/jcl/source/common/zlib.h
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- /* zlib.h -- interface of the 'zlib' general purpose compression library
- version 1.2.5, April 19th, 2010
- Copyright (C) 1995-2010 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
- jloup@gzip.org 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 http://www.ietf.org/rfc/rfc1950.txt
- (zlib format), rfc1951.txt (deflate format) and rfc1952.txt (gzip format).
- */
- #ifndef ZLIB_H
- #define ZLIB_H
- #include "zconf.h"
- #ifdef __cplusplus
- extern "C" {
- #endif
- #define ZLIB_VERSION "1.2.5"
- #define ZLIB_VERNUM 0x1250
- #define ZLIB_VER_MAJOR 1
- #define ZLIB_VER_MINOR 2
- #define ZLIB_VER_REVISION 5
- #define ZLIB_VER_SUBREVISION 0
- /*
- 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 will be added later and will have the same stream
- interface.
- Compression can be done in a single step if the buffers are large enough,
- 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 compressed data format used by default by the in-memory functions is
- the zlib format, which is a zlib wrapper documented in RFC 1950, wrapped
- around a deflate stream, which is itself documented in RFC 1951.
- The library also supports reading and writing files in gzip (.gz) format
- with an interface similar to that of stdio using the functions that start
- with "gz". The gzip format is different from the zlib format. gzip is a
- gzip wrapper, documented in RFC 1952, wrapped around a deflate stream.
- This library can optionally read and write gzip streams in memory as well.
- The zlib format was designed to be compact and fast for use in memory
- and on communications channels. The gzip format was designed for single-
- file compression on file systems, has a larger header than zlib to maintain
- directory information, and uses a different, slower check method than zlib.
- The library does not install any signal handler. The decoder checks
- the consistency of the compressed data, so the library should never crash
- even in case 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: binary or text */
- uLong adler; /* adler32 value of the uncompressed data */
- uLong reserved; /* reserved for future use */
- } z_stream;
- typedef z_stream FAR *z_streamp;
- /*
- gzip header information passed to and from zlib routines. See RFC 1952
- for more details on the meanings of these fields.
- */
- typedef struct gz_header_s {
- int text; /* true if compressed data believed to be text */
- uLong time; /* modification time */
- int xflags; /* extra flags (not used when writing a gzip file) */
- int os; /* operating system */
- Bytef *extra; /* pointer to extra field or Z_NULL if none */
- uInt extra_len; /* extra field length (valid if extra != Z_NULL) */
- uInt extra_max; /* space at extra (only when reading header) */
- Bytef *name; /* pointer to zero-terminated file name or Z_NULL */
- uInt name_max; /* space at name (only when reading header) */
- Bytef *comment; /* pointer to zero-terminated comment or Z_NULL */
- uInt comm_max; /* space at comment (only when reading header) */
- int hcrc; /* true if there was or will be a header crc */
- int done; /* true when done reading gzip header (not used
- when writing a gzip file) */
- } gz_header;
- typedef gz_header FAR *gz_headerp;
- /*
- 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.
- If zlib is used in a multi-threaded application, zalloc and zfree must be
- thread safe.
- 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_SYNC_FLUSH 2
- #define Z_FULL_FLUSH 3
- #define Z_FINISH 4
- #define Z_BLOCK 5
- #define Z_TREES 6
- /* Allowed flush values; see deflate() and inflate() 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_RLE 3
- #define Z_FIXED 4
- #define Z_DEFAULT_STRATEGY 0
- /* compression strategy; see deflateInit2() below for details */
- #define Z_BINARY 0
- #define Z_TEXT 1
- #define Z_ASCII Z_TEXT /* for compatibility with 1.2.2 and earlier */
- #define Z_UNKNOWN 2
- /* Possible values of the data_type field (though see inflate()) */
- #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 */
- ZEXTERN const char * ZEXPORT 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.
- */
- /*
- ZEXTERN int ZEXPORT 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, or
- 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().
- */
- ZEXTERN int ZEXPORT deflate OF((z_streamp strm, int flush));
- /*
- deflate compresses as much data as possible, and stops when the input
- buffer becomes empty or the output buffer becomes full. It may introduce
- some output latency (reading input without producing any output) except when
- forced to flush.
- The detailed semantics are as follows. deflate 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.
- Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
- decide how much data to accumulate before producing output, in order to
- maximize compression.
- If the parameter flush is set to Z_SYNC_FLUSH, all pending output is
- flushed to the output buffer and the output is aligned on a byte boundary, so
- that the decompressor can get all input data available so far. (In
- particular avail_in is zero after the call if enough output space has been
- provided before the call.) Flushing may degrade compression for some
- compression algorithms and so it should be used only when necessary. This
- completes the current deflate block and follows it with an empty stored block
- that is three bits plus filler bits to the next byte, followed by four bytes
- (00 00 ff ff).
- If flush is set to Z_PARTIAL_FLUSH, all pending output is flushed to the
- output buffer, but the output is not aligned to a byte boundary. All of the
- input data so far will be available to the decompressor, as for Z_SYNC_FLUSH.
- This completes the current deflate block and follows it with an empty fixed
- codes block that is 10 bits long. This assures that enough bytes are output
- in order for the decompressor to finish the block before the empty fixed code
- block.
- If flush is set to Z_BLOCK, a deflate block is completed and emitted, as
- for Z_SYNC_FLUSH, but the output is not aligned on a byte boundary, and up to
- seven bits of the current block are held to be written as the next byte after
- the next deflate block is completed. In this case, the decompressor may not
- be provided enough bits at this point in order to complete decompression of
- the data provided so far to the compressor. It may need to wait for the next
- block to be emitted. This is for advanced applications that need to control
- the emission of deflate blocks.
- If flush is set to Z_FULL_FLUSH, all output is flushed as with
- Z_SYNC_FLUSH, and the compression state is reset so that decompression can
- restart from this point if previous compressed data has been damaged or if
- random access is desired. Using Z_FULL_FLUSH too often can seriously degrade
- 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). In the case of a Z_FULL_FLUSH or Z_SYNC_FLUSH, make sure that
- avail_out is greater than six to avoid repeated flush markers due to
- avail_out == 0 on return.
- 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 the
- value returned by deflateBound (see below). If deflate does not return
- Z_STREAM_END, then it must be called again as described above.
- deflate() sets strm->adler to the adler32 checksum of all input read
- so far (that is, total_in bytes).
- deflate() may update strm->data_type if it can make a good guess about
- the input data type (Z_BINARY or Z_TEXT). 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 Z_NULL), Z_BUF_ERROR if no progress is possible
- (for example avail_in or avail_out was zero). Note that Z_BUF_ERROR is not
- fatal, and deflate() can be called again with more input and more output
- space to continue compressing.
- */
- ZEXTERN int ZEXPORT 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).
- */
- /*
- ZEXTERN int ZEXPORT inflateInit OF((z_streamp strm));
- Initializes the internal stream state for decompression. The fields
- next_in, avail_in, zalloc, zfree and opaque must be initialized before by
- the caller. If next_in is not Z_NULL and avail_in is large enough (the
- exact value depends on the compression method), inflateInit determines the
- compression method from the zlib header and allocates all data structures
- accordingly; otherwise the allocation will be deferred to the first call of
- inflate. 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, or Z_STREAM_ERROR if the parameters are
- invalid, such as a null pointer to the structure. msg is set to null if
- there is no error message. inflateInit does not perform any decompression
- apart from possibly reading the zlib header if present: actual decompression
- will be done by inflate(). (So next_in and avail_in may be modified, but
- next_out and avail_out are unused and unchanged.) The current implementation
- of inflateInit() does not process any header information -- that is deferred
- until inflate() is called.
- */
- ZEXTERN int ZEXPORT inflate OF((z_streamp strm, int flush));
- /*
- inflate decompresses as much data as possible, and stops when the input
- buffer becomes empty or the output buffer becomes full. It may introduce
- some output latency (reading input without producing any output) except when
- forced to flush.
- The detailed semantics are as follows. inflate 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.
- The flush parameter of inflate() can be Z_NO_FLUSH, Z_SYNC_FLUSH, Z_FINISH,
- Z_BLOCK, or Z_TREES. Z_SYNC_FLUSH requests that inflate() flush as much
- output as possible to the output buffer. Z_BLOCK requests that inflate()
- stop if and when it gets to the next deflate block boundary. When decoding
- the zlib or gzip format, this will cause inflate() to return immediately
- after the header and before the first block. When doing a raw inflate,
- inflate() will go ahead and process the first block, and will return when it
- gets to the end of that block, or when it runs out of data.
- The Z_BLOCK option assists in appending to or combining deflate streams.
- Also to assist in this, on return inflate() will set strm->data_type to the
- number of unused bits in the last byte taken from strm->next_in, plus 64 if
- inflate() is currently decoding the last block in the deflate stream, plus
- 128 if inflate() returned immediately after decoding an end-of-block code or
- decoding the complete header up to just before the first byte of the deflate
- stream. The end-of-block will not be indicated until all of the uncompressed
- data from that block has been written to strm->next_out. The number of
- unused bits may in general be greater than seven, except when bit 7 of
- data_type is set, in which case the number of unused bits will be less than
- eight. data_type is set as noted here every time inflate() returns for all
- flush options, and so can be used to determine the amount of currently
- consumed input in bits.
- The Z_TREES option behaves as Z_BLOCK does, but it also returns when the
- end of each deflate block header is reached, before any actual data in that
- block is decoded. This allows the caller to determine the length of the
- deflate block header for later use in random access within a deflate block.
- 256 is added to the value of strm->data_type when inflate() returns
- immediately after reaching the end of the deflate block header.
- 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 approach may be used for the single
- inflate() call.
- In this implementation, inflate() always flushes as much output as
- possible to the output buffer, and always uses the faster approach on the
- first call. So the only effect of the flush parameter in this implementation
- is on the return value of inflate(), as noted below, or when it returns early
- because Z_BLOCK or Z_TREES is used.
- If a preset dictionary is needed after this call (see inflateSetDictionary
- below), inflate sets strm->adler to the adler32 checksum of the dictionary
- chosen by the compressor and returns Z_NEED_DICT; otherwise it sets
- strm->adler to the adler32 checksum of all output produced so far (that is,
- total_out bytes) and returns Z_OK, Z_STREAM_END or an error code as described
- below. At the end of the stream, inflate() checks that its computed adler32
- checksum is equal to that saved by the compressor and returns Z_STREAM_END
- only if the checksum is correct.
- inflate() can decompress and check either zlib-wrapped or gzip-wrapped
- deflate data. The header type is detected automatically, if requested when
- initializing with inflateInit2(). Any information contained in the gzip
- header is not retained, so applications that need that information should
- instead use raw inflate, see inflateInit2() below, or inflateBack() and
- perform their own processing of the gzip header and trailer.
- 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, Z_DATA_ERROR if the input data was
- corrupted (input stream not conforming to the zlib format or incorrect check
- value), Z_STREAM_ERROR if the stream structure was inconsistent (for example
- next_in or next_out was Z_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. Note that Z_BUF_ERROR is not fatal, and
- inflate() can be called again with more input and more output space to
- continue decompressing. If Z_DATA_ERROR is returned, the application may
- then call inflateSync() to look for a good compression block if a partial
- recovery of the data is desired.
- */
- ZEXTERN int ZEXPORT 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.
- */
- /*
- ZEXTERN int ZEXPORT 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.
- 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. 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.
- windowBits can also be -8..-15 for raw deflate. In this case, -windowBits
- determines the window size. deflate() will then generate raw deflate data
- with no zlib header or trailer, and will not compute an adler32 check value.
- windowBits can also be greater than 15 for optional gzip encoding. Add
- 16 to windowBits to write a simple gzip header and trailer around the
- compressed data instead of a zlib wrapper. The gzip header will have no
- file name, no extra data, no comment, no modification time (set to zero), no
- header crc, and the operating system will be set to 255 (unknown). If a
- gzip stream is being written, strm->adler is a crc32 instead of an adler32.
- 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), Z_HUFFMAN_ONLY to force Huffman encoding only (no
- string match), or Z_RLE to limit match distances to one (run-length
- encoding). 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_STRATEGY and Z_HUFFMAN_ONLY. Z_RLE is designed to be almost as
- fast as Z_HUFFMAN_ONLY, but give better compression for PNG image data. The
- strategy parameter only affects the compression ratio but not the
- correctness of the compressed output even if it is not set appropriately.
- Z_FIXED prevents the use of dynamic Huffman codes, allowing for a simpler
- decoder for special applications.
- deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was not enough
- memory, Z_STREAM_ERROR if any parameter is invalid (such as an invalid
- method), or 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. deflateInit2 does not perform any
- compression: this will be done by deflate().
- */
- ZEXTERN int ZEXPORT deflateSetDictionary OF((z_streamp strm,
- const Bytef *dictionary,
- uInt dictLength));
- /*
- 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
- provided in deflateInit or deflateInit2. Thus the strings most likely to be
- useful should be put at the end of the dictionary, not at the front. In
- addition, the current implementation of deflate will use at most the window
- size minus 262 bytes of the provided dictionary.
- 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.) If a raw deflate was requested, then the
- adler32 value is not computed and strm->adler is not set.
- deflateSetDictionary returns Z_OK if success, or Z_STREAM_ERROR if a
- parameter is invalid (e.g. dictionary being Z_NULL) 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().
- */
- ZEXTERN int ZEXPORT deflateCopy OF((z_streamp dest,
- z_streamp source));
- /*
- 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 Z_NULL). msg is left unchanged in both source and
- destination.
- */
- ZEXTERN int ZEXPORT 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 Z_NULL).
- */
- ZEXTERN int ZEXPORT deflateParams OF((z_streamp strm,
- int level,
- int strategy));
- /*
- 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.
- */
- ZEXTERN int ZEXPORT deflateTune OF((z_streamp strm,
- int good_length,
- int max_lazy,
- int nice_length,
- int max_chain));
- /*
- Fine tune deflate's internal compression parameters. This should only be
- used by someone who understands the algorithm used by zlib's deflate for
- searching for the best matching string, and even then only by the most
- fanatic optimizer trying to squeeze out the last compressed bit for their
- specific input data. Read the deflate.c source code for the meaning of the
- max_lazy, good_length, nice_length, and max_chain parameters.
- deflateTune() can be called after deflateInit() or deflateInit2(), and
- returns Z_OK on success, or Z_STREAM_ERROR for an invalid deflate stream.
- */
- ZEXTERN uLong ZEXPORT deflateBound OF((z_streamp strm,
- uLong sourceLen));
- /*
- deflateBound() returns an upper bound on the compressed size after
- deflation of sourceLen bytes. It must be called after deflateInit() or
- deflateInit2(), and after deflateSetHeader(), if used. This would be used
- to allocate an output buffer for deflation in a single pass, and so would be
- called before deflate().
- */
- ZEXTERN int ZEXPORT deflatePrime OF((z_streamp strm,
- int bits,
- int value));
- /*
- deflatePrime() inserts bits in the deflate output stream. The intent
- is that this function is used to start off the deflate output with the bits
- leftover from a previous deflate stream when appending to it. As such, this
- function can only be used for raw deflate, and must be used before the first
- deflate() call after a deflateInit2() or deflateReset(). bits must be less
- than or equal to 16, and that many of the least significant bits of value
- will be inserted in the output.
- deflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
- stream state was inconsistent.
- */
- ZEXTERN int ZEXPORT deflateSetHeader OF((z_streamp strm,
- gz_headerp head));
- /*
- deflateSetHeader() provides gzip header information for when a gzip
- stream is requested by deflateInit2(). deflateSetHeader() may be called
- after deflateInit2() or deflateReset() and before the first call of
- deflate(). The text, time, os, extra field, name, and comment information
- in the provided gz_header structure are written to the gzip header (xflag is
- ignored -- the extra flags are set according to the compression level). The
- caller must assure that, if not Z_NULL, name and comment are terminated with
- a zero byte, and that if extra is not Z_NULL, that extra_len bytes are
- available there. If hcrc is true, a gzip header crc is included. Note that
- the current versions of the command-line version of gzip (up through version
- 1.3.x) do not support header crc's, and will report that it is a "multi-part
- gzip file" and give up.
- If deflateSetHeader is not used, the default gzip header has text false,
- the time set to zero, and os set to 255, with no extra, name, or comment
- fields. The gzip header is returned to the default state by deflateReset().
- deflateSetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
- stream state was inconsistent.
- */
- /*
- ZEXTERN int ZEXPORT inflateInit2 OF((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 zero to request that inflate use the window size in
- the zlib header of the compressed stream.
- 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_VERSION_ERROR if the zlib library version is incompatible with the
- version assumed by the caller, or Z_STREAM_ERROR if the parameters are
- invalid, such as a null pointer to the structure. msg is set to null if
- there is no error message. inflateInit2 does not perform any decompression
- apart from possibly reading the zlib header if present: actual decompression
- will be done by inflate(). (So next_in and avail_in may be modified, but
- next_out and avail_out are unused and unchanged.) The current implementation
- of inflateInit2() does not process any header information -- that is
- deferred until inflate() is called.
- */
- ZEXTERN int ZEXPORT inflateSetDictionary OF((z_streamp strm,
- const Bytef *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 (e.g. dictionary being Z_NULL) 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().
- */
- ZEXTERN int ZEXPORT inflateSync OF((z_streamp strm));
- /*
- 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.
- */
- ZEXTERN int ZEXPORT inflateCopy OF((z_streamp dest,
- z_streamp source));
- /*
- Sets the destination stream as a complete copy of the source stream.
- This function can be useful when randomly accessing a large stream. The
- first pass through the stream can periodically record the inflate state,
- allowing restarting inflate at those points when randomly accessing the
- stream.
- inflateCopy 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 Z_NULL). msg is left unchanged in both source and
- destination.
- */
- ZEXTERN int ZEXPORT 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 Z_NULL).
- */
- ZEXTERN int ZEXPORT inflateReset2 OF((z_streamp strm,
- int windowBits));
- /*
- This function is the same as inflateReset, but it also permits changing
- the wrap and window size requests. The windowBits parameter is interpreted
- the same as it is for inflateInit2.
- inflateReset2 returns Z_OK if success, or Z_STREAM_ERROR if the source
- stream state was inconsistent (such as zalloc or state being Z_NULL), or if
- the windowBits parameter is invalid.
- */
- ZEXTERN int ZEXPORT inflatePrime OF((z_streamp strm,
- int bits,
- int value));
- /*
- This function inserts bits in the inflate input stream. The intent is
- that this function is used to start inflating at a bit position in the
- middle of a byte. The provided bits will be used before any bytes are used
- from next_in. This function should only be used with raw inflate, and
- should be used before the first inflate() call after inflateInit2() or
- inflateReset(). bits must be less than or equal to 16, and that many of the
- least significant bits of value will be inserted in the input.
- If bits is negative, then the input stream bit buffer is emptied. Then
- inflatePrime() can be called again to put bits in the buffer. This is used
- to clear out bits leftover after feeding inflate a block description prior
- to feeding inflate codes.
- inflatePrime returns Z_OK if success, or Z_STREAM_ERROR if the source
- stream state was inconsistent.
- */
- ZEXTERN long ZEXPORT inflateMark OF((z_streamp strm));
- /*
- This function returns two values, one in the lower 16 bits of the return
- value, and the other in the remaining upper bits, obtained by shifting the
- return value down 16 bits. If the upper value is -1 and the lower value is
- zero, then inflate() is currently decoding information outside of a block.
- If the upper value is -1 and the lower value is non-zero, then inflate is in
- the middle of a stored block, with the lower value equaling the number of
- bytes from the input remaining to copy. If the upper value is not -1, then
- it is the number of bits back from the current bit position in the input of
- the code (literal or length/distance pair) currently being processed. In
- that case the lower value is the number of bytes already emitted for that
- code.
- A code is being processed if inflate is waiting for more input to complete
- decoding of the code, or if it has completed decoding but is waiting for
- more output space to write the literal or match data.
- inflateMark() is used to mark locations in the input data for random
- access, which may be at bit positions, and to note those cases where the
- output of a code may span boundaries of random access blocks. The current
- location in the input stream can be determined from avail_in and data_type
- as noted in the description for the Z_BLOCK flush parameter for inflate.
- inflateMark returns the value noted above or -1 << 16 if the provided
- source stream state was inconsistent.
- */
- ZEXTERN int ZEXPORT inflateGetHeader OF((z_streamp strm,
- gz_headerp head));
- /*
- inflateGetHeader() requests that gzip header information be stored in the
- provided gz_header structure. inflateGetHeader() may be called after
- inflateInit2() or inflateReset(), and before the first call of inflate().
- As inflate() processes the gzip stream, head->done is zero until the header
- is completed, at which time head->done is set to one. If a zlib stream is
- being decoded, then head->done is set to -1 to indicate that there will be
- no gzip header information forthcoming. Note that Z_BLOCK or Z_TREES can be
- used to force inflate() to return immediately after header processing is
- complete and before any actual data is decompressed.
- The text, time, xflags, and os fields are filled in with the gzip header
- contents. hcrc is set to true if there is a header CRC. (The header CRC
- was valid if done is set to one.) If extra is not Z_NULL, then extra_max
- contains the maximum number of bytes to write to extra. Once done is true,
- extra_len contains the actual extra field length, and extra contains the
- extra field, or that field truncated if extra_max is less than extra_len.
- If name is not Z_NULL, then up to name_max characters are written there,
- terminated with a zero unless the length is greater than name_max. If
- comment is not Z_NULL, then up to comm_max characters are written there,
- terminated with a zero unless the length is greater than comm_max. When any
- of extra, name, or comment are not Z_NULL and the respective field is not
- present in the header, then that field is set to Z_NULL to signal its
- absence. This allows the use of deflateSetHeader() with the returned
- structure to duplicate the header. However if those fields are set to
- allocated memory, then the application will need to save those pointers
- elsewhere so that they can be eventually freed.
- If inflateGetHeader is not used, then the header information is simply
- discarded. The header is always checked for validity, including the header
- CRC if present. inflateReset() will reset the process to discard the header
- information. The application would need to call inflateGetHeader() again to
- retrieve the header from the next gzip stream.
- inflateGetHeader returns Z_OK if success, or Z_STREAM_ERROR if the source
- stream state was inconsistent.
- */
- /*
- ZEXTERN int ZEXPORT inflateBackInit OF((z_streamp strm, int windowBits,
- unsigned char FAR *window));
- Initialize the internal stream state for decompression using inflateBack()
- calls. The fields zalloc, zfree and opaque in strm must be initialized
- before the call. If zalloc and zfree are Z_NULL, then the default library-
- derived memory allocation routines are used. windowBits is the base two
- logarithm of the window size, in the range 8..15. window is a caller
- supplied buffer of that size. Except for special applications where it is
- assured that deflate was used with small window sizes, windowBits must be 15
- and a 32K byte window must be supplied to be able to decompress general
- deflate streams.
- See inflateBack() for the usage of these routines.
- inflateBackInit will return Z_OK on success, Z_STREAM_ERROR if any of
- the paramaters are invalid, Z_MEM_ERROR if the internal state could not be
- allocated, or Z_VERSION_ERROR if the version of the library does not match
- the version of the header file.
- */
- typedef unsigned (*in_func) OF((void FAR *, unsigned char FAR * FAR *));
- typedef int (*out_func) OF((void FAR *, unsigned char FAR *, unsigned));
- ZEXTERN int ZEXPORT inflateBack OF((z_streamp strm,…