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Fixed lost 8080 interrupts, and added new CPU-driven setTimer() functionality

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This commit is contained in:
Jeff Parsons 2016-08-17 11:58:01 -07:00
commit 99023617fd
6 changed files with 562 additions and 447 deletions
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39
modules/pc8080/lib/cpustate.js
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@ -938,47 +938,50 @@ CPUState.prototype.pushWord = function(w)
CPUState.prototype.checkINTR = function()
{
if ((this.intFlags & CPUDef.INTFLAG.INTR) && this.getIF()) {
var bRST = CPUDef.OPCODE.RST0 | ((this.intFlags & CPUDef.INTFLAG.INTL) << 3);
this.intFlags &= ~CPUDef.INTFLAG.HALT;
this.clearINTR();
for (var nLevel = 0; nLevel < 8; nLevel++) {
if (this.intFlags & (1 << nLevel)) break;
}
this.clearINTR(nLevel);
this.clearIF();
this.aOps[bRST].call(this);
this.intFlags &= ~CPUDef.INTFLAG.HALT;
this.aOps[CPUDef.OPCODE.RST0 | (nLevel << 3)].call(this);
return true;
}
return false;
};
/**
* clearINTR()
* clearINTR(nLevel)
*
* Clear the corresponding interrupt level.
*
* nLevel can either be a valid interrupt level (0-7), or -1 to clear all pending interrupts
* (eg, in the event of a system-wide reset).
*
* @this {CPUState}
* @param {number} nLevel (0-7, or -1 for all)
*/
CPUState.prototype.clearINTR = function()
CPUState.prototype.clearINTR = function(nLevel)
{
this.intFlags &= ~(CPUDef.INTFLAG.INTL | CPUDef.INTFLAG.INTR);
var bitsClear = nLevel < 0? 0xff : (1 << nLevel);
this.intFlags &= ~bitsClear;
};
/**
* requestINTR(nLevel)
*
* This is called by any component that wants to request a h/w interrupt.
* Request the corresponding interrupt level.
*
* NOTE: We allow INTR to be set regardless of the current state of interrupt flag (IF), on the theory
* that if/when the CPU briefly turns interrupts off, it shouldn't lose the last h/w interrupt requested.
* So instead of ignoring INTR here, checkINTR() ignores INTR as long as the interrupt flag (IF) is clear.
*
* The downside is that, as long as the CPU has interrupts disabled, an active INTR state will slow stepCPU()
* down slightly. We could avoid that by introducing a two-stage interrupt tracking system, where a separate
* variable keeps track of the last interrupt requested whenever the interrupt flag (IF) is clear, and when
* setIF() finally occurs, that interrupt is propagated to intFlags. But for now, we're going to assume that
* scenario is rare.
* Each interrupt level (0-7) has its own intFlags bit (0-7). If one or more of those bits are set,
* and the Interrupt Flag (IF) is also set, indicating that interrupts are enabled, then checkINTR()
* chooses one of those bits, clears it, clears IF, and executes the corresponding RST opcode.
*
* @this {CPUState}
* @param {number} nLevel (0-7)
*/
CPUState.prototype.requestINTR = function(nLevel)
{
this.intFlags = (this.intFlags & ~CPUDef.INTFLAG.INTL) | nLevel | CPUDef.INTFLAG.INTR;
this.intFlags |= (1 << nLevel);
};
/**