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Using a bisection search for sampling

--- a/dnn/nnet.c

+++ b/dnn/nnet.c

@@ -399,9 +399,22 @@

     }

     /* Do the sampling (from the cdf). */

     r = tmp[N-1] * ((rand()+.5f)/(RAND_MAX+1.f));

+#if 1 /* Bisection search in the CDF (faster than the equivalent linear one below). */

+    {

+        int start=-1;

+        int end = N-1;

+        while (end > start+1) {

+            int mid = (start+end)>>1;

+            if (r <= tmp[mid]) end = mid;

+            else start = mid;

+        }

+        return end;

+    }

+#else

     for (i=0;i<N-1;i++)

     {

         if (r <= tmp[i]) return i;

     }

     return N-1;

+#endif

 }

-- 

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