Patent ID: 6993028

Claim:
An apparatus for reordering sequence indicated information units, comprising: (a) a double-back shifter having plural storage devices, the shifter being for receiving and simultaneously storing a plurality of sequence indicated information units in corresponding ones of its storage devices, where the received units can be initially organized logically and upon receipt in an initial sequential order other than a proper order defined by respective sequence indicators received with and included in the received information units; and (b) at least a first test-and-reshuffle circuit coupled to first and second unit storage devices of said double-back shifter for testing the respective sequence indicators of valid information units, if any, stored in the first and second storage devices for proper relative order, and for reshuffling at least the relative logical order of the tested units within the double-back shifter if said testing shows the tested information units to be out of proper relative sequential order, said testing and reshuffling being repeatable for further information units that next shift into at least one of the first and second unit storage devices so that after being reshuffled, received but out of order information units can emerge in proper relative sequence when finally shifted out of said double-back shifter.