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 /* XXX: See <board.h> for hash3_t typedef. */
  23
  24 /* Source pattern encoding:
  25  * X: black;  O: white;  .: empty;  #: edge
  26  * x: !black; o: !white; ?: any
  27  *
  28  * extra X: pattern valid only for one side;
  29  * middle point ignored. */
  30
  31 void pattern3s_init(struct pattern3s *p, char src[][11], int src_n);
  32
  33 /* Compute pattern3 hash at local position. */
  34 static hash3_t pattern3_hash(struct board *b, coord_t c);
  35
  36 /* Check if we match any 3x3 pattern centered on given move. */
  37 static bool pattern3_move_here(struct pattern3s *p, struct board *b, struct move *m);
  38
  39 /* Generate all transpositions of given pattern, stored in an
  40  * hash3_t[8] array. */
  41 void pattern3_transpose(hash3_t pat, hash3_t (*transp)[8]);
  42
  43 /* Reverse pattern to opposite color assignment. */
  44 static hash3_t pattern3_reverse(hash3_t pat);
  45
  46
  47 static inline hash3_t
  48 pattern3_hash(struct board *b, coord_t c)
  49 {
  50         hash3_t pat = 0;
  51         int x = coord_x(c, b), y = coord_y(c, b);
  52         pat |= (board_atxy(b, x - 1, y - 1) << 14)
  53                 | (board_atxy(b, x, y - 1) << 12)
  54                 | (board_atxy(b, x + 1, y - 1) << 10);
  55         pat |= (board_atxy(b, x - 1, y) << 8)
  56                 | (board_atxy(b, x + 1, y) << 6);
  57         pat |= (board_atxy(b, x - 1, y + 1) << 4)
  58                 | (board_atxy(b, x, y + 1) << 2)
  59                 | (board_atxy(b, x + 1, y + 1));
  60         return pat;
  61 }
  62
  63 static inline bool
  64 pattern3_move_here(struct pattern3s *p, struct board *b, struct move *m)
  65 {
  66 #ifdef BOARD_PAT3
  67         hash3_t pat = b->pat3[m->coord];
  68 #else
  69         hash3_t pat = pattern3_hash(b, m->coord);
  70 #endif
  71         return (p->hash[pat] & m->color);
  72 }
  73
  74 static inline hash3_t
  75 pattern3_reverse(hash3_t pat)
  76 {
  77         /* Reverse color assignment - achieved by swapping odd and even bits */
  78         return ((pat >> 1) & 0x5555) | ((pat & 0x5555) << 1);
  79 }
  80
  81 #endif