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 static inline void
  23 probdist_add(struct probdist *pd, coord_t c, float val)
  24 {
  25         assert(c >= 0 && c < pd->bsize2);
  26         assert(val >= 0);
  27         pd->moves[c] += val;
  28         pd->total += val;
  29 }
  30
  31 static inline void
  32 probdist_mul(struct probdist *pd, coord_t c, float val)
  33 {
  34         assert(c >= 0 && c < pd->bsize2);
  35         assert(val >= 0);
  36         float t = pd->total - pd->moves[c];
  37         pd->moves[c] *= val;
  38         pd->total = t + pd->moves[c];
  39 }
  40
  41 static inline void
  42 probdist_punch(struct probdist *pd, coord_t c)
  43 {
  44         assert(c >= 0 && c < pd->bsize2);
  45         pd->total -= pd->moves[c];
  46         pd->moves[c] = 0;
  47 }
  48
  49 #endif