From 80564bcfcd3523c2a61e7a2c4bee36d4aada49d1 Mon Sep 17 00:00:00 2001
From: mstembera <MissingEmail@email>
Date: Sun, 2 Jul 2023 19:48:18 -0700
Subject: [PATCH] Simplify lookup_count and clean up pieces().

https://github.com/official-stockfish/Stockfish/pull/4656

No functional change
---
 src/nnue/layers/affine_transform_sparse_input.h | 12 ++----------
 src/position.h                                  |  4 ++--
 2 files changed, 4 insertions(+), 12 deletions(-)

diff --git a/src/nnue/layers/affine_transform_sparse_input.h b/src/nnue/layers/affine_transform_sparse_input.h
index e0c3a8a0..18c166cd 100644
--- a/src/nnue/layers/affine_transform_sparse_input.h
+++ b/src/nnue/layers/affine_transform_sparse_input.h
@@ -24,6 +24,7 @@
 #include <iostream>
 #include <algorithm>
 #include <array>
+#include <bitset>
 #include <type_traits>
 #include "../nnue_common.h"
 #include "affine_transform.h"
@@ -77,16 +78,7 @@ namespace Stockfish::Eval::NNUE::Layers {
   alignas(CacheLineSize) static inline const std::array<unsigned, 256> lookup_count = [](){
     std::array<unsigned, 256> v;
     for (int i = 0; i < 256; ++i)
-    {
-      int j = i;
-      int k = 0;
-      while(j)
-      {
-        j &= j - 1;
-        ++k;
-      }
-      v[i] = k;
-    }
+      v[i] = unsigned(std::bitset<8>(i).count());
     return v;
   }();
 
diff --git a/src/position.h b/src/position.h
index 2e6014db..7d4b3771 100644
--- a/src/position.h
+++ b/src/position.h
@@ -91,7 +91,7 @@ public:
   std::string fen() const;
 
   // Position representation
-  Bitboard pieces(PieceType pt) const;
+  Bitboard pieces(PieceType pt = ALL_PIECES) const;
   template<typename ...PieceTypes> Bitboard pieces(PieceType pt, PieceTypes... pts) const;
   Bitboard pieces(Color c) const;
   template<typename ...PieceTypes> Bitboard pieces(Color c, PieceTypes... pts) const;
@@ -224,7 +224,7 @@ inline Piece Position::moved_piece(Move m) const {
   return piece_on(from_sq(m));
 }
 
-inline Bitboard Position::pieces(PieceType pt = ALL_PIECES) const {
+inline Bitboard Position::pieces(PieceType pt) const {
   return byTypeBB[pt];
 }
 
-- 
2.39.2