private void DoIOT()
{
//
// Dispatch the IOT instruction to the correct device, if one is registered.
// We use the Data field (the full 9 bits including the device and IOP code)
// as the index. See the comments in IIOTDevice for the reasoning here.
//
// We special case IOT 60 here -- this does not appear in any documentation but it does
// show up in the 2nd-stage loader on a number of tapes as the first instruction.
// Unsure what the purpose is (there are some hints that doing an IOT (any IOT) is needed to
// trigger something) but ignoring it works fine for now.
//
if (_currentInstruction.Data == 0x30)
{
return;
}
IIOTDevice device = _iotDispatch[_currentInstruction.Data];
if (device != null)
{
device.ExecuteIOT(_currentInstruction.Data);
}
else
{
Trace.Log(LogType.Processor, "Unimplemented IOT device {0}, IOT opcode {1}", Helpers.ToOctal((ushort)_currentInstruction.IOTDevice), Helpers.ToOctal(_currentInstruction.Data));
}
}
public Processor(ImlacSystem system)
{
_system = system;
_mem = _system.Memory;
_iotDispatch = new IIOTDevice[0x200]; // 9 bits of IOT instructions
Reset();
InitializeCache();
}
public void RegisterDeviceIOTs(IIOTDevice device)
{
int[] handledIOTs = device.GetHandledIOTs();
foreach (int i in handledIOTs)
{
if (_iotDispatch[i] == null)
{
_iotDispatch[i] = device;
}
else
{
// We have an overlap here; can't have two devices sharing the same
// IOT. It would be bad.
throw new InvalidOperationException(String.Format("IOT conflict on {0:x3} between {1} and {2}.", i, _iotDispatch[i], device));
}
}
}
