Add NNUE evaluation

[stockfish] / src / nnue / layers / input_slice.h

diff --git a/src/nnue/layers/input_slice.h b/src/nnue/layers/input_slice.h
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+++ b/src/nnue/layers/input_slice.h
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+/*
+  Stockfish, a UCI chess playing engine derived from Glaurung 2.1
+  Copyright (C) 2004-2020 The Stockfish developers (see AUTHORS file)
+
+  Stockfish is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  Stockfish is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+// NNUE evaluation function layer InputSlice definition
+
+#ifndef NNUE_LAYERS_INPUT_SLICE_H_INCLUDED
+#define NNUE_LAYERS_INPUT_SLICE_H_INCLUDED
+
+#include "../nnue_common.h"
+
+namespace Eval::NNUE::Layers {
+
+// Input layer
+template <IndexType OutputDimensions, IndexType Offset = 0>
+class InputSlice {
+ public:
+  // Need to maintain alignment
+  static_assert(Offset % kMaxSimdWidth == 0, "");
+
+  // Output type
+  using OutputType = TransformedFeatureType;
+
+  // Output dimensionality
+  static constexpr IndexType kOutputDimensions = OutputDimensions;
+
+  // Size of forward propagation buffer used from the input layer to this layer
+  static constexpr std::size_t kBufferSize = 0;
+
+  // Hash value embedded in the evaluation file
+  static constexpr std::uint32_t GetHashValue() {
+    std::uint32_t hash_value = 0xEC42E90Du;
+    hash_value ^= kOutputDimensions ^ (Offset << 10);
+    return hash_value;
+  }
+
+  // Read network parameters
+  bool ReadParameters(std::istream& /*stream*/) {
+    return true;
+  }
+
+  // Forward propagation
+  const OutputType* Propagate(
+      const TransformedFeatureType* transformed_features,
+      char* /*buffer*/) const {
+    return transformed_features + Offset;
+  }
+
+ private:
+};
+
+}  // namespace Layers
+
+#endif // #ifndef NNUE_LAYERS_INPUT_SLICE_H_INCLUDED