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Commit	Line	Data
	1	/* inftrees.h -- header to use inftrees.c
	2	* Copyright (C) 1995-2005, 2010 Mark Adler
	3	* For conditions of distribution and use, see copyright notice in zlib.h
	4	*/
	5
	6	/* WARNING: this file should not be used by applications. It is
	7	part of the implementation of the compression library and is
	8	subject to change. Applications should only use zlib.h.
	9	*/
	10
	11	/* Structure for decoding tables. Each entry provides either the
	12	information needed to do the operation requested by the code that
	13	indexed that table entry, or it provides a pointer to another
	14	table that indexes more bits of the code. op indicates whether
	15	the entry is a pointer to another table, a literal, a length or
	16	distance, an end-of-block, or an invalid code. For a table
	17	pointer, the low four bits of op is the number of index bits of
	18	that table. For a length or distance, the low four bits of op
	19	is the number of extra bits to get after the code. bits is
	20	the number of bits in this code or part of the code to drop off
	21	of the bit buffer. val is the actual byte to output in the case
	22	of a literal, the base length or distance, or the offset from
	23	the current table to the next table. Each entry is four bytes. */
	24	typedef struct {
	25	unsigned char op; /* operation, extra bits, table bits */
	26	unsigned char bits; /* bits in this part of the code */
	27	unsigned short val; /* offset in table or code value */
	28	} code;
	29
	30	/* op values as set by inflate_table():
	31	00000000 - literal
	32	0000tttt - table link, tttt != 0 is the number of table index bits
	33	0001eeee - length or distance, eeee is the number of extra bits
	34	01100000 - end of block
	35	01000000 - invalid code
	36	*/
	37
	38	/* Maximum size of the dynamic table. The maximum number of code structures is
	39	1444, which is the sum of 852 for literal/length codes and 592 for distance
	40	codes. These values were found by exhaustive searches using the program
	41	examples/enough.c found in the zlib distribtution. The arguments to that
	42	program are the number of symbols, the initial root table size, and the
	43	maximum bit length of a code. "enough 286 9 15" for literal/length codes
	44	returns returns 852, and "enough 30 6 15" for distance codes returns 592.
	45	The initial root table size (9 or 6) is found in the fifth argument of the
	46	inflate_table() calls in inflate.c and infback.c. If the root table size is
	47	changed, then these maximum sizes would be need to be recalculated and
	48	updated. */
	49	#define ENOUGH_LENS 852
	50	#define ENOUGH_DISTS 592
	51	#define ENOUGH (ENOUGH_LENS+ENOUGH_DISTS)
	52
	53	/* Type of code to build for inflate_table() */
	54	typedef enum {
	55	CODES,
	56	LENS,
	57	DISTS
	58	} codetype;
	59
	60	int ZLIB_INTERNAL inflate_table OF((codetype type, unsigned short FAR *lens,
	61	unsigned codes, code FAR * FAR *table,
	62	unsigned FAR bits, unsigned short FAR work));