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/*
* deflate_constants.h - constants for the DEFLATE compression format
*/
#ifndef LIB_DEFLATE_CONSTANTS_H
#define LIB_DEFLATE_CONSTANTS_H
/* Valid block types */
#define DEFLATE_BLOCKTYPE_UNCOMPRESSED 0
#define DEFLATE_BLOCKTYPE_STATIC_HUFFMAN 1
#define DEFLATE_BLOCKTYPE_DYNAMIC_HUFFMAN 2
/* Minimum and maximum supported match lengths (in bytes) */
#define DEFLATE_MIN_MATCH_LEN 3
#define DEFLATE_MAX_MATCH_LEN 258
/* Minimum and maximum supported match offsets (in bytes) */
#define DEFLATE_MIN_MATCH_OFFSET 1
#define DEFLATE_MAX_MATCH_OFFSET 32768
#define DEFLATE_MAX_WINDOW_SIZE 32768
/* Number of symbols in each Huffman code. Note: for the literal/length
* and offset codes, these are actually the maximum values; a given block
* might use fewer symbols. */
#define DEFLATE_NUM_PRECODE_SYMS 19
#define DEFLATE_NUM_LITLEN_SYMS 288
#define DEFLATE_NUM_OFFSET_SYMS 32
/* The maximum number of symbols across all codes */
#define DEFLATE_MAX_NUM_SYMS 288
/* Division of symbols in the literal/length code */
#define DEFLATE_NUM_LITERALS 256
#define DEFLATE_END_OF_BLOCK 256
#define DEFLATE_NUM_LEN_SYMS 31
/* Maximum codeword length, in bits, within each Huffman code */
#define DEFLATE_MAX_PRE_CODEWORD_LEN 7
#define DEFLATE_MAX_LITLEN_CODEWORD_LEN 15
#define DEFLATE_MAX_OFFSET_CODEWORD_LEN 15
/* The maximum codeword length across all codes */
#define DEFLATE_MAX_CODEWORD_LEN 15
/* Maximum possible overrun when decoding codeword lengths */
#define DEFLATE_MAX_LENS_OVERRUN 137
/*
* Maximum number of extra bits that may be required to represent a match
* length or offset.
*
* TODO: are we going to have full DEFLATE64 support? If so, up to 16
* length bits must be supported.
*/
#define DEFLATE_MAX_EXTRA_LENGTH_BITS 5
#define DEFLATE_MAX_EXTRA_OFFSET_BITS 14
/* The maximum number of bits in which a match can be represented. This
* is the absolute worst case, which assumes the longest possible Huffman
* codewords and the maximum numbers of extra bits. */
#define DEFLATE_MAX_MATCH_BITS \
(DEFLATE_MAX_LITLEN_CODEWORD_LEN + DEFLATE_MAX_EXTRA_LENGTH_BITS + \
DEFLATE_MAX_OFFSET_CODEWORD_LEN + DEFLATE_MAX_EXTRA_OFFSET_BITS)
#endif /* LIB_DEFLATE_CONSTANTS_H */
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