probdist.h

   1 #ifndef ZZGO_PROBDIST_H
   2 #define ZZGO_PROBDIST_H
   3
   4 /* Tools for picking a move according to a probability distribution. */
   5
   6 #include "move.h"
   7
   8 struct probdist {
   9         int bsize2;
  10         float *moves; // [bsize2]
  11         float total;
  12 };
  13
  14 struct probdist *probdist_init(struct probdist *pd, int bsize2);
  15 static void probdist_add(struct probdist *pd, coord_t c, float val);
  16 static void probdist_mul(struct probdist *pd, coord_t c, float val);
  17 static void probdist_punch(struct probdist *pd, coord_t c); // Remove c from probability distribution
  18 coord_t probdist_pick(struct probdist *pd);
  19 void probdist_done(struct probdist *pd); // Doesn't free pd itself
  20
  21
  22 /* We disable the assertions here since this is quite time-critical
  23  * part of code, and also the compiler is reluctant to include the
  24  * functions otherwise. */
  25
  26 static inline void
  27 probdist_add(struct probdist *pd, coord_t c, float val)
  28 {
  29 #if 0
  30         assert(c >= 0 && c < pd->bsize2);
  31         assert(val >= 0);
  32 #endif
  33         pd->moves[c] += val;
  34         pd->total += val;
  35 }
  36
  37 static inline void
  38 probdist_mul(struct probdist *pd, coord_t c, float val)
  39 {
  40 #if 0
  41         assert(c >= 0 && c < pd->bsize2);
  42         assert(val >= 0);
  43 #endif
  44         pd->total += (val - 1) * pd->moves[c];
  45         pd->moves[c] *= val;
  46 }
  47
  48 static inline void
  49 probdist_punch(struct probdist *pd, coord_t c)
  50 {
  51         assert(c >= 0 && c < pd->bsize2);
  52         pd->total -= pd->moves[c];
  53         pd->moves[c] = 0;
  54 }
  55
  56 #endif