ADD_INTERLOCKED

 The ADD_INTERLOCKED function adds the value of an expression  to
 the  value of a variable, stores the newly computed value in the
 variable, and returns an integer value:  -1 if the new value  is
 negative, 0 if it is zero, and 1 if it is positive.


 Syntax:

    ADD_INTERLOCKED( e, v )


 The type of the expression 'e'  must  be  assignment  compatible
 with  that  of  the  variable  'v'.  The variable 'v' must be an
 integer or an unsigned subrange; 'v'  must  have  an  allocation
 size  of  two bytes and must be aligned on a word boundary.  The
 type of 'e' must be assignment compatible with that of 'v'.