2 Stockfish, a UCI chess playing engine derived from Glaurung 2.1
3 Copyright (C) 2004-2021 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 Stockfish::Eval::NNUE {
34 // Input feature converter
35 LargePagePtr<FeatureTransformer> featureTransformer;
37 // Evaluation function
38 AlignedPtr<Network> network;
40 // Evaluation function file name
42 std::string netDescription;
46 // Initialize the evaluation function parameters
48 void initialize(AlignedPtr<T>& pointer) {
50 pointer.reset(reinterpret_cast<T*>(std_aligned_alloc(alignof(T), sizeof(T))));
51 std::memset(pointer.get(), 0, sizeof(T));
55 void initialize(LargePagePtr<T>& pointer) {
57 static_assert(alignof(T) <= 4096, "aligned_large_pages_alloc() may fail for such a big alignment requirement of T");
58 pointer.reset(reinterpret_cast<T*>(aligned_large_pages_alloc(sizeof(T))));
59 std::memset(pointer.get(), 0, sizeof(T));
62 // Read evaluation function parameters
64 bool read_parameters(std::istream& stream, T& reference) {
67 header = read_little_endian<std::uint32_t>(stream);
68 if (!stream || header != T::get_hash_value()) return false;
69 return reference.read_parameters(stream);
72 // Write evaluation function parameters
74 bool write_parameters(std::ostream& stream, const T& reference) {
76 write_little_endian<std::uint32_t>(stream, T::get_hash_value());
77 return reference.write_parameters(stream);
82 // Initialize the evaluation function parameters
85 Detail::initialize(featureTransformer);
86 Detail::initialize(network);
89 // Read network header
90 bool read_header(std::istream& stream, std::uint32_t* hashValue, std::string* desc)
92 std::uint32_t version, size;
94 version = read_little_endian<std::uint32_t>(stream);
95 *hashValue = read_little_endian<std::uint32_t>(stream);
96 size = read_little_endian<std::uint32_t>(stream);
97 if (!stream || version != Version) return false;
99 stream.read(&(*desc)[0], size);
100 return !stream.fail();
103 // Write network header
104 bool write_header(std::ostream& stream, std::uint32_t hashValue, const std::string& desc)
106 write_little_endian<std::uint32_t>(stream, Version);
107 write_little_endian<std::uint32_t>(stream, hashValue);
108 write_little_endian<std::uint32_t>(stream, desc.size());
109 stream.write(&desc[0], desc.size());
110 return !stream.fail();
113 // Read network parameters
114 bool read_parameters(std::istream& stream) {
116 std::uint32_t hashValue;
117 if (!read_header(stream, &hashValue, &netDescription)) return false;
118 if (hashValue != HashValue) return false;
119 if (!Detail::read_parameters(stream, *featureTransformer)) return false;
120 if (!Detail::read_parameters(stream, *network)) return false;
121 return stream && stream.peek() == std::ios::traits_type::eof();
124 // Write network parameters
125 bool write_parameters(std::ostream& stream) {
127 if (!write_header(stream, HashValue, netDescription)) return false;
128 if (!Detail::write_parameters(stream, *featureTransformer)) return false;
129 if (!Detail::write_parameters(stream, *network)) return false;
133 // Evaluation function. Perform differential calculation.
134 Value evaluate(const Position& pos) {
136 // We manually align the arrays on the stack because with gcc < 9.3
137 // overaligning stack variables with alignas() doesn't work correctly.
139 constexpr uint64_t alignment = CacheLineSize;
141 #if defined(ALIGNAS_ON_STACK_VARIABLES_BROKEN)
142 TransformedFeatureType transformedFeaturesUnaligned[
143 FeatureTransformer::BufferSize + alignment / sizeof(TransformedFeatureType)];
144 char bufferUnaligned[Network::BufferSize + alignment];
146 auto* transformedFeatures = align_ptr_up<alignment>(&transformedFeaturesUnaligned[0]);
147 auto* buffer = align_ptr_up<alignment>(&bufferUnaligned[0]);
150 TransformedFeatureType transformedFeatures[FeatureTransformer::BufferSize];
151 alignas(alignment) char buffer[Network::BufferSize];
154 ASSERT_ALIGNED(transformedFeatures, alignment);
155 ASSERT_ALIGNED(buffer, alignment);
157 featureTransformer->transform(pos, transformedFeatures);
158 const auto output = network->propagate(transformedFeatures, buffer);
160 return static_cast<Value>(output[0] / OutputScale);
163 // Load eval, from a file stream or a memory stream
164 bool load_eval(std::string name, std::istream& stream) {
168 return read_parameters(stream);
171 // Save eval, to a file stream or a memory stream
172 bool save_eval(std::ostream& stream) {
174 if (fileName.empty())
177 return write_parameters(stream);
180 } // namespace Stockfish::Eval::NNUE