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Retire subfactor()

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Directly lookup in Binomial[] table.
This commit is contained in:
Marco Costalba 2016-04-27 09:16:12 +02:00
parent 145c9d943b
commit f83a6f54e4
1 changed files with 3 additions and 19 deletions
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22
src/syzygy/tbprobe.cpp
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@ -751,22 +751,6 @@ uint64_t encode_pawn(uint8_t pawns[], uint8_t *norm, Square *pos, int *factor, i
return idx;
}
// place k like pieces on n squares
int subfactor(int k, int n)
{
assert(n > 0 && k > 0 && k <= n);
int numerator = n;
int denominator = 1;
for (int i = 1; i < k; ++i) {
numerator *= n - i;
denominator *= i + 1;
}
return numerator / denominator;
}
template<typename T>
uint64_t set_factors(T& p, int num, int order)
{
@ -779,7 +763,7 @@ uint64_t set_factors(T& p, int num, int order)
result *= p.hasUniquePieces ? 31332 : 462;
} else {
p.factor[i] = (int)result;
result *= subfactor(p.norm[i], n);
result *= Binomial[p.norm[i] - 1][n];
n -= p.norm[i];
i += p.norm[i];
}
@ -806,10 +790,10 @@ uint64_t calc_factors_pawn(int *factor, int num, int order, int order2, uint8_t
result *= Pfactor[norm[0] - 1][f];
} else if (k == order2) {
factor[norm[0]] = (int)result;
result *= subfactor(norm[norm[0]], 48 - norm[0]);
result *= Binomial[norm[norm[0]] - 1][48 - norm[0]];
} else {
factor[i] = (int)result;
result *= subfactor(norm[i], n);
result *= Binomial[norm[i] - 1][n];
n -= norm[i];
i += norm[i];
}