Keep analogy stack pointer

This prepares for maintaining an analogy stack, for recrding suspected
spite checks at eveny (check, evasion) pair that loses material. We also
treat anaEval as a more general replacement (with wider scope) for curEval.
None of this affects the search yet.

diff --git a/dropper.c b/dropper.c
index d590bc2..c8019d9 100644 (file)
--- a/dropper.c
+++ b/dropper.c
@@ -72,6 +72,7 @@ unsigned int moveStack[500*MAXPLY];
 int killers[MAXPLY][2];
 int path[MAXPLY], deprec[MAXPLY];
 int history[1<<16], mateKillers[1<<17];
+int anaSP;
 unsigned char checkHist[MAXMOVES+MAXPLY];
 int repKey[512+20];
 
@@ -1103,11 +1104,11 @@ int
 Search (int stm, int alpha, int beta, StackFrame *ff, int depth, int reduction, int maxDepth)
 {
     MoveStack m; StackFrame f; HashEntry *entry;
-    int oldSP = moveSP, *pvStart = pvPtr, oldLimit = depthLimit;
+    int oldSP = moveSP, *pvStart = pvPtr, oldLimit = depthLimit, oldAna;
     int killer1 = killers[ply][0], killer2 = killers[ply][1], hashMove;
     int bestNr, bestScore, startAlpha, startScore, resultDepth, iterDepth=0, originalReduction = reduction;
     int hit, hashKeyH, ran=0, ipMask=0;
-    int curEval, score;
+    int curEval, anaEval, score;
 
     // legality
     int earlyGen = (ff->toPiece == stm+31); // King was moved
@@ -1186,10 +1187,12 @@ if(hashMove && board[hashMove>>8&255] == 0) {char s[100];sprintf(s,"bad hash mov
        depth -= reduction;
     } else reduction = originalReduction = 0;
     checkHist[moveNr+ply+1] = f.checker;
+    oldAna = anaSP; anaSP += (ff->checker != CK_NONE); // node after evasion: accept new analogy
+    anaEval = curEval;
+
     // stand pat or null move
     startAlpha = alpha; startScore = -INF;
     if(depth <= 0) { // QS
-        int anaEval = curEval;
        if(ff->checker != CK_NONE && ff->tpGain > 0) anaEval = 50-INF; // forbid stand pat if horizon check tossed material
        if(anaEval > alpha) {
            if(anaEval >= beta) { ff->depth = 1; moveSP = oldSP; return anaEval; } // stand-pat cutoff
@@ -1198,7 +1201,7 @@ if(hashMove && board[hashMove>>8&255] == 0) {char s[100];sprintf(s,"bad hash mov
        if(maxDepth <= 0) {
            if(board[toDecode[hashMove&255]] == 0) hashMove = 0;
 #ifdef IDQS
-           if(ply >= depthLimit) { ff->depth = 1; moveSP = oldSP; return curEval + 150; } // hit depth limit; give hefty stm bonus
+           if(ply >= depthLimit) { ff->depth = 1; moveSP = oldSP; anaSP = oldAna; return anaEval + 150; } // hit depth limit; give hefty stm bonus
            if(depthLimit == MAXPLY) depthLimit = ply+10; // we just entered pure QS; set up depth limit
 #endif
        }
@@ -1212,7 +1215,7 @@ if(hashMove && board[hashMove>>8&255] == 0) {char s[100];sprintf(s,"bad hash mov
        deprec[ply] = maxDepth << 16 | depth << 8; path[ply++] = 0;
        score = -Search(stm, -beta, 1-beta, &f, nullDepth, 0, nullDepth);
        ply--;
-       if(score >= beta) { ff->depth = f.depth +  originalReduction + 3; moveSP = oldSP; return beta + 1; }
+       if(score >= beta) { ff->depth = f.depth +  originalReduction + 3; moveSP = oldSP; anaSP = oldAna; return beta + 1; }
     }
 
     // move generation
@@ -1238,7 +1241,7 @@ if(hashMove && board[hashMove>>8&255] == 0) {char s[100];sprintf(s,"bad hash mov
        bonus += bonus >> 1;
        int newEval = curEval + bonus;
        if(newEval > alpha) {
-           if(newEval >= beta) { ff->depth = 1; moveSP = oldSP; depthLimit = oldLimit; return newEval; } // stand-pat cutoff
+           if(newEval >= beta) { ff->depth = 1; moveSP = oldSP; depthLimit = oldLimit; anaSP = oldAna; return newEval; } // stand-pat cutoff
            alpha = startScore = newEval; maxDepth = 0; // we will not fail low, so no extra iterations
        }
    }
@@ -1334,7 +1337,7 @@ int m=moveStack[curMove];
 printf("%d:%d:%d %2d. %08x %c%d%c%d %6d %6d %6d\n",ply,depth,iterDepth,curMove,m,(m>>8&255)%22+'a',(m>>8&255)/22+1,toDecode[m&255]%22+'a',toDecode[m&255]/22+1,f.pstEval,score,bestScore);
 }
 
-           if(abortFlag) { moveSP = oldSP; depthLimit = oldLimit; return -INF; }
+           if(abortFlag) { moveSP = oldSP; depthLimit = oldLimit; anaSP = oldAna; return -INF; }
 
            // minimaxing
            if(f.depth < resultDepth) resultDepth = f.depth;
@@ -1408,7 +1411,7 @@ if(PATH)printf("%d:%d:%d iter end, max=%d, alpha=%d start=%d\n", ply, depth,iter
 if(PATH || f.hashKey == 0x1348708590)printf("%d:%d   Hash store %16llx, d=%d, checker=%x move=%s\n",ply,depth,f.hashKey,resultDepth,entry->checker,MoveToText(entry->move));
 
     // return results
-    moveSP = oldSP; pvPtr = pvStart; depthLimit = oldLimit;
+    moveSP = oldSP; anaSP = oldAna; pvPtr = pvStart; depthLimit = oldLimit;
     ff->depth = resultDepth + 1 + originalReduction; // report valid depth as seen from parent
     return bestScore;
 }