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Internal iterative deepening #285

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Internal iterative deepening #285

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e390c3c
Bishop coloured pawns evaluation (#283)
GediminasMasaitis Dec 22, 2023
5b5e14a
IID
GediminasMasaitis Dec 22, 2023
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2 changes: 1 addition & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ bash build-mini.sh

## 4ku-mini Size
```
3,970 bytes
4,043 bytes
```

---
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78 changes: 54 additions & 24 deletions src/main.cpp
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Expand Up @@ -422,50 +422,51 @@ void generate_piece_moves(Move *const movelist,
}

const i32 phases[] = {0, 1, 1, 2, 4, 0};
const i32 max_material[] = {137, 443, 446, 837, 1693, 0, 0};
const i32 material[] = {S(93, 137), S(325, 443), S(334, 446), S(440, 837), S(750, 1693), 0};
const i32 max_material[] = {139, 432, 482, 837, 1703, 0, 0};
const i32 material[] = {S(95, 139), S(326, 432), S(372, 482), S(442, 837), S(744, 1703), 0};
const i32 pst_rank[] = {
0, S(-3, 0), S(-3, -1), S(-1, -1), S(1, 0), S(5, 2), 0, 0, // Pawn
S(-3, -4), S(-1, -3), S(0, -1), S(2, 2), S(3, 3), S(6, 1), S(4, 0), S(-12, 1), // Knight
S(-1, -1), S(2, -1), S(2, 0), S(2, 0), S(2, 1), S(3, 0), 0, S(-8, 2), // Bishop
S(-2, -4), S(-1, -2), S(0, -1), S(2, 2), S(3, 3), S(6, 1), S(4, 0), S(-12, 1), // Knight
S(-1, -2), S(2, -1), S(2, 0), S(2, 0), S(2, 1), S(3, 0), 0, S(-9, 2), // Bishop
S(0, -3), S(-1, -3), S(-2, -2), S(-3, 0), S(0, 2), S(2, 2), S(1, 3), S(3, 1), // Rook
S(2, -11), S(3, -8), S(1, -4), S(0, 1), S(-1, 5), S(0, 5), S(-3, 6), S(-1, 5), // Queen
S(2, -11), S(3, -8), S(1, -4), S(0, 1), S(-1, 5), S(0, 5), S(-3, 6), S(-1, 6), // Queen
S(-1, -5), S(1, -2), 0, S(-2, 2), S(0, 4), S(5, 4), S(2, 3), S(1, -3) // King
};
const i32 pst_file[] = {
S(-1, 1), S(-2, 1), S(-1, 0), S(0, -1), S(1, 0), S(2, 0), S(2, 0), S(-1, -1), // Pawn
S(-5, -3), S(-2, -1), S(0, 1), S(2, 3), S(2, 2), S(2, 0), S(1, 0), S(-1, -3), // Knight
S(-2, 0), 0, S(1, 0), S(0, 1), S(1, 1), S(-1, 1), S(2, 0), S(0, -1), // Bishop
S(-5, -2), S(-2, -1), S(0, 1), S(2, 2), S(2, 2), S(2, 0), S(1, 0), S(-1, -2), // Knight
S(-2, -1), 0, S(1, 0), S(0, 1), S(1, 1), S(-1, 1), S(2, -1), S(0, -1), // Bishop
S(-2, 0), S(-1, 1), S(0, 1), S(1, 0), S(2, -1), S(1, 0), S(1, 0), S(-2, 0), // Rook
S(-2, -4), S(-1, -2), S(-1, 0), S(0, 1), S(0, 2), S(1, 2), S(2, 1), S(1, -1), // Queen
S(-2, -5), S(2, -2), S(-1, 1), S(-2, 2), S(-3, 2), S(-1, 1), S(2, -1), S(0, -5) // King
};
const i32 open_files[] = {
// Semi open files
S(1, 5),
S(-5, 19),
S(2, 6),
S(-5, 17),
S(18, 15),
S(3, 18),
S(-21, 9),
S(2, 18),
S(-22, 9),
// Open files
S(-3, -11),
S(-11, 0),
S(46, 0),
S(-15, 37),
S(-2, -9),
S(-12, -3),
S(46, 1),
S(-15, 38),
S(-59, 1),
};
const i32 mobilities[] = {S(9, 5), S(8, 7), S(3, 4), S(4, 2), S(-5, 0)};
const i32 king_attacks[] = {S(10, -4), S(19, -5), S(27, -9), S(20, 5), 0};
const i32 pawn_protection[] = {S(22, 14), S(2, 14), S(6, 17), S(8, 9), S(-5, 19), S(-30, 24)};
const i32 pawn_threat_penalty[] = {S(-4, 1), S(21, 2), S(11, 6), S(10, 17), S(9, 16), S(5, 5)};
const i32 passers[] = {S(3, 14), S(33, 50), S(63, 124), S(195, 253)};
const i32 pawn_passed_protected = S(10, 18);
const i32 mobilities[] = {S(9, 7), S(7, 5), S(3, 5), S(4, 2), S(-5, -1)};
const i32 king_attacks[] = {S(11, -4), S(19, -5), S(27, -9), S(21, 4), 0};
const i32 pawn_protection[] = {S(22, 15), S(2, 11), S(7, 24), S(8, 8), S(-5, 18), S(-30, 23)};
const i32 pawn_threat_penalty[] = {S(-4, 0), S(22, 4), S(10, 4), S(11, 18), S(10, 16), S(5, 5)};
const i32 passers[] = {S(2, 14), S(33, 51), S(62, 125), S(195, 256)};
const i32 pawn_passed_protected = S(11, 18);
const i32 pawn_doubled_penalty = S(10, 36);
const i32 pawn_phalanx = S(12, 12);
const i32 pawn_passed_blocked_penalty[] = {S(8, 13), S(-7, 40), S(-9, 82), S(-10, 158)};
const i32 pawn_passed_blocked_penalty[] = {S(9, 11), S(-6, 38), S(-8, 80), S(-10, 159)};
const i32 pawn_passed_king_distance[] = {S(1, -6), S(-4, 11)};
const i32 bishop_pair = S(32, 71);
const i32 king_shield[] = {S(35, -11), S(27, -6)};
const i32 bishop_pair = S(35, 70);
const i32 bishop_pawns_penalty[] = {S(6, 14), S(5, 1)};
const i32 king_shield[] = {S(36, -11), S(28, -6)};
const i32 pawn_attacked_penalty[] = {S(63, 14), S(156, 140)};

[[nodiscard]] i32 eval(Position &pos) {
Expand Down Expand Up @@ -568,6 +569,15 @@ const i32 pawn_attacked_penalty[] = {S(63, 14), S(156, 140)};
if (!(0x101010101010101ull << file & pawns[0]))
score += open_files[!(0x101010101010101ull << file & pawns[1]) * 5 + p - 1];

// Pawns on bishop coloured squares
if (p == Bishop) {
u64 mask = 0xAA55AA55AA55AA55ull;
if (piece_bb & ~mask)
mask = ~mask;
for (i32 i = 0; i < 2; ++i)
score -= bishop_pawns_penalty[i] * count(pawns[i] & mask);
}

if (p == King && piece_bb & 0xC3D7) {
// C3D7 = Reasonable king squares
// Pawn cover is fixed in position, so it won't
Expand Down Expand Up @@ -724,6 +734,26 @@ i32 alphabeta(Position &pos,
}
}

// Internal iterative deepening
if (depth > 4 && alpha != beta - 1 && tt_move == no_move) {
alphabeta(pos,
alpha,
beta,
depth - 4,
ply,
// minify enable filter delete
nodes,
// minify disable filter delete
stop_time,
stack,
stop,
hash_history,
hh_table,
false);

tt_move = stack[ply].move;
}

hash_history.emplace_back(tt_key);
u8 tt_flag = Upper;

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