Method and system for dividing a data segment of unknown length into first and second halves, for example, for interleaving the first and second halves. Units of the data segment are written into first and second register files. With respect to the first register file, responsive to determining that the last unit of the data segment has been written into the first register file, units of the data segment in the first register file that are not units of the first half of the data segment are removed, wherein the first register file stores the first half of the data segment. With respect to the second register file, responsive to writing each unit of the data segment into the second register file, data currently stored in the second register file is adjusted to comprise a last half of the data so far written into the second register file, wherein, when the last unit of the data segment has been written into the second register file, and the data currently stored in the second register file has been adjusted, the data currently stored in the second register file comprises the second half of the data segment.