Dynamic Trace Exit - sample device driver           
 Author: Richard Moore
 Date:    1st December 1997
 Version: 1.0

 Sample Dynamic Trace Device Driver Kernel Exit for OS2 Warp v3 
 Fix Pack 35 or later.

 This device drive implements a number of functions that are 
 invoked using the CALL DD RPN command follows:


   push parm1
   ....
   push parmn
   push function
   call dd

 The functions implemented are:

 0 - log the buffer contents and reset the buffer
 1 - compare two ASCIIZ strings from flat addresses
     The addresses are popped from the RPN stack and
     the result of the compare is pushed. If the
     addresses are equal then the result is 0, if not
     then the result is -1. If an exception occurs then
     a error message is logged and no result is pushed.
 2 - compare two ASCIIZ strings from segmented addresses.
     An offset, then segment of the first comparand is 
     popped from the RPN stack, followed by the offset
     and segment of the 2nd comparand. This functions 
     then proceeds as for function 1.
 3/4 Test device driver fault handler behaviour.
 5 - Get a DWORD global variable. An index (0-15) is popped
     from the RPN stack and the value of the corresponding
     global variable is pushed onto the stack.
 6 - Put a DWORD value into a global variable. An index (0-15) is 
     popped followed by the variable value.
     The corresponding global variable is updated.
     Global variable may be shared across dynamic trace objects,
     unlike local variables, which are local to a DTO.

 7 - log the buffer contents skipping the initial 3-byte prefix 
     and reset the buffer. If the buffer contains less than 3 bytes
     then a null record is logged.

     See DYNDD.RPN for example of these functions being used.