S(20,20), S(40,40), S(0, 0), S(0, 0) };
// Bonus for file distance of the two outermost pawns
- const Score PawnsFileSpan = S(0, 15);
+ const Score PawnsFileSpan = S(0, 8);
// Unsupported pawn penalty
const Score UnsupportedPawnPenalty = S(20, 10);
namespace Pawns {
+/// init() initializes some tables used by evaluation. Instead of hard-coded
+/// tables, when makes sense, we prefer to calculate them with a formula to
+/// reduce independent parameters and to allow easier tuning and better insight.
+
void init()
{
- const int c[RANK_NB] = {0, 6, 15, 10, 57, 75, 135, 258};
+ static const int Seed[RANK_NB] = { 0, 6, 15, 10, 57, 75, 135, 258 };
- for (Rank r = RANK_2; r <= RANK_7; ++r)
- for (int opposed = false; opposed <= true; ++opposed)
- for (int phalanx = false; phalanx <= true; ++phalanx)
+ for (int opposed = 0; opposed <= 1; ++opposed)
+ for (int phalanx = 0; phalanx <= 1; ++phalanx)
+ for (Rank r = RANK_2; r < RANK_8; ++r)
{
- int bonus = c[r] + (phalanx ? (c[r + 1] - c[r]) / 2 : 0);
+ int bonus = Seed[r] + (phalanx ? (Seed[r + 1] - Seed[r]) / 2 : 0);
Connected[opposed][phalanx][r] = make_score(bonus / 2, bonus >> opposed);
}
}
+
/// probe() takes a position as input, computes a Entry object, and returns a
/// pointer to it. The result is also stored in a hash table, so we don't have
/// to recompute everything when the same pawn structure occurs again.