From: H.G.Muller <hgm@hgm-xboard.(none)>
Date: Mon, 15 May 2017 10:02:46 +0000 (+0200)
Subject: Consider extra moves in some horizon nodes
X-Git-Url: http://winboard.nl/cgi-bin?a=commitdiff_plain;h=7d3be87f815ede5fa3ac1ecb9ad9a5223c664118;p=crazywa.git

Consider extra moves in some horizon nodes

The first node of QS now not only considers captures, but, if the
move leading to it was a check evasion, also check drops. In case
the previous move of the same side was a check evasion, we also try
the killers (which might have been postponed due to the need to evade),
plus check drops.
---

diff --git a/dropper.c b/dropper.c
index 6aa164d..f3f4ee1 100644
--- a/dropper.c
+++ b/dropper.c
@@ -1275,7 +1275,23 @@ if(PATH)printf("%d:%d:%d new iter moveStack[%d..%d]\n",ply,depth,iterDepth,m.fir
 		    moveStack[bestNr] = moveStack[curMove]; moveStack[curMove] = bestCapt; // swap it to front
 		    m.unsorted = curMove + 1; // sorted set now includes move
 		} else {
-		    if(maxDepth <= 0) { resultDepth = 0; if(bestScore < curEval) bestScore = curEval; break; } // in QS we stop after captures
+		    if(maxDepth <= 0) { 
+			resultDepth = 0; if(bestScore < anaEval) bestScore = anaEval;
+			if(m.stage) break;
+			moveSP = curMove;
+			if(ff->checker != CK_NONE && depthLimit != MAXPLY && oldLimit == MAXPLY) { // last move before QS was evasion
+			    CheckDrops(stm, f.xking); // also do check drops
+			    if(moveSP > curMove) { m.stage = 3; m.unsorted = moveSP; curMove--; continue; }
+			}
+			if(depthLimit == MAXPLY || oldLimit != MAXPLY || checkHist[moveNr+ply-1] == CK_NONE) break;
+			if(killer1 && PseudoLegal(stm, killer1)) moveStack[moveSP++] = moveStack[m.late], moveStack[m.late++] = killer1; // try (possibly inherited) killers
+			if(killer2 && PseudoLegal(stm, killer2)) moveStack[moveSP++] = moveStack[m.late], moveStack[m.late++] = killer2;
+			CheckDrops(stm, f.xking);
+			if(curMove >= moveSP) break;
+			m.stage = 3; m.unsorted = moveSP;
+			curMove--;
+			continue;
+		    } // in QS we stop after captures
 		    switch(m.stage) { // we reached non-captures
 		      case 0:
 			if(f.checker == CK_NONE) { // do not use killers when in check