From 2201fb4598f9f6ba1b8019b42edc75f945d5a725 Mon Sep 17 00:00:00 2001
From: syzygy1 <3028851+syzygy1@users.noreply.github.com>
Date: Sun, 12 Jul 2020 00:27:25 +0200
Subject: [PATCH] Cfish 11a This fixes a minor problem causing diverging node
 counts and re-enables large pages on Linux. It also fixes the one-by-off
 error in reported seldepth.

---
 src/misc.c      |  2 +-
 src/ntsearch.c  | 16 +++++++---------
 src/position.h  |  3 ++-
 src/search.c    |  4 ++--
 src/ucioption.c |  2 ++
 5 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/src/misc.c b/src/misc.c
index 5e87a888..934a1a6a 100644
--- a/src/misc.c
+++ b/src/misc.c
@@ -36,7 +36,7 @@
 
 // Version number. If Version is left empty, then compile date in the format
 // DD-MM-YY and show in engine_info.
-char Version[] = "11";
+char Version[] = "11a";
 
 #ifndef _WIN32
 pthread_mutex_t ioMutex = PTHREAD_MUTEX_INITIALIZER;
diff --git a/src/ntsearch.c b/src/ntsearch.c
index 75a87301..906e52a8 100644
--- a/src/ntsearch.c
+++ b/src/ntsearch.c
@@ -281,7 +281,7 @@ Value search_NonPV(Pos *pos, Stack *ss, Value alpha, Depth depth, int cutNode)
       && ss->staticEval >= beta - 32 * depth + 292 - improving * 30
       && !excludedMove
       && non_pawn_material_c(stm())
-      && (ss->ply >= pos->nmpPly || ss->ply % 2 != pos->nmpOdd))
+      && (ss->ply >= pos->nmpMinPly || stm() != pos->nmpColor))
   {
     assert(eval - beta >= 0);
 
@@ -301,19 +301,17 @@ Value search_NonPV(Pos *pos, Stack *ss, Value alpha, Depth depth, int cutNode)
       if (nullValue >= VALUE_MATE_IN_MAX_PLY)
         nullValue = beta;
 
-      if (   (depth < 13 || pos->nmpPly)
-          && abs(beta) < VALUE_KNOWN_WIN)
+      if (pos->nmpMinPly || (abs(beta) < VALUE_KNOWN_WIN && depth < 13))
         return nullValue;
 
-      // Do verification search at high depths
-      // Disable null move pruning for side to move for the first part of
-      // the remaining search tree
-      pos->nmpPly = ss->ply + 3 * (depth-R) / 4;
-      pos->nmpOdd = ss->ply & 1;
+      // Do verification search at high depths, with null move pruning
+      // disabled for us, until ply exceeds nmpMinPly
+      pos->nmpMinPly = ss->ply + 3 * (depth-R) / 4;
+      pos->nmpColor = stm();
 
       Value v = search_NonPV(pos, ss, beta-1, depth-R, 0);
 
-      pos->nmpOdd = pos->nmpPly = 0;
+      pos->nmpMinPly = 0;
 
       if (v >= beta)
         return nullValue;
diff --git a/src/position.h b/src/position.h
index d0e9790a..ab938508 100644
--- a/src/position.h
+++ b/src/position.h
@@ -156,7 +156,8 @@ struct Pos {
   uint64_t tbHits;
   uint64_t ttHitAverage;
   int pvIdx, pvLast;
-  int selDepth, nmpPly, nmpOdd;
+  int selDepth, nmpMinPly;
+  uint32_t nmpColor;
   Depth rootDepth;
   Depth completedDepth;
   Score contempt;
diff --git a/src/search.c b/src/search.c
index e7d599d9..b97227a6 100644
--- a/src/search.c
+++ b/src/search.c
@@ -864,7 +864,7 @@ static void uci_print_pv(Pos *pos, Depth depth, Value alpha, Value beta)
       TB_expand_mate(pos, &rm->move[i]);
 
     printf("info depth %d seldepth %d multipv %d score %s",
-           d, rm->move[i].selDepth, i + 1,
+           d, rm->move[i].selDepth + 1, i + 1,
            uci_value(buf, v));
 
     if (!tb && i == pvIdx)
@@ -1010,7 +1010,7 @@ void start_thinking(Pos *root)
   for (int idx = 0; idx < Threads.numThreads; idx++) {
     Pos *pos = Threads.pos[idx];
     pos->selDepth = 0;
-    pos->nmpPly = pos->nmpOdd = 0;
+    pos->nmpMinPly = 0;
     pos->rootDepth = 0;
     pos->nodes = pos->tbHits = 0;
     RootMoves *rm = pos->rootMoves;
diff --git a/src/ucioption.c b/src/ucioption.c
index 28a75258..fcc82589 100644
--- a/src/ucioption.c
+++ b/src/ucioption.c
@@ -18,6 +18,8 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+#define _GNU_SOURCE
+
 #include <assert.h>
 #include <ctype.h>
 #include <stdio.h>