====== Chess - Programming - BCH Hashing ======

**BCH Hashing** provides a fast incremental Hash function to transform a board position into a number of a set length, quite similar to Zobrist Hashing.

  * It relys on BCH codes.
  * A BCH signature length of 81 (or more) bits is used to protect 16 bits from the full position string of 749 (64*12 - 2*2*8 + 4 + 8 + 1) bits, which is sufficient to avoid collisions within an 8 ply search.
  * 63 bits of the BCH signature are stored as "lock" inside the table, and the 18 (or more) lower bits used as index.

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===== References =====

https://en.wikipedia.org/wiki/BCH_code

http://web.archive.org/web/20111017213934/http://en.wikipedia.org/wiki/BCH_code