libmap.c

   1 #include <assert.h>
   2 #include <limits.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5
   6 #include "board.h"
   7 #include "debug.h"
   8 #include "libmap.h"
   9 #include "move.h"
  10 #include "tactics/util.h"
  11
  12
  13 hash_t
  14 group_to_libmap(struct board *b, group_t group)
  15 {
  16         hash_t h = 0;
  17 #define hbits (sizeof(hash_t)*CHAR_BIT)
  18
  19         enum stone color = board_at(b, group);
  20         struct group *gi = &board_group_info(b, group);
  21         int libs = gi->libs < GROUP_REFILL_LIBS ? gi->libs : GROUP_REFILL_LIBS;
  22
  23         for (int i = 0; i < libs; i++) {
  24                 hash_t hlib = hash_at(b, gi->lib[i], color);
  25                 /* Rotate the hash based on prospects of the liberty. */
  26                 int p = immediate_liberty_count(b, gi->lib[i]) +
  27                           4 * neighbor_count_at(b, gi->lib[i], color);
  28                 hlib = (hlib << p) | ((hlib >> (hbits - p)) & ((1<<p) - 1));
  29                 /* Add to hash. */
  30                 h ^= hlib;
  31         }
  32
  33         return h;
  34 }