOF marker read, 1: record read; binary=true: binary record false: bcd record */
{
/* reset output values */
mrecord = null;
binary = false;
if (p7bflag) /* read p7b record */
{
int b; /* current character */
if (stored) /* fist byte of record already read? */
{
b = last; /* use it */
stored = false;
}
else
{
b = f.ReadByte(); /* read byte */
}
if (b < 0) /* end of media ? */
{
return(-1); /* EOM */
}
if ((b & 128) == 0) /* The first byte of a records must have bit 7 set */
{
throw new InvalidDataException("TapeReader:Bit 7 not set at record start");
}
List <byte> trecord = new List <byte>(160)
{
(byte)(b & 127)
}; /* remove record start marker, store character */
do
{
b = f.ReadByte();
if (b < 0 || (b & 128) != 0) /* next record or EOF */
{
stored = true; /* set flag */
last = b; /* store value for next call*/
break;
}
trecord.Add((byte)b);
}while (true);
TapeConverter.FromTape(trecord.ToArray(), out binary, out mrecord);
if (!binary && mrecord.Length == 1 && mrecord[0] == 15)
{
return(0); /* EOF */
}
return(1); /* no EOF */
}
else /* read tp record */
{
const int maxbuffer = 32000;
byte[] len = new byte[4];
if (f.Read(len, 0, 4) != 4) /* read length, check if readable */
{
return(-1);
}
if (!BitConverter.IsLittleEndian)
{
Array.Reverse(len);
}
uint l = BitConverter.ToUInt32(len, 0);
if (l == 0)
{
return(0); /* length of 0 means EOF */
}
else if (l == 0xFFFFFFFF)
{
return(-1);/* length of -1 means EOM */
}
else
{
if (l > maxbuffer)
{
return(-1);
}
byte[] trecord = new byte[l];
if (l != f.Read(trecord, 0, (int)l))
{
throw new Exception("read error");
}
byte[] elen = new byte[4];
if (4 != f.Read(elen, 0, 4))
{
throw new Exception("read error");
}
if (!BitConverter.IsLittleEndian)
{
Array.Reverse(elen);
}
if (l != BitConverter.ToUInt32(elen, 0))
{
throw new Exception("wrong elen");
}
TapeConverter.FromTape(trecord, out binary, out mrecord);
return(1); /* record was read */
}
}
}
