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Tweaks for interrupt handling; added one instruction delay after ION before enabling interrupts, interrupts are now clocked on the leading edge of the processor Fetch cycle rather than on every clock cycle.

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This commit is contained in:
Josh Dersch 2020-04-28 11:07:45 -07:00
parent aee6c5dc63
commit 3a7afbafc0
3 changed files with 33 additions and 13 deletions
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9
imlac/IO/InterruptFacility.cs
View File

@ -69,7 +69,7 @@ namespace imlac.IO
public void Clock()
{
if (_interruptsEnabled)
if (_interruptsEnabled && _interruptEnableCount == 0)
{
// Collect up devices that want to interrupt us.
_interruptStatus = 0;
@ -172,6 +172,10 @@ namespace imlac.IO
Trace.Log(LogType.Interrupt, "Interrupt triggered (for device(s) {0})", Helpers.ToOctal((ushort)(_interruptMask & _interruptStatus)));
}
}
else if (_interruptsEnabled)
{
_interruptEnableCount--;
}
}
public int[] GetHandledIOTs()
@ -195,6 +199,8 @@ namespace imlac.IO
case 0x72:
_interruptsEnabled = true;
// Interrupts are enabled the second instruction after the ION.
_interruptEnableCount = 1;
Trace.Log(LogType.Interrupt, "Interrupts enabled");
break;
@ -220,6 +226,7 @@ namespace imlac.IO
}
}
private int _interruptEnableCount;
private bool _interruptsEnabled;
private bool _interruptPending;
private int _interruptMask;

16
imlac/IO/TTY.cs
View File

@ -76,15 +76,15 @@ namespace imlac.IO
_rxData = _dataChannel.Read();
Trace.Log(LogType.TTY, "i");
}
}
// Are we waiting to send something?
if (_dataBufferFull && _dataChannel.OutputReady)
{
_dataChannel.Write(_txData);
Trace.Log(LogType.TTY, "o {0}", Helpers.ToOctal(_txData));
_dataBufferFull = false;
_dataSentLatch = true;
// Are we waiting to send something?
if (_dataBufferFull && _dataChannel.OutputReady)
{
_dataChannel.Write(_txData);
Trace.Log(LogType.TTY, "o {0}", Helpers.ToOctal(_txData));
_dataBufferFull = false;
_dataSentLatch = true;
}
}
}

21
imlac/System.cs
View File

@ -134,8 +134,12 @@ namespace imlac
_keyboard.Clock();
_clock.Clock();
// interrupts last so that devices that raise interrupts get clocked first
_interruptFacility.Clock();
// interrupts last so that devices that raise interrupts get clocked first.
// We clock interrupts on the leading edge of the processor's Fetch state.
if (_processor.InstructionState == ExecState.Fetch)
{
_interruptFacility.Clock();
}
}
//
@ -199,13 +203,22 @@ namespace imlac
return SystemExecutionState.UntilDisplayStart;
}
[DebuggerFunction("set bootstrap", "Loads the specified bootstrap into memory at 40", "<bootstrap>")]
private SystemExecutionState SetBootstrap(string bootstrap)
[DebuggerFunction("load bootstrap", "Loads the specified bootstrap into memory at 40", "<bootstrap>")]
private SystemExecutionState LoadBootstrap(string bootstrap)
{
LoadMemory(Paths.BuildBootPath(bootstrap), 0x20, 0x20);
return SystemExecutionState.Debugging;
}
[DebuggerFunction("boot", "Loads the specified bootstrap into memory at 40 and executes it", "<bootstrap>")]
private SystemExecutionState Boot(string bootstrap)
{
LoadMemory(Paths.BuildBootPath(bootstrap), 0x20, 0x20);
Processor.PC = 0x20;
Processor.State = ProcessorState.Running;
return SystemExecutionState.Running;
}
[DebuggerFunction("save memory", "Saves the specified range of memory to a file", "<file> <start> <length>")]
private SystemExecutionState SaveMemoryContents(string file, ushort start, ushort length)
{