Scan chain for rapidly identifying first or second objects of selected types in a sequential list

摘要

A scan chain (900) for sequential entries that store objects identifies an object of a first type following an object of a second type. Conceptually, if a preceding entry does not assert an "only" term, an entry storing an object of the second type generates a scan bit and asserts the "only" term which inhibits further generation of the scan bit. Each subsequent entry propagate the scan bit or if the entry stores an object of the first type, kills the scan bit and selects itself. Look-ahead logic (910, 920, 930, and 940) determines group terms from single-entry terms to indicate whether a scan bit would be generated, propagated, or killed by a group of entries. Combination of the group terms selects an entry without the delay for sequential propagation through all entries.