The present disclosure includes systems and techniques relating to FIFO
queue memory. In general, in one implementation, a queue memory receives
and stores information and supports first-in-first-out read and
out-of-order read operations with information shifting within the memory
relative to a read operation. The queue memory can include a write
pointer that increments upon a write operation and decrements upon the
read operation, a read pointer that identifies an oldest read entry of
the queue memory when the read operation is a first-in-first-out read and
that identifies a selected entry of the queue memory when the read
operation is an out-of-order read, and a multiplexer operative to select
entries of the queue memory responsive to the read pointer.