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zlib
inflate.h
Go to the documentation of this file.
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/* inflate.h -- internal inflate state definition
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* Copyright (C) 1995-2009 Mark Adler
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* For conditions of distribution and use, see copyright notice in zlib.h
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*/
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/* WARNING: this file should *not* be used by applications. It is
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part of the implementation of the compression library and is
8
subject to change. Applications should only use zlib.h.
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*/
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/* define NO_GZIP when compiling if you want to disable gzip header and
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trailer decoding by inflate(). NO_GZIP would be used to avoid linking in
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the crc code when it is not needed. For shared libraries, gzip decoding
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should be left enabled. */
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#ifndef NO_GZIP
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# define GUNZIP
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#endif
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/* Possible inflate modes between inflate() calls */
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typedef
enum
{
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HEAD
,
/* i: waiting for magic header */
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FLAGS
,
/* i: waiting for method and flags (gzip) */
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TIME
,
/* i: waiting for modification time (gzip) */
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OS
,
/* i: waiting for extra flags and operating system (gzip) */
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EXLEN
,
/* i: waiting for extra length (gzip) */
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EXTRA
,
/* i: waiting for extra bytes (gzip) */
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NAME
,
/* i: waiting for end of file name (gzip) */
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COMMENT
,
/* i: waiting for end of comment (gzip) */
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HCRC
,
/* i: waiting for header crc (gzip) */
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DICTID
,
/* i: waiting for dictionary check value */
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DICT
,
/* waiting for inflateSetDictionary() call */
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TYPE
,
/* i: waiting for type bits, including last-flag bit */
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TYPEDO
,
/* i: same, but skip check to exit inflate on new block */
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STORED
,
/* i: waiting for stored size (length and complement) */
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COPY_
,
/* i/o: same as COPY below, but only first time in */
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COPY
,
/* i/o: waiting for input or output to copy stored block */
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TABLE
,
/* i: waiting for dynamic block table lengths */
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LENLENS
,
/* i: waiting for code length code lengths */
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CODELENS
,
/* i: waiting for length/lit and distance code lengths */
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LEN_
,
/* i: same as LEN below, but only first time in */
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LEN
,
/* i: waiting for length/lit/eob code */
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LENEXT
,
/* i: waiting for length extra bits */
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DIST
,
/* i: waiting for distance code */
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DISTEXT
,
/* i: waiting for distance extra bits */
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MATCH
,
/* o: waiting for output space to copy string */
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LIT
,
/* o: waiting for output space to write literal */
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CHECK
,
/* i: waiting for 32-bit check value */
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LENGTH
,
/* i: waiting for 32-bit length (gzip) */
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DONE
,
/* finished check, done -- remain here until reset */
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BAD
,
/* got a data error -- remain here until reset */
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MEM
,
/* got an inflate() memory error -- remain here until reset */
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SYNC
/* looking for synchronization bytes to restart inflate() */
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}
inflate_mode
;
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/*
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State transitions between above modes -
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(most modes can go to BAD or MEM on error -- not shown for clarity)
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Process header:
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HEAD -> (gzip) or (zlib) or (raw)
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(gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME -> COMMENT ->
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HCRC -> TYPE
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(zlib) -> DICTID or TYPE
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DICTID -> DICT -> TYPE
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(raw) -> TYPEDO
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Read deflate blocks:
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TYPE -> TYPEDO -> STORED or TABLE or LEN_ or CHECK
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STORED -> COPY_ -> COPY -> TYPE
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TABLE -> LENLENS -> CODELENS -> LEN_
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LEN_ -> LEN
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Read deflate codes in fixed or dynamic block:
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LEN -> LENEXT or LIT or TYPE
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LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
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LIT -> LEN
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Process trailer:
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CHECK -> LENGTH -> DONE
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*/
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/* state maintained between inflate() calls. Approximately 10K bytes. */
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struct
inflate_state
{
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inflate_mode
mode
;
/* current inflate mode */
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int
last
;
/* true if processing last block */
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int
wrap
;
/* bit 0 true for zlib, bit 1 true for gzip */
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int
havedict
;
/* true if dictionary provided */
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int
flags
;
/* gzip header method and flags (0 if zlib) */
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unsigned
dmax
;
/* zlib header max distance (INFLATE_STRICT) */
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unsigned
long
check
;
/* protected copy of check value */
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unsigned
long
total
;
/* protected copy of output count */
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gz_headerp
head
;
/* where to save gzip header information */
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/* sliding window */
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unsigned
wbits
;
/* log base 2 of requested window size */
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unsigned
wsize
;
/* window size or zero if not using window */
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unsigned
whave
;
/* valid bytes in the window */
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unsigned
wnext
;
/* window write index */
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unsigned
char
FAR
*
window
;
/* allocated sliding window, if needed */
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/* bit accumulator */
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unsigned
long
hold
;
/* input bit accumulator */
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unsigned
bits
;
/* number of bits in "in" */
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/* for string and stored block copying */
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unsigned
length
;
/* literal or length of data to copy */
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unsigned
offset
;
/* distance back to copy string from */
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/* for table and code decoding */
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unsigned
extra
;
/* extra bits needed */
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/* fixed and dynamic code tables */
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code
const
FAR
*
lencode
;
/* starting table for length/literal codes */
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code
const
FAR
*
distcode
;
/* starting table for distance codes */
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unsigned
lenbits
;
/* index bits for lencode */
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unsigned
distbits
;
/* index bits for distcode */
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/* dynamic table building */
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unsigned
ncode
;
/* number of code length code lengths */
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unsigned
nlen
;
/* number of length code lengths */
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unsigned
ndist
;
/* number of distance code lengths */
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unsigned
have
;
/* number of code lengths in lens[] */
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code
FAR
*
next
;
/* next available space in codes[] */
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unsigned
short
lens
[320];
/* temporary storage for code lengths */
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unsigned
short
work
[288];
/* work area for code table building */
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code
codes
[
ENOUGH
];
/* space for code tables */
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int
sane
;
/* if false, allow invalid distance too far */
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int
back
;
/* bits back of last unprocessed length/lit */
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unsigned
was
;
/* initial length of match */
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};
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