lib/zlib_inflate/inflate.h

   1 #ifndef INFLATE_H
   2 #define INFLATE_H
   3
   4 /* inflate.h -- internal inflate state definition
   5  * Copyright (C) 1995-2004 Mark Adler
   6  * For conditions of distribution and use, see copyright notice in zlib.h
   7  */
   8
   9 /* WARNING: this file should *not* be used by applications. It is
  10    part of the implementation of the compression library and is
  11    subject to change. Applications should only use zlib.h.
  12  */
  13
  14 #include "inftrees.h"
  15
  16 /* Possible inflate modes between inflate() calls */
  17 typedef enum {
  18     HEAD,       /* i: waiting for magic header */
  19     FLAGS,      /* i: waiting for method and flags (gzip) */
  20     TIME,       /* i: waiting for modification time (gzip) */
  21     OS,         /* i: waiting for extra flags and operating system (gzip) */
  22     EXLEN,      /* i: waiting for extra length (gzip) */
  23     EXTRA,      /* i: waiting for extra bytes (gzip) */
  24     NAME,       /* i: waiting for end of file name (gzip) */
  25     COMMENT,    /* i: waiting for end of comment (gzip) */
  26     HCRC,       /* i: waiting for header crc (gzip) */
  27     DICTID,     /* i: waiting for dictionary check value */
  28     DICT,       /* waiting for inflateSetDictionary() call */
  29         TYPE,       /* i: waiting for type bits, including last-flag bit */
  30         TYPEDO,     /* i: same, but skip check to exit inflate on new block */
  31         STORED,     /* i: waiting for stored size (length and complement) */
  32         COPY,       /* i/o: waiting for input or output to copy stored block */
  33         TABLE,      /* i: waiting for dynamic block table lengths */
  34         LENLENS,    /* i: waiting for code length code lengths */
  35         CODELENS,   /* i: waiting for length/lit and distance code lengths */
  36             LEN,        /* i: waiting for length/lit code */
  37             LENEXT,     /* i: waiting for length extra bits */
  38             DIST,       /* i: waiting for distance code */
  39             DISTEXT,    /* i: waiting for distance extra bits */
  40             MATCH,      /* o: waiting for output space to copy string */
  41             LIT,        /* o: waiting for output space to write literal */
  42     CHECK,      /* i: waiting for 32-bit check value */
  43     LENGTH,     /* i: waiting for 32-bit length (gzip) */
  44     DONE,       /* finished check, done -- remain here until reset */
  45     BAD,        /* got a data error -- remain here until reset */
  46     MEM,        /* got an inflate() memory error -- remain here until reset */
  47     SYNC        /* looking for synchronization bytes to restart inflate() */
  48 } inflate_mode;
  49
  50 /*
  51     State transitions between above modes -
  52
  53     (most modes can go to the BAD or MEM mode -- not shown for clarity)
  54
  55     Process header:
  56         HEAD -> (gzip) or (zlib)
  57         (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME
  58         NAME -> COMMENT -> HCRC -> TYPE
  59         (zlib) -> DICTID or TYPE
  60         DICTID -> DICT -> TYPE
  61     Read deflate blocks:
  62             TYPE -> STORED or TABLE or LEN or CHECK
  63             STORED -> COPY -> TYPE
  64             TABLE -> LENLENS -> CODELENS -> LEN
  65     Read deflate codes:
  66                 LEN -> LENEXT or LIT or TYPE
  67                 LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
  68                 LIT -> LEN
  69     Process trailer:
  70         CHECK -> LENGTH -> DONE
  71  */
  72
  73 /* state maintained between inflate() calls.  Approximately 7K bytes. */
  74 struct inflate_state {
  75     inflate_mode mode;          /* current inflate mode */
  76     int last;                   /* true if processing last block */
  77     int wrap;                   /* bit 0 true for zlib, bit 1 true for gzip */
  78     int havedict;               /* true if dictionary provided */
  79     int flags;                  /* gzip header method and flags (0 if zlib) */
  80     unsigned dmax;              /* zlib header max distance (INFLATE_STRICT) */
  81     unsigned long check;        /* protected copy of check value */
  82     unsigned long total;        /* protected copy of output count */
  83  /*   gz_headerp head; */           /* where to save gzip header information */
  84         /* sliding window */
  85     unsigned wbits;             /* log base 2 of requested window size */
  86     unsigned wsize;             /* window size or zero if not using window */
  87     unsigned whave;             /* valid bytes in the window */
  88     unsigned write;             /* window write index */
  89     unsigned char *window;  /* allocated sliding window, if needed */
  90         /* bit accumulator */
  91     unsigned long hold;         /* input bit accumulator */
  92     unsigned bits;              /* number of bits in "in" */
  93         /* for string and stored block copying */
  94     unsigned length;            /* literal or length of data to copy */
  95     unsigned offset;            /* distance back to copy string from */
  96         /* for table and code decoding */
  97     unsigned extra;             /* extra bits needed */
  98         /* fixed and dynamic code tables */
  99     code const *lencode;    /* starting table for length/literal codes */
 100     code const *distcode;   /* starting table for distance codes */
 101     unsigned lenbits;           /* index bits for lencode */
 102     unsigned distbits;          /* index bits for distcode */
 103         /* dynamic table building */
 104     unsigned ncode;             /* number of code length code lengths */
 105     unsigned nlen;              /* number of length code lengths */
 106     unsigned ndist;             /* number of distance code lengths */
 107     unsigned have;              /* number of code lengths in lens[] */
 108     code *next;             /* next available space in codes[] */
 109     unsigned short lens[320];   /* temporary storage for code lengths */
 110     unsigned short work[288];   /* work area for code table building */
 111     code codes[ENOUGH];         /* space for code tables */
 112 };
 113
 114 /* Reverse the bytes in a 32-bit value */
 115 #define REVERSE(q) \
 116     ((((q) >> 24) & 0xff) + (((q) >> 8) & 0xff00) + \
 117      (((q) & 0xff00) << 8) + (((q) & 0xff) << 24))
 118
 119 #endif