should be it

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

@@ -0,0 +1,47 @@
+//===----------------------------------------------------------------------===//
+//                         DuckDB
+//
+// parquet_bss_encoder.hpp
+//
+//
+//===----------------------------------------------------------------------===//
+
+#pragma once
+
+#include "decode_utils.hpp"
+
+namespace duckdb {
+
+class BssEncoder {
+public:
+	explicit BssEncoder(const idx_t total_value_count_p, const idx_t bit_width_p)
+	    : total_value_count(total_value_count_p), bit_width(bit_width_p), count(0) {
+	}
+
+public:
+	void BeginWrite(Allocator &allocator) {
+		buffer = allocator.Allocate(total_value_count * bit_width + 1);
+	}
+
+	template <class T>
+	void WriteValue(const T &value) {
+		D_ASSERT(sizeof(T) == bit_width);
+		for (idx_t i = 0; i < sizeof(T); i++) {
+			buffer.get()[i * total_value_count + count] = reinterpret_cast<const_data_ptr_t>(&value)[i];
+		}
+		count++;
+	}
+
+	void FinishWrite(WriteStream &writer) {
+		writer.WriteData(buffer.get(), total_value_count * bit_width);
+	}
+
+private:
+	const idx_t total_value_count;
+	const idx_t bit_width;
+
+	idx_t count;
+	AllocatedData buffer;
+};
+
+} // namespace duckdb