2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
5 Stockfish is free software: you can redistribute it and/or modify
6 it under the terms of the GNU General Public License as published by
7 the Free Software Foundation, either version 3 of the License, or
8 (at your option) any later version.
10 Stockfish is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 GNU General Public License for more details.
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>.
19 // Code for calculating NNUE evaluation function
24 #include "../evaluate.h"
25 #include "../position.h"
30 #include "evaluate_nnue.h"
32 namespace Eval::NNUE {
34 // Input feature converter
35 LargePagePtr<FeatureTransformer> feature_transformer;
37 // Evaluation function
38 AlignedPtr<Network> network;
40 // Evaluation function file name
45 // Initialize the evaluation function parameters
47 void Initialize(AlignedPtr<T>& pointer) {
49 pointer.reset(reinterpret_cast<T*>(std_aligned_alloc(alignof(T), sizeof(T))));
50 std::memset(pointer.get(), 0, sizeof(T));
54 void Initialize(LargePagePtr<T>& pointer) {
56 static_assert(alignof(T) <= 4096, "aligned_large_pages_alloc() may fail for such a big alignment requirement of T");
57 pointer.reset(reinterpret_cast<T*>(aligned_large_pages_alloc(sizeof(T))));
58 std::memset(pointer.get(), 0, sizeof(T));
61 // Read evaluation function parameters
63 bool ReadParameters(std::istream& stream, T& reference) {
66 header = read_little_endian<std::uint32_t>(stream);
67 if (!stream || header != T::GetHashValue()) return false;
68 return reference.ReadParameters(stream);
73 // Initialize the evaluation function parameters
76 Detail::Initialize(feature_transformer);
77 Detail::Initialize(network);
80 // Read network header
81 bool ReadHeader(std::istream& stream, std::uint32_t* hash_value, std::string* architecture)
83 std::uint32_t version, size;
85 version = read_little_endian<std::uint32_t>(stream);
86 *hash_value = read_little_endian<std::uint32_t>(stream);
87 size = read_little_endian<std::uint32_t>(stream);
88 if (!stream || version != kVersion) return false;
89 architecture->resize(size);
90 stream.read(&(*architecture)[0], size);
91 return !stream.fail();
94 // Read network parameters
95 bool ReadParameters(std::istream& stream) {
97 std::uint32_t hash_value;
98 std::string architecture;
99 if (!ReadHeader(stream, &hash_value, &architecture)) return false;
100 if (hash_value != kHashValue) return false;
101 if (!Detail::ReadParameters(stream, *feature_transformer)) return false;
102 if (!Detail::ReadParameters(stream, *network)) return false;
103 return stream && stream.peek() == std::ios::traits_type::eof();
106 // Evaluation function. Perform differential calculation.
107 Value evaluate(const Position& pos) {
109 // We manually align the arrays on the stack because with gcc < 9.3
110 // overaligning stack variables with alignas() doesn't work correctly.
112 constexpr uint64_t alignment = kCacheLineSize;
114 #if defined(ALIGNAS_ON_STACK_VARIABLES_BROKEN)
115 TransformedFeatureType transformed_features_unaligned[
116 FeatureTransformer::kBufferSize + alignment / sizeof(TransformedFeatureType)];
117 char buffer_unaligned[Network::kBufferSize + alignment];
119 auto* transformed_features = align_ptr_up<alignment>(&transformed_features_unaligned[0]);
120 auto* buffer = align_ptr_up<alignment>(&buffer_unaligned[0]);
123 TransformedFeatureType transformed_features[FeatureTransformer::kBufferSize];
124 alignas(alignment) char buffer[Network::kBufferSize];
127 ASSERT_ALIGNED(transformed_features, alignment);
128 ASSERT_ALIGNED(buffer, alignment);
130 feature_transformer->Transform(pos, transformed_features);
131 const auto output = network->Propagate(transformed_features, buffer);
133 return static_cast<Value>(output[0] / FV_SCALE);
136 // Load eval, from a file stream or a memory stream
137 bool load_eval(std::string name, std::istream& stream) {
141 return ReadParameters(stream);
144 } // namespace Eval::NNUE