Reduce size of eval to i16

src/search/negamax.rs

@@ -14,14 +14,14 @@ use super::{
 
 pub fn negamax(
     game: &mut Game,
-    mut alpha: i32,
-    beta: i32,
+    mut alpha: i16,
+    beta: i16,
     mut depth: u8,
     plies: u8,
     time: &TimeInfo,
     nodes: &mut u64,
     do_nmp: bool,
-) -> Result<i32> {
+) -> Result<i16> {
     if time.exceed_hard_limit() {
         bail!("Hard limit exceeded in negamax");
     }
@@ -137,7 +137,7 @@ pub fn negamax(
 
     if legal_moves == 0 {
         if in_check {
-            return Ok(-MATE_SCORE + plies as i32);
+            return Ok(-MATE_SCORE + plies as i16);
         }
         return Ok(0);
     }