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Factored trap checks into separate function: checkTraps()

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This commit is contained in:
Jeff 2016-11-11 15:49:37 -08:00 • committed by Jeff Parsons
commit b87c77b0a0
4 changed files with 365 additions and 327 deletions
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100
modules/pdp11/lib/cpustate.js
View file

@ -739,11 +739,12 @@ CPUStatePDP11.prototype.removeTrigger = function(trigger)
CPUStatePDP11.prototype.setTrigger = function(trigger)
{
/*
* For now, we will not dispatch interrupts immediately, but always defer to checkInterrupts() instead.
* We COULD dispatch interrupts immediately, but there are compatibility reasons for ONLY doing so
* inside the stepCPU() loop; see that function for details.
*
if (this.dispatchInterrupt(trigger.vector, trigger.priority)) {
return true;
}
* if (this.dispatchInterrupt(trigger.vector, trigger.priority)) {
* return true;
* }
*/
this.insertTrigger(trigger);
this.opFlags |= PDP11.OPFLAG.INTQ;
@ -834,6 +835,65 @@ CPUStatePDP11.prototype.dispatchInterrupt = function(vector, priority)
return false;
};
/**
* checkTraps()
*
* NOTE: The following code processes these "deferred" traps in priority order. Unfortunately, that
* order seems to have changed since the 11/20. For reference, here's the priority list for the 11/20:
*
* 1. Bus Errors
* 2. Instruction Traps
* 3. Trace Trap
* 4. Stack Overflow Trap
* 5. Power Failure Trap
*
* and for the 11/70:
*
* 1. HALT (Instruction, Switch, or Command)
* 2. MMU Faults
* 3. Parity Errors
* 4. Bus Errors (including stack overflow traps?)
* 5. Floating Point Traps
* 6. TRAP Instruction
* 7. TRACE Trap
* 8. OVFL Trap
* 9. Power Fail Trap
* 10. Console Bus Request (Front Panel Operation)
* 11. PIR 7, BR 7, PIR 6, BR 6, PIR 5, BR 5, PIR 4, BR 4, PIR 3, BR 3, PIR 2, PIR 1
* 12. WAIT Loop
*
* TODO: Determine 1) if the 11/20 Handbook was wrong, or 2) if the 11/70 really has different priorities.
*
* Also, as the PDP-11/20 Handbook (1971), p.100, notes:
*
* If a bus error is caused by the trap process handling instruction traps, trace traps, stack overflow
* traps, or a previous bus error, the processor is halted.
*
* If a stack overflow is caused by the trap process in handling bus errors, instruction traps, or trace traps,
* the process is completed and then the stack overflow trap is sprung.
*
* TODO: Based on the above notes, we should probably be halting the CPU when a bus error occurs during a trap.
*
* @this {CPUStatePDP11}
* @return {boolean} (true if dispatched, false if not)
*/
CPUStatePDP11.prototype.checkTraps = function()
{
if (this.opFlags & PDP11.OPFLAG.TRAP_MMU) {
this.trap(PDP11.TRAP.MMU, PDP11.OPFLAG.TRAP_MMU, PDP11.REASON.TRAP);
return true;
}
if (this.opFlags & PDP11.OPFLAG.TRAP_SP) {
this.trap(PDP11.TRAP.BUS_ERROR, PDP11.OPFLAG.TRAP_SP, PDP11.REASON.STACK);
return true;
}
if (this.opFlags & PDP11.OPFLAG.TRAP_TF) {
this.trap(PDP11.TRAP.BPT, PDP11.OPFLAG.TRAP_TF, PDP11.REASON.TRACE);
return true;
}
return false;
};
/**
* isWaiting()
*
@ -2257,42 +2317,14 @@ CPUStatePDP11.prototype.stepCPU = function(nMinCycles)
}
}
/*
* Check for any pending traps.
* Next, check for any pending traps (which, as noted above, must be done after checkInterrupts()).
*
* I've moved this TRAP_MASK check BEFORE we decode the next instruction instead of immediately AFTER,
* just in case the last instruction threw an exception that kicked us out before we reached the bottom
* of the stepCPU() loop.
*
* NOTE: The following code processes these "deferred" traps in priority order. Unfortunately, that
* order seems to have changed since the 11/20. For reference, here's the priority list for the 11/70:
*
* 1. HALT (Instruction, Switch, or Command)
* 2. MMU Faults
* 3. Parity Errors
* 4. Bus Errors (which includes stack overflow traps)
* 5. Floating Point Traps
* 6. TRAP Instruction
* 7. TRACE Trap
* 8. OVFL Trap
* 9. Power Fail Trap
* 10. Console Bus Request (Front Panel Operation)
* 11. PIR 7, BR 7, PIR 6, BR 6, PIR 5, BR 5, PIR 4, BR 4, PIR 3, BR 3, PIR 2, PIR 1
* 12. WAIT Loop
*
* TODO: Determine 1) if the 11/20 Handbook was wrong, or 2) if the 11/70 really has different priorities.
*/
if (this.opFlags & PDP11.OPFLAG.TRAP_MASK) {
if (this.opFlags & PDP11.OPFLAG.TRAP_MMU) {
this.trap(PDP11.TRAP.MMU, PDP11.OPFLAG.TRAP_MMU, PDP11.REASON.TRAP);
if (nDebugState < 0) break;
}
else if (this.opFlags & PDP11.OPFLAG.TRAP_SP) {
this.trap(PDP11.TRAP.BUS_ERROR, PDP11.OPFLAG.TRAP_SP, PDP11.REASON.STACK);
if (nDebugState < 0) break;
}
else /* if (this.opFlags & PDP11.OPFLAG.TRAP_TF) */ {
this.assert(this.opFlags & PDP11.OPFLAG.TRAP_TF);
this.trap(PDP11.TRAP.BPT, PDP11.OPFLAG.TRAP_TF, PDP11.REASON.TRACE);
if (this.checkTraps()) {
if (nDebugState < 0) break;
}
}

8
modules/shared/templates/components.css
View file

@ -234,9 +234,15 @@
}
.pcjs-registers {
width: 100% !important;
max-width: none !important;
padding-left: 0 !important;
padding-right: 0 !important;
}
.pdp11-device {
width: 100% !important;
width: 98% !important;
max-width: none !important;
margin-left: 8px !important;
padding-left: 0 !important;
padding-right: 0 !important;
}
}