mq.h

   1 #ifndef ZZGO_MQ_H
   2 #define ZZGO_MQ_H
   3
   4 /* Move queues; in fact, they are more like move lists, used to accumulate
   5  * equally good move candidates, then choosing from them randomly. */
   6
   7 #include "move.h"
   8 #include "random.h"
   9
  10 #define MQL 64
  11 struct move_queue {
  12         int moves;
  13         coord_t move[MQL];
  14 };
  15
  16 /* Pick a random move from the queue. */
  17 static coord_t mq_pick(struct move_queue *q);
  18
  19 /* Add a move to the queue. */
  20 static void mq_add(struct move_queue *q, coord_t c);
  21
  22 /* Cat two queues together. */
  23 static void mq_append(struct move_queue *qd, struct move_queue *qs);
  24
  25 /* Check if the last move in queue is not a dupe, and remove it
  26  * in that case. */
  27 static void mq_nodup(struct move_queue *q);
  28
  29
  30 static inline coord_t
  31 mq_pick(struct move_queue *q)
  32 {
  33         return q->moves ? q->move[fast_random(q->moves)] : pass;
  34 }
  35
  36 static inline void
  37 mq_nodup(struct move_queue *q)
  38 {
  39         if ((q->moves > 1 && q->move[q->moves - 2] == q->move[q->moves - 1])
  40             || (q->moves > 2 && q->move[q->moves - 3] == q->move[q->moves - 1])
  41             || (q->moves > 3 && q->move[q->moves - 4] == q->move[q->moves - 1]))
  42                 q->moves--;
  43 }
  44
  45 static inline void
  46 mq_append(struct move_queue *qd, struct move_queue *qs)
  47 {
  48         assert(qd->moves + qs->moves < MQL);
  49         memcpy(&qd->move[qd->moves], qs->move, qs->moves * sizeof(*qs->move));
  50         qd->moves += qs->moves;
  51 }
  52
  53 static inline void
  54 mq_add(struct move_queue *q, coord_t c)
  55 {
  56         assert(q->moves < MQL);
  57         q->move[q->moves++] = c;
  58 }
  59
  60 #endif