Case structure

[desh]

i want to develop case structures such that a selected case should not be available for next selection
e.g
there are three case structures A, B, C
Each having cases 0,1,2,3.... (same cases for all three case structures)
suppose we select case 0 for Case structure A, then 0 should not appear for selecting cases for B & C
thus each case structure should have different cases

please get me some ideas for the same

[smercurio_fc]

I believe you may be going about this the wrong way. You need to implement the logic of disallowing the "selection" of case 0 in your example, rather than the "existence" of case 0. You don't want to eliminate case structures "on the fly". Rather, based on a previous selection you can limit the value of the wire that gets fed to the case selector of the next case structure. How you do it depends on your criteria and the basic logic in your application. If you have a "not allowed" case (like one with a value of -1), you can use this to trap errors. For instance, what drives case structure 1? What drives case structure 2? If the driving signals are independent, then you should drive case structure 2 as the boolean output of the value of signal 2 and signal 1, which chose the case for case structure 1.