Prohibit attacks by sittuyin promotion

Fix interpretation of rule 3.9 c.4 that does not allow captures and attacks
by the general as part of promotion moves.

Closes #14.

diff --git a/src/movegen.cpp b/src/movegen.cpp
index 665ce4b..bf20c95 100644 (file)
--- a/src/movegen.cpp
+++ b/src/movegen.cpp
@@ -203,7 +203,11 @@ namespace {
                     b &= target;
 
                 while (b)
-                    *moveList++ = make<PROMOTION>(from, pop_lsb(&b), pt);
+                {
+                    Square to = pop_lsb(&b);
+                    if (!(attacks_bb(Us, pt, to, pos.pieces() ^ from) & pos.pieces(Them)))
+                        *moveList++ = make<PROMOTION>(from, to, pt);
+                }
             }
         }
     }

diff --git a/tests/perft.sh b/tests/perft.sh
index 8d88a90..354fc9b 100755 (executable)
--- a/tests/perft.sh
+++ b/tests/perft.sh
@@ -57,8 +57,9 @@ if [[ $1 == "" || $1 == "variant" ]]; then
   expect perft.exp horde startpos 6 5396554 > /dev/null
   expect perft.exp placement startpos 4 1597696 > /dev/null
   expect perft.exp sittuyin startpos 3 580096 > /dev/null
-  expect perft.exp sittuyin "fen 8/8/6R1/s3r3/P5R1/1KP3p1/1F2kr2/8[-] b - - 0 72" 4 657824 > /dev/null
-  expect perft.exp sittuyin "fen 2r5/6k1/6p1/3s2P1/3npR2/8/p2N2F1/3K4 w - - 1 50" 4 394031 > /dev/null
+  expect perft.exp sittuyin "fen 8/8/6R1/s3r3/P5R1/1KP3p1/1F2kr2/8[] b - - 0 72" 4 652686 > /dev/null
+  expect perft.exp sittuyin "fen 2r5/6k1/6p1/3s2P1/3npR2/8/p2N2F1/3K4[] w - - 1 50" 4 373984 > /dev/null
+  expect perft.exp sittuyin "fen 8/6s1/5P2/3n4/pR2K2S/1P6/1k4p1/8[] w - - 1 50" 4 268869 > /dev/null
   expect perft.exp seirawan startpos 5 27639803 > /dev/null
   expect perft.exp seirawan "fen reb1k2r/ppppqppp/2nb1n2/4p3/4P3/N1P2N2/PB1PQPPP/RE2KBHR[h] b KQkqc - 3 7" 5 31463761 > /dev/null
 fi