namespace {
// There are 24 possible pawn squares: the first 4 files and ranks from 2 to 7
- const unsigned IndexMax = 2*24*64*64; // stm * psq * wksq * bksq = 196608
+ const unsigned MAX_INDEX = 2*24*64*64; // stm * psq * wksq * bksq = 196608
// Each uint32_t stores results of 32 positions, one per bit
- uint32_t KPKBitbase[IndexMax / 32];
+ uint32_t KPKBitbase[MAX_INDEX / 32];
// A KPK bitbase index is an integer in [0, IndexMax] range
//
- // Information is mapped in a way that minimizes number of iterations:
+ // Information is mapped in a way that minimizes the number of iterations:
//
// bit 0- 5: white king square (from SQ_A1 to SQ_H8)
// bit 6-11: black king square (from SQ_A1 to SQ_H8)
unsigned idx, repeat = 1;
std::vector<KPKPosition> db;
- db.reserve(IndexMax);
+ db.reserve(MAX_INDEX);
// Initialize db with known win / draw positions
- for (idx = 0; idx < IndexMax; ++idx)
+ for (idx = 0; idx < MAX_INDEX; ++idx)
db.push_back(KPKPosition(idx));
// Iterate through the positions until none of the unknown positions can be
// changed to either wins or draws (15 cycles needed).
while (repeat)
- for (repeat = idx = 0; idx < IndexMax; ++idx)
+ for (repeat = idx = 0; idx < MAX_INDEX; ++idx)
repeat |= (db[idx] == UNKNOWN && db[idx].classify(db) != UNKNOWN);
// Map 32 results into one KPKBitbase[] entry
- for (idx = 0; idx < IndexMax; ++idx)
+ for (idx = 0; idx < MAX_INDEX; ++idx)
if (db[idx] == WIN)
KPKBitbase[idx / 32] |= 1 << (idx & 0x1F);
}