X-Git-Url: https://git.sesse.net/?p=stockfish;a=blobdiff_plain;f=src%2Fbitcount.h;h=8bc06177ddb84493d7ead7d12aaefdff4c6a9388;hp=a69ad8e8418535fbe01645368800815d19491b9f;hb=950c8436edc50857b83eb3e0cbaca06407764655;hpb=9204a60dbbebf7e319bb588acc91bf691a3ede9a

diff --git a/src/bitcount.h b/src/bitcount.h
index a69ad8e8..8bc06177 100644
--- a/src/bitcount.h
+++ b/src/bitcount.h
@@ -1,7 +1,7 @@
 /*
   Stockfish, a UCI chess playing engine derived from Glaurung 2.1
   Copyright (C) 2004-2008 Tord Romstad (Glaurung author)
-  Copyright (C) 2008-2012 Marco Costalba, Joona Kiiski, Tord Romstad
+  Copyright (C) 2008-2015 Marco Costalba, Joona Kiiski, Tord Romstad
 
   Stockfish is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -18,10 +18,11 @@
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
-#if !defined(BITCOUNT_H_INCLUDED)
+#ifndef BITCOUNT_H_INCLUDED
 #define BITCOUNT_H_INCLUDED
 
 #include <cassert>
+
 #include "types.h"
 
 enum BitCountType {
@@ -32,14 +33,14 @@ enum BitCountType {
   CNT_HW_POPCNT
 };
 
-/// Determine at compile time the best popcount<> specialization according if
-/// platform is 32 or 64 bits, to the maximum number of nonzero bits to count
-/// and if hardware popcnt instruction is available.
-const BitCountType Full  = HasPopCnt ? CNT_HW_POPCNT : Is64Bit ? CNT_64 : CNT_32;
+/// Determine at compile time the best popcount<> specialization according to
+/// whether the platform is 32 or 64 bit, the maximum number of non-zero
+/// bits to count and if the hardware popcnt instruction is available.
+const BitCountType Full  = HasPopCnt ? CNT_HW_POPCNT : Is64Bit ? CNT_64       : CNT_32;
 const BitCountType Max15 = HasPopCnt ? CNT_HW_POPCNT : Is64Bit ? CNT_64_MAX15 : CNT_32_MAX15;
 
 
-/// popcount() counts the number of nonzero bits in a bitboard
+/// popcount() counts the number of non-zero bits in a bitboard
 template<BitCountType> inline int popcount(Bitboard);
 
 template<>
@@ -81,7 +82,7 @@ inline int popcount<CNT_32_MAX15>(Bitboard b) {
 template<>
 inline int popcount<CNT_HW_POPCNT>(Bitboard b) {
 
-#if !defined(USE_POPCNT)
+#ifndef USE_POPCNT
 
   assert(false);
   return b != 0; // Avoid 'b not used' warning
@@ -94,13 +95,11 @@ inline int popcount<CNT_HW_POPCNT>(Bitboard b) {
 
   return (int)__popcnt64(b);
 
-#else
+#else // Assumed gcc or compatible compiler
 
-  unsigned long ret;
-  __asm__("popcnt %1, %0" : "=r" (ret) : "r" (b));
-  return ret;
+  return __builtin_popcountll(b);
 
 #endif
 }
 
-#endif // !defined(BITCOUNT_H_INCLUDED)
+#endif // #ifndef BITCOUNT_H_INCLUDED