Abstract: A method for scheduling instructions for clustered digital signal processors, the processors including a plurality of clusters, each cluster including at least two functional units and a first register file having a first unit, a second unit and a single set of access ports shared by the functional units, includes the steps of checking whether executing one instruction needs data to be read from the first unit and the second unit of the first register file, generating a copying instruction to transfer data from the first unit to the second unit of the first register file, checking whether there is a prior operation cycle available to perform the copying instruction, scheduling the copying instruction in the prior operation cycle, and scheduling the instruction after the copying instruction.