Module onejoker::cards::hashes

wiki | Various hash functions for cards

The common FNV hashes are often used for implementing hash tables and doing quick checksumming for tests. They are not collision-free, but are fast and simple.

Positional hashes treat cards (or ranks) as digits of a base-n number, They are therefore order-dependent and limited in size, but inherently collision-free and useful for ranking hands.

Bitfield hashes represent each card as a bit in a 64-bit integer. This is inherently order-independent and collision-free, and very fast, but can’t handle duplicate cards and produces huge numbers.

Prime hashes based on the product of prime numbers are inherently collision-free, order-independent, handle duplicates, and produce smaller numbers, but can only handle very small sets.

The “mp” functions create minimal perfect hashes for particular games and are very specific to number of cards and type of deck.

Constants

• OJH_SPLIT_MIX_CONSTANT
  Original SplitMix64 constant

Functions

• ojh_base13_32cs_low
  wiki | 32-bit positional hash
• ojh_base13_mp5_low
  wiki | MPH for ace-to-five low
• ojh_base16_32cs
  wiki | 32-bit positional rank hash
• ojh_base16_64cs
  wiki | 64-bit positional rank hash
• ojh_base64_32c
  wiki | 32-bit positional hash
• ojh_base64_64c
  wiki | 64-bit positional hash
• ojh_bitfield_64co
  wiki | 64-bit bitfield hash
• ojh_bitfield_mp4_english
  wiki | Convert bitfield to MPH Given a bitfield with exactly 4 bits set, return the lexicographic index of that particular set of bits for minimal perfect hash. High-ace deck version, 4 cards (for Badugi).
• ojh_bitfield_mp4_low
  wiki | Convert bitfield to MPH Given a bitfield with exactly 4 bits set, return the lexicographic index of that particular set of bits for minimal perfect hash. Low-ace deck version, 4 cards (for Badugi).
• ojh_bitfield_mp5_english
  wiki | Convert bitfield to MPH
• ojh_bitfield_mp5_low
  wiki | Convert bitfield to MPH Given a bitfield with exactly 5 bits set, return the lexicographic index of that particular set of bits for minimal perfect hash. Low-ace deck version, 5 cards.
• ojh_bitfield_mp5_stripped
  wiki | Convert bitfield to MPH Given a bitfield with exactly 5 bits set, return the lexicographic index of that particular set of bits for minimal perfect hash. Requires Stripped deck, 5 cards.
• ojh_bitfield_mp7_english
  wiki | Convert bitfield to MPH
• ojh_bitfield_mp7_low
  wiki | Convert bitfield to MPH
• ojh_fnv_32
  wiki | 32-bit FNV-1a hash
• ojh_fnv_64
  wiki | 64-bit FNV-1a hash
• ojh_mix_64_32
  wiki | 64-to-32-bit mixer
• ojh_prime_32cos
  wiki | 32-bit prime rank hash
• ojh_prime_64co
  wiki | 64-bit prime hash
• ojh_prime_64cos
  wiki | 64-bit prime rank hash
• ojh_uhash_32
  wiki | 32-bit universal hash
• ojh_uhash_64
  wiki | 64-bit universal hash