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Switched to a more robust IFSHLP.SYS INT 0x68 detection test

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This commit is contained in:
Jeff Parsons 2015-09-04 16:49:00 -07:00
commit 58018c8592
1 changed files with 10 additions and 8 deletions
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18
modules/pcjs/lib/debugger.js
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@ -1432,14 +1432,16 @@ if (DEBUGGER) {
var ES = cpu.segES.sel;
if (this.fWinDbgRM == null) {
/*
* It looks like IFSHLP.SYS issues a preliminary INT 0x68 before Windows 95 gets rolling,
* and the Windows Debugger would not have had a chance to load yet, so we need to ignore
* that call; the easiest way to do that is see if the real-mode segment in the INT 0x68
* vector points to ROM (it's also possible the vector was not initialized, but IFSHLP.SYS
* tries to be smart and skip the INT 0x68 in that case, so that's not a concern).
*/
if (AH == Interrupts.WINDBGRM.IS_LOADED && cpu.getShort(0x68*4+2) != 0xF000) {
if (AH == Interrupts.WINDBGRM.IS_LOADED) {
/*
* It looks like IFSHLP.SYS issues a preliminary INT 0x68 before Windows 95 gets rolling,
* and the Windows Debugger will not have had a chance to load yet, so we need to ignore
* that call. We detect IFSHLP.SYS by looking for "IFS$" in the caller's code segment,
* where the IFSHLP device driver header is located.
*/
if (cpu.getLong((cpu.segCS.sel << 4) + 0xA) == 0x24534649) {
return true;
}
/*
* We're only going to respond to this function if no one else did, in which case,
* we'll set fWinDbgRM to true and handle additional notifications.