FreeBSD/Linux Kernel Cross Reference
sys/net/zlib.h

     /* $FreeBSD$    */
     
     /*
      * This file is derived from zlib.h and zconf.h from the zlib-1.0.4
      * distribution by Jean-loup Gailly and Mark Adler, with some additions
      * by Paul Mackerras to aid in implementing Deflate compression and
      * decompression for PPP packets.
      */
     
    /*
     *  ==FILEVERSION 971127==
     *
     * This marker is used by the Linux installation script to determine
     * whether an up-to-date version of this file is already installed.
     */
    
    
    /* +++ zlib.h */
    /* zlib.h -- interface of the 'zlib' general purpose compression library
      version 1.0.4, Jul 24th, 1996.
    
      Copyright (C) 1995-1996 Jean-loup Gailly and Mark Adler
    
      This software is provided 'as-is', without any express or implied
      warranty.  In no event will the authors be held liable for any damages
      arising from the use of this software.
    
      Permission is granted to anyone to use this software for any purpose,
      including commercial applications, and to alter it and redistribute it
      freely, subject to the following restrictions:
    
      1. The origin of this software must not be misrepresented; you must not
         claim that you wrote the original software. If you use this software
         in a product, an acknowledgment in the product documentation would be
         appreciated but is not required.
      2. Altered source versions must be plainly marked as such, and must not be
         misrepresented as being the original software.
      3. This notice may not be removed or altered from any source distribution.
    
      Jean-loup Gailly        Mark Adler
      gzip@prep.ai.mit.edu    madler@alumni.caltech.edu
    
    
      The data format used by the zlib library is described by RFCs (Request for
      Comments) 1950 to 1952 in the files ftp://ds.internic.net/rfc/rfc1950.txt
      (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
    */
    
    #ifndef _ZLIB_H
    #define _ZLIB_H
    
    #ifdef __cplusplus
    extern "C" {
    #endif
    
    
    /* +++ zconf.h */
    /* zconf.h -- configuration of the zlib compression library
     * Copyright (C) 1995-1996 Jean-loup Gailly.
     * For conditions of distribution and use, see copyright notice in zlib.h 
     */
    
    /* From: zconf.h,v 1.20 1996/07/02 15:09:28 me Exp $ */
    
    #ifndef _ZCONF_H
    #define _ZCONF_H
    
    /*
     * If you *really* need a unique prefix for all types and library functions,
     * compile with -DZ_PREFIX. The "standard" zlib should be compiled without it.
     */
    #ifdef Z_PREFIX
    #  define deflateInit_  z_deflateInit_
    #  define deflate       z_deflate
    #  define deflateEnd    z_deflateEnd
    #  define inflateInit_  z_inflateInit_
    #  define inflate       z_inflate
    #  define inflateEnd    z_inflateEnd
    #  define deflateInit2_ z_deflateInit2_
    #  define deflateSetDictionary z_deflateSetDictionary
    #  define deflateCopy   z_deflateCopy
    #  define deflateReset  z_deflateReset
    #  define deflateParams z_deflateParams
    #  define inflateInit2_ z_inflateInit2_
    #  define inflateSetDictionary z_inflateSetDictionary
    #  define inflateSync   z_inflateSync
    #  define inflateReset  z_inflateReset
    #  define compress      z_compress
    #  define uncompress    z_uncompress
    #  define adler32       z_adler32
    #  define crc32         z_crc32
    #  define get_crc_table z_get_crc_table
    
    #  define Byte          z_Byte
    #  define uInt          z_uInt
    #  define uLong         z_uLong
    #  define Bytef         z_Bytef
    #  define charf         z_charf
    #  define intf          z_intf
   #  define uIntf         z_uIntf
   #  define uLongf        z_uLongf
   #  define voidpf        z_voidpf
   #  define voidp         z_voidp
   #endif
   
   #if (defined(_WIN32) || defined(__WIN32__)) && !defined(WIN32)
   #  define WIN32
   #endif
   #if defined(__GNUC__) || defined(WIN32) || defined(__386__) || defined(i386)
   #  ifndef __32BIT__
   #    define __32BIT__
   #  endif
   #endif
   #if defined(__MSDOS__) && !defined(MSDOS)
   #  define MSDOS
   #endif
   
   /*
    * Compile with -DMAXSEG_64K if the alloc function cannot allocate more
    * than 64k bytes at a time (needed on systems with 16-bit int).
    */
   #if defined(MSDOS) && !defined(__32BIT__)
   #  define MAXSEG_64K
   #endif
   #ifdef MSDOS
   #  define UNALIGNED_OK
   #endif
   
   #if (defined(MSDOS) || defined(_WINDOWS) || defined(WIN32))  && !defined(STDC)
   #  define STDC
   #endif
   #if (defined(__STDC__) || defined(__cplusplus)) && !defined(STDC)
   #  define STDC
   #endif
   
   #ifndef STDC
   #  ifndef const /* cannot use !defined(STDC) && !defined(const) on Mac */
   #    define const
   #  endif
   #endif
   
   /* Some Mac compilers merge all .h files incorrectly: */
   #if defined(__MWERKS__) || defined(applec) ||defined(THINK_C) ||defined(__SC__)
   #  define NO_DUMMY_DECL
   #endif
   
   /* Maximum value for memLevel in deflateInit2 */
   #ifndef MAX_MEM_LEVEL
   #  ifdef MAXSEG_64K
   #    define MAX_MEM_LEVEL 8
   #  else
   #    define MAX_MEM_LEVEL 9
   #  endif
   #endif
   
   /* Maximum value for windowBits in deflateInit2 and inflateInit2 */
   #ifndef MAX_WBITS
   #  define MAX_WBITS   15 /* 32K LZ77 window */
   #endif
   
   /* The memory requirements for deflate are (in bytes):
               1 << (windowBits+2)   +  1 << (memLevel+9)
    that is: 128K for windowBits=15  +  128K for memLevel = 8  (default values)
    plus a few kilobytes for small objects. For example, if you want to reduce
    the default memory requirements from 256K to 128K, compile with
        make CFLAGS="-O -DMAX_WBITS=14 -DMAX_MEM_LEVEL=7"
    Of course this will generally degrade compression (there's no free lunch).
   
      The memory requirements for inflate are (in bytes) 1 << windowBits
    that is, 32K for windowBits=15 (default value) plus a few kilobytes
    for small objects.
   */
   
                           /* Type declarations */
   
   #ifndef OF /* function prototypes */
   #  ifdef STDC
   #    define OF(args)  args
   #  else
   #    define OF(args)  ()
   #  endif
   #endif
   
   /* The following definitions for FAR are needed only for MSDOS mixed
    * model programming (small or medium model with some far allocations).
    * This was tested only with MSC; for other MSDOS compilers you may have
    * to define NO_MEMCPY in zutil.h.  If you don't need the mixed model,
    * just define FAR to be empty.
    */
   #if (defined(M_I86SM) || defined(M_I86MM)) && !defined(__32BIT__)
      /* MSC small or medium model */
   #  define SMALL_MEDIUM
   #  ifdef _MSC_VER
   #    define FAR __far
   #  else
   #    define FAR far
   #  endif
   #endif
   #if defined(__BORLANDC__) && (defined(__SMALL__) || defined(__MEDIUM__))
   #  ifndef __32BIT__
   #    define SMALL_MEDIUM
   #    define FAR __far
   #  endif
   #endif
   #ifndef FAR
   #   define FAR
   #endif
   
   typedef unsigned char  Byte;  /* 8 bits */
   typedef unsigned int   uInt;  /* 16 bits or more */
   typedef unsigned long  uLong; /* 32 bits or more */
   
   #if defined(__BORLANDC__) && defined(SMALL_MEDIUM)
      /* Borland C/C++ ignores FAR inside typedef */
   #  define Bytef Byte FAR
   #else
      typedef Byte  FAR Bytef;
   #endif
   typedef char  FAR charf;
   typedef int   FAR intf;
   typedef uInt  FAR uIntf;
   typedef uLong FAR uLongf;
   
   #ifdef STDC
      typedef void FAR *voidpf;
      typedef void     *voidp;
   #else
      typedef Byte FAR *voidpf;
      typedef Byte     *voidp;
   #endif
   
   
   /* Compile with -DZLIB_DLL for Windows DLL support */
   #if (defined(_WINDOWS) || defined(WINDOWS)) && defined(ZLIB_DLL)
   #  include <windows.h>
   #  define EXPORT  WINAPI
   #else
   #  define EXPORT
   #endif
   
   #endif /* _ZCONF_H */
   /* --- zconf.h */
   
   #define ZLIB_VERSION "1.0.4P"
   
   /* 
        The 'zlib' compression library provides in-memory compression and
     decompression functions, including integrity checks of the uncompressed
     data.  This version of the library supports only one compression method
     (deflation) but other algorithms may be added later and will have the same
     stream interface.
   
        For compression the application must provide the output buffer and
     may optionally provide the input buffer for optimization. For decompression,
     the application must provide the input buffer and may optionally provide
     the output buffer for optimization.
   
        Compression can be done in a single step if the buffers are large
     enough (for example if an input file is mmap'ed), or can be done by
     repeated calls of the compression function.  In the latter case, the
     application must provide more input and/or consume the output
     (providing more output space) before each call.
   
        The library does not install any signal handler. It is recommended to
     add at least a handler for SIGSEGV when decompressing; the library checks
     the consistency of the input data whenever possible but may go nuts
     for some forms of corrupted input.
   */
   
   typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
   typedef void   (*free_func)  OF((voidpf opaque, voidpf address));
   
   struct internal_state;
   
   typedef struct z_stream_s {
       Bytef    *next_in;  /* next input byte */
       uInt     avail_in;  /* number of bytes available at next_in */
       uLong    total_in;  /* total nb of input bytes read so far */
   
       Bytef    *next_out; /* next output byte should be put there */
       uInt     avail_out; /* remaining free space at next_out */
       uLong    total_out; /* total nb of bytes output so far */
   
       char     *msg;      /* last error message, NULL if no error */
       struct internal_state FAR *state; /* not visible by applications */
   
       alloc_func zalloc;  /* used to allocate the internal state */
       free_func  zfree;   /* used to free the internal state */
       voidpf     opaque;  /* private data object passed to zalloc and zfree */
   
       int     data_type;  /* best guess about the data type: ascii or binary */
       uLong   adler;      /* adler32 value of the uncompressed data */
       uLong   reserved;   /* reserved for future use */
   } z_stream;
   
   typedef z_stream FAR *z_streamp;
   
   /*
      The application must update next_in and avail_in when avail_in has
      dropped to zero. It must update next_out and avail_out when avail_out
      has dropped to zero. The application must initialize zalloc, zfree and
      opaque before calling the init function. All other fields are set by the
      compression library and must not be updated by the application.
   
      The opaque value provided by the application will be passed as the first
      parameter for calls of zalloc and zfree. This can be useful for custom
      memory management. The compression library attaches no meaning to the
      opaque value.
   
      zalloc must return Z_NULL if there is not enough memory for the object.
      On 16-bit systems, the functions zalloc and zfree must be able to allocate
      exactly 65536 bytes, but will not be required to allocate more than this
      if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
      pointers returned by zalloc for objects of exactly 65536 bytes *must*
      have their offset normalized to zero. The default allocation function
      provided by this library ensures this (see zutil.c). To reduce memory
      requirements and avoid any allocation of 64K objects, at the expense of
      compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
   
      The fields total_in and total_out can be used for statistics or
      progress reports. After compression, total_in holds the total size of
      the uncompressed data and may be saved for use in the decompressor
      (particularly if the decompressor wants to decompress everything in
      a single step).
   */
   
                           /* constants */
   
   #define Z_NO_FLUSH      0
   #define Z_PARTIAL_FLUSH 1
   #define Z_PACKET_FLUSH  2
   #define Z_SYNC_FLUSH    3
   #define Z_FULL_FLUSH    4
   #define Z_FINISH        5
   /* Allowed flush values; see deflate() below for details */
   
   #define Z_OK            0
   #define Z_STREAM_END    1
   #define Z_NEED_DICT     2
   #define Z_ERRNO        (-1)
   #define Z_STREAM_ERROR (-2)
   #define Z_DATA_ERROR   (-3)
   #define Z_MEM_ERROR    (-4)
   #define Z_BUF_ERROR    (-5)
   #define Z_VERSION_ERROR (-6)
   /* Return codes for the compression/decompression functions. Negative
    * values are errors, positive values are used for special but normal events.
    */
   
   #define Z_NO_COMPRESSION         0
   #define Z_BEST_SPEED             1
   #define Z_BEST_COMPRESSION       9
   #define Z_DEFAULT_COMPRESSION  (-1)
   /* compression levels */
   
   #define Z_FILTERED            1
   #define Z_HUFFMAN_ONLY        2
   #define Z_DEFAULT_STRATEGY    0
   /* compression strategy; see deflateInit2() below for details */
   
   #define Z_BINARY   0
   #define Z_ASCII    1
   #define Z_UNKNOWN  2
   /* Possible values of the data_type field */
   
   #define Z_DEFLATED   8
   /* The deflate compression method (the only one supported in this version) */
   
   #define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
   
   #define zlib_version zlibVersion()
   /* for compatibility with versions < 1.0.2 */
   
                           /* basic functions */
   
   extern const char * EXPORT zlibVersion OF((void));
   /* The application can compare zlibVersion and ZLIB_VERSION for consistency.
      If the first character differs, the library code actually used is
      not compatible with the zlib.h header file used by the application.
      This check is automatically made by deflateInit and inflateInit.
    */
   
   /* 
   extern int EXPORT deflateInit OF((z_streamp strm, int level));
   
        Initializes the internal stream state for compression. The fields
      zalloc, zfree and opaque must be initialized before by the caller.
      If zalloc and zfree are set to Z_NULL, deflateInit updates them to
      use default allocation functions.
   
        The compression level must be Z_DEFAULT_COMPRESSION, or between 0 and 9:
      1 gives best speed, 9 gives best compression, 0 gives no compression at
      all (the input data is simply copied a block at a time).
      Z_DEFAULT_COMPRESSION requests a default compromise between speed and
      compression (currently equivalent to level 6).
   
        deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
      enough memory, Z_STREAM_ERROR if level is not a valid compression level,
      Z_VERSION_ERROR if the zlib library version (zlib_version) is incompatible
      with the version assumed by the caller (ZLIB_VERSION).
      msg is set to null if there is no error message.  deflateInit does not
      perform any compression: this will be done by deflate().
   */
   
   
   extern int EXPORT deflate OF((z_streamp strm, int flush));
   /*
     Performs one or both of the following actions:
   
     - Compress more input starting at next_in and update next_in and avail_in
       accordingly. If not all input can be processed (because there is not
       enough room in the output buffer), next_in and avail_in are updated and
       processing will resume at this point for the next call of deflate().
   
     - Provide more output starting at next_out and update next_out and avail_out
       accordingly. This action is forced if the parameter flush is non zero.
       Forcing flush frequently degrades the compression ratio, so this parameter
       should be set only when necessary (in interactive applications).
       Some output may be provided even if flush is not set.
   
     Before the call of deflate(), the application should ensure that at least
     one of the actions is possible, by providing more input and/or consuming
     more output, and updating avail_in or avail_out accordingly; avail_out
     should never be zero before the call. The application can consume the
     compressed output when it wants, for example when the output buffer is full
     (avail_out == 0), or after each call of deflate(). If deflate returns Z_OK
     and with zero avail_out, it must be called again after making room in the
     output buffer because there might be more output pending.
   
       If the parameter flush is set to Z_PARTIAL_FLUSH, the current compression
     block is terminated and flushed to the output buffer so that the
     decompressor can get all input data available so far. For method 9, a future
     variant on method 8, the current block will be flushed but not terminated.
     Z_SYNC_FLUSH has the same effect as partial flush except that the compressed
     output is byte aligned (the compressor can clear its internal bit buffer)
     and the current block is always terminated; this can be useful if the
     compressor has to be restarted from scratch after an interruption (in which
     case the internal state of the compressor may be lost).
       If flush is set to Z_FULL_FLUSH, the compression block is terminated, a
     special marker is output and the compression dictionary is discarded; this
     is useful to allow the decompressor to synchronize if one compressed block
     has been damaged (see inflateSync below).  Flushing degrades compression and
     so should be used only when necessary.  Using Z_FULL_FLUSH too often can
     seriously degrade the compression. If deflate returns with avail_out == 0,
     this function must be called again with the same value of the flush
     parameter and more output space (updated avail_out), until the flush is
     complete (deflate returns with non-zero avail_out).
   
       If the parameter flush is set to Z_PACKET_FLUSH, the compression
     block is terminated, and a zero-length stored block is output,
     omitting the length bytes (the effect of this is that the 3-bit type
     code 000 for a stored block is output, and the output is then
     byte-aligned).  This is designed for use at the end of a PPP packet.
   
       If the parameter flush is set to Z_FINISH, pending input is processed,
     pending output is flushed and deflate returns with Z_STREAM_END if there
     was enough output space; if deflate returns with Z_OK, this function must be
     called again with Z_FINISH and more output space (updated avail_out) but no
     more input data, until it returns with Z_STREAM_END or an error. After
     deflate has returned Z_STREAM_END, the only possible operations on the
     stream are deflateReset or deflateEnd.
     
       Z_FINISH can be used immediately after deflateInit if all the compression
     is to be done in a single step. In this case, avail_out must be at least
     0.1% larger than avail_in plus 12 bytes.  If deflate does not return
     Z_STREAM_END, then it must be called again as described above.
   
       deflate() may update data_type if it can make a good guess about
     the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
     binary. This field is only for information purposes and does not affect
     the compression algorithm in any manner.
   
       deflate() returns Z_OK if some progress has been made (more input
     processed or more output produced), Z_STREAM_END if all input has been
     consumed and all output has been produced (only when flush is set to
     Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
     if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
   */
   
   
   extern int EXPORT deflateEnd OF((z_streamp strm));
   /*
        All dynamically allocated data structures for this stream are freed.
      This function discards any unprocessed input and does not flush any
      pending output.
   
        deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
      stream state was inconsistent, Z_DATA_ERROR if the stream was freed
      prematurely (some input or output was discarded). In the error case,
      msg may be set but then points to a static string (which must not be
      deallocated).
   */
   
   
   /* 
   extern int EXPORT inflateInit OF((z_streamp strm));
   
        Initializes the internal stream state for decompression. The fields
      zalloc, zfree and opaque must be initialized before by the caller.  If
      zalloc and zfree are set to Z_NULL, inflateInit updates them to use default
      allocation functions.
   
        inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
      enough memory, Z_VERSION_ERROR if the zlib library version is incompatible
      with the version assumed by the caller.  msg is set to null if there is no
      error message. inflateInit does not perform any decompression: this will be
      done by inflate().
   */
   
   #if defined(__FreeBSD__) && (defined(KERNEL) || defined(_KERNEL))
   #define inflate       inflate_ppp     /* FreeBSD already has an inflate :-( */
   #endif
   
   extern int EXPORT inflate OF((z_streamp strm, int flush));
   /*
     Performs one or both of the following actions:
   
     - Decompress more input starting at next_in and update next_in and avail_in
       accordingly. If not all input can be processed (because there is not
       enough room in the output buffer), next_in is updated and processing
       will resume at this point for the next call of inflate().
   
     - Provide more output starting at next_out and update next_out and avail_out
       accordingly.  inflate() provides as much output as possible, until there
       is no more input data or no more space in the output buffer (see below
       about the flush parameter).
   
     Before the call of inflate(), the application should ensure that at least
     one of the actions is possible, by providing more input and/or consuming
     more output, and updating the next_* and avail_* values accordingly.
     The application can consume the uncompressed output when it wants, for
     example when the output buffer is full (avail_out == 0), or after each
     call of inflate(). If inflate returns Z_OK and with zero avail_out, it
     must be called again after making room in the output buffer because there
     might be more output pending.
   
       If the parameter flush is set to Z_PARTIAL_FLUSH or Z_PACKET_FLUSH,
     inflate flushes as much output as possible to the output buffer. The
     flushing behavior of inflate is not specified for values of the flush
     parameter other than Z_PARTIAL_FLUSH, Z_PACKET_FLUSH or Z_FINISH, but the
     current implementation actually flushes as much output as possible
     anyway.  For Z_PACKET_FLUSH, inflate checks that once all the input data
     has been consumed, it is expecting to see the length field of a stored
     block; if not, it returns Z_DATA_ERROR.
   
       inflate() should normally be called until it returns Z_STREAM_END or an
     error. However if all decompression is to be performed in a single step
     (a single call of inflate), the parameter flush should be set to
     Z_FINISH. In this case all pending input is processed and all pending
     output is flushed; avail_out must be large enough to hold all the
     uncompressed data. (The size of the uncompressed data may have been saved
     by the compressor for this purpose.) The next operation on this stream must
     be inflateEnd to deallocate the decompression state. The use of Z_FINISH
     is never required, but can be used to inform inflate that a faster routine
     may be used for the single inflate() call.
   
       inflate() returns Z_OK if some progress has been made (more input
     processed or more output produced), Z_STREAM_END if the end of the
     compressed data has been reached and all uncompressed output has been
     produced, Z_NEED_DICT if a preset dictionary is needed at this point (see
     inflateSetDictionary below), Z_DATA_ERROR if the input data was corrupted,
     Z_STREAM_ERROR if the stream structure was inconsistent (for example if
     next_in or next_out was NULL), Z_MEM_ERROR if there was not enough memory,
     Z_BUF_ERROR if no progress is possible or if there was not enough room in
     the output buffer when Z_FINISH is used. In the Z_DATA_ERROR case, the
     application may then call inflateSync to look for a good compression block.
     In the Z_NEED_DICT case, strm->adler is set to the Adler32 value of the
     dictionary chosen by the compressor.
   */
   
   
   extern int EXPORT inflateEnd OF((z_streamp strm));
   /*
        All dynamically allocated data structures for this stream are freed.
      This function discards any unprocessed input and does not flush any
      pending output.
   
        inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
      was inconsistent. In the error case, msg may be set but then points to a
      static string (which must not be deallocated).
   */
   
                           /* Advanced functions */
   
   /*
       The following functions are needed only in some special applications.
   */
   
   /*   
   extern int EXPORT deflateInit2 OF((z_streamp strm,
                                      int  level,
                                      int  method,
                                      int  windowBits,
                                      int  memLevel,
                                      int  strategy));
   
        This is another version of deflateInit with more compression options. The
      fields next_in, zalloc, zfree and opaque must be initialized before by
      the caller.
   
        The method parameter is the compression method. It must be Z_DEFLATED in
      this version of the library. (Method 9 will allow a 64K history buffer and
      partial block flushes.)
   
        The windowBits parameter is the base two logarithm of the window size
      (the size of the history buffer).  It should be in the range 8..15 for this
      version of the library (the value 16 will be allowed for method 9). Larger
      values of this parameter result in better compression at the expense of
      memory usage. The default value is 15 if deflateInit is used instead.
   
        The memLevel parameter specifies how much memory should be allocated
      for the internal compression state. memLevel=1 uses minimum memory but
      is slow and reduces compression ratio; memLevel=9 uses maximum memory
      for optimal speed. The default value is 8. See zconf.h for total memory
      usage as a function of windowBits and memLevel.
   
        The strategy parameter is used to tune the compression algorithm. Use the
      value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data produced by a
      filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
      string match).  Filtered data consists mostly of small values with a
      somewhat random distribution. In this case, the compression algorithm is
      tuned to compress them better. The effect of Z_FILTERED is to force more
      Huffman coding and less string matching; it is somewhat intermediate
      between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
      the compression ratio but not the correctness of the compressed output even
      if it is not set appropriately.
   
        If next_in is not null, the library will use this buffer to hold also
      some history information; the buffer must either hold the entire input
      data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
      is null, the library will allocate its own history buffer (and leave next_in
      null). next_out need not be provided here but must be provided by the
      application for the next call of deflate().
   
        If the history buffer is provided by the application, next_in must
      must never be changed by the application since the compressor maintains
      information inside this buffer from call to call; the application
      must provide more input only by increasing avail_in. next_in is always
      reset by the library in this case.
   
         deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
      not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
      an invalid method). msg is set to null if there is no error message.
      deflateInit2 does not perform any compression: this will be done by
      deflate(). 
   */
                               
   extern int EXPORT deflateSetDictionary OF((z_streamp strm,
                                              const Bytef *dictionary,
                                              uInt  dictLength));
   /*
        Initializes the compression dictionary (history buffer) from the given
      byte sequence without producing any compressed output. This function must
      be called immediately after deflateInit or deflateInit2, before any call
      of deflate. The compressor and decompressor must use exactly the same
      dictionary (see inflateSetDictionary).
        The dictionary should consist of strings (byte sequences) that are likely
      to be encountered later in the data to be compressed, with the most commonly
      used strings preferably put towards the end of the dictionary. Using a
      dictionary is most useful when the data to be compressed is short and
      can be predicted with good accuracy; the data can then be compressed better
      than with the default empty dictionary. In this version of the library,
      only the last 32K bytes of the dictionary are used.
        Upon return of this function, strm->adler is set to the Adler32 value
      of the dictionary; the decompressor may later use this value to determine
      which dictionary has been used by the compressor. (The Adler32 value
      applies to the whole dictionary even if only a subset of the dictionary is
      actually used by the compressor.)
   
        deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
      parameter is invalid (such as NULL dictionary) or the stream state
      is inconsistent (for example if deflate has already been called for this
      stream). deflateSetDictionary does not perform any compression: this will
      be done by deflate(). 
   */
   
   extern int EXPORT deflateCopy OF((z_streamp dest,
                                     z_streamp source));
   /*
        Sets the destination stream as a complete copy of the source stream.  If
      the source stream is using an application-supplied history buffer, a new
      buffer is allocated for the destination stream.  The compressed output
      buffer is always application-supplied. It's the responsibility of the
      application to provide the correct values of next_out and avail_out for the
      next call of deflate.
   
        This function can be useful when several compression strategies will be
      tried, for example when there are several ways of pre-processing the input
      data with a filter. The streams that will be discarded should then be freed
      by calling deflateEnd.  Note that deflateCopy duplicates the internal
      compression state which can be quite large, so this strategy is slow and
      can consume lots of memory.
   
        deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
      enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
      (such as zalloc being NULL). msg is left unchanged in both source and
      destination.
   */
   
   extern int EXPORT deflateReset OF((z_streamp strm));
   /*
        This function is equivalent to deflateEnd followed by deflateInit,
      but does not free and reallocate all the internal compression state.
      The stream will keep the same compression level and any other attributes
      that may have been set by deflateInit2.
   
         deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
      stream state was inconsistent (such as zalloc or state being NULL).
   */
   
   extern int EXPORT deflateParams OF((z_streamp strm, int level, int strategy));
   /*
        Dynamically update the compression level and compression strategy.
      This can be used to switch between compression and straight copy of
      the input data, or to switch to a different kind of input data requiring
      a different strategy. If the compression level is changed, the input
      available so far is compressed with the old level (and may be flushed);
      the new level will take effect only at the next call of deflate().
   
        Before the call of deflateParams, the stream state must be set as for
      a call of deflate(), since the currently available input may have to
      be compressed and flushed. In particular, strm->avail_out must be non-zero.
   
        deflateParams returns Z_OK if success, Z_STREAM_ERROR if the source
      stream state was inconsistent or if a parameter was invalid, Z_BUF_ERROR
      if strm->avail_out was zero.
   */
   
   extern int EXPORT deflateOutputPending OF((z_streamp strm));
   /*
        Returns the number of bytes of output which are immediately
      available from the compressor (i.e. without any further input
      or flush).
   */
   
   /*   
   extern int EXPORT inflateInit2 OF((z_streamp strm,
                                      int  windowBits));
   
        This is another version of inflateInit with more compression options. The
      fields next_out, zalloc, zfree and opaque must be initialized before by
      the caller.
   
        The windowBits parameter is the base two logarithm of the maximum window
      size (the size of the history buffer).  It should be in the range 8..15 for
      this version of the library (the value 16 will be allowed soon). The
      default value is 15 if inflateInit is used instead. If a compressed stream
      with a larger window size is given as input, inflate() will return with
      the error code Z_DATA_ERROR instead of trying to allocate a larger window.
   
        If next_out is not null, the library will use this buffer for the history
      buffer; the buffer must either be large enough to hold the entire output
      data, or have at least 1<<windowBits bytes.  If next_out is null, the
      library will allocate its own buffer (and leave next_out null). next_in
      need not be provided here but must be provided by the application for the
      next call of inflate().
   
        If the history buffer is provided by the application, next_out must
      never be changed by the application since the decompressor maintains
      history information inside this buffer from call to call; the application
      can only reset next_out to the beginning of the history buffer when
      avail_out is zero and all output has been consumed.
   
         inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
      not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
      windowBits < 8). msg is set to null if there is no error message.
      inflateInit2 does not perform any decompression: this will be done by
      inflate().
   */
   
   extern int EXPORT inflateSetDictionary OF((z_streamp strm,
                                              const Bytef *dictionary,
                                              uInt  dictLength));
   /*
        Initializes the decompression dictionary (history buffer) from the given
      uncompressed byte sequence. This function must be called immediately after
      a call of inflate if this call returned Z_NEED_DICT. The dictionary chosen
      by the compressor can be determined from the Adler32 value returned by this
      call of inflate. The compressor and decompressor must use exactly the same
      dictionary (see deflateSetDictionary).
   
        inflateSetDictionary returns Z_OK if success, Z_STREAM_ERROR if a
      parameter is invalid (such as NULL dictionary) or the stream state is
      inconsistent, Z_DATA_ERROR if the given dictionary doesn't match the
      expected one (incorrect Adler32 value). inflateSetDictionary does not
      perform any decompression: this will be done by subsequent calls of
      inflate().
   */
   
   extern int EXPORT inflateSync OF((z_streamp strm));
   /* 
       Skips invalid compressed data until the special marker (see deflate()
     above) can be found, or until all available input is skipped. No output
     is provided.
   
       inflateSync returns Z_OK if the special marker has been found, Z_BUF_ERROR
     if no more input was provided, Z_DATA_ERROR if no marker has been found,
     or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
     case, the application may save the current current value of total_in which
     indicates where valid compressed data was found. In the error case, the
     application may repeatedly call inflateSync, providing more input each time,
     until success or end of the input data.
   */
   
   extern int EXPORT inflateReset OF((z_streamp strm));
   /*
        This function is equivalent to inflateEnd followed by inflateInit,
      but does not free and reallocate all the internal decompression state.
      The stream will keep attributes that may have been set by inflateInit2.
   
         inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
      stream state was inconsistent (such as zalloc or state being NULL).
   */
   
   extern int inflateIncomp OF((z_stream *strm));
   /*
        This function adds the data at next_in (avail_in bytes) to the output
      history without performing any output.  There must be no pending output,
      and the decompressor must be expecting to see the start of a block.
      Calling this function is equivalent to decompressing a stored block
      containing the data at next_in (except that the data is not output).
   */
   
                           /* utility functions */
   
   /*
        The following utility functions are implemented on top of the
      basic stream-oriented functions. To simplify the interface, some
      default options are assumed (compression level, window size,
      standard memory allocation functions). The source code of these
      utility functions can easily be modified if you need special options.
   */
   
   extern int EXPORT compress OF((Bytef *dest,   uLongf *destLen,
                                  const Bytef *source, uLong sourceLen));
   /*
        Compresses the source buffer into the destination buffer.  sourceLen is
      the byte length of the source buffer. Upon entry, destLen is the total
      size of the destination buffer, which must be at least 0.1% larger than
      sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
      compressed buffer.
        This function can be used to compress a whole file at once if the
      input file is mmap'ed.
        compress returns Z_OK if success, Z_MEM_ERROR if there was not
      enough memory, Z_BUF_ERROR if there was not enough room in the output
      buffer.
   */
   
   extern int EXPORT uncompress OF((Bytef *dest,   uLongf *destLen,
                                    const Bytef *source, uLong sourceLen));
   /*
        Decompresses the source buffer into the destination buffer.  sourceLen is
      the byte length of the source buffer. Upon entry, destLen is the total
      size of the destination buffer, which must be large enough to hold the
      entire uncompressed data. (The size of the uncompressed data must have
      been saved previously by the compressor and transmitted to the decompressor
      by some mechanism outside the scope of this compression library.)
      Upon exit, destLen is the actual size of the compressed buffer.
        This function can be used to decompress a whole file at once if the
      input file is mmap'ed.
   
        uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
      enough memory, Z_BUF_ERROR if there was not enough room in the output
      buffer, or Z_DATA_ERROR if the input data was corrupted.
   */
   
   
   typedef voidp gzFile;
   
   extern gzFile EXPORT gzopen  OF((const char *path, const char *mode));
   /*
        Opens a gzip (.gz) file for reading or writing. The mode parameter
      is as in fopen ("rb" or "wb") but can also include a compression level
      ("wb9").  gzopen can be used to read a file which is not in gzip format;
      in this case gzread will directly read from the file without decompression.
        gzopen returns NULL if the file could not be opened or if there was
      insufficient memory to allocate the (de)compression state; errno
      can be checked to distinguish the two cases (if errno is zero, the
      zlib error is Z_MEM_ERROR).
   */
   
   extern gzFile EXPORT gzdopen  OF((int fd, const char *mode));
   /*
        gzdopen() associates a gzFile with the file descriptor fd.  File
      descriptors are obtained from calls like open, dup, creat, pipe or
      fileno (in the file has been previously opened with fopen).
      The mode parameter is as in gzopen.
        The next call of gzclose on the returned gzFile will also close the
      file descriptor fd, just like fclose(fdopen(fd), mode) closes the file
      descriptor fd. If you want to keep fd open, use gzdopen(dup(fd), mode).
        gzdopen returns NULL if there was insufficient memory to allocate
      the (de)compression state.
   */
   
   extern int EXPORT    gzread  OF((gzFile file, voidp buf, unsigned len));
   /*
        Reads the given number of uncompressed bytes from the compressed file.
      If the input file was not in gzip format, gzread copies the given number
      of bytes into the buffer.
        gzread returns the number of uncompressed bytes actually read (0 for
      end of file, -1 for error). */
   
   extern int EXPORT    gzwrite OF((gzFile file, const voidp buf, unsigned len));
   /*
        Writes the given number of uncompressed bytes into the compressed file.
      gzwrite returns the number of uncompressed bytes actually written
      (0 in case of error).
   */
   
   extern int EXPORT    gzflush OF((gzFile file, int flush));
   /*
        Flushes all pending output into the compressed file. The parameter
      flush is as in the deflate() function. The return value is the zlib
      error number (see function gzerror below). gzflush returns Z_OK if
      the flush parameter is Z_FINISH and all output could be flushed.
        gzflush should be called only when strictly necessary because it can
      degrade compression.
   */
   
   extern int EXPORT    gzclose OF((gzFile file));
   /*
        Flushes all pending output if necessary, closes the compressed file
      and deallocates all the (de)compression state. The return value is the zlib
      error number (see function gzerror below).
   */
   
   extern const char * EXPORT gzerror OF((gzFile file, int *errnum));
   /*
        Returns the error message for the last error which occurred on the
      given compressed file. errnum is set to zlib error number. If an
      error occurred in the file system and not in the compression library,
      errnum is set to Z_ERRNO and the application may consult errno
      to get the exact error code.
   */
   
                           /* checksum functions */
   
   /*
        These functions are not related to compression but are exported
      anyway because they might be useful in applications using the
      compression library.
   */
   
   extern uLong EXPORT adler32 OF((uLong adler, const Bytef *buf, uInt len));
   
   /*
        Update a running Adler-32 checksum with the bytes buf[0..len-1] and
      return the updated checksum. If buf is NULL, this function returns
      the required initial value for the checksum.
      An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
      much faster. Usage example:
   
        uLong adler = adler32(0L, Z_NULL, 0);
   
        while (read_buffer(buffer, length) != EOF) {
          adler = adler32(adler, buffer, length);
        }
        if (adler != original_adler) error();
   */
   
   extern uLong EXPORT crc32   OF((uLong crc, const Bytef *buf, uInt len));
   /*
        Update a running crc with the bytes buf[0..len-1] and return the updated
      crc. If buf is NULL, this function returns the required initial value
      for the crc. Pre- and post-conditioning (one's complement) is performed
      within this function so it shouldn't be done by the application.
      Usage example:
   
        uLong crc = crc32(0L, Z_NULL, 0);
   
        while (read_buffer(buffer, length) != EOF) {
          crc = crc32(crc, buffer, length);
        }
        if (crc != original_crc) error();
   */
   
   
                           /* various hacks, don't look :) */
   
   /* deflateInit and inflateInit are macros to allow checking the zlib version
    * and the compiler's view of z_stream:
    */
   extern int EXPORT deflateInit_ OF((z_streamp strm, int level,
                                      const char *version, int stream_size));
   extern int EXPORT inflateInit_ OF((z_streamp strm,
                                      const char *version, int stream_size));
   extern int EXPORT deflateInit2_ OF((z_streamp strm, int  level, int  method,
                                       int windowBits, int memLevel, int strategy,
                                       const char *version, int stream_size));
   extern int EXPORT inflateInit2_ OF((z_streamp strm, int  windowBits,
                                       const char *version, int stream_size));
   #define deflateInit(strm, level) \
           deflateInit_((strm), (level),       ZLIB_VERSION, sizeof(z_stream))
   #define inflateInit(strm) \
           inflateInit_((strm),                ZLIB_VERSION, sizeof(z_stream))
   #define deflateInit2(strm, level, method, windowBits, memLevel, strategy) \
           deflateInit2_((strm),(level),(method),(windowBits),(memLevel),\
                         (strategy),           ZLIB_VERSION, sizeof(z_stream))
   #define inflateInit2(strm, windowBits) \
          inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
  
  #if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
      struct internal_state {int dummy;}; /* hack for buggy compilers */
  #endif
  
  uLongf *get_crc_table OF((void)); /* can be used by asm versions of crc32() */
  
  #ifdef __cplusplus
  }
  #endif
  
  #endif /* _ZLIB_H */
  /* --- zlib.h */

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