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Introduce bitcount.h

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It will be used for POPCNT intrinsics.

For now no bianry and functional change.

Signed-off-by: Marco Costalba <mcostalba@gmail.com>
This commit is contained in:
Marco Costalba
2009-05-21 15:29:28 +02:00
parent 1b0888708d
commit 3376c68f4b
8 changed files with 192 additions and 90 deletions
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65
src/bitboard.h
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@@ -22,7 +22,6 @@
#if !defined(BITBOARD_H_INCLUDED)
#define BITBOARD_H_INCLUDED
////
//// Defines
////
@@ -47,15 +46,10 @@
//#define USE_32BIT_ATTACKS
#define USE_FOLDED_BITSCAN
#define BITCOUNT_SWAR_64
//#define BITCOUNT_SWAR_32
//#define BITCOUNT_LOOP
#else
#define USE_32BIT_ATTACKS
#define USE_FOLDED_BITSCAN
#define BITCOUNT_SWAR_32
#endif
@@ -429,65 +423,6 @@ inline Bitboard isolated_pawn_mask(Square s) {
}
/// count_1s() counts the number of nonzero bits in a bitboard.
#if defined(BITCOUNT_LOOP)
inline int count_1s(Bitboard b) {
int r;
for(r = 0; b; r++, b &= b - 1);
return r;
}
inline int count_1s_max_15(Bitboard b) {
return count_1s(b);
}
#elif defined(BITCOUNT_SWAR_32)
inline int count_1s(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);
}
inline int count_1s_max_15(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);
}
#elif defined(BITCOUNT_SWAR_64)
inline int count_1s(Bitboard b) {
b -= ((b>>1) & 0x5555555555555555ULL);
b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
b = ((b>>4) + b) & 0x0F0F0F0F0F0F0F0FULL;
b *= 0x0101010101010101ULL;
return int(b >> 56);
}
inline int count_1s_max_15(Bitboard b) {
b -= (b>>1) & 0x5555555555555555ULL;
b = ((b>>2) & 0x3333333333333333ULL) + (b & 0x3333333333333333ULL);
b *= 0x1111111111111111ULL;
return int(b >> 60);
}
#endif // BITCOUNT
////
//// Prototypes
////