Hardware interview practice
Scoreboard immutable counter snapshots
Verify a monitor that snapshots 16 counters on a load handshake and answers inclusive range-sum queries from that immutable state until the next accepted load.
Reviewed example
Work through one case
Input
load counters=[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]; query inclusive [2,4]; mutate the external source after load; stall responseExpected output
sum=3+4+5=12 from the immutable snapshot; response stays 12 until acceptedEach query clones the accepted snapshot, so later source changes cannot affect the pending prediction.
What to cover
Requirements
- Update the model snapshot only on a load handshake and assert that load and query are never accepted together.
- Clone the active snapshot into each accepted query expectation before predicting its inclusive sum.
- Return error with a zero sum for query-before-load or for left greater than right.
- Allow one outstanding query, forbid load while it is pending, and compare only on an accepted response.
- Hold the response stable during stalls; reset invalidates the snapshot and clears any pending expectation.