> autogenerate a state machine that will map each of the above 160,000 things, at any rotation within a 4 byte register, to a unique bin in a hash table. The state machine will have one 32 bit state register (16 bits to output, 16 to carry over to the next cycle) where every cycle a lookup in the state transition table is done, and the next 4 bytes of data XOR'ed on top.
You are basically describing a perfect hash, right?
nearly but not quite - you can deliberately 'collide' when there is no data you need to keep going forward (the obvious example being when you end on a '\r' character). This is necessary to keep an upper bound on the state space.
Remember that in the extreme, a state could mean "city A, temp zero, city b" - "0\rB" so it isn't a direct mapping from state machine state to city.
You are basically describing a perfect hash, right?