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

Fixed SGDT/SIDT (hopefully)

Browse source
This commit is contained in:
Jeff Parsons 2015-05-03 10:11:18 -07:00 • committed by jeffpar
commit 5d2a7b13a3
2 changed files with 33 additions and 3 deletions
Download patch file Download diff file Expand all files Collapse all files

2
modules/pcjs/lib/rom.js
View file

@ -282,7 +282,7 @@ ROM.prototype.copyROM = function()
if (this.abROM.length != this.sizeROM) {
/*
* Note that setError() sets the component's fError flag, which in turn prevents setReady() from
* marking the component ready. TODO: Revisit this decision. One the one hand, it sounds like a
* marking the component ready. TODO: Revisit this decision. On the one hand, it sounds like a
* good idea to stop the machine in its tracks whenever a setError() occurs, but there may also be
* times when we'd like to forge ahead anyway.
*/

34
modules/pcjs/lib/x86func.js
View file

@ -2599,6 +2599,7 @@ X86.fnSGDT = function SGDT(dst, src)
* calls us does that automatically with the value we return (dst).
*/
dst = this.addrGDTLimit - this.addrGDT;
this.assert(!(dst & ~0xffff));
/*
* We previously left the 6th byte of the target operand "undefined". But it turns out we have to set
* it to *something*, because there's processor detection in PC-DOS 7.0 (at least in the SETUP portion)
@ -2628,8 +2629,26 @@ X86.fnSGDT = function SGDT(dst, src)
* 145E:4BC3 CB RETF
*
* This code is expecting SGDT on an 80286 to set the 6th "undefined" byte to 0xFF.
*
* The 80386 adds an additional wrinkle: the 6th byte must be 0x00 if the OPERAND size is 2, whereas
* it must passed through if the OPERAND size is 4.
*
* In addition, when the OPERAND size is 4, the ModRM group decoder will call setLong(dst) rather than
* setShort(dst); we could fix that by forcing the dataSize to 2, but it seems simpler to set the high
* bits (16-31) of dst to match the low bits (0-15) of addr, so that the caller will harmlessly rewrite
* what we already wrote with the setLong() below.
*/
var addr = this.addrGDT | (this.model == X86.MODEL_80286? (0xff000000|0) : 0);
var addr = this.addrGDT;
if (this.model == X86.MODEL_80286) {
addr |= (0xff000000|0);
}
else if (this.model >= X86.MODEL_80386) {
if (this.dataSize == 2) {
addr &= 0x00ffffff;
} else {
dst |= (addr << 16);
}
}
this.setLong(this.regEA + 2, addr);
this.nStepCycles -= 11;
}
@ -2977,11 +2996,22 @@ X86.fnSIDT = function SIDT(dst, src)
* us does that automatically with the value we return (dst).
*/
dst = this.addrIDTLimit - this.addrIDT;
this.assert(!(dst & ~0xffff));
/*
* As with SGDT, the 6th byte is technically "undefined" on an 80286, but we now set it to 0xFF, for the
* same reasons discussed in SGDT (above).
*/
var addr = this.addrIDT | (this.model == X86.MODEL_80286? (0xff000000|0) : 0);
var addr = this.addrIDT;
if (this.model == X86.MODEL_80286) {
addr |= (0xff000000|0);
}
else if (this.model >= X86.MODEL_80386) {
if (this.dataSize == 2) {
addr &= 0x00ffffff;
} else {
dst |= (addr << 16);
}
}
this.setLong(this.regEA + 2, addr);
this.nStepCycles -= 12;
}