zlib
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04-22 作者:漠青 在www.zlib.n
et 得到资料.自己整理了 下,翻译了一部分. 整理成两部分,第一部 分是提炼出来的函数列 表.第二部分是原来的 使用手册+自己翻译的 .是用来自己用的.如 果能给别人带来方便, 也是意外的惊喜阿 .哈哈. ----------
---------- ---------- ---------- -------- First Part ---------- ---------- ---------- ---------- ---------- ------ Zlib函数列表
实用函数
int compress (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen)
; int compress2 (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen,
int level); int uncompress
(Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen) ; typedef voidp gzFile;
gzFile gzopen (const char *path, const char *mode);
gzFile gzdopen (int fd, const char *mode);
int gzsetparam
s (gzFile file, int level, int strategy); int gzread (gzFile file, voidp buf, unsigned len);
int gzwrite (gzFile file, const voidp buf, unsigned len);
int VA gzprintf (gzFile file, const char *format, ...);
int gzputs (gzFile file, const char *s);
char * gzgets (gzFile file, char *buf, int len);
int gzputc (gzFile file, int c);
int gzgetc (gzFile file);
int gzflush (gzFile file, int flush);
z_off_t gzseek (gzFile file, z_off_t offset, int whence);
z_off_t gztell (gzFile file);
int gzrewind (gzFile file);
int gzeof (gzFile file);
int gzclose (gzFile file);
const char * gzerror (gzFile file, int *errnum);
基本函数:
const char * zlibVersio
n (void); int deflateIni
t (z_streamp strm, int level); int deflate (z_streamp
strm, int flush); int deflateEnd
(z_streamp strm); int inflateIni
t (z_streamp strm); int inflate (z_streamp
strm, int flush); int inflateEnd
(z_streamp strm); 高级函数:
int deflateIni
t2 (z_streamp strm, int deflateSet
Dictionary (z_streamp strm, const Bytef *dictionar y, uInt dictLength ); int deflateCop
y (z_streamp dest, z_streamp source); int deflateRes
et (z_streamp strm); int deflatePar
ams (z_streamp strm, int level, int strategy); int inflateIni
t2 (z_streamp strm, int windowBits ); int inflateSet
Dictionary (z_streamp strm, const Bytef *dictionar y, uInt dictLength ); int inflateSyn
c (z_streamp strm); int inflateRes
et (z_streamp strm); 校验函数
uLong adler32 (uLong adler, const Bytef *buf, uInt len);
uLong crc32 (uLong crc, const Bytef *buf, uInt len);
struct z_stream_s
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_s
tate FAR *state; /* not visible by applicatio ns */ 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: ascii or binary */ uLong adler; /* adler32 value of the uncompress
ed data */ uLong reserved; /* reserved for future use */
} z_stream ;
typedef z_stream FAR * z_streamp;
常量:
#define Z_NO_FLUSH
0 #define Z_PARTIAL_
FLUSH 1 /* 将要被删除, 使用Z_SYNC_F LUSH 代替他们 */ #define Z_SYNC_FLU
SH 2 #define Z_FULL_FLU
SH 3 #define Z_FINISH 4 /* Allowed flush values ; see deflate() below for details */
#define Z_OK 0
#define Z_STREAM_E
ND 1 #define Z_NEED_DIC
T 2 #define Z_ERRNO (-1)
#define Z_STREAM_E
RROR (-2) #define Z_DATA_ERR
OR (-3) #define Z_MEM_ERRO
R (-4) #define Z_BUF_ERRO
R (-5) #define Z_VERSION_
ERROR (-6) /* 压缩/解压缩的返回值 .负值是错误,正值是 特殊但是正常的值. */ #define Z_NO_COMPR
ESSION 0 #define Z_BEST_SPE
ED 1 #define Z_BEST_COM
PRESSION 9 #define Z_DEFAULT_
COMPRESSIO N (-1) /* 压缩级别 */ #define Z_FILTERED
1 #define Z_HUFFMAN_
ONLY 2 #define Z_DEFAULT_
STRATEGY 0 /* 压缩策略; see deflateIni t2() below for details */ #define Z_BINARY 0
#define Z_ASCII 1
#define Z_UNKNOWN 2 /* Possible values of the data_type field */
#define Z_DEFLATED
8/* The deflate compressio n method (the only one supported in this version) */ #define Z_NULL 0 /* 用于初始化zallo
c, zfree, opaque */ #define zlib_versi
on zlibVersio n() /* 用于和1.0.2以前 的版本兼容*/ 另外一些函数:
const char * zError (int err);
int inflateSyn
cPoint (z_streamp z); const uLongf * get_crc_ta
ble (void); ----------
---------- ---------- ---------- ---SecondP art ---------- ---------- ---------- ---------- ---------- -------- zlib 1.1.4 手册
----------
---------- ---------- ---------- ---------- ---------- ---------- ---------- 目录
序言
介绍
实用函数
基本函数
高级函数
常量
结构 z_stream_s
校验函数
Misc
----------
---------- ---------- ---------- ---------- ---------- ---------- ---------- 序言
'zlib'常用的流
行的压缩库 。版本:1.1.4。 Copyright (C) 1995-2002 Jean-loup Gailly and Mark Adler
本软件对在使用中所产
生的任何问题,不承担 任何的责任。 许可任何人使用本软件
用于任何目的,包括商 业程序,或修改它,从 新自由发布。 不过以下行为被限制:
1。本软件的起源不能
被更改。 2。修改的版本必须被
标记,不能搅乱原始版 本。 3。本声明不能被移除
,或修改。 /*
The origin of this software must not be misreprese
nted ; you must not claim that you wrote the original software. If you use this software in a product, an acknowledg ment in the product documentat ion would be appreciate d but is not required. Altered source versions must be plainly marked as such, and must not be misreprese
nted as being the original software. This notice may not be removed or altered from any source distributi
on. */
----------
---------- ---------- ---------- ---------- ---------- ---------- ---------- 介绍
zlib压缩库提供内
存内压缩/解压缩函数 。包括解压验证。 这个版本只有一种压缩
方式,但是以后其他的 算法也会被加入进来, 并且接口是一样的。 如果缓存区足够大,压
缩被一次完成,否则就 重复调用压缩。在后一 种情况,程序必须在每 次调用时提供更多的输 入或更多输出空间。 本压缩库也支持gzi
p(.gz)格式的读 写操作。接口也和st dio相似。 本压缩库不安装任何信
号处理,解码器检查压 缩数据的一致性,所以 ,本压缩库决不会使输 入崩溃。 ----------
---------- ---------- ---------- ---------- ---------- ---------- ---------- 实用函数
以下实用函数的实现建
立在basic stream-ori ented 函数上。 为了了简化接口,设置
了一些默认选项(压缩 级别,内存使用,标准 内存分配器功能)这些 实用函数的源代码很容 易被修改,如果你要实 现有些特殊选项。 函数列表:
int compress (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen)
; int compress2 (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen,
int level); int uncompress
(Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen) ; typedef voidp gzFile;
gzFile gzopen (const char *path, const char *mode);
gzFile gzdopen (int fd, const char *mode);
int gzsetparam
s (gzFile file, int level, int strategy); int gzread (gzFile file, voidp buf, unsigned len);
int gzwrite (gzFile file, const voidp buf, unsigned len);
int VA gzprintf (gzFile file, const char *format, ...);
int gzputs (gzFile file, const char *s);
char * gzgets (gzFile file, char *buf, int len);
int gzputc (gzFile file, int c);
int gzgetc (gzFile file);
int gzflush (gzFile file, int flush);
z_off_t gzseek (gzFile file, z_off_t offset, int whence);
z_off_t gztell (gzFile file);
int gzrewind (gzFile file);
int gzeof (gzFile file);
int gzclose (gzFile file);
const char * gzerror (gzFile file, int *errnum);
函数说明:
int compress (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen)
; 压缩source buffer到des
tination buffer。 sourceLen是
source buffer的长度( byte)。 destLen是de
stination buffer的总共长 度(byte)。调用 前 destLen的长度 必须至少source Len长度的0.1% 再加上12个byte .调用后。destL en是实际的comp ressed buffer长度。 如果输入文件是mma
p'ed,这个函数可 以用于压缩整个文件。 如果压缩成功返回Z_
OK, 如果没有足够的内存返 回Z_MEM_ERR OR,如果没有足够的 空间输出文件返回Z_ BUF_ERROR. int compress2 (Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen,
int level); 压缩source buffer到des
tination buffer。 参数级level和d
efalteInit 一样。 destLen是de
stination buffer的总共长 度(byte)。调用 前 destLen的长度 必须至少source Len长度的0.1% 再加上12个byte .调用后。destL en是实际的comp ressed buffer长度。 如果压缩成功返回Z_
OK, 如果没有足够的内存返 回Z_MEM_ERR OR,如果没有足够的 空间输出文件返回Z_ BUF_ERROR. 如果level是无效
的,返回Z_STRE AM_ERROR. int uncompress
(Bytef *dest, uLongf *destLen, const Bytef *source, uLong sourceLen) ; Decompress
es the source buffer into the destinatio n buffer. sourceLen is the byte length of the source buffer. Upon entry, destLen is the total size of the destinatio n buffer, which must be large enough to hold the entire uncompress ed data. (The size of the uncompress ed data must have been saved previously by the compressor and transmitte d to the decompress or by some mechanism outside the scope of this compressio n 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_ERRO R if there was not enough memory, Z_BUF_ERRO R if there was not enough room in the output buffer, or Z_DATA_ERR OR if the input data was corrupted. typedef voidp gzFile;
gzFile gzopen (const char *path, const char *mode);
打开一个gzip文件
进行读/写,mode 和fopen("rb "或" wb")一样.也可以 包括压缩级别如:"w b9",或着一个策略 "f"作为过滤数据" wb6f", "h"是为了"huf fman" 压缩,如:"wb1h ". gzopen用于读一
个没有gzip格式的 文件.gzread直 接从没有解压缩的文件 中读数据. 如果文件不能被打开或
是没有足够的内存,g zopen将返回NU LL. gzFile gzdopen (int fd, const char *mode);
gzdopen() associates
a gzFile with the file descriptor fd. File descriptor s 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 gzopen. The next call of gzclose on the returned gzFile will also close the file descriptor
fd, just like fclose(fdo pen(fd), mode) closes the file descriptor fd. If you want to keep fd open, use gzdopen(du p(fd), mode). gzdopen returns NULL if there was insufficie
nt memory to allocate the (de)compre ssion state. int gzsetparam
s (gzFile file, int level, int strategy); Dynamicall
y update the compressio n level or strategy. See the descriptio n of deflateIni t2 for the meaning of these parameters . gzsetparam
s returns Z_OK if success, or Z_STREAM_E RROR if the file was not opened for writing. int gzread (gzFile file, voidp buf, unsigned len);
Reads the given number of uncompress
ed 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 uncompress
ed bytes actually read (0 for end of file, -1 for error). int gzwrite (gzFile file, const voidp buf, unsigned len);
Writes the given number of uncompress
ed bytes into the compressed file. gzwrite returns the number of uncompress ed bytes actually written (0 in case of error). int VA gzprintf (gzFile file, const char *format, ...);
Converts, formats, and writes the args to the compressed
file under control of the format string, as in fprintf. gzprintf returns the number of uncompress ed bytes actually written (0 in case of error). int gzputs (gzFile file, const char *s);
Writes the given null-termi
nated string to the compressed file, excluding the terminatin g null character. gzputs returns the number of characters
written, or -1 in case of error. char * gzgets (gzFile file, char *buf, int len);
Reads bytes from the compressed
file until len-1 characters are read, or a newline character is read and transferre d to buf, or an end-of-fil e condition is encountere d. The string is then terminated with a null character. gzgets returns buf, or Z_NULL in case of error.
int gzputc (gzFile file, int c);
Writes c, converted to an unsigned char, into the compressed
file. gzputc returns the value that was written, or -1 in case of error. int gzgetc (gzFile file);
Reads one byte from the compressed
file. gzgetc returns this byte or -1 in case of end of file or error. int gzflush (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 compressio
n. z_off_t gzseek (gzFile file, z_off_t offset, int whence);
Sets the starting position for the next gzread or gzwrite on the given compressed
file. The offset represents a number of bytes in the uncompress ed data stream. The whence parameter is defined as in lseek(2); the value SEEK_END is not supported. 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 ; gzseek then compresses
a sequence of zeroes up to the new starting position. gzseek returns the resulting offset location as measured in bytes from the beginning of the uncompress
ed 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. int gzrewind (gzFile file);
Rewinds the given file. This function is supported only for reading.
gzrewind(f
ile) is equivalent to (int)gzsee k(file, 0L, SEEK_SET) z_off_t gztell (gzFile file);
Returns the starting position for the next gzread or gzwrite on the given compressed
file. This position represents a number of bytes in the uncompress ed data stream. gztell(fil
e) is equivalent to gzseek(fil e, 0L, SEEK_CUR) int gzeof (gzFile file);
Returns 1 when EOF has previously
been detected reading the given input stream, otherwise zero. int gzclose (gzFile file);
Flushes all pending output if necessary,
closes the compressed file and deallocate s all the (de)compre ssion state. The return value is the zlib error number (see function gzerror below). const char * gzerror (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 compressio n library, errnum is set to Z_ERRNO and the applicatio n may consult errno to get the exact error code. ----------
---------- ---------- ---------- ---------- ---------- ---------- ---------- 基本函数:
函数列表:
const char * zlibVersio
n (void); int deflateIni
t (z_streamp strm, int level); int deflate (z_streamp
strm, int flush); int deflateEnd
(z_streamp strm); int inflateIni
t (z_streamp strm); int inflate (z_streamp
strm, int flush); int inflateEnd
(z_streamp strm); 函数说明:
const char * zlibVersio
n (void); 应用程序会比较zli
bVersion和Z LIB_VERSIO N的一致性。 如果第一个字不同,说
明zlib和应用程序 使用的zlib.h是 不一致的。这个检查将 被defalteIn it和infalte Init自动调用。 int deflateIni
t (z_streamp strm, int level); 为压缩初始化内部流的
状态。 Initialize
s the internal stream state for compressio n. The fields zalloc, zfree and opaque must be initialize d before by the caller. If zalloc and zfree are set to Z_NULL, deflateIni t updates them to use default allocation functions. The compressio
n level must be Z_DEFAULT_ COMPRESSIO N, or between 0 and 9: 1 gives best speed, 9 gives best compressio n, 0 gives no compressio n at all (the input data is simply copied a block at a time). Z_DEFAULT_
COMPRESSIO N requests a default compromise between speed and compressio n (currently equivalent to level 6). deflateIni
t returns Z_OK if success, Z_MEM_ERRO R if there was not enough memory, Z_STREAM_E RROR if level is not a valid compressio n level, Z_VERSION_ ERROR if the zlib library version (zlib_vers ion) is incompatib le with the version assumed by the caller (ZLIB_VERS ION). msg is set to null if there is no error message. deflateIni t does not perform any compressio n: this will be done by deflate(). int deflate (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 accordingl
y. 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 accordingl
y. This action is forced if the parameter flush is non zero. Forcing flush frequently degrades the compressio n ratio, so this parameter should be set only when necessary (in interactiv e applicatio ns). Some output may be provided even if flush is not set. Before the call of deflate(),
the applicatio n 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 accordingl y ; avail_out should never be zero before the call. The applicatio n 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. If the parameter flush is set to Z_SYNC_FLU
SH, all pending output is flushed to the output buffer and the output is aligned on a byte boundary, so that the decompress or 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 compressio n for some compressio n algorithms and so it should be used only when necessary. If flush is set to Z_FULL_FLU
SH, all output is flushed as with Z_SYNC_FLU SH, and the compressio n state is reset so that decompress ion can restart from this point if previous compressed data has been damaged or if random access is desired. Using Z_FULL_FLU SH too often can seriously degrade the compressio n. 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) . If the parameter flush is set to Z_FINISH, pending input is processed,
pending output is flushed and deflate returns with Z_STREAM_E ND 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_E ND or an error. After deflate has returned Z_STREAM_E ND, the only possible operations on the stream are deflateRes et or deflateEnd . Z_FINISH can be used immediatel
y after deflateIni t if all the compressio n 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_E ND, 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 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 informatio n purposes and does not affect the compressio n algorithm in any manner. deflate() returns Z_OK if some progress has been made (more input processed or more output produced),
Z_STREAM_E ND if all input has been consumed and all output has been produced (only when flush is set to Z_FINISH), Z_STREAM_E RROR if the stream state was inconsiste nt (for example if next_in or next_out was NULL), Z_BUF_ERRO R if no progress is possible (for example avail_in or avail_out was zero). int deflateEnd
(z_streamp strm); All dynamicall
y allocated data structures for this stream are freed. This function discards any unprocesse d input and does not flush any pending output. deflateEnd
returns Z_OK if success, Z_STREAM_E RROR if the stream state was inconsiste nt, Z_DATA_ERR OR if the stream was freed prematurel y (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 deallocate d). int inflateIni
t (z_streamp strm); Initialize
s the internal stream state for decompress ion. The fields next_in, avail_in, zalloc, zfree and opaque must be initialize d before by the caller. If next_in is not Z_NULL and avail_in is large enough (the exact value depends on the compressio n method), inflateIni t determines the compressio n method from the zlib header and allocates all data structures accordingl y ; otherwise the allocation will be deferred to the first call of inflate. If zalloc and zfree are set to Z_NULL, inflateIni t updates them to use default allocation functions. inflateIni
t returns Z_OK if success, Z_MEM_ERRO R if there was not enough memory, Z_VERSION_ ERROR if the zlib library version is incompatib le with the version assumed by the caller. msg is set to null if there is no error message. inflateIni t does not perform any decompress ion apart from reading the zlib header if present: this will be done by inflate(). (So next_in and avail_in may be modified, but next_out and avail_out are unchanged. ) int inflate (z_streamp
strm, int flush); inflate decompress
es 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. 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 accordingl y. 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 accordingl
y. 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 applicatio n 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 accordingl y. The applicatio n can consume the uncompress ed 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. If the parameter flush is set to Z_SYNC_FLU
SH, 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_SYNC_FLU SH and Z_FINISH, but the current implementa tion actually flushes as much output as possible anyway. inflate() should normally be called until it returns Z_STREAM_E
ND or an error. However if all decompress ion 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 uncompress ed data. (The size of the uncompress ed data may have been saved by the compressor for this purpose.) The next operation on this stream must be inflateEnd to deallocate the decompress ion state. The use of Z_FINISH is never required, but can be used to inform inflate that a faster routine may be used for the single inflate() call. If a preset dictionary
is needed at this point (see inflateSet Dictionary below), inflate sets strm-adler to the adler32 checksum of the dictionary chosen by the compressor and returns Z_NEED_DIC T ; 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_E ND 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_E ND only if the checksum is correct. inflate() returns Z_OK if some progress has been made (more input processed or more output produced),
Z_STREAM_E ND if the end of the compressed data has been reached and all uncompress ed output has been produced, Z_NEED_DIC T if a preset dictionary is needed at this point, Z_DATA_ERR OR if the input data was corrupted (input stream not conforming to the zlib format or incorrect adler32 checksum), Z_STREAM_E RROR if the stream structure was inconsiste nt (for example if next_in or next_out was NULL), Z_MEM_ERRO R if there was not enough memory, Z_BUF_ERRO R 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_ERR OR case, the applicatio n may then call inflateSyn c to look for a good compressio n block. int inflateEnd
(z_streamp strm); 所有为这个strea
m动态分派的数据结构 在这被释放。 这个函数丢弃所有未处 理的输入和不输出任何 未决的输出。 如果成功, inflateEnd
返回 Z_OK ;如果stream是 不一致的 返回Z_STREAM _ERROR, 在错误情形中,msg
信息可能被设置,然后 指向一个静态字符串。 ----------
---------- ---------- ---------- ---------- ---------- ---------- ---------- 高级函数:
以下函数应用于特殊应
用程序: 函数列表:
int deflateIni
t2 (z_streamp strm, int deflateSet
Dictionary (z_streamp strm, const Bytef *dictionar y, uInt dictLength ); int deflateCop
y (z_streamp dest, z_streamp source); int deflateRes
et (z_streamp strm); int deflatePar
ams (z_streamp strm, int level, int strategy); int inflateIni
t2 (z_streamp strm, int windowBits ); int inflateSet
Dictionary (z_streamp strm, const Bytef *dictionar y, uInt dictLength ); int inflateSyn
c (z_streamp strm); int inflateRes
et (z_streamp strm); 函数说明:
int deflateIni
t2 (z_streamp strm, int level, int method, int windowBits , int memLevel, int strategy); This is another version of deflateIni
t with more compressio n options. The fields next_in, zalloc, zfree and opaque must be initialize d before by the caller. The method parameter is the compressio
n 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 compressio n at the expense of memory usage. The default value is 15 if deflateIni t is used instead. The memLevel parameter specifies how much memory should be allocated for the internal compressio
n state. memLevel=1 uses minimum memory but is slow and reduces compressio n 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 compressio
n 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 distributi on. In this case, the compressio n 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 intermedia te between Z_DEFAULT and Z_HUFFMAN_ ONLY. The strategy parameter only affects the compressio n ratio but not the correctnes s of the compressed output even if it is not set appropriat ely. deflateIni
t2 returns Z_OK if success, Z_MEM_ERRO R if there was not enough memory, Z_STREAM_E RROR if a parameter is invalid (such as an invalid method). msg is set to null if there is no error message. deflateIni t2 does not perform any compressio n: this will be done by deflate(). int deflateSet
Dictionary (z_streamp strm, const Bytef *dictionar y, uInt dictLength ); Initialize
s the compressio n dictionary from the given byte sequence without producing any compressed output. This function must be called immediatel y after deflateIni t, deflateIni t2 or deflateRes et, before any call of deflate. The compressor and decompress or must use exactly the same dictionary (see inflateSet Dictionary ). The dictionary
should consist of strings (byte sequences) that are likely to be encountere d 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 compressio
n data structures selected by deflateIni t or deflateIni t2, a part of the dictionary may in effect be discarded, for example if the dictionary is larger than the window size in deflate or deflate2. Thus the strings most likely to be useful should be put at the end of the dictionary , not at the front. Upon return of this function, strm-> adler is set to the Adler32 value of the dictionary
; the decompress or 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 .) deflateSet
Dictionary returns Z_OK if success, or Z_STREAM_E RROR if a parameter is invalid (such as NULL dictionary ) or the stream state is inconsiste nt (for example if deflate has already been called for this stream or if the compressio n method is bsort). deflateSet Dictionary does not perform any compressio n: this will be done by deflate(). int deflateCop
y (z_streamp dest, z_streamp source); Sets the destinatio
n stream as a complete copy of the source stream. This function can be useful when several compressio
n strategies will be tried, for example when there are several ways of pre-proces sing the input data with a filter. The streams that will be discarded should then be freed by calling deflateEnd . Note that deflateCop y duplicates the internal compressio n state which can be quite large, so this strategy is slow and can consume lots of memory. deflateCop
y returns Z_OK if success, Z_MEM_ERRO R if there was not enough memory, Z_STREAM_E RROR if the source stream state was inconsiste nt (such as zalloc being NULL). msg is left unchanged in both source and destinatio n. int deflateRes
et (z_streamp strm); This function is equivalent
to deflateEnd followed by deflateIni t, but does not free and reallocate all the internal compressio n state. The stream will keep the same compressio n level and any other attributes that may have been set by deflateIni t2. deflateRes
et returns Z_OK if success, or Z_STREAM_E RROR if the source stream state was inconsiste nt (such as zalloc or state being NULL). int deflatePar
ams (z_streamp strm, int level, int strategy); Dynamicall
y update the compressio n level and compressio n strategy. The interpreta tion of level and strategy is as in deflateIni t2. This can be used to switch between compressio n and straight copy of the input data, or to switch to a different kind of input data requiring a different strategy. If the compressio n 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 deflatePar
ams, 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. deflatePar
ams returns Z_OK if success, Z_STREAM_E RROR if the source stream state was inconsiste nt or if a parameter was invalid, Z_BUF_ERRO R if strm->avai l_out was zero. int inflateIni
t2 (z_streamp strm, int windowBits ); This is another version of inflateIni
t with an extra parameter. The fields next_in, avail_in, zalloc, zfree and opaque must be initialize d 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 inflateIni t 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_ERR OR instead of trying to allocate a larger window. inflateIni
t2 returns Z_OK if success, Z_MEM_ERRO R if there was not enough memory, Z_STREAM_E RROR if a parameter is invalid (such as a negative memLevel). msg is set to null if there is no error message. inflateIni t2 does not perform any decompress ion apart from reading the zlib header if present: this will be done by inflate(). (So next_in and avail_in may be modified, but next_out and avail_out are unchanged. ) int inflateSet
Dictionary (z_streamp strm, const Bytef *dictionar y, uInt dictLength ); Initialize
s the decompress ion dictionary from the given uncompress ed byte sequence. This function must be called immediatel y after a call of inflate if this call returned Z_NEED_DIC T. The dictionary chosen by the compressor can be determined from the Adler32 value returned by this call of inflate. The compressor and decompress or must use exactly the same dictionary (see deflateSet Dictionary ). inflateSet
Dictionary returns Z_OK if success, Z_STREAM_E RROR if a parameter is invalid (such as NULL dictionary ) or the stream state is inconsiste nt, Z_DATA_ERR OR if the given dictionary doesn't match the expected one (incorrect Adler32 value). inflateSet Dictionary does not perform any decompress ion: this will be done by subsequent calls of inflate(). int inflateSyn
c (z_streamp strm); Skips invalid compressed
data until a full flush point (see above the descriptio n of deflate with Z_FULL_FLU SH) can be found, or until all available input is skipped. No output is provided. inflateSyn
c returns Z_OK if a full flush point has been found, Z_BUF_ERRO R if no more input was provided, Z_DATA_ERR OR if no flush point has been found, or Z_STREAM_E RROR if the stream structure was inconsiste nt. In the success case, the applicatio n may save the current current value of total_in which indicates where valid compressed data was found. In the error case, the applicatio n may repeatedly call inflateSyn c, providing more input each time, until success or end of the input data. int inflateRes
et (z_streamp strm); 这个函数伴随infl
ateInit,跟i nflateEnd是 等价的,但不释放和在 分配所有的内部解压缩 状态。 这个stream保持
被inflateIn it2设置的属性。 如果成功, inflateRes
et 返回 Z_OK ;如果stream是 不一致的 返回Z_STREAM _ERROR, ----------
---------- ---------- ---------- ---------- ---------- ---------- ---------- 校验函数
这些函数和压缩是没有
关系的.但是被公开是 因为他们在程序使用压 缩库时,可能是有用的 。 函数列表:
uLong adler32 (uLong adler, const Bytef *buf, uInt len);
uLong crc32 (uLong crc, const Bytef *buf, uInt len);
函数说明:
uLong adler32 (uLong adler, const Bytef *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_buff
er(buffer, length) != EOF) { adler = adler32(ad
ler, buffer, length); }
if (adler != original_a
dler) error(); uLong crc32 (uLong crc, const Bytef *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-condi tioning (one's complement ) is performed within this function so it shouldn't be done by the applicatio n. Usage example: uLong crc = crc32(0L, Z_NULL, 0);
while (read_buff
er(buffer, length) != EOF) { crc = crc32(crc,
buffer, length); }
if (crc != original_c
rc) error(); ----------
---------- ---------- ---------- ---------- ---------- ---------- ---------- struct z_stream_s
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_s
tate FAR *state; /* not visible by applicatio ns */ 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: ascii or binary */ uLong adler; /* adler32 value of the uncompress
ed data */ uLong reserved; /* reserved for future use */
} z_stream ;
typedef z_stream FAR * z_streamp;
? The applicatio
n 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 applicatio n must initialize zalloc, zfree and opaque before calling the init function. All other fields are set by the compressio n library and must not be updated by the applicatio n. The opaque value provided by the applicatio
n will be passed as the first parameter for calls of zalloc and zfree. This can be useful for custom memory management . The compressio n 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-thre
aded applicatio n, 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 requiremen ts and avoid any allocation of 64K objects, at the expense of compressio n ratio, compile the library with -DMAX_WBIT S=14 (see zconf.h). The fields total_in and total_out can be used for statistics
or progress reports. After compressio n, total_in holds the total size of the uncompress ed data and may be saved for use in the decompress or (particula rly if the decompress or wants to decompress everything in a single step). ----------
---------- ---------- ---------- ---------- ---------- ---------- ---------- 常量:
#define Z_NO_FLUSH
0 #define Z_PARTIAL_
FLUSH 1 /* 将要被删除, 使用Z_SYNC_F
LUSH 代替他们 */ #define Z_SYNC_FLU
SH 2 #define Z_FULL_FLU
SH 3 #define Z_FINISH 4
/* Allowed flush values ; see deflate() below for details */
#define Z_OK 0
#define Z_STREAM_E
ND 1 #define Z_NEED_DIC
T 2 #define Z_ERRNO (-1)
#define Z_STREAM_E
RROR (-2) #define Z_DATA_ERR
OR (-3) #define Z_MEM_ERRO
R (-4) #define Z_BUF_ERRO
R (-5) #define Z_VERSION_
ERROR (-6) /* 压缩/解压缩的返回值
.负值是错误,正值是 特殊但是正常的值. */ #define Z_NO_COMPR
ESSION 0 #define Z_BEST_SPE
ED 1 #define Z_BEST_COM
PRESSION 9 #define Z_DEFAULT_
COMPRESSIO N (-1) /* 压缩级别 */
#define Z_FILTERED
1 #define Z_HUFFMAN_
ONLY 2 #define Z_DEFAULT_
STRATEGY 0 /* 压缩策略; see deflateIni
t2() below for details */ #define Z_BINARY 0
#define Z_ASCII 1
#define Z_UNKNOWN 2
/* Possible values of the data_type field */
#define Z_DEFLATED
8 /* The deflate compressio
n method (the only one supported in this version) */ #define Z_NULL 0 /* 用于初始化zallo
c, zfree, opaque */ #define zlib_versi
on zlibVersio n() /* 用于和1.0.2以前
的版本兼容*/ ----------
---------- ---------- ---------- ---------- ---------- ---------- ---------- Misc
deflateIni
t 和 inflateIni t 是检查zlib版本和 z_stream的编 译器view的宏. 另外一些函数:
const char * zError (int err);
int inflateSyn
cPoint (z_streamp z); const uLongf * get_crc_ta
ble (void); ----------
---------- ---------- ---------- ---------- ---------- ---------- ---------- - (顶7下)(踩6下)
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