feat: add grain of 1cp to the score

2 files changed, 27 insertions, 22 deletions

diff --git a/src/grossmeister/evaluation.rs b/src/grossmeister/evaluation.rs
index 6fc4149..1b57f5a 100644
--- a/src/grossmeister/evaluation.rs
+++ b/src/grossmeister/evaluation.rs
@@ -4,7 +4,10 @@ use crate::{board::{piece::Piece, color::Color, CastlingSide}, bitboard::{Bitboa
 
 use super::Grossmeister;
 
-const PAWN_BONUS: [f32; 64] = [
+/// Score in pawns (not centipawns)
+pub type Score = f32;
+
+const PAWN_BONUS: [Score; 64] = [
   //  A      B      C      D      E      F      G      H
      0.00,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00,
      0.50,  0.50,  0.50,  0.50,  0.50,  0.50,  0.50,  0.50,
@@ -16,7 +19,7 @@ const PAWN_BONUS: [f32; 64] = [
      0.00,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00
 ];
 
-const PAWN_BONUS_PASSER_ENDGAME: [f32; 64] = [
+const PAWN_BONUS_PASSER_ENDGAME: [Score; 64] = [
   //  A      B      C      D      E      F      G      H
      0.00,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00,
      2.00,  2.00,  2.00,  2.00,  2.00,  2.00,  2.00,  2.00,
@@ -28,7 +31,7 @@ const PAWN_BONUS_PASSER_ENDGAME: [f32; 64] = [
      0.00,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00,
 ];
 
-const KNIGHT_BONUS: [f32; 64] = [
+const KNIGHT_BONUS: [Score; 64] = [
   //  A      B      C      D      E      F      G      H
     -0.50, -0.40, -0.30, -0.30, -0.30, -0.30, -0.40, -0.50,
     -0.40, -0.20,  0.00,  0.00,  0.00,  0.00, -0.20, -0.40,
@@ -40,7 +43,7 @@ const KNIGHT_BONUS: [f32; 64] = [
     -0.50, -0.40, -0.30, -0.30, -0.30, -0.30, -0.40, -0.50,
 ];
 
-const BISHOP_BONUS: [f32; 64] = [
+const BISHOP_BONUS: [Score; 64] = [
   //  A      B      C      D      E      F      G      H
     -0.20, -0.10, -0.10, -0.10, -0.10, -0.10, -0.10, -0.20,
     -0.10,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00, -0.10,
@@ -52,7 +55,7 @@ const BISHOP_BONUS: [f32; 64] = [
     -0.20, -0.10, -0.10, -0.10, -0.10, -0.10, -0.10, -0.20,
 ];
 
-const ROOK_BONUS: [f32; 64] = [
+const ROOK_BONUS: [Score; 64] = [
   //  A      B      C      D      E      F      G      H
      0.00,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00,
      0.05,  0.30,  0.30,  0.30,  0.30,  0.30,  0.30,  0.05,
@@ -64,7 +67,7 @@ const ROOK_BONUS: [f32; 64] = [
      0.00,  0.00,  0.00,  0.05,  0.05,  0.00,  0.00,  0.00
 ];
 
-const QUEEN_BONUS: [f32; 64] = [
+const QUEEN_BONUS: [Score; 64] = [
   //  A      B      C      D      E      F      G      H
     -0.20, -0.10, -0.10, -0.05, -0.05, -0.10, -0.10, -0.20,
     -0.10,  0.00,  0.00,  0.00,  0.00,  0.00,  0.00, -0.10,
@@ -76,7 +79,7 @@ const QUEEN_BONUS: [f32; 64] = [
     -0.20, -0.10, -0.10, -0.05, -0.05, -0.10, -0.10, -0.20
 ];
 
-const KING_BONUS: [f32; 64] = [
+const KING_BONUS: [Score; 64] = [
   //  A      B      C      D      E      F      G      H
     -0.30, -0.40, -0.40, -0.50, -0.50, -0.40, -0.40, -0.30,
     -0.30, -0.40, -0.40, -0.50, -0.50, -0.40, -0.40, -0.30,
@@ -88,7 +91,7 @@ const KING_BONUS: [f32; 64] = [
      0.20,  0.10,  0.30, -0.20,  0.00,  0.10,  0.30,  0.20
 ];
 
-const KING_BONUS_ENGAME: [f32; 64] = [
+const KING_BONUS_ENGAME: [Score; 64] = [
   //  A      B      C      D      E      F      G      H
     -0.50, -0.40, -0.30, -0.20, -0.20, -0.30, -0.40, -0.50,
     -0.30, -0.20, -0.10,  0.00,  0.00, -0.10, -0.20, -0.30,
@@ -209,7 +212,7 @@ impl Grossmeister {
 
 
     /// Evaluate a position relative to the current player
-    pub fn evaluate(&self) -> f32 {
+    pub fn evaluate(&self) -> Score {
         let color = self.board.color();
         let opponent_color = color.flip();
 
@@ -243,9 +246,11 @@ impl Grossmeister {
         let phase = self.phase();
         let tapered_eval = (middlegame_eval * phase as f32 + endgame_eval * (240 - phase) as f32) / 240.;
 
-        (material_advantage + tapered_eval)
+        let eval = (material_advantage + tapered_eval)
             .min(if winnable { INFINITY } else { 0.0 }) // Can not score > 0 if not winnable
-            .max(if loseable { -INFINITY } else { 0.0 }) // Can not score < 0 if not loseable
+            .max(if loseable { -INFINITY } else { 0.0 }); // Can not score < 0 if not loseable
+
+        (eval * 100.0).round() / 100.0
     }
 
     /// Count pseudo-legal moves without actually generating them
diff --git a/src/grossmeister/search.rs b/src/grossmeister/search.rs
index d3dc0b4..455fb6f 100644
--- a/src/grossmeister/search.rs
+++ b/src/grossmeister/search.rs
@@ -2,9 +2,9 @@ use std::f32::INFINITY;
 
 use crate::{moves::{Move, MoveKind}, board::io::IO};
 
-use super::{Grossmeister, ttable::{NodeType, TTABLE_SIZE, TranspositionTableItem}};
+use super::{Grossmeister, ttable::{NodeType, TTABLE_SIZE, TranspositionTableItem}, evaluation::Score};
 
-const SCORE_MATE: f32 = 20_000.0;
+const SCORE_MATE: Score = 20_000.0;
 
 #[derive(Debug, Default, PartialEq)]
 pub struct PerftResult {
@@ -18,9 +18,9 @@ pub struct PerftResult {
 impl Grossmeister {
     // Mate distance pruning
     // If a non-zero value (mating score) is returned, branch could be safely pruned
-    pub fn MDP(alpha: &mut f32, beta: &mut f32, root_distance: u8) -> f32 {
+    pub fn MDP(alpha: &mut Score, beta: &mut Score, root_distance: u8) -> Score {
         { // Update bound in case we are winning
-            let mating_score = SCORE_MATE - root_distance as f32;
+            let mating_score = SCORE_MATE - root_distance as Score;
             if mating_score < *beta {
                 *beta = mating_score;
                 if *alpha >= mating_score {
@@ -29,7 +29,7 @@ impl Grossmeister {
             }
         }
         { // Update bound in case we are losing
-            let mating_score = -SCORE_MATE + root_distance as f32;
+            let mating_score = -SCORE_MATE + root_distance as Score;
             if mating_score > *alpha {
                 *alpha = mating_score;
                 if *beta <= mating_score {
@@ -40,7 +40,7 @@ impl Grossmeister {
         0.0
     }
 
-    pub fn negamax_search(&mut self, mut alpha: f32, mut beta: f32, depth_left: u8, root_distance: u8) -> (f32, Vec<Move>) {
+    pub fn negamax_search(&mut self, mut alpha: Score, mut beta: Score, depth_left: u8, root_distance: u8) -> (Score, Vec<Move>) {
         let mut principal_variation = Vec::new();
         let color = self.board.color();
 
@@ -163,7 +163,7 @@ impl Grossmeister {
 
         if !legal_move_found {
             if self.board.is_king_in_check(color) {
-                return (-SCORE_MATE + root_distance as f32, principal_variation);
+                return (-SCORE_MATE + root_distance as Score, principal_variation);
             } else {
                 return (0.0, principal_variation);
             }
@@ -172,7 +172,7 @@ impl Grossmeister {
         (alpha, principal_variation)
     }
 
-    pub fn quiscence(&mut self, mut alpha: f32, mut beta: f32, root_distance: u8) -> f32 {
+    pub fn quiscence(&mut self, mut alpha: Score, mut beta: Score, root_distance: u8) -> Score {
         let color = self.board.color();
 
         if self.board.threefold_repetition() {
@@ -227,13 +227,13 @@ impl Grossmeister {
         }
 
         if !legal_move_found && self.board.is_king_in_check(color) {
-            return -SCORE_MATE + root_distance as f32
+            return -SCORE_MATE + root_distance as Score
         }
 
         alpha
     }
 
-    pub fn iterative_deepening(&mut self, max_depth: u8) -> Option<(f32, Vec<Move>)> {
+    pub fn iterative_deepening(&mut self, max_depth: u8) -> Option<(Score, Vec<Move>)> {
         let mut result = None;
         let mut depth = 1;
         let mut alpha = -INFINITY;
@@ -291,7 +291,7 @@ impl Grossmeister {
             println!();
 
             // If our score is mate in N, we break at depth N
-            if depth as f32 >= SCORE_MATE - search_result.0.abs() {
+            if depth as Score >= SCORE_MATE - search_result.0.abs() {
                 result = Some(search_result);
                 break;
             }