C macro: how do I concatenate a name and a number which is result of a math operation (done also by preprocessor)?

Consider the following code:

1. #define SUFFIX 5-5
 2. #define XFUNC_0( x )  (100 * x)
 3. #define XFUNC_1( x )  (101 * x)
 4. #define XFUNC_2( x )  (102 * x)
 5. #define CATX( x, y )  x##y
 6. #define CAT( x, y )   CATX( x, y )
 7. #define XFUNC         CAT( XFUNC_, SUFFIX )
 8. #if     XFUNC(2) == 200
 ...... etc
 N.