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Implemented (but have not yet tested) 286 LOADALL

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This commit is contained in:
Jeff Parsons 2014-10-31 13:40:19 -07:00 • committed by jeffpar
commit 5e6604b760
9 changed files with 335 additions and 173 deletions
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77
my_modules/pcjs-client/lib/x86seg.js
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@ -75,6 +75,7 @@ X86Seg.loadReal = function loadReal(sel, fSuppress)
{
this.sel = sel;
this.limit = 0xffff; // TODO: Consider NOT setting the limit field in real-mode (unless it's required for, say, LOADALL support?)
this.level = 0;
return this.base = sel << 4;
};
@ -110,51 +111,64 @@ X86Seg.loadProt = function loadProt(sel, fSuppress)
addrDT = this.cpu.segLDT.base;
addrDTLimit = this.cpu.segLDT.limit;
}
var offDT = addrDT + (sel & X86.SEL.MASK);
if (offDT + 7 <= addrDTLimit) {
this.checkRead = X86Seg.checkReadProtEnabled;
this.checkWrite = X86Seg.checkWriteProtEnabled;
var offDesc = addrDT + (sel & X86.SEL.MASK);
if (offDesc + 7 <= addrDTLimit) {
/*
* TODO: This is only the first of many steps toward accurately counting cycles in protected mode;
* I simply noted that "POP segreg" takes 5 cycles in real mode and 20 in protected mode, so I'm
* starting with a 15-cycle difference. Obviously the difference will be much greater when the load fails.
*/
this.cpu.nStepCycles -= 15;
return X86Seg.loadDesc.call(this, sel, offDesc, true);
}
return -1;
};
/*
* TODO: Use (direct) Bus memory interfaces instead of (indirect) CPU memory interfaces here?
*/
var limit = this.cpu.getWord(offDT + X86.DESC.LIMIT.OFFSET);
var acc = this.cpu.getWord(offDT + X86.DESC.ACC.OFFSET);
var base = this.cpu.getWord(offDT + X86.DESC.BASE.OFFSET) | ((acc & X86.DESC.ACC.BASE1623) << 16);
/**
* loadDesc(sel, offDesc, fProt)
*
* @this {X86Seg}
* @param {number} sel containing a selector
* @param {number} offDesc is the physical address of a descriptor
* @param {boolean} [fProt] is true if protected-mode, false if real-mode, undefined if TBD
* @return {number} base address of selected segment, or -1 if error
*/
X86Seg.loadDesc = function(sel, offDesc, fProt)
{
var limit = this.cpu.getWord(offDesc + X86.DESC.LIMIT.OFFSET);
var acc = this.cpu.getWord(offDesc + X86.DESC.ACC.OFFSET);
var base = this.cpu.getWord(offDesc + X86.DESC.BASE.OFFSET) | ((acc & X86.DESC.ACC.BASE1623) << 16);
Component.assert(this.cpu.getWord(offDT + 0x06) == 0);
Component.assert(this.cpu.getWord(offDesc + 0x06) == 0);
/*
* For LSL (which uses fSuppress), we must support X86.DESC.ACC.TYPE.SEG as well as TSS and LDT.
*/
var accType = (acc & X86.DESC.ACC.TYPE.MASK);
if (accType & X86.DESC.ACC.TYPE.SEG) {
fProt = this.setProt(fProt);
/*
* For LSL (which uses fSuppress), we must support X86.DESC.ACC.TYPE.SEG as well as TSS and LDT.
*/
var accType = (acc & X86.DESC.ACC.TYPE.MASK);
if (accType & X86.DESC.ACC.TYPE.SEG) {
if (fProt) {
if ((accType & X86.DESC.ACC.TYPE.CODE_READABLE) == X86.DESC.ACC.TYPE.CODE) {
this.checkWrite = X86Seg.checkReadProtDisabled;
}
if ((accType & X86.DESC.ACC.TYPE.CODE) || !(accType & X86.DESC.ACC.TYPE.WRITEABLE)) {
this.checkWrite = X86Seg.checkWriteProtDisabled;
}
this.sel = sel;
this.limit = limit;
this.acc = acc;
this.level = (acc & X86.DESC.ACC.LEVEL.MASK) >> X86.DESC.ACC.LEVEL.SHIFT;
return this.base = base;
}
else if (accType && accType <= X86.DESC.ACC.TYPE.TSS_BUSY) {
this.sel = sel;
this.limit = limit;
this.acc = acc;
this.level = (acc & X86.DESC.ACC.LEVEL.MASK) >> X86.DESC.ACC.LEVEL.SHIFT;
return this.base = base;
}
this.sel = sel;
this.limit = limit;
this.acc = acc;
this.level = (acc & X86.DESC.ACC.LEVEL.MASK) >> X86.DESC.ACC.LEVEL.SHIFT;
return this.base = base;
}
else if (accType && accType <= X86.DESC.ACC.TYPE.TSS_BUSY) {
this.sel = sel;
this.limit = limit;
this.acc = acc;
this.level = (acc & X86.DESC.ACC.LEVEL.MASK) >> X86.DESC.ACC.LEVEL.SHIFT;
return this.base = base;
}
return -1;
};
@ -321,8 +335,12 @@ X86Seg.prototype.setBase = function(addr)
/**
* setProt(fProt)
*
* This must be used to ensure that the segment register's state (ie, load and check methods) matches
* the current operating mode (real or protected).
*
* @this {X86Seg}
* @param {boolean} [fProt]
* @return {boolean}
*/
X86Seg.prototype.setProt = function(fProt)
{
@ -338,6 +356,7 @@ X86Seg.prototype.setProt = function(fProt)
this.checkRead = X86Seg.checkReadReal;
this.checkWrite = X86Seg.checkWriteReal;
}
return fProt;
};
if (typeof module !== 'undefined') module.exports = X86Seg;