intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 50 insertions, 0 deletions

diff --git a/library/cpp/codecs/float_huffman.h b/library/cpp/codecs/float_huffman.h
new file mode 100644
index 0000000000..786a8eae1d
--- /dev/null
+++ b/library/cpp/codecs/float_huffman.h
@@ -0,0 +1,50 @@
+#pragma once
+
+#include <util/generic/array_ref.h>
+#include <util/generic/vector.h>
+#include <util/generic/strbuf.h>
+
+#include <array>
+
+namespace NCodecs::NFloatHuff {
+    TString Encode(TArrayRef<const float> factors);
+
+    class TDecoder {
+    public:
+        explicit TDecoder(TStringBuf data);
+
+        TVector<float> DecodeAll(size_t sizeHint = 0);
+
+        // Returns number of decoded floats. May be fewer than requested if the EOS is found.
+        size_t Decode(TArrayRef<float> dest);
+
+        // Returns the number of skipped values.
+        size_t Skip(size_t count);
+
+        bool HasMore() const;
+
+    private:
+        struct TState {
+            ui64 Workspace = 0;
+            int WorkspaceSize = 0;
+            ui64 Position = 0;
+            TStringBuf Data;
+
+            ui64 NextBitsUnmasked(int count); // The upper 64 - count bits may be arbitrary
+            ui64 PeekBits(int count);
+            void SkipBits(int count);
+        };
+
+        void FillDecodeBuffer();
+
+        TState State;
+        std::array<float, 128> DecodeBuffer;
+        // The range of already decompressed numbers inside the DecodeBuffer.
+        // Always kept non-empty until the EOS is encountered.
+        float* Begin;
+        float* End;
+        bool HitEos = false;
+    };
+
+    TVector<float> Decode(TStringBuf data, size_t sizeHint = 0);
+}