Don't hide thresolds values

Show the real value in the code, not hide it
behind a variable name, especially when there
is only once occurence.

No functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>

src/search.cpp

@@ -62,28 +62,9 @@ namespace {
   const bool Slidings[18] = { 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 1, 1, 1 };
   inline bool piece_is_slider(Piece p) { return Slidings[p]; }
 
-  // Maximum depth for razoring
-  const Depth RazorDepth = 4 * ONE_PLY;
-
   // Dynamic razoring margin based on depth
   inline Value razor_margin(Depth d) { return Value(512 + 16 * int(d)); }
 
-  // Maximum depth for use of dynamic threat detection when null move fails low
-  const Depth ThreatDepth = 5 * ONE_PLY;
-
-  // Minimum depth for use of internal iterative deepening
-  const Depth IIDDepth[] = { 8 * ONE_PLY, 5 * ONE_PLY };
-
-  // At Non-PV nodes we do an internal iterative deepening search
-  // when the static evaluation is bigger then beta - IIDMargin.
-  const Value IIDMargin = Value(256);
-
-  // Minimum depth for use of singular extension
-  const Depth SingularExtensionDepth[] = { 8 * ONE_PLY, 6 * ONE_PLY };
-
-  // Futility margin for quiescence search
-  const Value FutilityMarginQS = Value(128);
-
   // Futility lookup tables (initialized at startup) and their access functions
   Value FutilityMargins[16][64]; // [depth][moveNumber]
   int FutilityMoveCounts[32];    // [depth]
@@ -644,7 +625,7 @@ namespace {
 
     // Step 6. Razoring (is omitted in PV nodes)
     if (   !PvNode
-        &&  depth < RazorDepth
+        &&  depth < 4 * ONE_PLY
         && !inCheck
         &&  refinedValue + razor_margin(depth) < beta
         &&  ttMove == MOVE_NONE
@@ -664,7 +645,7 @@ namespace {
     // the score by more than futility_margin(depth) if we do a null move.
     if (   !PvNode
         && !ss->skipNullMove
-        &&  depth < RazorDepth
+        &&  depth < 4 * ONE_PLY
         && !inCheck
         &&  refinedValue - futility_margin(depth, 0) >= beta
         &&  abs(beta) < VALUE_MATE_IN_MAX_PLY
@@ -723,7 +704,7 @@ namespace {
             // parent node, which will trigger a re-search with full depth).
             threatMove = (ss+1)->currentMove;
 
-            if (   depth < ThreatDepth
+            if (   depth < 5 * ONE_PLY
                 && (ss-1)->reduction
                 && threatMove != MOVE_NONE
                 && connected_moves(pos, (ss-1)->currentMove, threatMove))
@@ -736,7 +717,7 @@ namespace {
     // and a reduced search returns a value much above beta, we can (almost) safely
     // prune the previous move.
     if (   !PvNode
-        &&  depth >= RazorDepth + ONE_PLY
+        &&  depth >= 5 * ONE_PLY
         && !inCheck
         && !ss->skipNullMove
         &&  excludedMove == MOVE_NONE
@@ -765,9 +746,9 @@ namespace {
     }
 
     // Step 10. Internal iterative deepening
-    if (   depth >= IIDDepth[PvNode]
+    if (   depth >= (PvNode ? 5 * ONE_PLY : 8 * ONE_PLY)
         && ttMove == MOVE_NONE
-        && (PvNode || (!inCheck && ss->eval + IIDMargin >= beta)))
+        && (PvNode || (!inCheck && ss->eval + Value(256) >= beta)))
     {
         Depth d = (PvNode ? depth - 2 * ONE_PLY : depth / 2);
 
@@ -786,7 +767,7 @@ split_point_start: // At split points actual search starts from here
     value = bestValue; // Workaround a bogus 'uninitialized' warning under gcc
     singularExtensionNode =   !RootNode
                            && !SpNode
-                           &&  depth >= SingularExtensionDepth[PvNode]
+                           &&  depth >= (PvNode ? 6 * ONE_PLY : 8 * ONE_PLY)
                            &&  ttMove != MOVE_NONE
                            && !excludedMove // Recursive singular search is not allowed
                            && (tte->type() & BOUND_LOWER)
@@ -1175,7 +1156,7 @@ split_point_start: // At split points actual search starts from here
         if (PvNode && bestValue > alpha)
             alpha = bestValue;
 
-        futilityBase = ss->eval + evalMargin + FutilityMarginQS;
+        futilityBase = ss->eval + evalMargin + Value(128);
         enoughMaterial = pos.non_pawn_material(pos.side_to_move()) > RookValueMg;
     }