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Simplify popcnt

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Also a speedup(about 1%) on 64-bit w/o hardware popcnt

Retire Max15 and Full template parameters
(Contributed by Marco Costalba)

Now that we have just SW and HW versions, use
template default parameter to get rid of explicit
template parameters.

Retire bitcount.h and move the only defined
function to bitboard.h

No functional change

Resolves #620
This commit is contained in:
mstembera
2016-04-08 18:52:15 +01:00
committed by Joona Kiiski
parent 900279a06f
commit 8fb45caade
8 changed files with 60 additions and 129 deletions
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19
src/bitboard.cpp
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@@ -21,9 +21,9 @@
#include <algorithm>
#include "bitboard.h"
#include "bitcount.h"
#include "misc.h"
uint8_t PopCnt16[1 << 16];
int SquareDistance[SQUARE_NB][SQUARE_NB];
Bitboard RookMasks [SQUARE_NB];
@@ -74,6 +74,16 @@ namespace {
return Is64Bit ? (b * DeBruijn64) >> 58
: ((unsigned(b) ^ unsigned(b >> 32)) * DeBruijn32) >> 26;
}
// popcount16() counts the non-zero bits using SWAR-Popcount algorithm
uint8_t popcount16(uint16_t u) {
u -= (u >> 1) & 0x5555U;
u = ((u >> 2) & 0x3333U) + (u & 0x3333U);
u = ((u >> 4) + u) & 0x0F0FU;
return (u * 0x0101U) >> 8;
}
}
#ifdef NO_BSF
@@ -141,6 +151,9 @@ const std::string Bitboards::pretty(Bitboard b) {
void Bitboards::init() {
for (unsigned i = 0; i < (1 << 16); ++i)
PopCnt16[i] = popcount16(i);
for (Square s = SQ_A1; s <= SQ_H8; ++s)
{
SquareBB[s] = 1ULL << s;
@@ -265,7 +278,7 @@ namespace {
// the number of 1s of the mask. Hence we deduce the size of the shift to
// apply to the 64 or 32 bits word to get the index.
masks[s] = sliding_attack(deltas, s, 0) & ~edges;
shifts[s] = (Is64Bit ? 64 : 32) - popcount<Max15>(masks[s]);
shifts[s] = (Is64Bit ? 64 : 32) - popcount(masks[s]);
// Use Carry-Rippler trick to enumerate all subsets of masks[s] and
// store the corresponding sliding attack bitboard in reference[].
@@ -296,7 +309,7 @@ namespace {
do {
do
magics[s] = rng.sparse_rand<Bitboard>();
while (popcount<Max15>((magics[s] * masks[s]) >> 56) < 6);
while (popcount((magics[s] * masks[s]) >> 56) < 6);
// A good magic must map every possible occupancy to an index that
// looks up the correct sliding attack in the attacks[s] database.