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Small touches to bitbase.cpp

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Inspired by Lucas's code:

https://github.com/lucasart/chess/blob/master/src/kpk.cc

No functional change.
This commit is contained in:
Marco Costalba 2013-09-14 10:37:28 +02:00
parent fc17d0de77
commit 8d6d0223bf
1 changed files with 3 additions and 5 deletions
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8
src/bitbase.cpp
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@ -93,8 +93,7 @@ void Bitbases::init_kpk() {
// changed to either wins or draws (15 cycles needed).
while (repeat)
for (repeat = idx = 0; idx < IndexMax; idx++)
if (db[idx] == UNKNOWN && db[idx].classify(db) != UNKNOWN)
repeat = 1;
repeat |= (db[idx] == UNKNOWN && db[idx].classify(db) != UNKNOWN);
// Map 32 results into one KPKBitbase[] entry
for (idx = 0; idx < IndexMax; idx++)
@ -113,8 +112,7 @@ namespace {
psq = File ((idx >> 13) & 0x03) | Rank(RANK_7 - (idx >> 15));
// Check if two pieces are on the same square or if a king can be captured
if ( wksq == psq || wksq == bksq || bksq == psq
|| (StepAttacksBB[KING][wksq] & bksq)
if ( square_distance(wksq, bksq) <= 1 || wksq == psq || bksq == psq
|| (us == WHITE && (StepAttacksBB[PAWN][psq] & bksq)))
return res = INVALID;
@ -162,7 +160,7 @@ namespace {
Square s = psq + DELTA_N;
r |= db[index(BLACK, bksq, wksq, s)]; // Single push
if (rank_of(s) == RANK_3 && s != wksq && s != bksq)
if (rank_of(psq) == RANK_2 && s != wksq && s != bksq)
r |= db[index(BLACK, bksq, wksq, s + DELTA_N)]; // Double push
}