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Factored common RETF logic into opHelpRETF

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This commit is contained in:
Jeff Parsons 2014-12-01 14:50:38 -08:00 • committed by jeffpar
commit d628eacfc6
5 changed files with 72 additions and 37 deletions
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44
modules/pcjs/lib/x86help.js
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@ -222,7 +222,7 @@ var X86Help = {
opHelpBOUND: function(dst, src) {
if (this.regEA < 0) {
/*
* Generate a #UD fault (INT 0x06: Undefined Opcode) if src is not a memory operand.
* Generate UD_FAULT (INT 0x06: Invalid Opcode) if src is not a memory operand.
*/
X86OpXX.opInvalid.call(this);
return dst;
@ -436,7 +436,7 @@ var X86Help = {
},
/**
* opHelpCallF(off, sel)
* opHelpCALLF(off, sel)
*
* For protected-mode, this function must attempt to load the new code segment first, because if the new segment
* requires a change in privilege level, the return address must be pushed on the NEW stack, not the current stack.
@ -445,7 +445,7 @@ var X86Help = {
* @param {number} off
* @param {number} sel
*/
opHelpCallF: function(off, sel) {
opHelpCALLF: function(off, sel) {
var regCS = this.segCS.sel;
var regIP = this.regIP;
if (this.setCSIP(off, sel, true) != null) {
@ -453,6 +453,44 @@ var X86Help = {
this.pushWord(regIP);
}
},
/**
* opHelpRETF(n)
*
* For protected-mode, this function must be prepared to pop any arguments off the current stack AND
* whatever stack we may have switched to (setCSIP() returns true only when a stack switch has occurred).
*
* @this {X86CPU}
* @param {number} n
*/
opHelpRETF: function(n) {
var regIP = this.popWord();
var regCS = this.popWord();
if (n) this.regSP = (this.regSP + n) & 0xffff;
if (this.setCSIP(regIP, regCS, false)) {
if (n) this.regSP = (this.regSP + n) & 0xffff;
/*
* As per Intel documentation: "If any of [the DS or ES] registers refer to segments whose DPL is
* less than the new CPL (excluding conforming code segments), the segment register is loaded with
* the null selector."
*
* TODO: I'm not clear on whether a conforming code segment must also be marked readable, so I'm playing
* it safe and using CODE_CONFORMING instead of CODE_CONFORMING_READABLE. Also, for the record, I've not
* seen this situation occur in OS/2 1.0 yet.
*/
if ((this.segDS.sel & X86.SEL.MASK) && this.segDS.dpl < this.segCS.cpl && (this.segDS.acc & X86.DESC.ACC.TYPE.CODE_CONFORMING) != X86.DESC.ACC.TYPE.CODE_CONFORMING) {
this.assert(false); // I'm not asserting this is bad, I just want to see it in action
this.segDS.load(0);
}
if ((this.segES.sel & X86.SEL.MASK) && this.segES.dpl < this.segCS.cpl && (this.segES.acc & X86.DESC.ACC.TYPE.CODE_CONFORMING) != X86.DESC.ACC.TYPE.CODE_CONFORMING) {
this.assert(false); // I'm not asserting this is bad, I just want to see it in action
this.segES.load(0);
}
}
/*
* We check for possible "INT n" software interrupt returns only in the cases of "IRET" and "RETF 2".
*/
if (n == 2 && this.cIntReturn) this.checkIntReturn(this.regEIP);
},
/**
* opHelpINT(nIDT, nError, nCycles)
*