public static void Read(ushort unit, ushort address, short addressOffset, ushort len, ushort blockNo)
{
var offset = blockNo * 512u;
var track = blockNo / 8;
var sector = (blockNo & 7) * 2;
Debug.Assert(unit < DiskIO.MaxUnits);
var u = DiskIO.unitTable[unit];
if (u == null || u.Fd == null && u.Data == null)
{
PSystem.IOError(9);
return;
}
if (offset + len > u.Size)
{
PSystem.IOError(64);
return;
}
while (len != 0)
{
var size = 256;
var sec = sector;
if (len < size)
{
size = len;
}
//if (u.Translate != null)
// sec = u.Translate[sector];
int i;
if (u.Data != null)
{
for (i = 0; i < size; i++)
{
Memory.WriteByte
(
address,
(short)(addressOffset + i),
u.Data[(track * 16 + sec) * 256 + i]
);
}
}
else if (u.Fd != null)
{
var buf = new byte[256];
bool failed;
try
{
u.Fd.Seek((track * 16 + sec) * 256, SeekOrigin.Begin);
failed = u.Fd.Read(buf, 0, size) < size;
}
catch
{
failed = true;
}
if (failed)
{
PSystem.IOError(64);
return;
}
for (i = 0; i < size; i++)
{
Memory.WriteByte(address, (short)(addressOffset + i), buf[i]);
}
}
addressOffset += (short)size;
len -= (ushort)size;
sector++;
if (sector < 16)
{
continue;
}
track++;
sector = 0;
}
PSystem.IOError(0);
}
