From: invalid@nospicedham.lkntrgzxc.com   
      
   On Sat, 27 Oct 2018 14:51:35 +0200   
   "R.Wieser"  wrote:   
      
   > I'm dealing with a packet driver, which API (ABI?) can be put behind   
   > any available INT (by specifying the number when loading it).   
   >   
   > I would like my program to find the right INT at runtime (which is   
   > not hard, as the packet driver has a certain string at a certain   
   > place, just so you can check if its actually there) and than use that.   
   >   
      
   I would suggest hooking two interrupts.  One is for the random or   
   changing or relocatable interrupt that you call to access the API.  The   
   other would be on a fixed interrupt with a unique registers value, say   
   in AX, for the call to detect the presence or installation of the   
   packet driver API.  This is the same way you detect DPMI or XMS etc,   
   e.g., DPMI installs INT 0x2F, AX=1687h and XMS installs INT 0x2F,   
   4300h.  However, DPMI's main interrupt is on INT 0x31 whereas XMS   
   returns an address to a function on INT 0x2F, AX-4310h.  So, it seems   
   INT 0x2F might be a good place to install an installation check or   
   interrupt number check in your case.   
      
   DJGPP's online RBIL has a table of used or in-use AX values for INT   
   0x2F here:   
      
   http://www.delorie.com/djgpp/doc/rbinter/ix/2F/   
      
      
   Rod Pemberton   
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