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diff --git a/lib/jpegli/huffman.h b/lib/jpegli/huffman.h
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+// Copyright (c) the JPEG XL Project Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#ifndef LIB_JPEGLI_HUFFMAN_H_
+#define LIB_JPEGLI_HUFFMAN_H_
+
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "lib/jpegli/common_internal.h"
+
+namespace jpegli {
+
+constexpr int kJpegHuffmanRootTableBits = 8;
+// Maximum huffman lookup table size.
+// According to zlib/examples/enough.c, 758 entries are always enough for
+// an alphabet of 257 symbols (256 + 1 special symbol for the all 1s code) and
+// max bit length 16 if the root table has 8 bits.
+constexpr int kJpegHuffmanLutSize = 758;
+
+struct HuffmanTableEntry {
+  uint8_t bits;    // number of bits used for this symbol
+  uint16_t value;  // symbol value or table offset
+};
+
+void BuildJpegHuffmanTable(const uint32_t* count, const uint32_t* symbols,
+                           HuffmanTableEntry* lut);
+
+// This function will create a Huffman tree.
+//
+// The (data,length) contains the population counts.
+// The tree_limit is the maximum bit depth of the Huffman codes.
+//
+// The depth contains the tree, i.e., how many bits are used for
+// the symbol.
+//
+// See http://en.wikipedia.org/wiki/Huffman_coding
+void CreateHuffmanTree(const uint32_t* data, size_t length, int tree_limit,
+                       uint8_t* depth);
+
+void ValidateHuffmanTable(j_common_ptr cinfo, const JHUFF_TBL* table,
+                          bool is_dc);
+
+void AddStandardHuffmanTables(j_common_ptr cinfo, bool is_dc);
+
+}  // namespace jpegli
+
+#endif  // LIB_JPEGLI_HUFFMAN_H_