pattern3.h

   1 #ifndef ZZGO_PATTERN3_H
   2 #define ZZGO_PATTERN3_H
   3
   4 /* Fast matching of simple 3x3 patterns. */
   5
   6 #include "board.h"
   7 #include "tactics.h"
   8
   9 /* (Note that this is completely independent from the general pattern
  10  * matching infrastructure in pattern.[ch]. This is fast and simple.) */
  11
  12 struct board;
  13 struct move;
  14
  15 struct pattern3s {
  16         /* Hashtable: 2*8 bits (ignore middle point, 2 bits per intersection) */
  17         /* Value: 0: no pattern, 1: black pattern,
  18          * 2: white pattern, 3: both patterns */
  19         char hash[65536];
  20 };
  21
  22 /* Source pattern encoding:
  23  * X: black;  O: white;  .: empty;  #: edge
  24  * x: !black; o: !white; ?: any
  25  *
  26  * extra X: pattern valid only for one side;
  27  * middle point ignored. */
  28
  29 void pattern3s_init(struct pattern3s *p, char src[][11], int src_n);
  30
  31 /* Compute pattern3 hash at local position. */
  32 static int pattern3_hash(struct board *b, coord_t c);
  33
  34 /* Check if we match any pattern centered on given move; includes
  35  * self-atari test. */
  36 static bool test_pattern3_here(struct pattern3s *p, struct board *b, struct move *m);
  37
  38 /* Generate all transpositions of given pattern, stored in an
  39  * int[8] array. */
  40 void pattern3_transpose(int pat, int (*transp)[8]);
  41
  42 /* Reverse pattern to opposite color assignment. */
  43 static int pattern3_reverse(int pat);
  44
  45
  46 static inline int
  47 pattern3_hash(struct board *b, coord_t c)
  48 {
  49         int pat = 0;
  50         int x = coord_x(c, b), y = coord_y(c, b);
  51         pat |= (board_atxy(b, x - 1, y - 1) << 14)
  52                 | (board_atxy(b, x, y - 1) << 12)
  53                 | (board_atxy(b, x + 1, y - 1) << 10);
  54         pat |= (board_atxy(b, x - 1, y) << 8)
  55                 | (board_atxy(b, x + 1, y) << 6);
  56         pat |= (board_atxy(b, x - 1, y + 1) << 4)
  57                 | (board_atxy(b, x, y + 1) << 2)
  58                 | (board_atxy(b, x + 1, y + 1));
  59         return pat;
  60 }
  61
  62 /* TODO: Make use of the incremental spatial matching infrastructure
  63  * in board.h? */
  64 static inline bool
  65 test_pattern3_here(struct pattern3s *p, struct board *b, struct move *m)
  66 {
  67 #ifdef BOARD_PAT3
  68         int pat = b->pat3[m->coord];
  69 #else
  70         int pat = pattern3_hash(b, m->coord);
  71 #endif
  72         //fprintf(stderr, "(%d,%d) hashtable[%04x] = %d\n", x, y, pat, p->hash[pat]);
  73         return (p->hash[pat] & m->color) && !is_bad_selfatari(b, m->color, m->coord);
  74 }
  75
  76 static inline int
  77 pattern3_reverse(int pat)
  78 {
  79         /* Reverse color assignment - achieved by swapping odd and even bits */
  80         return ((pat >> 1) & 0x5555) | ((pat & 0x5555) << 1);
  81 }
  82
  83 #endif