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
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
55   data.  This version of the library supports only one compression method
60   enough (for example if an input file is mmap'ed), or can be done by
62   application must provide more input and/or consume the output
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-
79   crash even in case of corrupted input.
85     const Byte *next_in;   /* next input byte */
87     uLong    total_in;  /* total nb of input bytes read so far */
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).
145 #define Z_BLOCK         6 /* Only for inflate at present */
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)
178 /* The deflate compression method (the only one supported in this version) */
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,
210    all (the input data is simply copied a block at a time).
225     deflate compresses as much data as possible, and stops when the input
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
234     accordingly. If not all input can be processed (because there is not
238   - Provide more output starting at next_out and update next_out and avail_out
241     should be set only when necessary (in interactive applications).
245   one of the actions is possible, by providing more input and/or consuming
255   that the decompressor can get all input data available so far. (In particular
258   algorithms and so it should be used only when necessary.
268   avail_out), until the flush is complete (deflate returns with non-zero
271     If the parameter flush is set to Z_FINISH, pending input is processed,
275   more input data, until it returns with Z_STREAM_END or an error. After
276   deflate has returned Z_STREAM_END, the only possible operations on the
284     deflate() sets strm->adler to the adler32 checksum of all input read
288   the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
289   binary. This field is only for information purposes and does not affect
292     deflate() returns Z_OK if some progress has been made (more input
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
304    This function discards any unprocessed input and does not flush any
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().
345     inflate decompresses as much data as possible, and stops when the input
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
354     accordingly. If not all input can be processed (because there is not
358   - Provide more output starting at next_out and update next_out and avail_out
360     is no more input data or no more space in the output buffer (see below
364   one of the actions is possible, by providing more input and/or consuming
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
396   Z_FINISH. In this case all pending input is processed and all pending
406   first call. So the only effect of the flush parameter in this implementation
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,
417   only if the checksum is correct.
419     inflate() will decompress and check either zlib-wrapped or gzip-wrapped
426     inflate() returns Z_OK if some progress has been made (more input processed
429   preset dictionary is needed at this point, Z_DATA_ERROR if the input data was
430   corrupted (input stream not conforming to the zlib format or incorrect check
435   inflate() can be called again with more input and more output space to
445    This function discards any unprocessed input and does not flush any
456     The following functions are needed only in some special applications.
488    filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman encoding only (no
493    between Z_DEFAULT and Z_HUFFMAN_ONLY. The strategy parameter only affects
532    size is given as input, inflate() will return with the error code
535      windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
549    detection, or add 16 to decode only the gzip format (the zlib format will
550    return a Z_DATA_ERROR).  If a gzip stream is being decoded, strm->adler is