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diff --git a/compat/zlib/old/zlib.html b/compat/zlib/old/zlib.html new file mode 100644 index 0000000..8c1b190 --- /dev/null +++ b/compat/zlib/old/zlib.html @@ -0,0 +1,971 @@ +<html> +<head> + <title> + zlib general purpose compression library version 1.1.4 + </title> +</head> +<body bgcolor="White" text="Black" vlink="Red" alink="Navy" link="Red"> +<!-- background="zlibbg.gif" --> + +<h1> zlib 1.1.4 Manual </h1> +<hr> +<a name="Contents"><h2>Contents</h2> +<ol type="I"> +<li> <a href="#Prologue">Prologue</a> +<li> <a href="#Introduction">Introduction</a> +<li> <a href="#Utility functions">Utility functions</a> +<li> <a href="#Basic functions">Basic functions</a> +<li> <a href="#Advanced functions">Advanced functions</a> +<li> <a href="#Constants">Constants</a> +<li> <a href="#struct z_stream_s">struct z_stream_s</a> +<li> <a href="#Checksum functions">Checksum functions</a> +<li> <a href="#Misc">Misc</a> +</ol> +<hr> +<a name="Prologue"><h2> Prologue </h2> + 'zlib' general purpose compression library version 1.1.4, March 11th, 2002 + <p> + Copyright (C) 1995-2002 Jean-loup Gailly and Mark Adler + <p> + 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. + <p> + 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: + <ol> + <li> 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. + <li> Altered source versions must be plainly marked as such, and must not be + misrepresented as being the original software. + <li> This notice may not be removed or altered from any source distribution. + </ol> + + <dl> + <dt>Jean-loup Gailly + <dd><a href="mailto:jloup@gzip.org">jloup@gzip.org</a> + <dt>Mark Adler + <dd><a href="mailto:madler@alumni.caltech.edu">madler@alumni.caltech.edu</a> + </dl> + + The data format used by the zlib library is described by RFCs (Request for + Comments) 1950 to 1952 in the files + <a href="ftp://ds.internic.net/rfc/rfc1950.txt"> + ftp://ds.internic.net/rfc/rfc1950.txt </a> + (zlib format), + <a href="ftp://ds.internic.net/rfc/rfc1951.txt"> + rfc1951.txt </a> + (<a href="#deflate">deflate</a> format) and + <a href="ftp://ds.internic.net/rfc/rfc1952.txt"> + rfc1952.txt </a> + (gzip format). + <p> + This manual is converted from zlib.h by + <a href="mailto:piaip@csie.ntu.edu.tw"> piaip </a> + <p> + Visit <a href="http://ftp.cdrom.com/pub/infozip/zlib/"> + http://ftp.cdrom.com/pub/infozip/zlib/</a> + for the official zlib web page. + <p> + +<hr> +<a name="Introduction"><h2> Introduction </h2> + 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. + <p> + + 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. + <p> + + The library also supports reading and writing files in gzip (.gz) format + with an interface similar to that of stdio. + <p> + + 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. + <p> + +<hr> +<a name="Utility functions"><h2> Utility functions </h2> + The following utility functions are implemented on top of the + <a href="#Basic functions">basic stream-oriented functions</a>. + To simplify the interface, some + default options are assumed (compression level and memory usage, + standard memory allocation functions). The source code of these + utility functions can easily be modified if you need special options. +<h3> Function list </h3> +<ul> +<li> int <a href="#compress">compress</a> (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen); +<li> int <a href="#compress2">compress2</a> (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen, int level); +<li> int <a href="#uncompress">uncompress</a> (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen); +<li> typedef voidp gzFile; +<li> gzFile <a href="#gzopen">gzopen</a> (const char *path, const char *mode); +<li> gzFile <a href="#gzdopen">gzdopen</a> (int fd, const char *mode); +<li> int <a href="#gzsetparams">gzsetparams</a> (gzFile file, int level, int strategy); +<li> int <a href="#gzread">gzread</a> (gzFile file, voidp buf, unsigned len); +<li> int <a href="#gzwrite">gzwrite</a> (gzFile file, const voidp buf, unsigned len); +<li> int VA <a href="#gzprintf">gzprintf</a> (gzFile file, const char *format, ...); +<li> int <a href="#gzputs">gzputs</a> (gzFile file, const char *s); +<li> char * <a href="#gzgets">gzgets</a> (gzFile file, char *buf, int len); +<li> int <a href="#gzputc">gzputc</a> (gzFile file, int c); +<li> int <a href="#gzgetc">gzgetc</a> (gzFile file); +<li> int <a href="#gzflush">gzflush</a> (gzFile file, int flush); +<li> z_off_t <a href="#gzseek">gzseek</a> (gzFile file, z_off_t offset, int whence); +<li> z_off_t <a href="#gztell">gztell</a> (gzFile file); +<li> int <a href="#gzrewind">gzrewind</a> (gzFile file); +<li> int <a href="#gzeof">gzeof</a> (gzFile file); +<li> int <a href="#gzclose">gzclose</a> (gzFile file); +<li> const char * <a href="#gzerror">gzerror</a> (gzFile file, int *errnum); +</ul> +<h3> Function description </h3> +<dl> +<font color="Blue"><dt> int <a name="compress">compress</a> (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen);</font> +<dd> + 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.<p> + This function can be used to <a href="#compress">compress</a> a whole file at once if the + input file is mmap'ed.<p> + <a href="#compress">compress</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_MEM_ERROR">Z_MEM_ERROR</a> if there was not + enough memory, <a href="#Z_BUF_ERROR">Z_BUF_ERROR</a> if there was not enough room in the output + buffer.<p> + +<font color="Blue"><dt> int <a name="compress2">compress2</a> (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen, int level);</font> +<dd> + Compresses the source buffer into the destination buffer. The level + parameter has the same meaning as in <a href="#deflateInit">deflateInit</a>. 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. + <p> + + <a href="#compress2">compress2</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_MEM_ERROR">Z_MEM_ERROR</a> if there was not enough + memory, <a href="#Z_BUF_ERROR">Z_BUF_ERROR</a> if there was not enough room in the output buffer, + <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if the level parameter is invalid. + <p> + +<font color="Blue"><dt> int <a name="uncompress">uncompress</a> (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen);</font> +<dd> + 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. <p> + This function can be used to decompress a whole file at once if the + input file is mmap'ed. + <p> + + <a href="#uncompress">uncompress</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_MEM_ERROR">Z_MEM_ERROR</a> if there was not + enough memory, <a href="#Z_BUF_ERROR">Z_BUF_ERROR</a> if there was not enough room in the output + buffer, or <a href="#Z_DATA_ERROR">Z_DATA_ERROR</a> if the input data was corrupted. + <p> + +<dt> typedef voidp gzFile; +<dd> <p> + +<font color="Blue"><dt> gzFile <a name="gzopen">gzopen</a> (const char *path, const char *mode);</font> +<dd> + Opens a gzip (.gz) file for reading or writing. The mode parameter + is as in fopen ("rb" or "wb") but can also include a compression level + ("wb9") or a strategy: 'f' for filtered data as in "wb6f", 'h' for + Huffman only compression as in "wb1h". (See the description + of <a href="#deflateInit2">deflateInit2</a> for more information about the strategy parameter.) + <p> + + <a href="#gzopen">gzopen</a> can be used to read a file which is not in gzip format ; in this + case <a href="#gzread">gzread</a> will directly read from the file without decompression. + <p> + + <a href="#gzopen">gzopen</a> returns NULL if the file could not be opened or if there was + insufficient memory to allocate the (de)compression <a href="#state">state</a> ; errno + can be checked to distinguish the two cases (if errno is zero, the + zlib error is <a href="#Z_MEM_ERROR">Z_MEM_ERROR</a>). + <p> + +<font color="Blue"><dt> gzFile <a name="gzdopen">gzdopen</a> (int fd, const char *mode);</font> +<dd> + <a href="#gzdopen">gzdopen</a>() associates a gzFile with the file descriptor fd. File + descriptors are obtained from calls like open, dup, creat, pipe or + fileno (in the file has been previously opened with fopen). + The mode parameter is as in <a href="#gzopen">gzopen</a>. + <p> + The next call of <a href="#gzclose">gzclose</a> on the returned gzFile will also close the + file descriptor fd, just like fclose(fdopen(fd), mode) closes the file + descriptor fd. If you want to keep fd open, use <a href="#gzdopen">gzdopen</a>(dup(fd), mode). + <p> + <a href="#gzdopen">gzdopen</a> returns NULL if there was insufficient memory to allocate + the (de)compression <a href="#state">state</a>. + <p> + +<font color="Blue"><dt> int <a name="gzsetparams">gzsetparams</a> (gzFile file, int level, int strategy);</font> +<dd> + Dynamically update the compression level or strategy. See the description + of <a href="#deflateInit2">deflateInit2</a> for the meaning of these parameters. + <p> + <a href="#gzsetparams">gzsetparams</a> returns <a href="#Z_OK">Z_OK</a> if success, or <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if the file was not + opened for writing. + <p> + +<font color="Blue"><dt> int <a name="gzread">gzread</a> (gzFile file, voidp buf, unsigned len);</font> +<dd> + Reads the given number of uncompressed bytes from the compressed file. + If the input file was not in gzip format, <a href="#gzread">gzread</a> copies the given number + of bytes into the buffer. + <p> + <a href="#gzread">gzread</a> returns the number of uncompressed bytes actually read (0 for + end of file, -1 for error). + <p> + +<font color="Blue"><dt> int <a name="gzwrite">gzwrite</a> (gzFile file, const voidp buf, unsigned len);</font> +<dd> + Writes the given number of uncompressed bytes into the compressed file. + <a href="#gzwrite">gzwrite</a> returns the number of uncompressed bytes actually written + (0 in case of error). + <p> + +<font color="Blue"><dt> int VA <a name="gzprintf">gzprintf</a> (gzFile file, const char *format, ...);</font> +<dd> + Converts, formats, and writes the args to the compressed file under + control of the format string, as in fprintf. <a href="#gzprintf">gzprintf</a> returns the number of + uncompressed bytes actually written (0 in case of error). + <p> + +<font color="Blue"><dt> int <a name="gzputs">gzputs</a> (gzFile file, const char *s);</font> +<dd> + Writes the given null-terminated string to the compressed file, excluding + the terminating null character. + <p> + <a href="#gzputs">gzputs</a> returns the number of characters written, or -1 in case of error. + <p> + +<font color="Blue"><dt> char * <a name="gzgets">gzgets</a> (gzFile file, char *buf, int len);</font> +<dd> + Reads bytes from the compressed file until len-1 characters are read, or + a newline character is read and transferred to buf, or an end-of-file + condition is encountered. The string is then terminated with a null + character. + <p> + <a href="#gzgets">gzgets</a> returns buf, or <a href="#Z_NULL">Z_NULL</a> in case of error. + <p> + +<font color="Blue"><dt> int <a name="gzputc">gzputc</a> (gzFile file, int c);</font> +<dd> + Writes c, converted to an unsigned char, into the compressed file. + <a href="#gzputc">gzputc</a> returns the value that was written, or -1 in case of error. + <p> + +<font color="Blue"><dt> int <a name="gzgetc">gzgetc</a> (gzFile file);</font> +<dd> + Reads one byte from the compressed file. <a href="#gzgetc">gzgetc</a> returns this byte + or -1 in case of end of file or error. + <p> + +<font color="Blue"><dt> int <a name="gzflush">gzflush</a> (gzFile file, int flush);</font> +<dd> + Flushes all pending output into the compressed file. The parameter + flush is as in the <a href="#deflate">deflate</a>() function. The return value is the zlib + error number (see function <a href="#gzerror">gzerror</a> below). <a href="#gzflush">gzflush</a> returns <a href="#Z_OK">Z_OK</a> if + the flush parameter is <a href="#Z_FINISH">Z_FINISH</a> and all output could be flushed. + <p> + <a href="#gzflush">gzflush</a> should be called only when strictly necessary because it can + degrade compression. + <p> + +<font color="Blue"><dt> z_off_t <a name="gzseek">gzseek</a> (gzFile file, z_off_t offset, int whence);</font> +<dd> + Sets the starting position for the next <a href="#gzread">gzread</a> or <a href="#gzwrite">gzwrite</a> on the + given compressed file. The offset represents a number of bytes in the + uncompressed data stream. The whence parameter is defined as in lseek(2); + the value SEEK_END is not supported. + <p> + If the file is opened for reading, this function is emulated but can be + extremely slow. If the file is opened for writing, only forward seeks are + supported ; <a href="#gzseek">gzseek</a> then compresses a sequence of zeroes up to the new + starting position. + <p> + <a href="#gzseek">gzseek</a> returns the resulting offset location as measured in bytes from + the beginning of the uncompressed stream, or -1 in case of error, in + particular if the file is opened for writing and the new starting position + would be before the current position. + <p> + +<font color="Blue"><dt> int <a name="gzrewind">gzrewind</a> (gzFile file);</font> +<dd> + Rewinds the given file. This function is supported only for reading. + <p> + <a href="#gzrewind">gzrewind</a>(file) is equivalent to (int)<a href="#gzseek">gzseek</a>(file, 0L, SEEK_SET) + <p> + +<font color="Blue"><dt> z_off_t <a name="gztell">gztell</a> (gzFile file);</font> +<dd> + Returns the starting position for the next <a href="#gzread">gzread</a> or <a href="#gzwrite">gzwrite</a> on the + given compressed file. This position represents a number of bytes in the + uncompressed data stream. + <p> + + <a href="#gztell">gztell</a>(file) is equivalent to <a href="#gzseek">gzseek</a>(file, 0L, SEEK_CUR) + <p> + +<font color="Blue"><dt> int <a name="gzeof">gzeof</a> (gzFile file);</font> +<dd> + Returns 1 when EOF has previously been detected reading the given + input stream, otherwise zero. + <p> + +<font color="Blue"><dt> int <a name="gzclose">gzclose</a> (gzFile file);</font> +<dd> + Flushes all pending output if necessary, closes the compressed file + and deallocates all the (de)compression <a href="#state">state</a>. The return value is the zlib + error number (see function <a href="#gzerror">gzerror</a> below). + <p> + +<font color="Blue"><dt> const char * <a name="gzerror">gzerror</a> (gzFile file, int *errnum);</font> +<dd> + 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 <a href="#Z_ERRNO">Z_ERRNO</a> and the application may consult errno + to get the exact error code. + <p> +</dl> +<hr> +<a name="Basic functions"><h2> Basic functions </h2> +<h3> Function list </h3> +<ul> +<li> const char * <a href="#zlibVersion">zlibVersion</a> (void); +<li> int <a href="#deflateInit">deflateInit</a> (<a href="#z_streamp">z_streamp</a> strm, int level); +<li> int <a href="#deflate">deflate</a> (<a href="#z_streamp">z_streamp</a> strm, int flush); +<li> int <a href="#deflateEnd">deflateEnd</a> (<a href="#z_streamp">z_streamp</a> strm); +<li> int <a href="#inflateInit">inflateInit</a> (<a href="#z_streamp">z_streamp</a> strm); +<li> int <a href="#inflate">inflate</a> (<a href="#z_streamp">z_streamp</a> strm, int flush); +<li> int <a href="#inflateEnd">inflateEnd</a> (<a href="#z_streamp">z_streamp</a> strm); +</ul> + +<h3> Function description </h3> +<dl> +<font color="Blue"><dt> const char * <a name="zlibVersion">zlibVersion</a> (void);</font> +<dd> The application can compare <a href="#zlibVersion">zlibVersion</a> 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 <a href="#deflateInit">deflateInit</a> and <a href="#inflateInit">inflateInit</a>. + <p> + +<font color="Blue"><dt> int <a name="deflateInit">deflateInit</a> (<a href="#z_streamp">z_streamp</a> strm, int level);</font> +<dd> + Initializes the internal stream <a href="#state">state</a> for compression. The fields + <a href="#zalloc">zalloc</a>, <a href="#zfree">zfree</a> and <a href="#opaque">opaque</a> must be initialized before by the caller. + If <a href="#zalloc">zalloc</a> and <a href="#zfree">zfree</a> are set to <a href="#Z_NULL">Z_NULL</a>, <a href="#deflateInit">deflateInit</a> updates them to + use default allocation functions. + <p> + + The compression level must be <a href="#Z_DEFAULT_COMPRESSION">Z_DEFAULT_COMPRESSION</a>, 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). + <p> + + <a href="#Z_DEFAULT_COMPRESSION">Z_DEFAULT_COMPRESSION</a> requests a default compromise between speed and + compression (currently equivalent to level 6). + <p> + + <a href="#deflateInit">deflateInit</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_MEM_ERROR">Z_MEM_ERROR</a> if there was not + enough memory, <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if level is not a valid compression level, + <a href="#Z_VERSION_ERROR">Z_VERSION_ERROR</a> if the zlib library version (<a href="#zlib_version">zlib_version</a>) is incompatible + with the version assumed by the caller (ZLIB_VERSION). + <a href="#msg">msg</a> is set to null if there is no error message. <a href="#deflateInit">deflateInit</a> does not + perform any compression: this will be done by <a href="#deflate">deflate</a>(). + <p> + +<font color="Blue"><dt> int <a name="deflate">deflate</a> (<a href="#z_streamp">z_streamp</a> strm, int flush);</font> +<dd> + <a href="#deflate">deflate</a> 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.<p> + + The detailed semantics are as follows. <a href="#deflate">deflate</a> performs one or both of the + following actions: + + <ul> + <li> Compress more input starting at <a href="#next_in">next_in</a> and update <a href="#next_in">next_in</a> and <a href="#avail_in">avail_in</a> + accordingly. If not all input can be processed (because there is not + enough room in the output buffer), <a href="#next_in">next_in</a> and <a href="#avail_in">avail_in</a> are updated and + processing will resume at this point for the next call of <a href="#deflate">deflate</a>(). + + <li> + Provide more output starting at <a href="#next_out">next_out</a> and update <a href="#next_out">next_out</a> and <a href="#avail_out">avail_out</a> + 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. + </ul> <p> + + Before the call of <a href="#deflate">deflate</a>(), the application should ensure that at least + one of the actions is possible, by providing more input and/or consuming + more output, and updating <a href="#avail_in">avail_in</a> or <a href="#avail_out">avail_out</a> accordingly ; <a href="#avail_out">avail_out</a> + 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 + (<a href="#avail_out">avail_out</a> == 0), or after each call of <a href="#deflate">deflate</a>(). If <a href="#deflate">deflate</a> returns <a href="#Z_OK">Z_OK</a> + and with zero <a href="#avail_out">avail_out</a>, it must be called again after making room in the + output buffer because there might be more output pending. + <p> + + If the parameter flush is set to <a href="#Z_SYNC_FLUSH">Z_SYNC_FLUSH</a>, 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 + <a href="#avail_in">avail_in</a> 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. + <p> + + If flush is set to <a href="#Z_FULL_FLUSH">Z_FULL_FLUSH</a>, all output is flushed as with + <a href="#Z_SYNC_FLUSH">Z_SYNC_FLUSH</a>, and the compression <a href="#state">state</a> is reset so that decompression can + restart from this point if previous compressed data has been damaged or if + random access is desired. Using <a href="#Z_FULL_FLUSH">Z_FULL_FLUSH</a> too often can seriously degrade + the compression. + <p> + + If <a href="#deflate">deflate</a> returns with <a href="#avail_out">avail_out</a> == 0, this function must be called again + with the same value of the flush parameter and more output space (updated + <a href="#avail_out">avail_out</a>), until the flush is complete (<a href="#deflate">deflate</a> returns with non-zero + <a href="#avail_out">avail_out</a>). + <p> + + If the parameter flush is set to <a href="#Z_FINISH">Z_FINISH</a>, pending input is processed, + pending output is flushed and <a href="#deflate">deflate</a> returns with <a href="#Z_STREAM_END">Z_STREAM_END</a> if there + was enough output space ; if <a href="#deflate">deflate</a> returns with <a href="#Z_OK">Z_OK</a>, this function must be + called again with <a href="#Z_FINISH">Z_FINISH</a> and more output space (updated <a href="#avail_out">avail_out</a>) but no + more input data, until it returns with <a href="#Z_STREAM_END">Z_STREAM_END</a> or an error. After + <a href="#deflate">deflate</a> has returned <a href="#Z_STREAM_END">Z_STREAM_END</a>, the only possible operations on the + stream are <a href="#deflateReset">deflateReset</a> or <a href="#deflateEnd">deflateEnd</a>. + <p> + + <a href="#Z_FINISH">Z_FINISH</a> can be used immediately after <a href="#deflateInit">deflateInit</a> if all the compression + is to be done in a single step. In this case, <a href="#avail_out">avail_out</a> must be at least + 0.1% larger than <a href="#avail_in">avail_in</a> plus 12 bytes. If <a href="#deflate">deflate</a> does not return + <a href="#Z_STREAM_END">Z_STREAM_END</a>, then it must be called again as described above. + <p> + + <a href="#deflate">deflate</a>() sets strm-> <a href="#adler">adler</a> to the <a href="#adler32">adler32</a> checksum of all input read + so far (that is, <a href="#total_in">total_in</a> bytes). + <p> + + <a href="#deflate">deflate</a>() may update <a href="#data_type">data_type</a> if it can make a good guess about + the input data type (<a href="#Z_ASCII">Z_ASCII</a> or <a href="#Z_BINARY">Z_BINARY</a>). In doubt, the data is considered + binary. This field is only for information purposes and does not affect + the compression algorithm in any manner. + <p> + + <a href="#deflate">deflate</a>() returns <a href="#Z_OK">Z_OK</a> if some progress has been made (more input + processed or more output produced), <a href="#Z_STREAM_END">Z_STREAM_END</a> if all input has been + consumed and all output has been produced (only when flush is set to + <a href="#Z_FINISH">Z_FINISH</a>), <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if the stream <a href="#state">state</a> was inconsistent (for example + if <a href="#next_in">next_in</a> or <a href="#next_out">next_out</a> was NULL), <a href="#Z_BUF_ERROR">Z_BUF_ERROR</a> if no progress is possible + (for example <a href="#avail_in">avail_in</a> or <a href="#avail_out">avail_out</a> was zero). + <p> + +<font color="Blue"><dt> int <a name="deflateEnd">deflateEnd</a> (<a href="#z_streamp">z_streamp</a> strm);</font> +<dd> + All dynamically allocated data structures for this stream are freed. + This function discards any unprocessed input and does not flush any + pending output. + <p> + + <a href="#deflateEnd">deflateEnd</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if the + stream <a href="#state">state</a> was inconsistent, <a href="#Z_DATA_ERROR">Z_DATA_ERROR</a> if the stream was freed + prematurely (some input or output was discarded). In the error case, + <a href="#msg">msg</a> may be set but then points to a static string (which must not be + deallocated). + <p> + +<font color="Blue"><dt> int <a name="inflateInit">inflateInit</a> (<a href="#z_streamp">z_streamp</a> strm);</font> +<dd> + Initializes the internal stream <a href="#state">state</a> for decompression. The fields + <a href="#next_in">next_in</a>, <a href="#avail_in">avail_in</a>, <a href="#zalloc">zalloc</a>, <a href="#zfree">zfree</a> and <a href="#opaque">opaque</a> must be initialized before by + the caller. If <a href="#next_in">next_in</a> is not <a href="#Z_NULL">Z_NULL</a> and <a href="#avail_in">avail_in</a> is large enough (the exact + value depends on the compression method), <a href="#inflateInit">inflateInit</a> 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 + <a href="#inflate">inflate</a>. If <a href="#zalloc">zalloc</a> and <a href="#zfree">zfree</a> are set to <a href="#Z_NULL">Z_NULL</a>, <a href="#inflateInit">inflateInit</a> updates them to + use default allocation functions. + <p> + + <a href="#inflateInit">inflateInit</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_MEM_ERROR">Z_MEM_ERROR</a> if there was not enough + memory, <a href="#Z_VERSION_ERROR">Z_VERSION_ERROR</a> if the zlib library version is incompatible with the + version assumed by the caller. <a href="#msg">msg</a> is set to null if there is no error + message. <a href="#inflateInit">inflateInit</a> does not perform any decompression apart from reading + the zlib header if present: this will be done by <a href="#inflate">inflate</a>(). (So <a href="#next_in">next_in</a> and + <a href="#avail_in">avail_in</a> may be modified, but <a href="#next_out">next_out</a> and <a href="#avail_out">avail_out</a> are unchanged.) + <p> + +<font color="Blue"><dt> int <a name="inflate">inflate</a> (<a href="#z_streamp">z_streamp</a> strm, int flush);</font> +<dd> + <a href="#inflate">inflate</a> decompresses as much data as possible, and stops when the input + buffer becomes empty or the output buffer becomes full. It may some + introduce some output latency (reading input without producing any output) + except when forced to flush. + <p> + + The detailed semantics are as follows. <a href="#inflate">inflate</a> performs one or both of the + following actions: + + <ul> + <li> Decompress more input starting at <a href="#next_in">next_in</a> and update <a href="#next_in">next_in</a> and <a href="#avail_in">avail_in</a> + accordingly. If not all input can be processed (because there is not + enough room in the output buffer), <a href="#next_in">next_in</a> is updated and processing + will resume at this point for the next call of <a href="#inflate">inflate</a>(). + + <li> Provide more output starting at <a href="#next_out">next_out</a> and update <a href="#next_out">next_out</a> and + <a href="#avail_out">avail_out</a> accordingly. <a href="#inflate">inflate</a>() 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). + </ul> <p> + + Before the call of <a href="#inflate">inflate</a>(), 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 (<a href="#avail_out">avail_out</a> == 0), or after each + call of <a href="#inflate">inflate</a>(). If <a href="#inflate">inflate</a> returns <a href="#Z_OK">Z_OK</a> and with zero <a href="#avail_out">avail_out</a>, it + must be called again after making room in the output buffer because there + might be more output pending. + <p> + + If the parameter flush is set to <a href="#Z_SYNC_FLUSH">Z_SYNC_FLUSH</a>, <a href="#inflate">inflate</a> flushes as much + output as possible to the output buffer. The flushing behavior of <a href="#inflate">inflate</a> is + not specified for values of the flush parameter other than <a href="#Z_SYNC_FLUSH">Z_SYNC_FLUSH</a> + and <a href="#Z_FINISH">Z_FINISH</a>, but the current implementation actually flushes as much output + as possible anyway. + <p> + + <a href="#inflate">inflate</a>() should normally be called until it returns <a href="#Z_STREAM_END">Z_STREAM_END</a> or an + error. However if all decompression is to be performed in a single step + (a single call of <a href="#inflate">inflate</a>), the parameter flush should be set to + <a href="#Z_FINISH">Z_FINISH</a>. In this case all pending input is processed and all pending + output is flushed ; <a href="#avail_out">avail_out</a> 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 <a href="#inflateEnd">inflateEnd</a> to deallocate the decompression <a href="#state">state</a>. The use of <a href="#Z_FINISH">Z_FINISH</a> + is never required, but can be used to inform <a href="#inflate">inflate</a> that a faster routine + may be used for the single <a href="#inflate">inflate</a>() call. + <p> + + If a preset dictionary is needed at this point (see <a href="#inflateSetDictionary">inflateSetDictionary</a> + below), <a href="#inflate">inflate</a> sets strm-<a href="#adler">adler</a> to the <a href="#adler32">adler32</a> checksum of the + dictionary chosen by the compressor and returns <a href="#Z_NEED_DICT">Z_NEED_DICT</a> ; otherwise + it sets strm-> <a href="#adler">adler</a> to the <a href="#adler32">adler32</a> checksum of all output produced + so far (that is, <a href="#total_out">total_out</a> bytes) and returns <a href="#Z_OK">Z_OK</a>, <a href="#Z_STREAM_END">Z_STREAM_END</a> or + an error code as described below. At the end of the stream, <a href="#inflate">inflate</a>() + checks that its computed <a href="#adler32">adler32</a> checksum is equal to that saved by the + compressor and returns <a href="#Z_STREAM_END">Z_STREAM_END</a> only if the checksum is correct. + <p> + + <a href="#inflate">inflate</a>() returns <a href="#Z_OK">Z_OK</a> if some progress has been made (more input processed + or more output produced), <a href="#Z_STREAM_END">Z_STREAM_END</a> if the end of the compressed data has + been reached and all uncompressed output has been produced, <a href="#Z_NEED_DICT">Z_NEED_DICT</a> if a + preset dictionary is needed at this point, <a href="#Z_DATA_ERROR">Z_DATA_ERROR</a> if the input data was + corrupted (input stream not conforming to the zlib format or incorrect + <a href="#adler32">adler32</a> checksum), <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if the stream structure was inconsistent + (for example if <a href="#next_in">next_in</a> or <a href="#next_out">next_out</a> was NULL), <a href="#Z_MEM_ERROR">Z_MEM_ERROR</a> if there was not + enough memory, <a href="#Z_BUF_ERROR">Z_BUF_ERROR</a> if no progress is possible or if there was not + enough room in the output buffer when <a href="#Z_FINISH">Z_FINISH</a> is used. In the <a href="#Z_DATA_ERROR">Z_DATA_ERROR</a> + case, the application may then call <a href="#inflateSync">inflateSync</a> to look for a good + compression block. + <p> + +<font color="Blue"><dt> int <a name="inflateEnd">inflateEnd</a> (<a href="#z_streamp">z_streamp</a> strm);</font> +<dd> + All dynamically allocated data structures for this stream are freed. + This function discards any unprocessed input and does not flush any + pending output. + <p> + + <a href="#inflateEnd">inflateEnd</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if the stream <a href="#state">state</a> + was inconsistent. In the error case, <a href="#msg">msg</a> may be set but then points to a + static string (which must not be deallocated). +</dl> +<hr> +<a name="Advanced functions"><h2> Advanced functions </h2> + The following functions are needed only in some special applications. +<h3> Function list </h3> +<ul> +<li> int <a href="#deflateInit2">deflateInit2</a> (<a href="#z_streamp">z_streamp</a> strm, +<li> int <a href="#deflateSetDictionary">deflateSetDictionary</a> (<a href="#z_streamp">z_streamp</a> strm, const Bytef *dictionary, uInt dictLength); +<li> int <a href="#deflateCopy">deflateCopy</a> (<a href="#z_streamp">z_streamp</a> dest, <a href="#z_streamp">z_streamp</a> source); +<li> int <a href="#deflateReset">deflateReset</a> (<a href="#z_streamp">z_streamp</a> strm); +<li> int <a href="#deflateParams">deflateParams</a> (<a href="#z_streamp">z_streamp</a> strm, int level, int strategy); +<li> int <a href="#inflateInit2">inflateInit2</a> (<a href="#z_streamp">z_streamp</a> strm, int windowBits); +<li> int <a href="#inflateSetDictionary">inflateSetDictionary</a> (<a href="#z_streamp">z_streamp</a> strm, const Bytef *dictionary, uInt dictLength); +<li> int <a href="#inflateSync">inflateSync</a> (<a href="#z_streamp">z_streamp</a> strm); +<li> int <a href="#inflateReset">inflateReset</a> (<a href="#z_streamp">z_streamp</a> strm); + +</ul> +<h3> Function description </h3> +<dl> +<font color="Blue"><dt> int <a name="deflateInit2">deflateInit2</a> (<a href="#z_streamp">z_streamp</a> strm, int level, int method, int windowBits, int memLevel, int strategy);</font> + +<dd> This is another version of <a href="#deflateInit">deflateInit</a> with more compression options. The + fields <a href="#next_in">next_in</a>, <a href="#zalloc">zalloc</a>, <a href="#zfree">zfree</a> and <a href="#opaque">opaque</a> must be initialized before by + the caller.<p> + + The method parameter is the compression method. It must be <a href="#Z_DEFLATED">Z_DEFLATED</a> in + this version of the library.<p> + + 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 + <a href="#deflateInit">deflateInit</a> is used instead.<p> + + The memLevel parameter specifies how much memory should be allocated + for the internal compression <a href="#state">state</a>. 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.<p> + + The strategy parameter is used to tune the compression algorithm. Use the + value <a href="#Z_DEFAULT_STRATEGY">Z_DEFAULT_STRATEGY</a> for normal data, <a href="#Z_FILTERED">Z_FILTERED</a> for data produced by a + filter (or predictor), or <a href="#Z_HUFFMAN_ONLY">Z_HUFFMAN_ONLY</a> 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 <a href="#compress">compress</a> them better. The effect of <a href="#Z_FILTERED">Z_FILTERED</a> is to force more + Huffman coding and less string matching ; it is somewhat intermediate + between Z_DEFAULT and <a href="#Z_HUFFMAN_ONLY">Z_HUFFMAN_ONLY</a>. The strategy parameter only affects + the compression ratio but not the correctness of the compressed output even + if it is not set appropriately.<p> + + <a href="#deflateInit2">deflateInit2</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_MEM_ERROR">Z_MEM_ERROR</a> if there was not enough + memory, <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if a parameter is invalid (such as an invalid + method). <a href="#msg">msg</a> is set to null if there is no error message. <a href="#deflateInit2">deflateInit2</a> does + not perform any compression: this will be done by <a href="#deflate">deflate</a>().<p> + +<font color="Blue"><dt> int <a name="deflateSetDictionary">deflateSetDictionary</a> (<a href="#z_streamp">z_streamp</a> strm, const Bytef *dictionary, uInt dictLength);</font> +<dd> + Initializes the compression dictionary from the given byte sequence + without producing any compressed output. This function must be called + immediately after <a href="#deflateInit">deflateInit</a>, <a href="#deflateInit2">deflateInit2</a> or <a href="#deflateReset">deflateReset</a>, before any + call of <a href="#deflate">deflate</a>. The compressor and decompressor must use exactly the same + dictionary (see <a href="#inflateSetDictionary">inflateSetDictionary</a>).<p> + + 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.<p> + + Depending on the size of the compression data structures selected by + <a href="#deflateInit">deflateInit</a> or <a href="#deflateInit2">deflateInit2</a>, a part of the dictionary may in effect be + discarded, for example if the dictionary is larger than the window size in + <a href="#deflate">deflate</a> or deflate2. Thus the strings most likely to be useful should be + put at the end of the dictionary, not at the front.<p> + + Upon return of this function, strm-> <a href="#adler">adler</a> 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.)<p> + + <a href="#deflateSetDictionary">deflateSetDictionary</a> returns <a href="#Z_OK">Z_OK</a> if success, or <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if a + parameter is invalid (such as NULL dictionary) or the stream <a href="#state">state</a> is + inconsistent (for example if <a href="#deflate">deflate</a> has already been called for this stream + or if the compression method is bsort). <a href="#deflateSetDictionary">deflateSetDictionary</a> does not + perform any compression: this will be done by <a href="#deflate">deflate</a>().<p> + +<font color="Blue"><dt> int <a name="deflateCopy">deflateCopy</a> (<a href="#z_streamp">z_streamp</a> dest, <a href="#z_streamp">z_streamp</a> source);</font> +<dd> + Sets the destination stream as a complete copy of the source stream.<p> + + 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 <a href="#deflateEnd">deflateEnd</a>. Note that <a href="#deflateCopy">deflateCopy</a> duplicates the internal + compression <a href="#state">state</a> which can be quite large, so this strategy is slow and + can consume lots of memory.<p> + + <a href="#deflateCopy">deflateCopy</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_MEM_ERROR">Z_MEM_ERROR</a> if there was not + enough memory, <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if the source stream <a href="#state">state</a> was inconsistent + (such as <a href="#zalloc">zalloc</a> being NULL). <a href="#msg">msg</a> is left unchanged in both source and + destination.<p> + +<font color="Blue"><dt> int <a name="deflateReset">deflateReset</a> (<a href="#z_streamp">z_streamp</a> strm);</font> +<dd> This function is equivalent to <a href="#deflateEnd">deflateEnd</a> followed by <a href="#deflateInit">deflateInit</a>, + but does not free and reallocate all the internal compression <a href="#state">state</a>. + The stream will keep the same compression level and any other attributes + that may have been set by <a href="#deflateInit2">deflateInit2</a>.<p> + + <a href="#deflateReset">deflateReset</a> returns <a href="#Z_OK">Z_OK</a> if success, or <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if the source + stream <a href="#state">state</a> was inconsistent (such as <a href="#zalloc">zalloc</a> or <a href="#state">state</a> being NULL).<p> + +<font color="Blue"><dt> int <a name="deflateParams">deflateParams</a> (<a href="#z_streamp">z_streamp</a> strm, int level, int strategy);</font> +<dd> + Dynamically update the compression level and compression strategy. The + interpretation of level and strategy is as in <a href="#deflateInit2">deflateInit2</a>. 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 <a href="#deflate">deflate</a>().<p> + + Before the call of <a href="#deflateParams">deflateParams</a>, the stream <a href="#state">state</a> must be set as for + a call of <a href="#deflate">deflate</a>(), since the currently available input may have to + be compressed and flushed. In particular, strm-> <a href="#avail_out">avail_out</a> must be + non-zero.<p> + + <a href="#deflateParams">deflateParams</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if the source + stream <a href="#state">state</a> was inconsistent or if a parameter was invalid, <a href="#Z_BUF_ERROR">Z_BUF_ERROR</a> + if strm->avail_out was zero.<p> + +<font color="Blue"><dt> int <a name="inflateInit2">inflateInit2</a> (<a href="#z_streamp">z_streamp</a> strm, int windowBits);</font> + +<dd> This is another version of <a href="#inflateInit">inflateInit</a> with an extra parameter. The + fields <a href="#next_in">next_in</a>, <a href="#avail_in">avail_in</a>, <a href="#zalloc">zalloc</a>, <a href="#zfree">zfree</a> and <a href="#opaque">opaque</a> must be initialized + before by the caller.<p> + + 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 <a href="#inflateInit">inflateInit</a> is used + instead. If a compressed stream with a larger window size is given as + input, <a href="#inflate">inflate</a>() will return with the error code <a href="#Z_DATA_ERROR">Z_DATA_ERROR</a> instead of + trying to allocate a larger window.<p> + + <a href="#inflateInit2">inflateInit2</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_MEM_ERROR">Z_MEM_ERROR</a> if there was not enough + memory, <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if a parameter is invalid (such as a negative + memLevel). <a href="#msg">msg</a> is set to null if there is no error message. <a href="#inflateInit2">inflateInit2</a> + does not perform any decompression apart from reading the zlib header if + present: this will be done by <a href="#inflate">inflate</a>(). (So <a href="#next_in">next_in</a> and <a href="#avail_in">avail_in</a> may be + modified, but <a href="#next_out">next_out</a> and <a href="#avail_out">avail_out</a> are unchanged.)<p> + +<font color="Blue"><dt> int <a name="inflateSetDictionary">inflateSetDictionary</a> (<a href="#z_streamp">z_streamp</a> strm, const Bytef *dictionary, uInt dictLength);</font> +<dd> + Initializes the decompression dictionary from the given uncompressed byte + sequence. This function must be called immediately after a call of <a href="#inflate">inflate</a> + if this call returned <a href="#Z_NEED_DICT">Z_NEED_DICT</a>. The dictionary chosen by the compressor + can be determined from the Adler32 value returned by this call of + <a href="#inflate">inflate</a>. The compressor and decompressor must use exactly the same + dictionary (see <a href="#deflateSetDictionary">deflateSetDictionary</a>).<p> + + <a href="#inflateSetDictionary">inflateSetDictionary</a> returns <a href="#Z_OK">Z_OK</a> if success, <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if a + parameter is invalid (such as NULL dictionary) or the stream <a href="#state">state</a> is + inconsistent, <a href="#Z_DATA_ERROR">Z_DATA_ERROR</a> if the given dictionary doesn't match the + expected one (incorrect Adler32 value). <a href="#inflateSetDictionary">inflateSetDictionary</a> does not + perform any decompression: this will be done by subsequent calls of + <a href="#inflate">inflate</a>().<p> + +<font color="Blue"><dt> int <a name="inflateSync">inflateSync</a> (<a href="#z_streamp">z_streamp</a> strm);</font> + +<dd> Skips invalid compressed data until a full flush point (see above the + description of <a href="#deflate">deflate</a> with <a href="#Z_FULL_FLUSH">Z_FULL_FLUSH</a>) can be found, or until all + available input is skipped. No output is provided.<p> + + <a href="#inflateSync">inflateSync</a> returns <a href="#Z_OK">Z_OK</a> if a full flush point has been found, <a href="#Z_BUF_ERROR">Z_BUF_ERROR</a> + if no more input was provided, <a href="#Z_DATA_ERROR">Z_DATA_ERROR</a> if no flush point has been found, + or <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if the stream structure was inconsistent. In the success + case, the application may save the current current value of <a href="#total_in">total_in</a> which + indicates where valid compressed data was found. In the error case, the + application may repeatedly call <a href="#inflateSync">inflateSync</a>, providing more input each time, + until success or end of the input data.<p> + +<font color="Blue"><dt> int <a name="inflateReset">inflateReset</a> (<a href="#z_streamp">z_streamp</a> strm);</font> +<dd> + This function is equivalent to <a href="#inflateEnd">inflateEnd</a> followed by <a href="#inflateInit">inflateInit</a>, + but does not free and reallocate all the internal decompression <a href="#state">state</a>. + The stream will keep attributes that may have been set by <a href="#inflateInit2">inflateInit2</a>. + <p> + + <a href="#inflateReset">inflateReset</a> returns <a href="#Z_OK">Z_OK</a> if success, or <a href="#Z_STREAM_ERROR">Z_STREAM_ERROR</a> if the source + stream <a href="#state">state</a> was inconsistent (such as <a href="#zalloc">zalloc</a> or <a href="#state">state</a> being NULL). + <p> +</dl> + +<hr> +<a name="Checksum functions"><h2> Checksum functions </h2> + These functions are not related to compression but are exported + anyway because they might be useful in applications using the + compression library. +<h3> Function list </h3> +<ul> +<li> uLong <a href="#adler32">adler32</a> (uLong <a href="#adler">adler</a>, const Bytef *buf, uInt len); +<li> uLong <a href="#crc32">crc32</a> (uLong crc, const Bytef *buf, uInt len); +</ul> +<h3> Function description </h3> +<dl> +<font color="Blue"><dt> uLong <a name="adler32">adler32</a> (uLong <a href="#adler">adler</a>, const Bytef *buf, uInt len);</font> +<dd> + 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. + <p> + An Adler-32 checksum is almost as reliable as a CRC32 but can be computed + much faster. Usage example: + <pre> + + uLong <a href="#adler">adler</a> = <a href="#adler32">adler32</a>(0L, <a href="#Z_NULL">Z_NULL</a>, 0); + + while (read_buffer(buffer, length) != EOF) { + <a href="#adler">adler</a> = <a href="#adler32">adler32</a>(<a href="#adler">adler</a>, buffer, length); + } + if (<a href="#adler">adler</a> != original_adler) error(); + </pre> + +<font color="Blue"><dt> uLong <a name="crc32">crc32</a> (uLong crc, const Bytef *buf, uInt len);</font> +<dd> + 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: + <pre> + + uLong crc = <a href="#crc32">crc32</a>(0L, <a href="#Z_NULL">Z_NULL</a>, 0); + + while (read_buffer(buffer, length) != EOF) { + crc = <a href="#crc32">crc32</a>(crc, buffer, length); + } + if (crc != original_crc) error(); + </pre> +</dl> +<hr> +<a name="struct z_stream_s"><h2> struct z_stream_s </h2> +<font color="Blue"> +<a name="z_stream_s"> +<pre> +typedef struct z_stream_s { + Bytef *<a name="next_in">next_in</a>; /* next input byte */ + uInt <a name="avail_in">avail_in</a>; /* number of bytes available at <a href="#next_in">next_in</a> */ + uLong <a name="total_in">total_in</a>; /* total nb of input bytes read so far */ + + Bytef *<a name="next_out">next_out</a>; /* next output byte should be put there */ + uInt <a name="avail_out">avail_out</a>; /* remaining free space at <a href="#next_out">next_out</a> */ + uLong <a name="total_out">total_out</a>; /* total nb of bytes output so far */ + + char *<a name="msg">msg</a>; /* last error message, NULL if no error */ + struct internal_state FAR *<a name="state">state</a>; /* not visible by applications */ + + alloc_func <a name="zalloc">zalloc</a>; /* used to allocate the internal <a href="#state">state</a> */ + free_func <a name="zfree">zfree</a>; /* used to free the internal <a href="#state">state</a> */ + voidpf <a name="opaque">opaque</a>; /* private data object passed to <a href="#zalloc">zalloc</a> and <a href="#zfree">zfree</a> */ + + int <a name="data_type">data_type</a>; /* best guess about the data type: ascii or binary */ + uLong <a name="adler">adler</a>; /* <a href="#adler32">adler32</a> value of the uncompressed data */ + uLong <a name="reserved">reserved</a>; /* <a href="#reserved">reserved</a> for future use */ +} <a href="#z_stream_s">z_stream</a> ; + +typedef <a href="#z_stream_s">z_stream</a> FAR * <a name="z_streamp">z_streamp</a>; ÿ +</pre> +</font> + The application must update <a href="#next_in">next_in</a> and <a href="#avail_in">avail_in</a> when <a href="#avail_in">avail_in</a> has + dropped to zero. It must update <a href="#next_out">next_out</a> and <a href="#avail_out">avail_out</a> when <a href="#avail_out">avail_out</a> + has dropped to zero. The application must initialize <a href="#zalloc">zalloc</a>, <a href="#zfree">zfree</a> and + <a href="#opaque">opaque</a> before calling the init function. All other fields are set by the + compression library and must not be updated by the application. <p> + + The <a href="#opaque">opaque</a> value provided by the application will be passed as the first + parameter for calls of <a href="#zalloc">zalloc</a> and <a href="#zfree">zfree</a>. This can be useful for custom + memory management. The compression library attaches no meaning to the + <a href="#opaque">opaque</a> value. <p> + + <a href="#zalloc">zalloc</a> must return <a href="#Z_NULL">Z_NULL</a> if there is not enough memory for the object. + If zlib is used in a multi-threaded application, <a href="#zalloc">zalloc</a> and <a href="#zfree">zfree</a> must be + thread safe. <p> + + On 16-bit systems, the functions <a href="#zalloc">zalloc</a> and <a href="#zfree">zfree</a> 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 <a href="#zalloc">zalloc</a> 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). + <p> + + The fields <a href="#total_in">total_in</a> and <a href="#total_out">total_out</a> can be used for statistics or + progress reports. After compression, <a href="#total_in">total_in</a> 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). <p> + +<hr> +<a name="Constants"><h2> Constants </h2> +<font color="Blue"> +<pre> +#define <a name="Z_NO_FLUSH">Z_NO_FLUSH</a> 0 +#define <a name="Z_PARTIAL_FLUSH">Z_PARTIAL_FLUSH</a> 1 + /* will be removed, use <a href="#Z_SYNC_FLUSH">Z_SYNC_FLUSH</a> instead */ +#define <a name="Z_SYNC_FLUSH">Z_SYNC_FLUSH</a> 2 +#define <a name="Z_FULL_FLUSH">Z_FULL_FLUSH</a> 3 +#define <a name="Z_FINISH">Z_FINISH</a> 4 +/* Allowed flush values ; see <a href="#deflate">deflate</a>() below for details */ + +#define <a name="Z_OK">Z_OK</a> 0 +#define <a name="Z_STREAM_END">Z_STREAM_END</a> 1 +#define <a name="Z_NEED_DICT">Z_NEED_DICT</a> 2 +#define <a name="Z_ERRNO">Z_ERRNO</a> (-1) +#define <a name="Z_STREAM_ERROR">Z_STREAM_ERROR</a> (-2) +#define <a name="Z_DATA_ERROR">Z_DATA_ERROR</a> (-3) +#define <a name="Z_MEM_ERROR">Z_MEM_ERROR</a> (-4) +#define <a name="Z_BUF_ERROR">Z_BUF_ERROR</a> (-5) +#define <a name="Z_VERSION_ERROR">Z_VERSION_ERROR</a> (-6) +/* Return codes for the compression/decompression functions. Negative + * values are errors, positive values are used for special but normal events. + */ + +#define <a name="Z_NO_COMPRESSION">Z_NO_COMPRESSION</a> 0 +#define <a name="Z_BEST_SPEED">Z_BEST_SPEED</a> 1 +#define <a name="Z_BEST_COMPRESSION">Z_BEST_COMPRESSION</a> 9 +#define <a name="Z_DEFAULT_COMPRESSION">Z_DEFAULT_COMPRESSION</a> (-1) +/* compression levels */ + +#define <a name="Z_FILTERED">Z_FILTERED</a> 1 +#define <a name="Z_HUFFMAN_ONLY">Z_HUFFMAN_ONLY</a> 2 +#define <a name="Z_DEFAULT_STRATEGY">Z_DEFAULT_STRATEGY</a> 0 +/* compression strategy ; see <a href="#deflateInit2">deflateInit2</a>() below for details */ + +#define <a name="Z_BINARY">Z_BINARY</a> 0 +#define <a name="Z_ASCII">Z_ASCII</a> 1 +#define <a name="Z_UNKNOWN">Z_UNKNOWN</a> 2 +/* Possible values of the <a href="#data_type">data_type</a> field */ + +#define <a name="Z_DEFLATED">Z_DEFLATED</a> 8 +/* The <a href="#deflate">deflate</a> compression method (the only one supported in this version) */ + +#define <a name="Z_NULL">Z_NULL</a> 0 /* for initializing <a href="#zalloc">zalloc</a>, <a href="#zfree">zfree</a>, <a href="#opaque">opaque</a> */ + +#define <a name="zlib_version">zlib_version</a> <a href="#zlibVersion">zlibVersion</a>() +/* for compatibility with versions less than 1.0.2 */ +</pre> +</font> + +<hr> +<a name="Misc"><h2> Misc </h2> + <a href="#deflateInit">deflateInit</a> and <a href="#inflateInit">inflateInit</a> are macros to allow checking the zlib version + and the compiler's view of <a href="#z_stream_s">z_stream</a>. + <p> + Other functions: + <dl> + <font color="Blue"><dt> const char * <a name="zError">zError</a> (int err);</font> + <font color="Blue"><dt> int <a name="inflateSyncPoint">inflateSyncPoint</a> (<a href="#z_streamp">z_streamp</a> z);</font> + <font color="Blue"><dt> const uLongf * <a name="get_crc_table">get_crc_table</a> (void);</font> + </dl> + <hr> + <font size="-1"> + Last update: Wed Oct 13 20:42:34 1999<br> + piapi@csie.ntu.edu.tw + </font> + +</body> +</html> |