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diff --git a/third_party/jpeg-xl/lib/jxl/jpeg/enc_jpeg_huffman_decode.h b/third_party/jpeg-xl/lib/jxl/jpeg/enc_jpeg_huffman_decode.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.
+
+// Utility function for building a Huffman lookup table for the jpeg decoder.
+
+#ifndef LIB_JXL_JPEG_ENC_JPEG_HUFFMAN_DECODE_H_
+#define LIB_JXL_JPEG_ENC_JPEG_HUFFMAN_DECODE_H_
+
+#include <stdint.h>
+
+namespace jxl {
+namespace jpeg {
+
+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 {
+  // Initialize the value to an invalid symbol so that we can recognize it
+  // when reading the bit stream using a Huffman code with space > 0.
+  HuffmanTableEntry() : bits(0), value(0xffff) {}
+
+  uint8_t bits;    // number of bits used for this symbol
+  uint16_t value;  // symbol value or table offset
+};
+
+// Builds jpeg-style Huffman lookup table from the given symbols.
+// The symbols are in order of increasing bit lengths. The number of symbols
+// with bit length n is given in counts[n] for each n >= 1.
+void BuildJpegHuffmanTable(const uint32_t* counts, const uint32_t* symbols,
+                           HuffmanTableEntry* lut);
+
+}  // namespace jpeg
+}  // namespace jxl
+
+#endif  // LIB_JXL_JPEG_ENC_JPEG_HUFFMAN_DECODE_H_