Hash functions and CountHashTab #727
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lekcyjna123
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We're not supposed to implement some dreamed up hash functions, but some existing ones with established properties. The only thing to test is to compare a hardware implementation to a software one. |
tilk
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Sep 4, 2024
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| # Check if there is at least as many elements as we put inside (can be more because of aliasing) | ||
| assert count["count"] >= sum(map(lambda x: 1, filter(lambda x: x == in_val, input))) | ||
| assert count["count"] in self.table_snapshots[-1] |
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This is a very weak test. I believe a constant table which is filled with maximum values would satisfy it.
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Hi,
Here is a pull request which adds hash tables. In particularly:
-- Lookup3 (http://www.burtleburtle.net/bob/hash/doobs.html)
-- SipHash (https://eprint.iacr.org/2012/351.pdf)
I am not sure how to test them, so comments are welcome.
Hash functions I test using statistical test to check if they hash into uniform distribution, but sadly for small input data (from range [0,1023]) there is some bias and statistical tests fails... Whats more I am not sure if we want to have tests based on statistics, because this can cause instability.