diff zlib/zlib.h @ 3:5a977ccbc7a9 default tip

Empty changelog
author darius
date Sat, 06 Dec 1997 05:41:29 +0000
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+/* zlib.h -- interface of the 'zlib' general purpose compression library
+  version 0.92 May 3rd, 1995.
+
+  Copyright (C) 1995 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@cco.caltech.edu
+ */
+
+#ifndef _ZLIB_H
+#define _ZLIB_H
+
+#include "zconf.h"
+
+#define ZLIB_VERSION "0.92"
+
+/* 
+     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.
+*/
+
+typedef voidp (*alloc_func) __P((voidp opaque, uInt items, uInt size));
+typedef void  (*free_func)  __P((voidp opaque, voidp address));
+
+struct internal_state;
+
+typedef struct z_stream_s {
+    Byte     *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 */
+
+    Byte     *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 *state; /* not visible by applications */
+
+    alloc_func zalloc;  /* used to allocate the internal state */
+    free_func  zfree;   /* used to free the internal state */
+    voidp      opaque;  /* private data object passed to zalloc and zfree */
+
+    Byte     data_type; /* best guess about the data type: ascii or binary */
+
+} z_stream;
+
+/*
+   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_FULL_FLUSH    2
+#define Z_FINISH        4
+/* See deflate() below for the usage of these constants */
+
+#define Z_OK            0
+#define Z_STREAM_END    1
+#define Z_ERRNO        (-1)
+#define Z_STREAM_ERROR (-2)
+#define Z_DATA_ERROR   (-3)
+#define Z_MEM_ERROR    (-4)
+#define Z_BUF_ERROR    (-5)
+/* error codes for the compression/decompression functions */
+
+#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
+
+#define Z_BINARY   0
+#define Z_ASCII    1
+#define Z_UNKNOWN  2
+/* Used to set the data_type field */
+
+#define Z_NULL  0  /* for initializing zalloc, zfree, opaque */
+
+extern char *zlib_version;
+/* The application can compare zlib_version 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.
+ */
+
+                        /* basic functions */
+
+extern int deflateInit __P((z_stream *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 1 and 9:
+   1 gives best speed, 9 gives best compression. 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.
+   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 deflate __P((z_stream *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 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.
+  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 the parameter flush is set to Z_FINISH, all pending input is processed,
+  all 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 deflateEnd __P((z_stream *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. In the error case, msg may be set
+   but then points to a static string (which must not be deallocated).
+*/
+
+
+extern int inflateInit __P((z_stream *strm));
+/* 
+     Initializes the internal stream state for decompression. The fields
+   zalloc and zfree must be initialized before by the caller.  If zalloc and
+   zfree are set to Z_NULL, deflateInit updates them to use default allocation
+   functions.
+
+     inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
+   enough memory.  msg is set to null if there is no error message.
+   inflateInit does not perform any decompression: this will be done by
+   inflate().
+*/
+
+
+extern int inflate __P((z_stream *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() always provides as much output as possible
+    (until no more input data or no more space in the output buffer).
+
+  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 the parameter flush is set to Z_PARTIAL_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
+  and Z_FINISH, but the current implementation actually flushes as much output
+  as possible anyway.
+
+    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.
+
+    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_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.
+*/
+
+
+extern int inflateEnd __P((z_stream *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 deflateInit2 __P((z_stream *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 and zfree must be initialized before by the caller.
+
+     The method parameter is the compression method. It must be 8 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 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 deflateCopy __P((z_stream *dest,
+                            z_stream *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 is 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 deflateReset __P((z_stream *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 inflateInit2 __P((z_stream *strm,
+                             int  windowBits));
+/*   
+     This is another version of inflateInit with more compression options. The
+   fields next_out, zalloc and zfree 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 compression: this will be done by
+   inflate().
+*/
+
+extern int inflateSync __P((z_stream *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 inflateReset __P((z_stream *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).
+*/
+
+
+                        /* 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 compress __P((Byte *dest,   uLong *destLen,
+                         Byte *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 uncompress __P((Byte *dest,   uLong *destLen,
+                           Byte *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 gzopen  __P((char *path, char *mode));
+/*
+     Opens a gzip (.gz) file for reading or writing. The mode parameter
+   is as in fopen ("rb" or "wb"). gzopen can also 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 gzdopen  __P((int fd, char *mode));
+/*
+     gzdopen() associates a gzFile with the file descriptor fd.  File
+   descriptors are obtained from calls like open, dup, creat, or pipe.
+   The mode parameter is as in fopen ("rb" or "wb").
+     gzdopen returns NULL if there was insufficient memory to allocate
+   the (de)compression state.
+*/
+
+extern int    gzread  __P((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    gzwrite __P((gzFile file, 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    gzflush __P((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    gzclose __P((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 char*   gzerror __P((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 adler32 __P((uLong adler, Byte *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 crc32   __P((uLong crc, Byte *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();
+*/
+
+#ifndef _Z_UTIL_H
+    struct internal_state {int dummy;}; /* hack for buggy compilers */
+#endif
+
+#endif /* _ZLIB_H */