X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitboard.cpp;h=e0cb1c2021b9b65a94a01fbe3d46491bd1e1a31f;hp=298db7a7ee357764540bd61990df8f84929e63a6;hb=1ac2f501452ebd9249437b338c98ec398776b71a;hpb=2a3ebc884e9d8faae1a1cd4a2230cf8cfaead95c

diff --git a/src/bitboard.cpp b/src/bitboard.cpp
index 298db7a7..e0cb1c20 100644
--- a/src/bitboard.cpp
+++ b/src/bitboard.cpp
@@ -1,13 +1,14 @@
 /*
-  Glaurung, a UCI chess playing engine.
-  Copyright (C) 2004-2008 Tord Romstad
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
+  Copyright (C) 2008 Marco Costalba
 
-  Glaurung is free software: you can redistribute it and/or modify
+  Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
 
-  Glaurung is distributed in the hope that it will be useful,
+  Stockfish is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
@@ -21,14 +22,14 @@
 //// Includes
 ////
 
-#ifdef _MSC_VER
-    #include <intrin.h>
-    #ifdef _WIN64
-        #pragma intrinsic(_BitScanForward64)
-    #else
-        #pragma intrinsic(_BitScanForward)
-    #endif
-    #define USING_INTRINSICS
+#ifdef _MSC_VER
+    #include <intrin.h>
+    #ifdef _WIN64
+        #pragma intrinsic(_BitScanForward64)
+    #else
+        #pragma intrinsic(_BitScanForward)
+    #endif
+    #define USING_INTRINSICS
 #endif
 
 #include <iostream>
@@ -284,7 +285,7 @@ namespace {
 #if defined(USE_COMPACT_ROOK_ATTACKS)
   void init_file_and_rank_attacks();
 #endif
-};
+}
 
 
 ////
@@ -349,30 +350,39 @@ Square first_1(Bitboard b) {
 /// pop_1st_bit() finds and clears the least significant nonzero bit in a
 /// nonzero bitboard.
 
-#if defined(USE_32BIT_ATTACKS) && defined(_MSC_VER)
+#if defined(USE_32BIT_ATTACKS)
 
-// On 32bit system compiled with MSVC this verion seems
-// slightly faster then the standard one.
+// Use type-punning
+union b_union {
 
-Square pop_1st_bit(Bitboard *b) {
+    Bitboard b;
+    struct {
+        uint32_t l;
+        uint32_t h;
+    };
+};
 
-    unsigned long index;
-    uint32_t *l, *h;
-
-    if (*(l = (uint32_t*)b) != 0)
-    {
-        _BitScanForward(&index, *l);
-        *l &= ~(1 << index);
-    } 
-    else if (*(h = (uint32_t*)b + 1) != 0)
-    {
-        _BitScanForward(&index, *h);
-        *h &= ~(1 << index);
-        index += 32;
-    } else
-        return SQ_NONE;
-
-    return Square(index);
+// WARNING: Needs -fno-strict-aliasing compiler option
+Square pop_1st_bit(Bitboard *bb) {
+
+  b_union u;
+  uint32_t b;
+
+  u.b = *bb;
+
+  if (u.l)
+  {
+      b = u.l;
+      *((uint32_t*)bb) = b & (b - 1);
+      b ^= (b - 1);
+  }
+  else
+  {
+      b = u.h;
+      *((uint32_t*)bb+1) = b & (b - 1); // Little endian only?
+      b = ~(b ^ (b - 1));
+  }
+  return Square(BitTable[(b * 0x783a9b23) >> 26]);
 }
 
 #else