In case LTE FDD, Preparation of UL config done before 4 subframes, if so what about in TDD and how it varies?

Question

For FDD 20MHZ, no of DL RB = 100 and no of UL RB = 100. But in TDD, different UD configurations having different no of DL and UL subframes and few special subframes. Hence how to calculate no of Dl RB and no of UL RB in case of TDD?