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diff --git a/deps/libchdr/huffman.h b/deps/libchdr/huffman.h
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+++ b/deps/libchdr/huffman.h
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+// license:BSD-3-Clause
+// copyright-holders:Aaron Giles
+/***************************************************************************
+
+    huffman.h
+
+    Static Huffman compression and decompression helpers.
+
+***************************************************************************/
+
+#pragma once
+
+#ifndef __HUFFMAN_H__
+#define __HUFFMAN_H__
+
+#include "bitstream.h"
+
+
+//**************************************************************************
+//  CONSTANTS
+//**************************************************************************
+
+enum huffman_error
+{
+	HUFFERR_NONE = 0,
+	HUFFERR_TOO_MANY_BITS,
+	HUFFERR_INVALID_DATA,
+	HUFFERR_INPUT_BUFFER_TOO_SMALL,
+	HUFFERR_OUTPUT_BUFFER_TOO_SMALL,
+	HUFFERR_INTERNAL_INCONSISTENCY,
+	HUFFERR_TOO_MANY_CONTEXTS
+};
+
+
+
+//**************************************************************************
+//  TYPE DEFINITIONS
+//**************************************************************************
+
+typedef uint16_t lookup_value;
+
+// a node in the huffman tree
+struct node_t
+{
+	struct node_t*		parent;		// pointer to parent node
+	uint32_t			count;		// number of hits on this node
+	uint32_t			weight;		// assigned weight of this node
+	uint32_t			bits;		// bits used to encode the node
+	uint8_t				numbits;	// number of bits needed for this node
+};
+
+// ======================> huffman_context_base
+
+// context class for decoding
+struct huffman_decoder
+{
+	// internal state
+	uint32_t			numcodes;             // number of total codes being processed
+	uint8_t				maxbits;              // maximum bits per code
+	uint8_t 			prevdata;             // value of the previous data (for delta-RLE encoding)
+	int             	rleremaining;         // number of RLE bytes remaining (for delta-RLE encoding)
+	lookup_value *  	lookup;               // pointer to the lookup table
+	struct node_t *     huffnode;             // array of nodes
+	uint32_t *      	datahisto;            // histogram of data values
+
+	// array versions of the info we need
+	//node_t*			huffnode_array; //[_NumCodes];
+	//lookup_value*	lookup_array; //[1 << _MaxBits];	
+};
+
+// ======================> huffman_decoder
+
+struct huffman_decoder* create_huffman_decoder(int numcodes, int maxbits);
+
+// single item operations
+uint32_t huffman_decode_one(struct huffman_decoder* decoder, struct bitstream* bitbuf);
+
+enum huffman_error huffman_import_tree_rle(struct huffman_decoder* decoder, struct bitstream* bitbuf);
+enum huffman_error huffman_import_tree_huffman(struct huffman_decoder* decoder, struct bitstream* bitbuf);
+
+int huffman_build_tree(struct huffman_decoder* decoder, uint32_t totaldata, uint32_t totalweight);
+enum huffman_error huffman_assign_canonical_codes(struct huffman_decoder* decoder);
+enum huffman_error huffman_compute_tree_from_histo(struct huffman_decoder* decoder);
+
+void huffman_build_lookup_table(struct huffman_decoder* decoder);
+
+#endif