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Force all segment register writes to be 16-bit, even when the operand size is 32-bit

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This commit is contained in:
Jeff Parsons 2016-01-27 10:58:01 -08:00
commit adb2b9aa90
9 changed files with 1265 additions and 1216 deletions
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21
modules/pcjs/lib/x86func.js
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@ -567,8 +567,13 @@ X86.fnCALLF = function(off, sel)
var oldIP = this.getIP();
var oldSize = (I386? this.sizeData : 2);
if (this.setCSIP(off, sel, true) != null) {
this.pushData(this.opCS, oldSize);
this.pushData(oldIP, oldSize);
/*
* When the OPERAND size is 32 bits, the 80386 will decrement the stack pointer by 4, write the selector
* into the 2 lower bytes, and leave the 2 upper bytes untouched; at least, that's the case for all other
* segment register writes, so we assume this case is no different. Hence, the hard-coded size of 2.
*/
this.pushData(this.opCS, oldSize, 2);
this.pushData(oldIP, oldSize, oldSize);
}
this.opLSP = X86.ADDR_INVALID;
this.opCS = -1;
@ -1941,12 +1946,14 @@ X86.fnMOVn = function(dst, src)
*/
X86.fnMOVxx = function(dst, src)
{
/*
* When a 32-bit OPERAND size is in effect, segment register writes via opMOVwsr() must write 32 bits
* (zero-extended) if the destination is a register, but only 16 bits if the destination is memory,
* hence the setDataSize(2) below.
*
* The only other caller, opMOVrc(), is not affected, because it writes only to register destinations.
*/
if (this.regEAWrite !== X86.ADDR_INVALID) {
/*
* When a 32-bit OPERAND size is in effect, opMOVwsr() will write 32 bits (zero-extended) if the destination
* is a register, but only 16 bits if the destination is memory. The only other caller, opMOVrc(), is not
* affected, because it writes only to register destinations.
*/
this.setDataSize(2);
}
return X86.fnMOV.call(this, dst, this.regXX);