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Fixed INT and RETF when stack switches occur

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This commit is contained in:
Jeff Parsons 2014-11-26 16:34:54 -08:00 • committed by jeffpar
commit 38c2928882
7 changed files with 81 additions and 49 deletions
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30
modules/pcjs/lib/x86seg.js
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@ -59,7 +59,31 @@ function X86Seg(cpu, id, sName, fProt)
this.addrDesc = null;
this.cpl = 0;
this.dpl = 0;
/*
* The following properties are used for CODE segments only (ie, segCS); if the process of loading
* CS also requires a stack switch, then fStackSwitch will be set to true; additionally, if the stack
* switch was the result of a CALL (ie, fCall is true) and one or more (up to 32) parameters are on
* the old stack, they will be copied to awScratch, and then once the stack is switched, the parameters
* will be pushed from awScratch onto the new stack.
*
* The typical ways of loading a new segment into CS are JMPF, CALLF (or INT), and RETF (or IRET);
* prior to calling segCS.load(), each of those operations must first set segCS.fCall to one of null,
* true, or false, respectively.
*
* It's critical that fCall be properly set prior to calling segCS.load(); fCall == null means NO
* privilege level transition may occur, fCall == true allows a stack switch and a privilege transition
* to a numerically lower privilege, and fCall == false allows a stack switch (restore) and a privilege
* transition to a numerically greater privilege.
*
* As long as setCSIP() is used for all CS changes, the foregoing is automatically taken care of.
*
* TODO: Consider making fCall a parameter to load(), instead of a property that must be set prior to
* calling load(); the downside (and why I didn't do that in the first place) is that such a parameter
* to load() would be meaningless for segments other than segCS.
*/
this.awScratch = (this.id == X86Seg.ID.CODE? new Array(32) : []);
this.fCall = null;
this.fStackSwitch = false;
this.updateAccess(fProt);
}
@ -470,7 +494,7 @@ X86Seg.prototype.setBase = function(addr)
* save()
*
* Early versions of PCjs saved only segment selectors, since that's all that mattered in real-mode;
* newer versions need to save/restore the entire segment object.
* newer versions need to save/restore all the "defining" properties of the X86Seg object.
*
* @this {X86Seg}
* @return {Array}
@ -484,7 +508,7 @@ X86Seg.prototype.save = function()
* restore(a)
*
* Early versions of PCjs saved only segment selectors, since that's all that mattered in real-mode;
* newer versions need to save/restore the entire segment object.
* newer versions need to save/restore all the "defining" properties of the X86Seg object.
*
* @this {X86Seg}
* @param {Array|number} a
@ -555,8 +579,6 @@ X86Seg.prototype.updateAccess = function(fProt)
this.cpl = this.dpl = 0;
this.addrDesc = null;
}
this.fCall = null; // true if CALLF in progress, false if RETF in progress, null/undefined otherwise (X86Seg.ID.CODE only)
this.fStackSwitch = false; // true if a stack switch occurred on the last loadDesc8(), false otherwise (X86Seg.ID.CODE only)
return fProt;
};