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Replace repetitive math operations with functions #913

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Replace repetitive math operations with functions #913

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de4b061
init
Saphereye Apr 19, 2026
50cea24
remove quad
Saphereye Apr 19, 2026
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70 changes: 42 additions & 28 deletions src/search.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -525,10 +525,11 @@ fn search<NODE: NodeType>(
&& !excluded
&& estimated_score
>= beta
+ (1165 * depth * depth / 128 - (80 * improving as i32)
+ (1165 * depth * depth / 128
+ penalty_if(improving, 80)
+ 25 * depth
+ 560 * correction_value.abs() / 1024
- 59 * (td.board.all_threats() & td.board.colors(stm)).is_empty() as i32
+ scale(correction_value.abs(), 560)
+ penalty_if((td.board.all_threats() & td.board.colors(stm)).is_empty(), 59)
+ 30)
.max(0)
&& !is_loss(beta)
Expand All @@ -544,9 +545,10 @@ fn search<NODE: NodeType>(
&& !potential_singularity
&& estimated_score
>= beta
+ (-8 * depth + 116 * tt_pv as i32
- 106 * improvement / 1024
- 20 * (td.stack[ply + 1].cutoff_count < 2) as i32
+ (-8 * depth
+ bonus_if(tt_pv, 116)
+ scale(improvement, -106)
+ penalty_if(td.stack[ply + 1].cutoff_count < 2, 20)
+ 304)
.max(0)
&& ply as i32 >= td.nmp_min_ply
Expand Down Expand Up @@ -734,14 +736,14 @@ fn search<NODE: NodeType>(
if !in_check
&& !td.board.is_direct_check(mv)
&& is_quiet
&& move_count >= (3006 + 70 * improvement / 16 + 1455 * depth * depth + 68 * history / 1024) / 1024
&& move_count >= (3006 + 70 * improvement / 16 + 1455 * depth * depth + scale(history, 68)) / 1024
{
skip_quiets = true;
continue;
}

// Futility Pruning (FP)
let futility_value = eval + 79 * depth + 64 * history / 1024 + 84 * (eval >= beta) as i32 - 115;
let futility_value = eval + 79 * depth - 115 + scale(history, 64) + bonus_if(eval >= beta, 84);

if !in_check && is_quiet && depth < 15 && futility_value <= alpha && !td.board.is_direct_check(mv) {
if !is_decisive(best_score) && best_score < futility_value {
Expand All @@ -752,7 +754,7 @@ fn search<NODE: NodeType>(
}

// Bad Noisy Futility Pruning (BNFP)
let noisy_futility_value = eval + 71 * depth + 68 * history / 1024 + 23;
let noisy_futility_value = eval + 71 * depth + 23 + scale(history, 68);

if !in_check
&& depth < 11
Expand All @@ -768,9 +770,9 @@ fn search<NODE: NodeType>(

// Static Exchange Evaluation Pruning (SEE Pruning)
let threshold = if is_quiet {
(-17 * depth * depth + 52 * depth - 21 * history / 1024 + 20).min(0)
(-17 * depth * depth + 52 * depth + 20 + scale(history, -21)).min(0)
} else {
(-8 * depth * depth - 36 * depth - 32 * history / 1024 + 11).min(0)
(-8 * depth * depth - 36 * depth + 11 + scale(history, -32)).min(0)
};

if !td.board.see(mv, threshold) {
Expand All @@ -790,18 +792,18 @@ fn search<NODE: NodeType>(
let mut reduction = 225 * (move_count.ilog2() * depth.ilog2()) as i32;

reduction -= 68 * move_count;
reduction -= 3297 * correction_value.abs() / 1024;
reduction -= scale(correction_value.abs(), 3297);
reduction += 1306 * alpha_raises;

reduction += 546 * (is_valid(tt_score) && tt_score <= alpha) as i32;
reduction += 322 * (is_valid(tt_score) && tt_depth < depth) as i32;

if is_quiet {
reduction += 1806;
reduction -= 166 * history / 1024;
reduction -= scale(history, 166);
} else {
reduction += 1449;
reduction -= 109 * history / 1024;
reduction -= scale(history, 109);
}

if NODE::PV {
Expand All @@ -810,13 +812,13 @@ fn search<NODE: NodeType>(

if tt_pv {
reduction -= 361;
reduction -= 636 * (is_valid(tt_score) && tt_score > alpha) as i32;
reduction -= 830 * (is_valid(tt_score) && tt_depth >= depth) as i32;
reduction += penalty_if(is_valid(tt_score) && tt_score > alpha, 636);
reduction += penalty_if(is_valid(tt_score) && tt_depth >= depth, 830);
}

if !tt_pv && cut_node {
reduction += 1818;
reduction += 2118 * tt_move.is_null() as i32;
reduction += bonus_if(tt_move.is_null(), 2118);
}

if !improving {
Expand All @@ -840,8 +842,8 @@ fn search<NODE: NodeType>(
reduction += 129;
}

let reduced_depth =
(new_depth - reduction / 1024).clamp(1, new_depth + (move_count <= 3) as i32 + 1) + 2 * NODE::PV as i32;
let reduced_depth = (new_depth - reduction / 1024).clamp(1, new_depth + bonus_if(move_count <= 3, 1) + 1)
+ bonus_if(NODE::PV, 2);

td.stack[ply].reduction = reduction;
score = -search::<NonPV>(td, -alpha - 1, -alpha, reduced_depth, true, ply + 1);
Expand All @@ -866,24 +868,24 @@ fn search<NODE: NodeType>(
let mut reduction = 232 * (move_count.ilog2() * depth.ilog2()) as i32;

reduction -= 48 * move_count;
reduction -= 2408 * correction_value.abs() / 1024;
reduction -= scale(correction_value.abs(), 2408);

if is_quiet {
reduction += 1429;
reduction -= 152 * history / 1024;
reduction -= scale(history, 152);
} else {
reduction += 1053;
reduction -= 67 * history / 1024;
reduction -= scale(history, 67);
}

if tt_pv {
reduction -= 936;
reduction -= 1080 * (is_valid(tt_score) && tt_depth >= depth) as i32;
reduction += penalty_if(is_valid(tt_score) && tt_depth >= depth, 1080);
}

if !tt_pv && cut_node {
reduction += 1543;
reduction += 2058 * tt_move.is_null() as i32;
reduction += bonus_if(tt_move.is_null(), 2058);
}

if !improving {
Expand Down Expand Up @@ -1062,10 +1064,10 @@ fn search<NODE: NodeType>(
let prior_move = td.stack[ply - 1].mv;
if prior_move.is_quiet() {
let factor = 116
+ 202 * (td.stack[ply - 1].move_count > 7) as i32
+ 116 * (prior_move == td.stack[ply - 1].tt_move) as i32
+ 138 * (!in_check && best_score <= eval - 93) as i32
+ 321 * (is_valid(td.stack[ply - 1].eval) && best_score <= -td.stack[ply - 1].eval - 128) as i32;
+ bonus_if(td.stack[ply - 1].move_count > 7, 202)
+ bonus_if(prior_move == td.stack[ply - 1].tt_move, 116)
+ bonus_if(!in_check && best_score <= eval - 93, 138)
+ bonus_if(is_valid(td.stack[ply - 1].eval) && best_score <= -td.stack[ply - 1].eval - 128, 321);

let scaled_bonus = factor * (165 * depth - 35).min(2467) / 128;

Expand Down Expand Up @@ -1314,6 +1316,18 @@ fn qsearch<NODE: NodeType>(td: &mut ThreadData, mut alpha: i32, beta: i32, ply:
best_score
}

const fn scale(value: i32, scale: i32) -> i32 {
value * scale / 1024
}

const fn bonus_if(cond: bool, bonus: i32) -> i32 {
if cond { bonus } else { 0 }
}

const fn penalty_if(cond: bool, penalty: i32) -> i32 {
if cond { -penalty } else { 0 }
}

fn eval_correction(td: &ThreadData, ply: isize) -> i32 {
let stm = td.board.side_to_move();
let corrhist = td.corrhist();
Expand Down