X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fsearch.cpp;h=ff7a2c2309cb91624da7b083be34ff1bf5d8a4cc;hp=e008bec1e45d8a063cca7d05dd803411d7cb38c6;hb=5a7827d59de5e3dea0d90bdb3e7c57153c0a9f1f;hpb=217840a6a5a40b516cab59a450a9f36352997240

diff --git a/src/search.cpp b/src/search.cpp
index e008bec1..ff7a2c23 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -335,7 +335,12 @@ void Thread::search() {
   beta = VALUE_INFINITE;
 
   multiPV = Options["MultiPV"];
-  Skill skill(Options["Skill Level"]);
+  // Pick integer skill levels, but non-deterministically round up or down
+  // such that the average integer skill corresponds to the input floating point one.
+  PRNG rng(now());
+  int intLevel = int(Options["Skill Level"]) +
+        ((Options["Skill Level"] - int(Options["Skill Level"])) * 1024 > rng.rand<unsigned>() % 1024  ? 1 : 0);
+  Skill skill(intLevel);
 
   // When playing with strength handicap enable MultiPV search that we will
   // use behind the scenes to retrieve a set of possible moves.
@@ -1065,7 +1070,7 @@ moves_loop: // When in check, search starts from here
           Depth r = reduction(improving, depth, moveCount);
 
           // Reduction if other threads are searching this position.
-	  if (th.marked())
+          if (th.marked())
               r += ONE_PLY;
 
           // Decrease reduction if position is or has been on the PV
@@ -1110,7 +1115,7 @@ moves_loop: // When in check, search starts from here
                   r += ONE_PLY;
 
               // Decrease/increase reduction for moves with a good/bad history (~30 Elo)
-              r -= ss->statScore / 20000 * ONE_PLY;
+              r -= ss->statScore / 16384 * ONE_PLY;
           }
 
           Depth d = clamp(newDepth - r, ONE_PLY, newDepth);