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Chess - Programming - Polyglot Book Format - File Format

Polyglot files are usually named with a .bin extension.

The files contain one or more entries with each entry having the following information:

struct entry_t {
   uint64_t key;
   uint16_t move;
   uint16_t weight;
   uint32_t learn;
};

NOTE: All integers are stored highest byte first (regardless of size).

Sometimes the file format is shown as:

struct entry_t {
   uint64_t key;
   uint16_t move;
   uint16_t count;
   uint16_t n;
   uint16_t sum;
};