| /* 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 */ |