zlib.h

Axis 221 camera embedded programing interface

   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.

      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().
*/
                            
#if 0
extern int zlib_deflateSetDictionary (z_streamp strm,
						     const Byte *dictionary,
						     uInt  dictLength);
#endif
/*
     Initializes the compression dictionary from the given byte sequence
   without producing any compressed output. This function must be called
   immediately after deflateInit, deflateInit2 or deflateReset, 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.

     Depending on the size of the compression data structures selected by
   deflateInit or deflateInit2, a part of the dictionary may in effect be
   discarded, for example if the dictionary is larger than the window size in
   deflate or deflate2. Thus the strings most likely to be useful should be
   put at the end of the dictionary, not at the front.

     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
   or if the compression method is bsort). deflateSetDictionary does not
   perform any compression: this will be done by deflate().
*/

#if 0
extern int zlib_deflateCopy (z_streamp dest, z_streamp source);
#endif

/*
     Sets the destination stream as a complete copy of the source stream.

     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 zlib_deflateReset (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).
*/

static inline unsigned long deflateBound(unsigned long s)
{
	return s + ((s + 7) >> 3) + ((s + 63) >> 6) + 11;
}

#if 0
extern int zlib_deflateParams (z_streamp strm, int level, int strategy);
#endif
/*
     Dynamically update the compression level and compression strategy.  The
   interpretation of level and strategy is as in deflateInit2.  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 inflateInit2 (z_streamp strm, int  windowBits);

     This is another version of inflateInit with an extra parameter. The
   fields next_in, avail_in, 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 default value is 15 if inflateInit is used
   instead. windowBits must be greater than or equal to the windowBits value
   provided to deflateInit2() while compressing, or it must be equal to 15 if
   deflateInit2() was not used. 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.

     windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
   determines the window size. inflate() will then process raw deflate data,
   not looking for a zlib or gzip header, not generating a check value, and not
   looking for any check values for comparison at the end of the stream. This
   is for use with other formats that use the deflate compressed data format
   such as zip.  Those formats provide their own check values. If a custom
   format is developed using the raw deflate format for compressed data, it is
   recommended that a check value such as an adler32 or a crc32 be applied to
   the uncompressed data as is done in the zlib, gzip, and zip formats.  For
   most applications, the zlib format should be used as is. Note that comments
   above on the use in deflateInit2() applies to the magnitude of windowBits.

     windowBits can also be greater than 15 for optional gzip decoding. Add
   32 to windowBits to enable zlib and gzip decoding with automatic header
   detection, or add 16 to decode only the gzip format (the zlib format will
   return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is
   a crc32 instead of an adler32.

     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 a null strm). msg
   is set to null if there is no error message.  inflateInit2 does not perform
   any decompression apart from reading the zlib header if present: this will
   be done by inflate(). (So next_in and avail_in may be modified, but next_out
   and avail_out are unchanged.)
*/

extern int zlib_inflateSetDictionary (z_streamp strm,
						     const Byte *dictionary,
						     uInt  dictLength);
/*
     Initializes the decompression dictionary from the given uncompressed byte
   sequence. This function must be called immediately after a call of inflate,
   if that call returned Z_NEED_DICT. The dictionary chosen by the compressor
   can be determined from the adler32 value returned by that call of inflate.
   The compressor and decompressor must use exactly the same dictionary (see
   deflateSetDictionary).  For raw inflate, this function can be called
   immediately after inflateInit2() or inflateReset() and before any call of
   inflate() to set the dictionary.  The application must insure that the
   dictionary that was used for compression is provided.

     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().
*/

#if 0
extern int zlib_inflateSync (z_streamp strm);
#endif
/* 
    Skips invalid compressed data until a full flush point (see above the
  description of deflate with Z_FULL_FLUSH) can be found, or until all
  available input is skipped. No output is provided.

    inflateSync returns Z_OK if a full flush point has been found, Z_BUF_ERROR
  if no more input was provided, Z_DATA_ERROR if no flush point 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 zlib_inflateReset (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 zlib_inflateIncomp (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).
*/

#define zlib_deflateInit(strm, level) \
	zlib_deflateInit2((strm), (level), Z_DEFLATED, MAX_WBITS, \
			      DEF_MEM_LEVEL, Z_DEFAULT_STRATEGY)
#define zlib_inflateInit(strm) \
	zlib_inflateInit2((strm), DEF_WBITS)

extern int zlib_deflateInit2(z_streamp strm, int  level, int  method,
                                      int windowBits, int memLevel,
                                      int strategy);
extern int zlib_inflateInit2(z_streamp strm, int  windowBits);

#if !defined(_Z_UTIL_H) && !defined(NO_DUMMY_DECL)
    struct internal_state {int dummy;}; /* hack for buggy compilers */
#endif

#endif /* _ZLIB_H */