FreeBSD/Linux Kernel Cross Reference
sys/libkern/zlib/inflate.h

     /*
      * Copyright (c) 2008 Apple Inc. All rights reserved.
      *
      * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
      * 
      * This file contains Original Code and/or Modifications of Original Code
      * as defined in and that are subject to the Apple Public Source License
      * Version 2.0 (the 'License'). You may not use this file except in
      * compliance with the License. The rights granted to you under the License
     * may not be used to create, or enable the creation or redistribution of,
     * unlawful or unlicensed copies of an Apple operating system, or to
     * circumvent, violate, or enable the circumvention or violation of, any
     * terms of an Apple operating system software license agreement.
     * 
     * Please obtain a copy of the License at
     * http://www.opensource.apple.com/apsl/ and read it before using this file.
     * 
     * The Original Code and all software distributed under the License are
     * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
     * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
     * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
     * Please see the License for the specific language governing rights and
     * limitations under the License.
     * 
     * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
     */
    /* inflate.h -- internal inflate state definition
     * Copyright (C) 1995-2004 Mark Adler
     * For conditions of distribution and use, see copyright notice in zlib.h
     */
    
    /* WARNING: this file should *not* be used by applications. It is
       part of the implementation of the compression library and is
       subject to change. Applications should only use zlib.h.
     */
    
    /* define NO_GZIP when compiling if you want to disable gzip header and
       trailer decoding by inflate().  NO_GZIP would be used to avoid linking in
       the crc code when it is not needed.  For shared libraries, gzip decoding
       should be left enabled. */
    #ifndef NO_GZIP
    #  define GUNZIP
    #endif
    
    /* Possible inflate modes between inflate() calls */
    typedef enum {
        HEAD,       /* i: waiting for magic header */
        FLAGS,      /* i: waiting for method and flags (gzip) */
        TIME,       /* i: waiting for modification time (gzip) */
        OS,         /* i: waiting for extra flags and operating system (gzip) */
        EXLEN,      /* i: waiting for extra length (gzip) */
        EXTRA,      /* i: waiting for extra bytes (gzip) */
        NAME,       /* i: waiting for end of file name (gzip) */
        COMMENT,    /* i: waiting for end of comment (gzip) */
        HCRC,       /* i: waiting for header crc (gzip) */
        DICTID,     /* i: waiting for dictionary check value */
        DICT,       /* waiting for inflateSetDictionary() call */
            TYPE,       /* i: waiting for type bits, including last-flag bit */
            TYPEDO,     /* i: same, but skip check to exit inflate on new block */
            STORED,     /* i: waiting for stored size (length and complement) */
            COPY,       /* i/o: waiting for input or output to copy stored block */
            TABLE,      /* i: waiting for dynamic block table lengths */
            LENLENS,    /* i: waiting for code length code lengths */
            CODELENS,   /* i: waiting for length/lit and distance code lengths */
                LEN,        /* i: waiting for length/lit code */
                LENEXT,     /* i: waiting for length extra bits */
                DIST,       /* i: waiting for distance code */
                DISTEXT,    /* i: waiting for distance extra bits */
                MATCH,      /* o: waiting for output space to copy string */
                LIT,        /* o: waiting for output space to write literal */
        CHECK,      /* i: waiting for 32-bit check value */
        LENGTH,     /* i: waiting for 32-bit length (gzip) */
        DONE,       /* finished check, done -- remain here until reset */
        BAD,        /* got a data error -- remain here until reset */
        MEM,        /* got an inflate() memory error -- remain here until reset */
        SYNC        /* looking for synchronization bytes to restart inflate() */
    } inflate_mode;
    
    /*
        State transitions between above modes -
    
        (most modes can go to the BAD or MEM mode -- not shown for clarity)
    
        Process header:
            HEAD -> (gzip) or (zlib)
            (gzip) -> FLAGS -> TIME -> OS -> EXLEN -> EXTRA -> NAME
            NAME -> COMMENT -> HCRC -> TYPE
            (zlib) -> DICTID or TYPE
            DICTID -> DICT -> TYPE
        Read deflate blocks:
                TYPE -> STORED or TABLE or LEN or CHECK
                STORED -> COPY -> TYPE
                TABLE -> LENLENS -> CODELENS -> LEN
        Read deflate codes:
                    LEN -> LENEXT or LIT or TYPE
                    LENEXT -> DIST -> DISTEXT -> MATCH -> LEN
                    LIT -> LEN
        Process trailer:
           CHECK -> LENGTH -> DONE
    */
   
   /* state maintained between inflate() calls.  Approximately 7K bytes. */
   struct inflate_state {
       inflate_mode mode;          /* current inflate mode */
       int last;                   /* true if processing last block */
       int wrap;                   /* bit 0 true for zlib, bit 1 true for gzip */
       int havedict;               /* true if dictionary provided */
       int flags;                  /* gzip header method and flags (0 if zlib) */
       unsigned dmax;              /* zlib header max distance (INFLATE_STRICT) */
       unsigned long check;        /* protected copy of check value */
       unsigned long total;        /* protected copy of output count */
       gz_headerp head;            /* where to save gzip header information */
           /* sliding window */
       unsigned wbits;             /* log base 2 of requested window size */
       unsigned wsize;             /* window size or zero if not using window */
       unsigned whave;             /* valid bytes in the window */
       unsigned write;             /* window write index */
       unsigned char FAR *window;  /* allocated sliding window, if needed */
           /* bit accumulator */
       unsigned long hold;         /* input bit accumulator */
       unsigned bits;              /* number of bits in "in" */
           /* for string and stored block copying */
       unsigned length;            /* literal or length of data to copy */
       unsigned offset;            /* distance back to copy string from */
           /* for table and code decoding */
       unsigned extra;             /* extra bits needed */
           /* fixed and dynamic code tables */
       code const FAR *lencode;    /* starting table for length/literal codes */
       code const FAR *distcode;   /* starting table for distance codes */
       unsigned lenbits;           /* index bits for lencode */
       unsigned distbits;          /* index bits for distcode */
           /* dynamic table building */
       unsigned ncode;             /* number of code length code lengths */
       unsigned nlen;              /* number of length code lengths */
       unsigned ndist;             /* number of distance code lengths */
       unsigned have;              /* number of code lengths in lens[] */
       code FAR *next;             /* next available space in codes[] */
       unsigned short lens[320];   /* temporary storage for code lengths */
       unsigned short work[288];   /* work area for code table building */
       code codes[ENOUGH];         /* space for code tables */
   };

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