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Fixed 16-bit unsigned division overflow detection

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This commit is contained in:
Jeff Parsons 2015-10-31 07:31:32 -07:00
commit 8c67a50f92
4 changed files with 43 additions and 37 deletions
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6
modules/pcjs/lib/x86ops.js
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@ -4169,7 +4169,9 @@ X86.opGRP3b = function()
{
this.fMDSet = false;
this.aOpModGrpByte[this.getIPByte()].call(this, X86.aOpGrp3b, X86.fnSRCNone);
if (this.fMDSet) this.regEAX = (this.regEAX & ~this.maskData) | (this.regMDLo & this.maskData);
if (this.fMDSet) {
this.regEAX = (this.regEAX & ~this.maskData) | (this.regMDLo & this.maskData);
}
};
/**
@ -4184,7 +4186,7 @@ X86.opGRP3b = function()
* return value back into AX or DX, undoing fnMULw's update of DX:AX. And since fnMULw doesn't
* know what the target is (only the target's value), it cannot easily work around the problem.
*
* A simple, albeit kludgey, solution is for fnMULw to always save its result in a special
* A simple, albeit kludgy, solution is for fnMULw to always save its result in a special
* "register" (eg, regMDLo/regMDHi), which we will then put back into regEAX/regEDX if it's been
* updated. This also relieves us from having to decode any part of the ModRM byte, so maybe
* it's not such a bad work-around after all.