From f51c940b3f542af889e39ea1e64efeececc4aa98 Mon Sep 17 00:00:00 2001
From: Simon Gardling <titaniumtown@proton.me>
Date: Thu, 20 Mar 2025 01:12:27 -0400
Subject: [PATCH] improve PosMap

---
 Cargo.lock               |  7 +++++++
 Cargo.toml               |  1 +
 src/logic/board_value.rs |  8 +++++++-
 src/logic/move.rs        |  2 +-
 src/repr/board.rs        | 44 +++++++++++++++++-----------------------
 5 files changed, 35 insertions(+), 27 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index fbd6c34..0010c38 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -145,6 +145,12 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "const_for"
+version = "0.1.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d9c50fcfdf972929aff202c16b80086aa3cfc6a3a820af714096c58c7c1d0582"
+
 [[package]]
 name = "criterion"
 version = "0.5.1"
@@ -443,6 +449,7 @@ dependencies = [
  "allocative",
  "arrayvec",
  "console",
+ "const_for",
  "criterion",
  "crossbeam-channel",
  "either",
diff --git a/Cargo.toml b/Cargo.toml
index 28d2a98..6e2f99a 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -25,6 +25,7 @@ debug = true
 allocative = "0.3"
 arrayvec = "0.7"
 console = "0.15"
+const_for = "0.1"
 crossbeam-channel = "0.5"
 either = "1.13"
 indicatif = { version = "0.17", features = [ "rayon" ] }
diff --git a/src/logic/board_value.rs b/src/logic/board_value.rs
index 4c97690..a9d36eb 100644
--- a/src/logic/board_value.rs
+++ b/src/logic/board_value.rs
@@ -19,7 +19,7 @@ impl BoardValueMap {
     }
 
     /// Weights from: https://repub.eur.nl/pub/7142/ei2005-47.pdf
-    pub fn new() -> Self {
+    pub const fn weighted() -> Self {
         const POSITION_VALUES: [[i16; 8]; 8] = [
             [100, -20, 10, 5, 5, 10, -20, 100],
             [-20, -50, -2, -2, -2, -2, -50, -20],
@@ -32,4 +32,10 @@ impl BoardValueMap {
         ];
         Self(PosMap::from(POSITION_VALUES))
     }
+
+    pub const fn flat() -> Self {
+        Self(PosMap::from(
+            [[1; Board::SIZE as usize]; Board::SIZE as usize],
+        ))
+    }
 }
diff --git a/src/logic/move.rs b/src/logic/move.rs
index b390825..56645ab 100644
--- a/src/logic/move.rs
+++ b/src/logic/move.rs
@@ -37,7 +37,7 @@ pub struct Move {
     pub is_trimmed: bool,
 }
 
-static BVM: LazyLock<BoardValueMap> = LazyLock::new(BoardValueMap::new);
+const BVM: BoardValueMap = BoardValueMap::weighted();
 
 impl Move {
     pub fn new(coord: Option<CoordPair>, board: Board, color: Piece, agent_color: Piece) -> Self {
diff --git a/src/repr/board.rs b/src/repr/board.rs
index c199ba6..e3065db 100644
--- a/src/repr/board.rs
+++ b/src/repr/board.rs
@@ -1,45 +1,39 @@
 use super::{bitboard::BitBoard, piece::Piece, CoordAxis, CoordPair};
 use allocative::Allocative;
-use arrayvec::ArrayVec;
+use const_for::const_for;
 use rand::seq::IteratorRandom;
-use std::{cmp::Ordering, fmt};
+use std::{cmp::Ordering, fmt, mem::MaybeUninit};
 
 /// Map of all points on the board against some type T
 /// Used to index like so: example[i][j]
 /// with each coordinate
-pub struct PosMap<T>(ArrayVec<T, { Board::AREA.0 as usize }>);
+pub struct PosMap<T>([T; Board::AREA.0 as usize]);
 
-impl<T: Default> PosMap<T> {
-    #[allow(clippy::new_without_default)]
-    pub fn new() -> Self {
-        Self(ArrayVec::from_iter(
-            (0..Board::AREA.0).map(|_| Default::default()),
-        ))
+impl<T: Copy> PosMap<T> {
+    pub const unsafe fn uninit() -> Self {
+        Self([MaybeUninit::zeroed().assume_init(); Board::AREA.0 as usize])
     }
 
-    pub fn get(&self, coords: CoordPair) -> &T {
+    pub const fn from(v: [[T; Board::SIZE as usize]; Board::SIZE as usize]) -> Self {
+        let mut n = unsafe { Self::uninit() };
+
+        const_for!(i in 0..Board::SIZE => {
+            const_for!(j in 0..Board::SIZE => {
+                n.set(CoordPair::from_axes(i, j), v[i as usize][j as usize]);
+            });
+        });
+        n
+    }
+
+    pub const fn get(&self, coords: CoordPair) -> &T {
         &self.0[coords.0 as usize]
     }
 
-    pub fn set(&mut self, coords: CoordPair, value: T) {
+    pub const fn set(&mut self, coords: CoordPair, value: T) {
         self.0[coords.0 as usize] = value;
     }
 }
 
-type PosMapOrig<T> = [[T; Board::SIZE as usize]; Board::SIZE as usize];
-
-impl<T: Default + Copy> From<PosMapOrig<T>> for PosMap<T> {
-    fn from(value: PosMapOrig<T>) -> Self {
-        let mut new = Self::new();
-        for i in 0..Board::SIZE {
-            for j in 0..Board::SIZE {
-                new.set((i, j).into(), value[i as usize][j as usize]);
-            }
-        }
-        new
-    }
-}
-
 #[derive(PartialEq, Eq, Copy, Clone, Debug, Allocative)]
 pub enum Winner {
     Player(Piece),