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GNU Go Documentation

14.2.4 Hash Functions

The following functions are defined in `hash.c':

• void hash_init()

  Initialize the entire hash system.

• int hashdata_compare(Hash_data *key1, Hash_data *key2)

  Returns 0 if *key1 == *key2, 2 if the hashvalues differ, or 1 if only the hashpositions differ. This adheres (almost) to the standard compare function semantics which are used e.g. by the comparison functions used in qsort().

• void hashposition_dump(Hashposition *pos, FILE *outfile)

  Dump an ASCII representation of the contents of a Hashposition onto the FILE outfile.

• int hashdata_diff_dump(Hash_data *key1,Hash_data *key2 )

  Compare two Hashdata structs. If equal: return zero. If not: dump a human readable summary of any differences to stderr. The return value is the same as for hashdata_compare. This function is primarily intended to be used in assert statements.

• void hashdata_recalc(Hash_data *target, Intersection *p, int kopos)

  Calculate the compactboard and the hashvalue in one function. They are always used together and it saves us a loop and a function call.

• void hashdata_set_ko(Hash_data *hd, int pos)

  Set or remove a ko at pos.

• void hashdata_remove_ko(Hash_data *hd)

  Remove any ko from the hash value and hash position.

• void hashdata_invert_stone(Hash_data *hd, int pos, int color)

  Set or remove a stone of color at pos in a Hash_data.

• void read_result_dump(Read_result *result, FILE *outfile)

  Dump an ASCII representation of the contents of a Read_result onto the FILE outfile.

• void hashnode_dump(Hashnode *node, FILE *outfile)

  Dump an ASCII representation of the contents of a Hashnode onto the FILE outfile.

• int hashtable_init(Hashtable *table, int tablesize, int num_nodes, int num_results)

  Initialize a hash table for a given total size and size of the hash table. Returns 0 if something went wrong. Just now this means that there wasn't enough memory available.

• Hashtable * hashtable_new(int tablesize, int num_nodes, int num_results)

  Allocate a new hash table and return a pointer to it. Return NULL if there is insufficient memory.

• void hashtable_clear(Hashtable *table)

  Clear an existing hash table.

• void hashtable_clear_if_full(Hashtable *table)

  Clear an existing hash table only if it happens to be full. By full we mean that we are either out of positions or read results.

• Hashnode * hashtable_enter_position(Hashtable *table, Hash_data *hd)

  Enter a position with a given hash value into the table. Return a pointer to the hash node where it was stored. If it is already there, don't enter it again, but return a pointer to the old one.

• Hashnode * hashtable_search(Hashtable *table, Hash_data *hd)

  Given a Hashposition and a Hash value, find the hashnode which contains this position with the given hash value.

• void hashtable_dump(Hashtable *table, FILE *outfile)

  Dump an ASCII representation of the contents of a Hashtable onto the FILE outfile.

The following macros are defined in `hash.h'

• rr_get_komaster(rr)
• rr_get_kom_pos(rr)
• rr_get_routine(rr)
• rr_get_str1(rr)
• rr_get_stackp(rr)
• rr_get_str2(rr)
• rr_get_str(rr)
• rr_get_status(rr)
• rr_get_result1(rr)
• rr_get_result2(rr)
• rr_get_move(rr)
• rr_get_result(rr)

  Get the constituent parts of a Read_result.

The following macros and functions are defined in `engine/reading.c':

• static int get_read_result(int routine, int *si, int *sj, Read_result **read_result)

  Return a Read_result for the current position, routine and location. For performance, the location is changed to the origin of the string.

• READ_RETURN0(Read_result *read_result)

  Cache a negative read result.

• READ_RETURN(Read_result *read_result, int *pointi, int *pointj, int resulti, int resultj, int value)

  If pointi and pointj are not null pointers, then give (*pointi, *pointj) the values (resulti, resultj). Then cache the read_result. Clear the hashtable if full and return value.