Add some tablebase positions to bench

This makes it easier to check for regressions in the tablebase code.

Bench: 9489202
5-man bench: 8943906

Resolves #145

src/benchmark.cpp

@@ -64,7 +64,18 @@ const char* Defaults[] = {
   "6k1/6p1/P6p/r1N5/5p2/7P/1b3PP1/4R1K1 w - - 0 1",
   "1r3k2/4q3/2Pp3b/3Bp3/2Q2p2/1p1P2P1/1P2KP2/3N4 w - - 0 1",
   "6k1/4pp1p/3p2p1/P1pPb3/R7/1r2P1PP/3B1P2/6K1 w - - 0 1",
-  "8/3p3B/5p2/5P2/p7/PP5b/k7/6K1 w - - 0 1"
+  "8/3p3B/5p2/5P2/p7/PP5b/k7/6K1 w - - 0 1",
+
+  // 5-man positions
+  "8/8/8/8/5kp1/P7/8/1K1N4 w - - 0 1", // Kc2 - mate
+  "8/8/8/5N2/8/p7/8/2NK3k w - - 0 1", // Na2 - mate
+  "8/3k4/8/8/8/4B3/4KB2/2B5 w - - 0 1", // draw
+  // 6-man positions
+  "8/8/1P6/5pr1/8/4R3/7k/2K5 w - - 0 1", // Re5 - mate
+  "8/2p4P/8/kr6/6R1/8/8/1K6 w - - 0 1", // Ka2 - mate
+  "8/8/3P3k/8/1p6/8/1P6/1K3n2 b - - 0 1", // Nd2 - draw
+  // 7-man positions
+  "8/R7/2q5/8/6k1/8/1P5p/K6R w - - 0 124", // Draw
 };
 
 } // namespace
@@ -107,7 +118,7 @@ void benchmark(const Position& current, istream& is) {
       limits.depth = atoi(limit.c_str());
 
   if (fenFile == "default")
-      fens.assign(Defaults, Defaults + 30);
+      fens.assign(Defaults, Defaults + 37);
 
   else if (fenFile == "current")
       fens.push_back(current.fen());