should be it

external/duckdb/extension/parquet/include/parquet_bss_decoder.hpp

@@ -0,0 +1,61 @@
+//===----------------------------------------------------------------------===//
+//                         DuckDB
+//
+// parquet_bss_decoder.hpp
+//
+//
+//===----------------------------------------------------------------------===//
+
+#pragma once
+#include "parquet_types.h"
+#include "resizable_buffer.hpp"
+
+namespace duckdb {
+
+/// Decoder for the Byte Stream Split encoding
+class BssDecoder {
+public:
+	/// Create a decoder object. buffer/buffer_len is the encoded data.
+	BssDecoder(data_ptr_t buffer, uint32_t buffer_len) : buffer_(buffer, buffer_len), value_offset_(0) {
+	}
+
+public:
+	template <typename T>
+	void GetBatch(data_ptr_t values_target_ptr, uint32_t batch_size) {
+		if (buffer_.len % sizeof(T) != 0) {
+			duckdb::stringstream error;
+			error << "Data buffer size for the BYTE_STREAM_SPLIT encoding (" << buffer_.len
+			      << ") should be a multiple of the type size (" << sizeof(T) << ")";
+			throw std::runtime_error(error.str());
+		}
+		uint32_t num_buffer_values = buffer_.len / sizeof(T);
+
+		buffer_.available((value_offset_ + batch_size) * sizeof(T));
+
+		for (uint32_t byte_offset = 0; byte_offset < sizeof(T); ++byte_offset) {
+			data_ptr_t input_bytes = buffer_.ptr + byte_offset * num_buffer_values + value_offset_;
+			for (uint32_t i = 0; i < batch_size; ++i) {
+				values_target_ptr[byte_offset + i * sizeof(T)] = *(input_bytes + i);
+			}
+		}
+		value_offset_ += batch_size;
+	}
+
+	template <typename T>
+	void Skip(uint32_t batch_size) {
+		if (buffer_.len % sizeof(T) != 0) {
+			duckdb::stringstream error;
+			error << "Data buffer size for the BYTE_STREAM_SPLIT encoding (" << buffer_.len
+			      << ") should be a multiple of the type size (" << sizeof(T) << ")";
+			throw std::runtime_error(error.str());
+		}
+		buffer_.available((value_offset_ + batch_size) * sizeof(T));
+		value_offset_ += batch_size;
+	}
+
+private:
+	ByteBuffer buffer_;
+	uint32_t value_offset_;
+};
+
+} // namespace duckdb