include/linux/zlib.h

1 /* zlib.h -- interface of the 'zlib' general purpose compression library
3   Copyright (C) 1995-2005 Jean-loup Gailly and Mark Adler
5   This software is provided 'as-is', without any express or implied
6   warranty.  In no event will the authors be held liable for any damages
21   Jean-loup Gailly        Mark Adler
44       this checks there is no more input data available and the next data
53      The 'zlib' compression library provides in-memory compression and
62   application must provide more input and/or consume the output
63   (providing more output space) before each call.
65      The compressed data format used by default by the in-memory functions is
73   and on communications channels.  The gzip format was designed for single-
89     Byte    *next_out;  /* next output byte should be put there */
91     uLong    total_out; /* total nb of bytes output so far */
93     char     *msg;      /* last error message, NULL if no error */
114    memory management. The compression library attaches no meaning to the
118    If zlib is used in a multi-threaded application, zalloc and zfree must be
121    On 16-bit systems, the functions zalloc and zfree must be able to allocate
128    compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
151 #define Z_ERRNO        (-1)
152 #define Z_STREAM_ERROR (-2)
153 #define Z_DATA_ERROR   (-3)
154 #define Z_MEM_ERROR    (-4)
155 #define Z_BUF_ERROR    (-5)
156 #define Z_VERSION_ERROR (-6)
164 #define Z_DEFAULT_COMPRESSION  (-1)
184    Returns the number of bytes that needs to be allocated for a per-
186    number of bytes should be returned in stream->workspace before
196    Returns 1 if Deflate-Conversion facility is installed and enabled,
209    1 gives best speed, 9 gives best compression, 0 gives no compression at
218    msg is set to null if there is no error message.  deflateInit does not
226   buffer becomes empty or the output buffer becomes full. It may introduce some
227   output latency (reading input without producing any output) except when
233   - Compress more input starting at next_in and update next_in and avail_in
235     enough room in the output buffer), next_in and avail_in are updated and
238   - Provide more output starting at next_out and update next_out and avail_out
242     Some output may be provided even if flush is not set.
246   more output, and updating avail_in or avail_out accordingly; avail_out
248   compressed output when it wants, for example when the output buffer is full
251   output buffer because there might be more output pending.
253     If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
254   flushed to the output buffer and the output is aligned on a byte boundary, so
256   avail_in is zero after the call if enough output space has been provided
260     If flush is set to Z_FULL_FLUSH, all output is flushed as with
267   with the same value of the flush parameter and more output space (updated
268   avail_out), until the flush is complete (deflate returns with non-zero
272   pending output is flushed and deflate returns with Z_STREAM_END if there
273   was enough output space; if deflate returns with Z_OK, this function must be
274   called again with Z_FINISH and more output space (updated avail_out) but no
284     deflate() sets strm->adler to the adler32 checksum of all input read
293   processed or more output produced), Z_STREAM_END if all input has been
294   consumed and all output has been produced (only when flush is set to
296   if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible
305    pending output.
309    prematurely (some input or output was discarded). In the error case,
317    Returns the number of bytes that needs to be allocated for a per-
319    returned in stream->workspace before calling zlib_inflateInit().
336    version assumed by the caller.  msg is set to null if there is no error
346   buffer becomes empty or the output buffer becomes full. It may introduce
347   some output latency (reading input without producing any output) except when
353   - Decompress more input starting at next_in and update next_in and avail_in
355     enough room in the output buffer), next_in is updated and processing
358   - Provide more output starting at next_out and update next_out and avail_out
359     accordingly.  inflate() provides as much output as possible, until there
360     is no more input data or no more space in the output buffer (see below
365   more output, and updating the next_* and avail_* values accordingly.
366   The application can consume the uncompressed output when it wants, for
367   example when the output buffer is full (avail_out == 0), or after each
369   must be called again after making room in the output buffer because there
370   might be more output pending.
374   output as possible to the output buffer. Z_BLOCK requests that inflate() stop
382   Also to assist in this, on return inflate() will set strm->data_type to the
383   number of unused bits in the last byte taken from strm->next_in, plus 64
385   plus 128 if inflate() returned immediately after decoding an end-of-block
387   deflate stream. The end-of-block will not be indicated until all of the
388   uncompressed data from that block has been written to strm->next_out.  The
397   output is flushed; avail_out must be large enough to hold all the
404      In this implementation, inflate() always flushes as much output as
405   possible to the output buffer, and always uses the faster approach on the
411   below), inflate sets strm->adler to the adler32 checksum of the dictionary
413   strm->adler to the adler32 checksum of all output produced so far (that is,
419     inflate() will decompress and check either zlib-wrapped or gzip-wrapped
427   or more output produced), Z_STREAM_END if the end of the compressed data has
428   been reached and all uncompressed output has been produced, Z_NEED_DICT if a
433   Z_BUF_ERROR if no progress is possible or if there was not enough room in the
434   output buffer when Z_FINISH is used. Note that Z_BUF_ERROR is not fatal, and
435   inflate() can be called again with more input and more output space to
446    pending output.
488    filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
494    the compression ratio but not the correctness of the compressed output even
499    method). msg is set to null if there is no error message.  deflateInit2 does
535      windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
550    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is
555    is set to null if there is no error message.  inflateInit2 does not perform
573      This function adds the data at next_in (avail_in bytes) to the output
574    history without performing any output.  There must be no pending output,
577    containing the data at next_in (except that the data is not output).