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

Added support for segment wrap-around in 8086/8088 real-mode (all stack operations, instruction fetches, and operand accesses should wrap now); real-mode wrap-around on newer processors should trigger a GP fault instead

Browse source
This commit is contained in:
Jeff 2017-07-23 14:59:26 -07:00 • committed by Jeff Parsons
commit 6a3f7f4a5d
15 changed files with 3156 additions and 2906 deletions
Download patch file Download diff file Expand all files Collapse all files

45
modules/pcx86/lib/x86seg.js
View file

@ -83,8 +83,8 @@ class X86Seg {
this.maskData = this.maskAddr = 0xffff;
this.loadV86 = this.loadReal;
this.checkReadV86 = this.checkReadReal;
this.checkWriteV86 = this.checkWriteReal;
this.checkReadV86 = this.checkReadWriteReal;
this.checkWriteV86 = this.checkReadWriteReal;
/*
* Preallocated object for "probed" segment loads
@ -109,14 +109,20 @@ class X86Seg {
*
* loadIDT() sets fCall to true unconditionally in protected-mode (fCall has no meaning in real-mode).
*/
if (this.id == 1) { // X86Seg.ID.CODE (don't use until it's defined, or the Closure Compiler won't inline it)
if (this.id == 1 /* X86Seg.ID.CODE */) { // don't use X86Seg.ID.CODE until it's defined, or the Closure Compiler won't inline it
this.offIP = 0;
this.fCall = null;
this.fStackSwitch = false;
this.awParms = new Array(32);
this.aCallBreaks = [];
}
this.updateMode(true, fProt);
if (this.id == 0 /* X86Seg.ID.NULL */) {
this.checkRead = this.checkReadWriteNone;
this.checkWrite = this.checkReadWriteNone;
}
}
/**
@ -301,34 +307,39 @@ class X86Seg {
}
/**
* checkReadReal(off, cb)
*
* TODO: Invoke X86.helpFault.call(this.cpu, X86.EXCEPTION.GP_FAULT) if off+cb is beyond offMax on 80186 and up;
* also, determine whether helpFault() call should include an error code, since this is happening in real-mode.
* checkReadWriteNone(off, cb)
*
* @this {X86Seg}
* @param {number} off is a segment-relative offset
* @param {number} cb is number of bytes to check (1, 2 or 4)
* @return {number} corresponding linear address if valid, or X86.ADDR_INVALID if error (TODO: No error conditions yet)
* @return {number} corresponding linear address
*/
checkReadReal(off, cb)
checkReadWriteNone(off, cb)
{
return (this.base + off)|0;
}
/**
* checkWriteReal(off, cb)
*
* TODO: Invoke X86.helpFault.call(this.cpu, X86.EXCEPTION.GP_FAULT) if off+cb is beyond offMax on 80186 and up;
* also, determine whether helpFault() call should include an error code, since this is happening in real-mode.
* checkReadWriteReal(off, cb)
*
* @this {X86Seg}
* @param {number} off is a segment-relative offset
* @param {number} cb is number of bytes to check (1, 2 or 4)
* @return {number} corresponding linear address if valid, or X86.ADDR_INVALID if error (TODO: No error conditions yet)
* @return {number} corresponding linear address
*/
checkWriteReal(off, cb)
checkReadWriteReal(off, cb)
{
/*
* Since off could be a 32-bit value with the sign bit (bit 31) set, we must convert
* it to an unsigned value using ">>>"; offMax was already converted at segment load time.
*/
if ((off >>> 0) + cb > this.offMax) {
if (this.cpu.model <= X86.MODEL_8088) {
this.cpu.opFlags |= X86.OPFLAG.WRAP;
} else {
X86.helpFault.call(this.cpu, X86.EXCEPTION.GP_FAULT);
}
}
return (this.base + off)|0;
}
@ -1542,8 +1553,8 @@ class X86Seg {
*/
this.load = this.loadReal;
this.loadIDT = this.loadIDTReal;
this.checkRead = this.checkReadReal;
this.checkWrite = this.checkWriteReal;
this.checkRead = this.checkReadWriteReal;
this.checkWrite = this.checkReadWriteReal;
this.cpl = this.dpl = 0;
this.addrDesc = X86.ADDR_INVALID;
this.fStackSwitch = false;