dep: Add libchdr

dep/libchdr/include/libchdr/huffman.h

@@ -0,0 +1,89 @@
+/* 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 */
+#if 0
+	node_t*			huffnode_array; /* [_NumCodes]; */
+	lookup_value*	lookup_array; /* [1 << _MaxBits]; */
+#endif
+};
+
+/* ======================> 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