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integrated material eval into psqt

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Moritz 2025-11-18 20:14:47 +01:00
parent 7b84e8a0ab
commit b69323665c
4 changed files with 127 additions and 120 deletions
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109
src/eval/basic.rs
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@ -1,74 +1,67 @@
use crate::board::*;
use crate::eval::piece_square_tables::PSQT;
// Pawn, Knight, Bishop, Rook, Queen
pub const MATERIAL_WEIGHTS: [i32; 5] = [100, 300, 300, 500, 900];
pub const PHASE_WEIGHTS: [i32; 5] = [0, 1, 1, 2, 4];
pub fn evaluate_board(board: &Board) -> i32 {
let mut mg_score = 0_i32;
let mut eg_score = 0_i32;
let mut phase = 0_i32;
// --- WHITE PIECES ---
// Iterating Pawn (0) to Queen (4) for Material + Phase + PSQT
for pt in 0..5 {
let mut pieces = board.pieces[pt][Color::White as usize];
let count = pieces.count_ones() as i32;
mg_score += count * MATERIAL_WEIGHTS[pt];
eg_score += count * MATERIAL_WEIGHTS[pt];
phase += count * PHASE_WEIGHTS[pt];
// We use a macro to force loop unrolling.
// This enables the compiler to use constant offsets for PSQT access
// instead of calculating addresses at runtime based on a loop variable.
macro_rules! score_piece {
($pt:expr, $phase_weight:expr) => {
// --- WHITE ---
let mut pieces = board.pieces[$pt][Color::White as usize];
if pieces > 0 {
// Phase calculation uses count_ones (POPPCNT) which is very fast
phase += (pieces.count_ones() as i32) * $phase_weight;
while pieces > 0 {
let sq = pieces.trailing_zeros() as usize;
pieces &= pieces - 1; // Clear LS1B
// Access: [Piece][Color][Phase (0=MG, 1=EG)][Square]
mg_score += PSQT[pt][Color::White as usize][0][sq];
eg_score += PSQT[pt][Color::White as usize][1][sq];
}
while pieces > 0 {
let sq = pieces.trailing_zeros() as usize;
pieces &= pieces - 1; // Clear LS1B
// Material is already baked into PSQT, so we just add the table value
// Since $pt is a const literal here, this compiles to a direct memory access
mg_score += PSQT[$pt][Color::White as usize][0][sq];
eg_score += PSQT[$pt][Color::White as usize][1][sq];
}
}
// --- BLACK ---
let mut pieces = board.pieces[$pt][Color::Black as usize];
if pieces > 0 {
phase += (pieces.count_ones() as i32) * $phase_weight;
while pieces > 0 {
let sq = pieces.trailing_zeros() as usize;
pieces &= pieces - 1;
mg_score -= PSQT[$pt][Color::Black as usize][0][sq];
eg_score -= PSQT[$pt][Color::Black as usize][1][sq];
}
}
};
}
// King (Index 5) - No Material/Phase weight, only PSQT
let mut white_king = board.pieces[5][Color::White as usize];
if white_king > 0 {
let sq = white_king.trailing_zeros() as usize;
mg_score += PSQT[5][Color::White as usize][0][sq];
eg_score += PSQT[5][Color::White as usize][1][sq];
}
// Explicitly unrolled execution order
// Pawn (0), Weight 0
score_piece!(0, 0);
// Knight (1), Weight 1
score_piece!(1, 1);
// Bishop (2), Weight 1
score_piece!(2, 1);
// Rook (3), Weight 2
score_piece!(3, 2);
// Queen (4), Weight 4
score_piece!(4, 4);
// King (5), Weight 0 (Phase doesn't change)
score_piece!(5, 0);
// --- BLACK PIECES ---
// Iterating Pawn (0) to Queen (4)
for pt in 0..5 {
let mut pieces = board.pieces[pt][Color::Black as usize];
let count = pieces.count_ones() as i32;
mg_score -= count * MATERIAL_WEIGHTS[pt];
eg_score -= count * MATERIAL_WEIGHTS[pt];
phase += count * PHASE_WEIGHTS[pt];
while pieces > 0 {
let sq = pieces.trailing_zeros() as usize;
pieces &= pieces - 1;
mg_score -= PSQT[pt][Color::Black as usize][0][sq];
eg_score -= PSQT[pt][Color::Black as usize][1][sq];
}
}
// King (Index 5) for Black
let mut black_king = board.pieces[5][Color::Black as usize];
if black_king > 0 {
let sq = black_king.trailing_zeros() as usize;
mg_score -= PSQT[5][Color::Black as usize][0][sq];
eg_score -= PSQT[5][Color::Black as usize][1][sq];
}
// Tapered Evaluation Interpolation
let phase = phase.min(24); // Clamp to 24 max
// Tapered Evaluation
let phase = phase.min(24);
let mg_phase = phase;
let eg_phase = 24 - phase;
((mg_score * mg_phase) + (eg_score * eg_phase)) / 24
}
}