From: H.G.Muller <hgm@hgm-xboard.(none)>
Date: Tue, 10 Apr 2018 15:42:31 +0000 (+0200)
Subject: Implement promotion drops
X-Git-Url: http://winboard.nl/cgi-bin?a=commitdiff_plain;h=29db067bd8cc5b56686bdd78c2a4092f1ea1c4a6;p=crazywa.git

Implement promotion drops

The various routines for generating drop moves are now also able to
generate drops of the promoted version of the piece in hand, controlled
by a variable 'promoDrops'. For now this variable is set to forbid such
drops.
---

diff --git a/dropper.c b/dropper.c
index 9685e96..e7b834c 100644
--- a/dropper.c
+++ b/dropper.c
@@ -65,7 +65,7 @@ int moveNr;              // part of game state; incremented by MakeMove
 #define promoGain (rawGain + 1)
 
 int pvStack[MAXPLY*MAXPLY/2];
-int nrRanks, nrFiles, specials, pinCodes, maxDrop, moveSP, pawn, queen, lanceMask, knightLim, *pvPtr = pvStack, boardEnd, perpLoses, searchNr;
+int nrRanks, nrFiles, specials, pinCodes, maxDrop, promoDrops, moveSP, pawn, queen, lanceMask, knightLim, *pvPtr = pvStack, boardEnd, perpLoses, searchNr;
 int  frontier, killZone, impasse, frontierPenalty, killPenalty;
 int rawInts[21*22], pieceValues[96], pieceCode[96];
 signed char   rawChar[32*22], steps[512];
@@ -485,6 +485,7 @@ GameInit (char *name)
     lanceMask = lances[v];
     knightLim = (v >= KNIGHTLESS) * 6; // 6 for variants where last piece can be dropped on last two ranks
     perpLoses = v; // this works for now, as only zh allows perpetuals
+    promoDrops = 0;
 
     if((p = betza[v])) { // configure GUI for this variant
 	printf("setup (%s) %dx%d+%d_%s %s 0 1", ptc[v], nrFiles, nrRanks, maxDrop+1, (pieces == waIDs ? "chu" : "shogi"), startPos);
@@ -905,10 +906,22 @@ CheckDrops (int stm, int king)
     int i, lowest = 0;
     if(perpLoses) lowest = !!(pawnCount[sqr2file[king]] & maxBulk[stm]); // in Shogi no Pawn if file already crowded with those
     else lowest = (stm == WHITE ? king < 2*22 : king >= 6*22);           // in zh no Pawn from back rank
-    for(i=maxDrop; i>=lowest; i--) {
+    for(i=maxDrop; i>=0; i--) {
 	int piece = stm + i, from = handSlot[piece^COLOR];
 	if((signed char)board[from] < -1) { // piece type is in hand
-	    int step, dir = 2*firstDir[piece-WHITE];
+	    int step, dir;
+	    if(promoDrops) { // for variants that also can drop promoted side up
+		dir = 2*firstDir[piece-WHITE+16];
+		while((step = steps[dir++])) {
+		    int to = king, range = steps[dir++];
+		    while(board[to-=step] == 0) {
+			moveStack[moveSP++] = to + 11 | from << 8;
+			if((range -= 8) <= 0) break;
+		    }
+		}
+	    }
+	    if(i < lowest) break; // suppresses back-rank Pawn drops in zh
+	    dir = 2*firstDir[piece-WHITE];
 	    while((step = steps[dir++])) {
 		int to = king, range = steps[dir++];
 		if((range & 3) == 2) continue; // non-capture direction
@@ -924,7 +937,7 @@ CheckDrops (int stm, int king)
 void
 EvasionDrops (int stm, StackFrame *f, int mask)
 {
-    int i, x = f->checker, v = f->checkDir, s = stm ^ COLOR;
+    int i, j, x = f->checker, v = f->checkDir, s = stm ^ COLOR;
     while(board[x+=v] == 0) { // all squares on check ray
 	int last = maxDrop;
 	if((mask >>= 1) & 1) continue; // suppress 'futile interpositions'
@@ -937,6 +950,11 @@ EvasionDrops (int stm, StackFrame *f, int mask)
 	    }
 	    if(pawnCount[sqr2file[x]] & maxBulk[stm]) i += !i; // no Pawn in pawn-crowded file
 	}
+	if(promoDrops) for(j=0; j<=maxDrop; j++) { // all droppable types
+	    int piece = s + j, from = handSlot[piece];
+	    if((signed char)board[from] < -1) // piece type is in hand
+		moveStack[moveSP++] = from << 8 | x + 11;
+	}
 	for(; i<=last; i++) { // all droppable types
 	    int piece = s + i, from = handSlot[piece];
 	    if((signed char)board[from] < -1) // piece type is in hand
@@ -958,6 +976,10 @@ AllDrops (int stm)
 		if(stm == BLACK || !perpLoses) start = badZone;
 		if(stm == WHITE || !perpLoses) end  -= badZone;
 	    }
+	    if(promoDrops) { // for variants where pieces can be dropped with either side up
+		for(f=0; f<nrFiles; f++) for(r=0; r<boardEnd; r+=22) // no forbidden ranks then
+		    if(board[r+f] == 0) moveStack[moveSP++] = from << 8 | f + r + 11;
+	    }
 	    for(f=0; f<nrFiles; f++) {
 		if(i == 0 && pawnCount[f] & maxBulk[stm]) continue;
 		for(r=start; r<end; r+=22)