In this paper, an area-efficient Reed-Solomon (RS) codec IP with composite-field inverter is presented. For some specific applications such as flash memory controller using RS (528,518) code over GF(210) to correct 4 errors, the RS decoder will stop receiving any new codeword until the on-going erroneous codeword to be corrected. It is that the circuit complexity can be reduced by sharing the registers and finite-field operation units. Moreover, the proposed hardware sharing architecture also includes the RS encoder. After implementing by 0.18μm 1P6M standard cell slow library, the RS (528, 518) codec IP totally requires 2 finite-field multiplier, 1 composite-field inverter and 17(=4t+l) registers, where t is the number of correctable errors. In contrast with other architectures, at least 42% circuit complexity can be reduced in our proposal.