probdist.c

   1 #include <assert.h>
   2 #include <math.h>
   3 #include <stdio.h>
   4 #include <stdlib.h>
   5
   6 #include "move.h"
   7 #include "probdist.h"
   8 #include "random.h"
   9
  10 int
  11 probdist_pick(struct probdist *pd)
  12 {
  13         assert(probdist_total(pd) >= 0);
  14         /* TODO: float random */
  15         double stab = fast_frandom() * probdist_total(pd);
  16         //fprintf(stderr, "stab %f / %f\n", stab, pd->items[pd->n - 1]);
  17         for (int i = 0; i < pd->n; i++) {
  18                 if (stab <= pd->items[i])
  19                         return i;
  20                 stab -= pd->items[i];
  21         }
  22         //fprintf(stderr, "overstab %f (total %f, sum %f)\n", stab, pd->items[pd->n - 1], sum);
  23         assert(0);
  24         return -1;
  25 }