Retro/pcjs
Watch
1
0
Fork
You've already forked pcjs
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Fixed LGDT and LIDT, fixed read-only memory, and fixed mode transition tests

Browse source
This commit is contained in:
Jeff Parsons 2015-05-06 16:24:28 -07:00 • committed by jeffpar
commit cfa4e0207f
5 changed files with 158 additions and 104 deletions
Download patch file Download diff file Expand all files Collapse all files

14
modules/pcjs/lib/x86seg.js
View file

@ -157,12 +157,18 @@ X86Seg.prototype.loadProt = function loadProt(sel, fSuppress)
*/
sel &= 0xffff;
/*
* When comparing descriptor addresses, we must be mindful that any addresses above 2Gb will be negative;
* that in itself is not a problem UNLESS the descriptor table straddles the 2Gb boundary, meaning the
* starting address is positive but the ending (limit) address is negative. Although that situation is
* highly unlikely, the safest thing to do is coerce the bounding addresses to unsigned values, using ">>> 0."
*/
if (!(sel & X86.SEL.LDT)) {
addrDT = cpu.addrGDT;
addrDTLimit = cpu.addrGDTLimit;
addrDT = cpu.addrGDT >>> 0;
addrDTLimit = cpu.addrGDTLimit >>> 0;
} else {
addrDT = cpu.segLDT.base;
addrDTLimit = addrDT + cpu.segLDT.limit;
addrDT = cpu.segLDT.base >>> 0;
addrDTLimit = addrDT + cpu.segLDT.limit; // segment limit properties are already coerced unsigned
}
/*
* The ROM BIOS POST executes some test code in protected-mode without properly initializing the LDT,