Add null move

The WB Alien null-move notation is recognized on input, and generated
on output. The internal representation is a move towards the same square
by a piece that has this capability. (This currently fails on a1, due
to 0 being used as representation for invalid moves!)
Only one null move is generated and added to the move list.
The null move is not searched yet.

diff --git a/hachu.c b/hachu.c
index ff3c901..fd6cbfe 100644 (file)
--- a/hachu.c
+++ b/hachu.c
@@ -46,7 +46,7 @@
 #define EMPTY      0\r
 #define EDGE   (1<<11)\r
 #define TYPE   (WHITE|BLACK|EDGE)\r
-#define ABSENT  4095\r
+#define ABSENT  2047\r
 #define INF     8000\r
 #define NPIECES 2000               /* length of piece list    */\r
 \r
@@ -1289,6 +1289,11 @@ if(flag && depth>= 0) printf("phase=%d: first/curr/last = %d / %d / %d\n", phase
            break;\r
          case 7: // bad captures\r
          case 8: // PV null move\r
+           phase = 9;\r
+           if(nullMove != ABSENT) {\r
+             moveStack[msp++] = nullMove + (nullMove << SQLEN) | DEFER; // kludge: setting DEFER guarantees != 0, and has no effect\r
+           }\r
+printf("# %d. sqr = %08x null = %08x\n", msp, nullMove, moveStack[msp-1]);\r
          case 9:\r
            goto cutoff;\r
        }\r
@@ -1533,6 +1538,7 @@ MoveToText (MOVE move, int multiLine)
 {\r
   static char buf[50];\r
   int f = move>>SQLEN & SQUARE, g = f, t = move & SQUARE;\r
+  if(f == t) { sprintf(buf, "@@@@"); return buf; } // null-move notation in WB protocol\r
   buf[0] = '\0';\r
   if(t >= SPECIAL) { // kludgy! Print as side effect non-standard WB command to remove victims from double-capture (breaks hint command!)\r
     int e = f + epList[t - SPECIAL];\r
@@ -1565,6 +1571,7 @@ MOVE
 ParseMove (char *moveText)\r
 {\r
   int i, j, f, t, t2, e, ret, deferred=0;\r
+  char c = moveText[0];\r
   moveText += ReadSquare(moveText, &f);\r
   moveText += ReadSquare(moveText, &t); t2 = t;\r
   if(*moveText == ',') {\r
@@ -1581,9 +1588,12 @@ ParseMove (char *moveText)
   }\r
   ret = f<<SQLEN | t2;\r
   if(*moveText == '+') ret |= PROMOTE;\r
+printf("# suppress = %c%d\n", sup1%BW+'a', sup1/BW);\r
 MapFromScratch(attacks);\r
   Search(-INF-1, INF+1, 0, 1, sup1, sup2);\r
   for(i=retFirst; i<retMSP; i++) {\r
+    if(moveStack[i] == INVALID) continue;\r
+    if(c == '@' && (moveStack[i] & SQUARE) == (moveStack[i] >> SQLEN & SQUARE)) break; // any null move matches @@@@\r
     if((moveStack[i] & (PROMOTE | DEFER-1)) == ret) break;\r
     if((moveStack[i] & DEFER-1) == ret) deferred = i; // promoted version of entered non-promotion is legal\r
   }\r