private void HashBlockers(int sqInd, bool rook)
{
ulong mask = SaveMask(sqInd, rook);
int[] bitsArr = rook ? RBits : BBits;
int bits = bitsArr[sqInd];
int combinations = 1 << bits;
ulong[] blockers = new ulong[combinations];
ulong[] attacks = new ulong[combinations];
for (int i = 0; i < combinations; i++)
{
blockers[i] = GetBlockersByIndex(i, mask);
attacks[i] = rook ? SlidingPieceUtils.GetRookAtt(sqInd, blockers[i]) : SlidingPieceUtils.GetBishopAtt(sqInd, blockers[i]);
}
ulong magic = rook ? rookMagics[sqInd] : bishopMagics[sqInd];
ulong[][] attacksTable = rook ? rookAttacksTable : bishopAttacksTable;
attacksTable[sqInd] = new ulong[combinations];
for (int i = 0; i < combinations; i++)
{
ulong hashed = ApplyMagic(blockers[i], magic, bits);
attacksTable[sqInd][hashed] = attacks[i];
}
}
private ulong SaveMask(int sqInd, bool rook)
{
ulong mask;
if (rook)
{
mask = rookMasks[sqInd] = SlidingPieceUtils.GetRookMask(sqInd);
}
else
{
mask = bishopMasks[sqInd] = SlidingPieceUtils.GetBishopMask(sqInd);
}
return(mask);
}
private ulong FindMagic(int sqInd, bool rook, out ulong[] hashTable)
{
ulong mask = SaveMask(sqInd, rook);
int[] bitsArr = rook ? RBits : BBits;
int bits = bitsArr[sqInd];
int combinations = 1 << bits;
ulong[] blockers = new ulong[combinations];
ulong[] attacks = new ulong[combinations];
hashTable = new ulong[combinations];
for (int i = 0; i < combinations; i++)
{
blockers[i] = GetBlockersByIndex(i, mask);
attacks[i] = rook ? SlidingPieceUtils.GetRookAtt(sqInd, blockers[i]) : SlidingPieceUtils.GetBishopAtt(sqInd, blockers[i]);
}
for (int k = 0; k < 100000000; k++)
{
ulong magic = RandomUInt64FewBits();
ulong[] attacksTable = new ulong[combinations];
bool fail = false;
for (int i = 0; i < combinations && !fail; i++)
{
ulong hashed = ApplyMagic(blockers[i], magic, bits);
if (attacksTable[hashed] == 0)
{
attacksTable[hashed] = attacks[i];
}
else if (attacksTable[hashed] != attacks[i])
{
fail = true;
}
}
if (!fail)
{
hashTable = attacksTable;
return(magic);
}
}
throw new Exception("Failed to find magic");
}