X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;ds=inline;f=src%2Fbitcount.h;h=f84c51cb8596caf76e658d126330c898dafde7f8;hb=2f92e3b5251e8da1c573a9860b8f42afca4f9366;hp=9d25a5e5c1b4d7b7bd19c0bd0cd60234209741a5;hpb=e9296d694c72c2378b71ad29cfff2f2c7b45bb0c;p=stockfish
diff --git a/src/bitcount.h b/src/bitcount.h
index 9d25a5e5..f84c51cb 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) 2008-2014 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
@@ -18,7 +18,7 @@
along with this program. If not, see .
*/
-#if !defined(BITCOUNT_H_INCLUDED)
+#ifndef BITCOUNT_H_INCLUDED
#define BITCOUNT_H_INCLUDED
#include
@@ -32,65 +32,59 @@ 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 or
-/// use hardware popcnt instruction when available.
+/// 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 inline int popcount(Bitboard);
template<>
inline int popcount(Bitboard b) {
- b -= ((b>>1) & 0x5555555555555555ULL);
- b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
- b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
- b *= 0x0101010101010101ULL;
- return int(b >> 56);
+ b -= (b >> 1) & 0x5555555555555555ULL;
+ b = ((b >> 2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
+ b = ((b >> 4) + b) & 0x0F0F0F0F0F0F0F0FULL;
+ return (b * 0x0101010101010101ULL) >> 56;
}
template<>
inline int popcount(Bitboard b) {
- b -= (b>>1) & 0x5555555555555555ULL;
- b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
- b *= 0x1111111111111111ULL;
- return int(b >> 60);
+ b -= (b >> 1) & 0x5555555555555555ULL;
+ b = ((b >> 2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
+ return (b * 0x1111111111111111ULL) >> 60;
}
template<>
inline int popcount(Bitboard b) {
unsigned w = unsigned(b >> 32), v = unsigned(b);
- v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
- w -= (w >> 1) & 0x55555555;
- v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
- w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
- v = ((v >> 4) + v) & 0x0F0F0F0F; // 0-8 in 8 bits
- v += (((w >> 4) + w) & 0x0F0F0F0F); // 0-16 in 8 bits
- v *= 0x01010101; // mul is fast on amd procs
- return int(v >> 24);
+ v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
+ w -= (w >> 1) & 0x55555555;
+ v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
+ w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
+ v = ((v >> 4) + v + (w >> 4) + w) & 0x0F0F0F0F;
+ return (v * 0x01010101) >> 24;
}
template<>
inline int popcount(Bitboard b) {
unsigned w = unsigned(b >> 32), v = unsigned(b);
- v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
- w -= (w >> 1) & 0x55555555;
- v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
- w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
- v += w; // 0-8 in 4 bits
- v *= 0x11111111;
- return int(v >> 28);
+ v -= (v >> 1) & 0x55555555; // 0-2 in 2 bits
+ w -= (w >> 1) & 0x55555555;
+ v = ((v >> 2) & 0x33333333) + (v & 0x33333333); // 0-4 in 4 bits
+ w = ((w >> 2) & 0x33333333) + (w & 0x33333333);
+ return ((v + w) * 0x11111111) >> 28;
}
template<>
inline int popcount(Bitboard b) {
-#if !defined(USE_POPCNT)
+#ifndef USE_POPCNT
assert(false);
- return int(b != 0); // Avoid 'b not used' warning
+ return b != 0; // Avoid 'b not used' warning
#elif defined(_MSC_VER) && defined(__INTEL_COMPILER)
@@ -102,11 +96,10 @@ inline int popcount(Bitboard b) {
#else
- unsigned long ret;
- __asm__("popcnt %1, %0" : "=r" (ret) : "r" (b));
- return ret;
+ __asm__("popcnt %1, %0" : "=r" (b) : "r" (b));
+ return b;
#endif
}
-#endif // !defined(BITCOUNT_H_INCLUDED)
+#endif // #ifndef BITCOUNT_H_INCLUDED