X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=src%2Fbitboard.h;h=85852e5e5b8567557a75ac289025073a2df61ef3;hb=46a50cbf38bdfa5e48358585f4c98668507700ae;hp=6f3a0048226eb620e6e9c07d9c4185145ad27b68;hpb=19540c9ee824abc156d5a12ab353c250a083da4b;p=stockfish

diff --git a/src/bitboard.h b/src/bitboard.h
index 6f3a0048..85852e5e 100644
--- a/src/bitboard.h
+++ b/src/bitboard.h
@@ -224,9 +224,15 @@ inline bool single_bit(Bitboard b) {
 #if defined(_MSC_VER) && !defined(__INTEL_COMPILER)
 
 FORCE_INLINE Square first_1(Bitboard b) {
-   unsigned long index;
-   _BitScanForward64(&index, b);
-   return (Square) index;
+  unsigned long index;
+  _BitScanForward64(&index, b);
+  return (Square) index;
+}
+
+FORCE_INLINE Square last_1(Bitboard b) {
+  unsigned long index;
+  _BitScanReverse64(&index, b);
+  return (Square) index;
 }
 #else
 
@@ -235,6 +241,12 @@ FORCE_INLINE Square first_1(Bitboard b) { // Assembly code by Heinz van Saanen
   __asm__("bsfq %1, %0": "=r"(dummy): "rm"(b) );
   return (Square) dummy;
 }
+
+FORCE_INLINE Square last_1(Bitboard b) {
+  Bitboard dummy;
+  __asm__("bsrq %1, %0": "=r"(dummy): "rm"(b) );
+  return (Square) dummy;
+}
 #endif
 
 FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
@@ -246,10 +258,20 @@ FORCE_INLINE Square pop_1st_bit(Bitboard* b) {
 #else // if !defined(USE_BSFQ)
 
 extern Square first_1(Bitboard b);
+extern Square last_1(Bitboard b);
 extern Square pop_1st_bit(Bitboard* b);
 
 #endif
 
+// relative_rank() returns the relative rank of the closest bit set on the Bitboard.
+// Only to be used with bitboards that contain a single file.
+
+template<Color Us>
+inline Rank relative_rank(Bitboard b) {
+  Square s = Us == WHITE ?  first_1(b)
+                         : ~last_1(b);
+  return rank_of(s);
+}
 
 extern void print_bitboard(Bitboard b);
 extern void bitboards_init();