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Merged
Jan-Frase merged 3 commits into from
Oct 19, 2025
Merged

Pawns #38

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91c53a2
Feat: Started pawn optimizations.
Oct 15, 2025
53ab6aa
Feat: Pawn capture moves optimizations.
Oct 17, 2025
5dd2f70
Refactor: Removed old pawn code.
Oct 19, 2025
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23 changes: 3 additions & 20 deletions src/backend/compile_time/gen_caches.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,9 +3,8 @@ use crate::backend::compile_time::gen_caches_non_sliders::{
};
use crate::backend::compile_time::gen_caches_sliders::{PEXT_TABLE_SIZE, gen_cache_sliders};
use crate::backend::compile_time::generated::caches::{
CACHE_BISHOP_PEXT_INDEX, CACHE_BISHOP_PEXT_MASK, CACHE_CAPTURE_PAWN, CACHE_DOUBLE_PUSH_PAWN,
CACHE_KING, CACHE_KNIGHT, CACHE_PEXT_TABLE, CACHE_QUIET_PAWN, CACHE_ROOK_PEXT_INDEX,
CACHE_ROOK_PEXT_MASK,
CACHE_BISHOP_PEXT_INDEX, CACHE_BISHOP_PEXT_MASK, CACHE_CAPTURE_PAWN, CACHE_KING, CACHE_KNIGHT,
CACHE_PEXT_TABLE, CACHE_ROOK_PEXT_INDEX, CACHE_ROOK_PEXT_MASK,
};
use crate::backend::constants::{SIDES, SQUARES_AMOUNT};
use crate::backend::state::board::bitboard::BitBoard;
Expand Down Expand Up @@ -35,13 +34,9 @@ use std::fs;
pub const KING_MOVES: [BitBoard; SQUARES_AMOUNT] = read_bb_cache(&CACHE_KING);
pub const KNIGHT_MOVES: [BitBoard; SQUARES_AMOUNT] = read_bb_cache(&CACHE_KNIGHT);

// Various pawn caches:
pub const PAWN_QUIET_MOVES: [[BitBoard; SQUARES_AMOUNT]; SIDES] =
read_2d_bb_cache(CACHE_QUIET_PAWN);
// Due for removal, only exists until check_decider gets reworked.
pub const PAWN_CAPTURE_MOVES: [[BitBoard; SQUARES_AMOUNT]; SIDES] =
read_2d_bb_cache(CACHE_CAPTURE_PAWN);
pub const PAWN_DOUBLE_PUSH_MOVES: [[BitBoard; SQUARES_AMOUNT]; SIDES] =
read_2d_bb_cache(CACHE_DOUBLE_PUSH_PAWN);

// Various slider caches:
pub const ROOK_PEXT_MASK: [BitBoard; SQUARES_AMOUNT] = read_bb_cache(&CACHE_ROOK_PEXT_MASK);
Expand Down Expand Up @@ -95,12 +90,8 @@ pub fn write_caches() {
let knight_moves = calculate_potential_moves_cache(Piece::Knight);
let knight_moves = knight_moves.map(|b| b.value);

let quiet_pawn_moves = generate_pawn_moves(PawnMoveType::Quiet);
let quiet_pawn_moves = quiet_pawn_moves.map(|a| a.map(|b| b.value));
let capture_pawn_moves = generate_pawn_moves(PawnMoveType::Capture);
let capture_pawn_moves = capture_pawn_moves.map(|a| a.map(|b| b.value));
let double_push_pawn_moves = generate_pawn_moves(PawnMoveType::DoublePush);
let double_push_pawn_moves = double_push_pawn_moves.map(|a| a.map(|b| b.value));

let pext_data = gen_cache_sliders();
let rook_pext_mask = pext_data.rook_pext_mask;
Expand All @@ -115,18 +106,10 @@ pub fn write_caches() {
let cache_strings = [
format!("pub const CACHE_KING: [u64; 64] = {:?};", king_moves),
format!("pub const CACHE_KNIGHT: [u64; 64] = {:?};", knight_moves),
format!(
"pub const CACHE_QUIET_PAWN: [[u64; 64]; 2] = {:?};",
quiet_pawn_moves
),
format!(
"pub const CACHE_CAPTURE_PAWN: [[u64; 64]; 2] = {:?};",
capture_pawn_moves
),
format!(
"pub const CACHE_DOUBLE_PUSH_PAWN: [[u64; 64]; 2] = {:?};",
double_push_pawn_moves
),
format!(
"pub const CACHE_ROOK_PEXT_MASK: [u64; 64] = {:?};",
rook_pext_mask
Expand Down
6 changes: 0 additions & 6 deletions src/backend/compile_time/generated/caches.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,15 +4,9 @@ pub const CACHE_KING: [u64; 64] = [770, 1797, 3594, 7188, 14376, 28752, 57504, 4
#[rustfmt::skip]
pub const CACHE_KNIGHT: [u64; 64] = [132096, 329728, 659712, 1319424, 2638848, 5277696, 10489856, 4202496, 33816580, 84410376, 168886289, 337772578, 675545156, 1351090312, 2685403152, 1075839008, 8657044482, 21609056261, 43234889994, 86469779988, 172939559976, 345879119952, 687463207072, 275414786112, 2216203387392, 5531918402816, 11068131838464, 22136263676928, 44272527353856, 88545054707712, 175990581010432, 70506185244672, 567348067172352, 1416171111120896, 2833441750646784, 5666883501293568, 11333767002587136, 22667534005174272, 45053588738670592, 18049583422636032, 145241105196122112, 362539804446949376, 725361088165576704, 1450722176331153408, 2901444352662306816, 5802888705324613632, 11533718717099671552, 4620693356194824192, 288234782788157440, 576469569871282176, 1224997833292120064, 2449995666584240128, 4899991333168480256, 9799982666336960512, 1152939783987658752, 2305878468463689728, 1128098930098176, 2257297371824128, 4796069720358912, 9592139440717824, 19184278881435648, 38368557762871296, 4679521487814656, 9077567998918656];

#[rustfmt::skip]
pub const CACHE_QUIET_PAWN: [[u64; 64]; 2] = [[256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728, 268435456, 536870912, 1073741824, 2147483648, 4294967296, 8589934592, 17179869184, 34359738368, 68719476736, 137438953472, 274877906944, 549755813888, 1099511627776, 2199023255552, 4398046511104, 8796093022208, 17592186044416, 35184372088832, 70368744177664, 140737488355328, 281474976710656, 562949953421312, 1125899906842624, 2251799813685248, 4503599627370496, 9007199254740992, 18014398509481984, 36028797018963968, 72057594037927936, 144115188075855872, 288230376151711744, 576460752303423488, 1152921504606846976, 2305843009213693952, 4611686018427387904, 9223372036854775808, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, 32768, 65536, 131072, 262144, 524288, 1048576, 2097152, 4194304, 8388608, 16777216, 33554432, 67108864, 134217728, 268435456, 536870912, 1073741824, 2147483648, 4294967296, 8589934592, 17179869184, 34359738368, 68719476736, 137438953472, 274877906944, 549755813888, 1099511627776, 2199023255552, 4398046511104, 8796093022208, 17592186044416, 35184372088832, 70368744177664, 140737488355328, 281474976710656, 562949953421312, 1125899906842624, 2251799813685248, 4503599627370496, 9007199254740992, 18014398509481984, 36028797018963968]];

#[rustfmt::skip]
pub const CACHE_CAPTURE_PAWN: [[u64; 64]; 2] = [[512, 1280, 2560, 5120, 10240, 20480, 40960, 16384, 131072, 327680, 655360, 1310720, 2621440, 5242880, 10485760, 4194304, 33554432, 83886080, 167772160, 335544320, 671088640, 1342177280, 2684354560, 1073741824, 8589934592, 21474836480, 42949672960, 85899345920, 171798691840, 343597383680, 687194767360, 274877906944, 2199023255552, 5497558138880, 10995116277760, 21990232555520, 43980465111040, 87960930222080, 175921860444160, 70368744177664, 562949953421312, 1407374883553280, 2814749767106560, 5629499534213120, 11258999068426240, 22517998136852480, 45035996273704960, 18014398509481984, 144115188075855872, 360287970189639680, 720575940379279360, 1441151880758558720, 2882303761517117440, 5764607523034234880, 11529215046068469760, 4611686018427387904, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 2, 5, 10, 20, 40, 80, 160, 64, 512, 1280, 2560, 5120, 10240, 20480, 40960, 16384, 131072, 327680, 655360, 1310720, 2621440, 5242880, 10485760, 4194304, 33554432, 83886080, 167772160, 335544320, 671088640, 1342177280, 2684354560, 1073741824, 8589934592, 21474836480, 42949672960, 85899345920, 171798691840, 343597383680, 687194767360, 274877906944, 2199023255552, 5497558138880, 10995116277760, 21990232555520, 43980465111040, 87960930222080, 175921860444160, 70368744177664, 562949953421312, 1407374883553280, 2814749767106560, 5629499534213120, 11258999068426240, 22517998136852480, 45035996273704960, 18014398509481984]];

#[rustfmt::skip]
pub const CACHE_DOUBLE_PUSH_PAWN: [[u64; 64]; 2] = [[0, 0, 0, 0, 0, 0, 0, 0, 16777216, 33554432, 67108864, 134217728, 268435456, 536870912, 1073741824, 2147483648, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4294967296, 8589934592, 17179869184, 34359738368, 68719476736, 137438953472, 274877906944, 549755813888, 0, 0, 0, 0, 0, 0, 0, 0]];

#[rustfmt::skip]
pub const CACHE_ROOK_PEXT_MASK: [u64; 64] = [282578800148862, 565157600297596, 1130315200595066, 2260630401190006, 4521260802379886, 9042521604759646, 18085043209519166, 36170086419038334, 282578800180736, 565157600328704, 1130315200625152, 2260630401218048, 4521260802403840, 9042521604775424, 18085043209518592, 36170086419037696, 282578808340736, 565157608292864, 1130315208328192, 2260630408398848, 4521260808540160, 9042521608822784, 18085043209388032, 36170086418907136, 282580897300736, 565159647117824, 1130317180306432, 2260632246683648, 4521262379438080, 9042522644946944, 18085043175964672, 36170086385483776, 283115671060736, 565681586307584, 1130822006735872, 2261102847592448, 4521664529305600, 9042787892731904, 18085034619584512, 36170077829103616, 420017753620736, 699298018886144, 1260057572672512, 2381576680245248, 4624614895390720, 9110691325681664, 18082844186263552, 36167887395782656, 35466950888980736, 34905104758997504, 34344362452452352, 33222877839362048, 30979908613181440, 26493970160820224, 17522093256097792, 35607136465616896, 9079539427579068672, 8935706818303361536, 8792156787827803136, 8505056726876686336, 7930856604974452736, 6782456361169985536, 4485655873561051136, 9115426935197958144];

Expand Down
233 changes: 142 additions & 91 deletions src/backend/movegen/move_gen_pawn_util.rs
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Original file line number Diff line number Diff line change
@@ -1,123 +1,174 @@
use crate::backend::compile_time::gen_caches::{
PAWN_CAPTURE_MOVES, PAWN_DOUBLE_PUSH_MOVES, PAWN_QUIET_MOVES,
};
use crate::backend::movegen::moove::Moove;
use crate::backend::movegen::move_gen::iterate_over_bitboard_for_non_slider;
use crate::backend::state::board::bb_manager::BBManager;
use crate::backend::state::board::bitboard::BitBoard;
use crate::backend::state::game::state::State;
use crate::backend::state::piece::Piece::{Pawn, Queen};
use crate::backend::state::piece::Piece::Pawn;
use crate::backend::state::piece::{PROMOTABLE_PIECES, Side};
use crate::backend::state::square::Square;

const BLACK_PROMOTION_RANK_BB: BitBoard = BitBoard::new_from_rank(0);
const WHITE_PROMOTION_RANK_BB: BitBoard = BitBoard::new_from_rank(7);
const WHITE_PAWN_START_RANK_BB: BitBoard = BitBoard::new_from_rank(1);
const BLACK_PAWN_START_RANK_BB: BitBoard = BitBoard::new_from_rank(6);
const PROMOTION_RANKS_BB: BitBoard = BitBoard {
value: (BLACK_PROMOTION_RANK_BB.value | WHITE_PROMOTION_RANK_BB.value),
};
const LEFT_SIDE_BB: BitBoard = BitBoard::new_from_file(0);
const RIGHT_SIDE_BB: BitBoard = BitBoard::new_from_file(7);

pub fn gen_pawn_moves(
moves: &mut Vec<Moove>,
game_state: &State,
state: &State,
friendly_pieces_bb: BitBoard,
enemy_pieces_bb: BitBoard,
active_color: Side,
) {
let mut pawn_moves = Vec::new();
// Quiet pawn moves
iterate_over_bitboard_for_non_slider(
&mut pawn_moves,
PAWN_QUIET_MOVES[active_color as usize],
game_state
.bb_manager
.get_colored_piece_bb(Pawn, active_color),
friendly_pieces_bb | enemy_pieces_bb,
);
let occupancy_bb = friendly_pieces_bb | enemy_pieces_bb;
let pawn_bb = state.bb_manager.get_colored_piece_bb(Pawn, active_color);

let rank_offset = match active_color {
Side::White => -1,
Side::Black => 1,
};

// Capture pawn moves
iterate_over_bitboard_for_non_slider(
&mut pawn_moves,
PAWN_CAPTURE_MOVES[active_color as usize],
game_state
.bb_manager
.get_colored_piece_bb(Pawn, active_color),
create_pawn_capture_mask(game_state, enemy_pieces_bb),
// single push
single_push(moves, active_color, occupancy_bb, pawn_bb, rank_offset);

// double push
double_push(moves, active_color, occupancy_bb, pawn_bb, rank_offset);

let mut possible_captures_bb = enemy_pieces_bb;
match state.irreversible_data.en_passant_square {
None => {}
Some(square) => {
possible_captures_bb.fill_square(square);
}
}
// left captures
let shift = match active_color {
Side::White => 7,
Side::Black => -9,
};
one_dir_capture(
moves,
possible_captures_bb,
pawn_bb,
rank_offset,
shift,
LEFT_SIDE_BB,
1,
);
promotion_logic(&mut pawn_moves);
moves.append(&mut pawn_moves);

// Double pawn push moves
let mut pawn_moves = get_double_pawn_push_moves(
&game_state.bb_manager,
active_color,
friendly_pieces_bb | enemy_pieces_bb,

// right captures
let shift = match active_color {
Side::White => 9,
Side::Black => -7,
};
one_dir_capture(
moves,
possible_captures_bb,
pawn_bb,
rank_offset,
shift,
RIGHT_SIDE_BB,
-1,
);
moves.append(&mut pawn_moves);
}
pub fn get_double_pawn_push_moves(
bitboard_manager: &BBManager,
active_color: Side,
all_pieces_bb: BitBoard,
) -> Vec<Moove> {
let mut moves: Vec<Moove> = Vec::new();

let mut pawn_bitboard = bitboard_manager.get_colored_piece_bb(Pawn, active_color);

let starting_bitboard = match active_color {
Side::White => BitBoard::new_from_rank(1),
Side::Black => BitBoard::new_from_rank(6),
fn single_push(
moves: &mut Vec<Moove>,
active_color: Side,
occupancy_bb: BitBoard,
pawn_bb: BitBoard,
rank_offset: i8,
) {
let mut push_pawn_bb = match active_color {
Side::White => pawn_bb << 8,
Side::Black => pawn_bb >> 8,
};
// cant go there if something is there
push_pawn_bb &= !occupancy_bb;

pawn_bitboard &= starting_bitboard;
let no_promotion_push_pawn_bb = push_pawn_bb & !PROMOTION_RANKS_BB;
pawn_bb_to_moves_no_promotion(moves, no_promotion_push_pawn_bb, 0, rank_offset);

for square in pawn_bitboard {
let mut single_push_bb = PAWN_QUIET_MOVES[active_color as usize][square.square_to_index()];
single_push_bb &= all_pieces_bb;
if !single_push_bb.is_empty() {
continue;
}
let promotion_push_pawn_bb = push_pawn_bb & PROMOTION_RANKS_BB;
pawn_bb_to_moves_promotion(moves, promotion_push_pawn_bb, 0, rank_offset);
}

let mut double_push_bb =
PAWN_DOUBLE_PUSH_MOVES[active_color as usize][square.square_to_index()];
double_push_bb &= all_pieces_bb;
if !double_push_bb.is_empty() {
continue;
fn double_push(
moves: &mut Vec<Moove>,
active_color: Side,
occupancy_bb: BitBoard,
pawn_bb: BitBoard,
rank_offset: i8,
) {
let double_push_bb = match active_color {
Side::White => {
(((pawn_bb & WHITE_PAWN_START_RANK_BB) << 8) & !occupancy_bb) << 8 & !occupancy_bb
}
Side::Black => {
(((pawn_bb & BLACK_PAWN_START_RANK_BB) >> 8) & !occupancy_bb) >> 8 & !occupancy_bb
}
};
pawn_bb_to_moves_no_promotion(moves, double_push_bb, 0, 2 * rank_offset);
}

let moove = Moove::new(
square,
square
.forward_by_one(active_color)
.forward_by_one(active_color),
);
moves.push(moove);
fn one_dir_capture(
moves: &mut Vec<Moove>,
enemy_pieces_bb: BitBoard,
mut pawn_bb: BitBoard,
rank_offset: i8,
shift: i32,
mask: BitBoard,
file_offset: i8,
) {
pawn_bb &= !mask;

if shift.is_negative() {
pawn_bb >>= shift.unsigned_abs();
} else {
pawn_bb <<= shift;
}
let capture_bb = pawn_bb & enemy_pieces_bb;

let capture_no_promotion = capture_bb & !PROMOTION_RANKS_BB;
pawn_bb_to_moves_no_promotion(moves, capture_no_promotion, file_offset, rank_offset);

moves
let captures_promotion = capture_bb & PROMOTION_RANKS_BB;
pawn_bb_to_moves_promotion(moves, captures_promotion, file_offset, rank_offset);
}

pub fn create_pawn_capture_mask(game_state: &State, enemy_pieces_bitboard: BitBoard) -> BitBoard {
// Capture pawn moves
let mut pawn_capture_mask = enemy_pieces_bitboard;
match game_state.irreversible_data.en_passant_square {
None => {}
Some(ep_square) => {
pawn_capture_mask.fill_square(ep_square);
}
fn pawn_bb_to_moves_no_promotion(
moves: &mut Vec<Moove>,
pawn_bb: BitBoard,
file_offset: i8,
rank_offset: i8,
) {
for square in pawn_bb {
let from_square = Square {
file: square.file + file_offset,
rank: square.rank + rank_offset,
};
let moove = Moove::new(from_square, square);
moves.push(moove);
}
pawn_capture_mask = !pawn_capture_mask;
pawn_capture_mask
}

pub fn promotion_logic(moves: &mut Vec<Moove>) {
if moves.is_empty() {
return;
}
for index in (0..moves.len()).rev() {
let moove = moves[index];
if moove.to.is_on_promotion_rank() {
for piece_type in PROMOTABLE_PIECES {
if piece_type == Queen {
moves[index].promotion_type = Some(Queen);
continue;
}
let mut moove = moove;
moove.promotion_type = Some(piece_type);
moves.push(moove);
}
fn pawn_bb_to_moves_promotion(
moves: &mut Vec<Moove>,
pawn_bb: BitBoard,
file_offset: i8,
rank_offset: i8,
) {
for square in pawn_bb {
let from_square = Square {
file: square.file + file_offset,
rank: square.rank + rank_offset,
};
for piece_type in PROMOTABLE_PIECES {
let mut moove = Moove::new(from_square, square);
moove.promotion_type = Some(piece_type);
moves.push(moove);
}
}
}
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