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1 /* zlib.h -- interface of the 'zlib' general purpose compression library
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2 version 0.95, Aug 16th, 1995.
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3
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4 Copyright (C) 1995 Jean-loup Gailly and Mark Adler
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5
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6 This software is provided 'as-is', without any express or implied
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7 warranty. In no event will the authors be held liable for any damages
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8 arising from the use of this software.
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9
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10 Permission is granted to anyone to use this software for any purpose,
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11 including commercial applications, and to alter it and redistribute it
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12 freely, subject to the following restrictions:
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13
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14 1. The origin of this software must not be misrepresented; you must not
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15 claim that you wrote the original software. If you use this software
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16 in a product, an acknowledgment in the product documentation would be
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17 appreciated but is not required.
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18 2. Altered source versions must be plainly marked as such, and must not be
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19 misrepresented as being the original software.
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20 3. This notice may not be removed or altered from any source distribution.
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21
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22 Jean-loup Gailly Mark Adler
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23 gzip@prep.ai.mit.edu madler@alumni.caltech.edu
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24 */
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25
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26 #ifndef _ZLIB_H
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27 #define _ZLIB_H
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28
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29 #include "zconf.h"
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30
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31 #define ZLIB_VERSION "0.95"
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32
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33 /*
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34 The 'zlib' compression library provides in-memory compression and
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35 decompression functions, including integrity checks of the uncompressed
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36 data. This version of the library supports only one compression method
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37 (deflation) but other algorithms may be added later and will have the same
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38 stream interface.
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39
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40 For compression the application must provide the output buffer and
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41 may optionally provide the input buffer for optimization. For decompression,
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42 the application must provide the input buffer and may optionally provide
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43 the output buffer for optimization.
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44
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45 Compression can be done in a single step if the buffers are large
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46 enough (for example if an input file is mmap'ed), or can be done by
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47 repeated calls of the compression function. In the latter case, the
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48 application must provide more input and/or consume the output
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49 (providing more output space) before each call.
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50 */
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51
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52 typedef voidpf (*alloc_func) OF((voidpf opaque, uInt items, uInt size));
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53 typedef void (*free_func) OF((voidpf opaque, voidpf address));
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54
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55 struct internal_state;
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56
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57 typedef struct z_stream_s {
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58 Bytef *next_in; /* next input byte */
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59 uInt avail_in; /* number of bytes available at next_in */
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60 uLong total_in; /* total nb of input bytes read so far */
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61
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62 Bytef *next_out; /* next output byte should be put there */
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63 uInt avail_out; /* remaining free space at next_out */
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64 uLong total_out; /* total nb of bytes output so far */
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65
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66 char *msg; /* last error message, NULL if no error */
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67 struct internal_state FAR *state; /* not visible by applications */
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68
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69 alloc_func zalloc; /* used to allocate the internal state */
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70 free_func zfree; /* used to free the internal state */
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71 voidp opaque; /* private data object passed to zalloc and zfree */
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72
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73 Byte data_type; /* best guess about the data type: ascii or binary */
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74
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75 } z_stream;
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76
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77 /*
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78 The application must update next_in and avail_in when avail_in has
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79 dropped to zero. It must update next_out and avail_out when avail_out
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80 has dropped to zero. The application must initialize zalloc, zfree and
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81 opaque before calling the init function. All other fields are set by the
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82 compression library and must not be updated by the application.
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83
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84 The opaque value provided by the application will be passed as the first
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85 parameter for calls of zalloc and zfree. This can be useful for custom
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86 memory management. The compression library attaches no meaning to the
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87 opaque value.
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88
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89 zalloc must return Z_NULL if there is not enough memory for the object.
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90 On 16-bit systems, the functions zalloc and zfree must be able to allocate
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91 exactly 65536 bytes, but will not be required to allocate more than this
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92 if the symbol MAXSEG_64K is defined (see zconf.h). WARNING: On MSDOS,
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93 pointers returned by zalloc for objects of exactly 65536 bytes *must*
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94 have their offset normalized to zero. The default allocation function
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95 provided by this library ensures this (see zutil.c). To reduce memory
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96 requirements and avoid any allocation of 64K objects, at the expense of
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97 compression ratio, compile the library with -DMAX_WBITS=14 (see zconf.h).
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98
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99 The fields total_in and total_out can be used for statistics or
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100 progress reports. After compression, total_in holds the total size of
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101 the uncompressed data and may be saved for use in the decompressor
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102 (particularly if the decompressor wants to decompress everything in
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103 a single step).
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104 */
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105
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106 /* constants */
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107
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108 #define Z_NO_FLUSH 0
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109 #define Z_PARTIAL_FLUSH 1
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110 #define Z_FULL_FLUSH 2
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111 #define Z_SYNC_FLUSH 3 /* experimental: partial_flush + byte align */
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112 #define Z_FINISH 4
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113 /* See deflate() below for the usage of these constants */
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114
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115 #define Z_OK 0
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116 #define Z_STREAM_END 1
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117 #define Z_ERRNO (-1)
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118 #define Z_STREAM_ERROR (-2)
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119 #define Z_DATA_ERROR (-3)
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120 #define Z_MEM_ERROR (-4)
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121 #define Z_BUF_ERROR (-5)
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122 /* error codes for the compression/decompression functions */
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123
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124 #define Z_BEST_SPEED 1
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125 #define Z_BEST_COMPRESSION 9
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126 #define Z_DEFAULT_COMPRESSION (-1)
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127 /* compression levels */
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128
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129 #define Z_FILTERED 1
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130 #define Z_HUFFMAN_ONLY 2
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131 #define Z_DEFAULT_STRATEGY 0
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132
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133 #define Z_BINARY 0
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134 #define Z_ASCII 1
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135 #define Z_UNKNOWN 2
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136 /* Used to set the data_type field */
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137
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138 #define Z_NULL 0 /* for initializing zalloc, zfree, opaque */
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139
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140 extern char *zlib_version;
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141 /* The application can compare zlib_version and ZLIB_VERSION for consistency.
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142 If the first character differs, the library code actually used is
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143 not compatible with the zlib.h header file used by the application.
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144 */
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145
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146 /* basic functions */
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147
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148 extern int deflateInit OF((z_stream *strm, int level));
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149 /*
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150 Initializes the internal stream state for compression. The fields
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151 zalloc, zfree and opaque must be initialized before by the caller.
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152 If zalloc and zfree are set to Z_NULL, deflateInit updates them to
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153 use default allocation functions.
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154
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155 The compression level must be Z_DEFAULT_COMPRESSION, or between 1 and 9:
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156 1 gives best speed, 9 gives best compression. Z_DEFAULT_COMPRESSION requests
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157 a default compromise between speed and compression (currently equivalent
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158 to level 6).
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159
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160 deflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
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161 enough memory, Z_STREAM_ERROR if level is not a valid compression level.
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162 msg is set to null if there is no error message. deflateInit does not
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163 perform any compression: this will be done by deflate().
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164 */
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165
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166
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167 extern int deflate OF((z_stream *strm, int flush));
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168 /*
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169 Performs one or both of the following actions:
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170
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171 - Compress more input starting at next_in and update next_in and avail_in
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172 accordingly. If not all input can be processed (because there is not
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173 enough room in the output buffer), next_in and avail_in are updated and
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174 processing will resume at this point for the next call of deflate().
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175
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176 - Provide more output starting at next_out and update next_out and avail_out
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177 accordingly. This action is forced if the parameter flush is non zero.
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178 Forcing flush frequently degrades the compression ratio, so this parameter
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179 should be set only when necessary (in interactive applications).
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180 Some output may be provided even if flush is not set.
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181
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182 Before the call of deflate(), the application should ensure that at least
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183 one of the actions is possible, by providing more input and/or consuming
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184 more output, and updating avail_in or avail_out accordingly; avail_out
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185 should never be zero before the call. The application can consume the
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186 compressed output when it wants, for example when the output buffer is full
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187 (avail_out == 0), or after each call of deflate().
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188
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189 If the parameter flush is set to Z_PARTIAL_FLUSH, the current compression
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190 block is terminated and flushed to the output buffer so that the
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191 decompressor can get all input data available so far. For method 9, a future
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192 variant on method 8, the current block will be flushed but not terminated.
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193 If flush is set to Z_FULL_FLUSH, the compression block is terminated, a
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194 special marker is output and the compression dictionary is discarded; this
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195 is useful to allow the decompressor to synchronize if one compressed block
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196 has been damaged (see inflateSync below). Flushing degrades compression and
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197 so should be used only when necessary. Using Z_FULL_FLUSH too often can
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198 seriously degrade the compression. If deflate returns with avail_out == 0,
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199 this function must be called again with the same value of the flush
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200 parameter and more output space (updated avail_out), until the flush is
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201 complete (deflate returns with non-zero avail_out).
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202
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203 If the parameter flush is set to Z_FINISH, all pending input is processed,
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204 all pending output is flushed and deflate returns with Z_STREAM_END if there
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205 was enough output space; if deflate returns with Z_OK, this function must be
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206 called again with Z_FINISH and more output space (updated avail_out) but no
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207 more input data, until it returns with Z_STREAM_END or an error. After
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208 deflate has returned Z_STREAM_END, the only possible operations on the
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209 stream are deflateReset or deflateEnd.
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210
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211 Z_FINISH can be used immediately after deflateInit if all the compression
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212 is to be done in a single step. In this case, avail_out must be at least
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213 0.1% larger than avail_in plus 12 bytes. If deflate does not return
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214 Z_STREAM_END, then it must be called again as described above.
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215
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216 deflate() may update data_type if it can make a good guess about
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217 the input data type (Z_ASCII or Z_BINARY). In doubt, the data is considered
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218 binary. This field is only for information purposes and does not affect
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219 the compression algorithm in any manner.
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220
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221 deflate() returns Z_OK if some progress has been made (more input
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222 processed or more output produced), Z_STREAM_END if all input has been
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223 consumed and all output has been produced (only when flush is set to
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224 Z_FINISH), Z_STREAM_ERROR if the stream state was inconsistent (for example
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225 if next_in or next_out was NULL), Z_BUF_ERROR if no progress is possible.
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226 */
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227
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228
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229 extern int deflateEnd OF((z_stream *strm));
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230 /*
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231 All dynamically allocated data structures for this stream are freed.
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232 This function discards any unprocessed input and does not flush any
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233 pending output.
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234
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235 deflateEnd returns Z_OK if success, Z_STREAM_ERROR if the
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236 stream state was inconsistent. In the error case, msg may be set
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237 but then points to a static string (which must not be deallocated).
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238 */
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239
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240
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241 extern int inflateInit OF((z_stream *strm));
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242 /*
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243 Initializes the internal stream state for decompression. The fields
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244 zalloc and zfree must be initialized before by the caller. If zalloc and
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245 zfree are set to Z_NULL, inflateInit updates them to use default allocation
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246 functions.
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247
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248 inflateInit returns Z_OK if success, Z_MEM_ERROR if there was not
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249 enough memory. msg is set to null if there is no error message.
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250 inflateInit does not perform any decompression: this will be done by
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251 inflate().
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252 */
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253
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254
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255 extern int inflate OF((z_stream *strm, int flush));
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256 /*
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257 Performs one or both of the following actions:
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258
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259 - Decompress more input starting at next_in and update next_in and avail_in
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260 accordingly. If not all input can be processed (because there is not
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261 enough room in the output buffer), next_in is updated and processing
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262 will resume at this point for the next call of inflate().
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263
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264 - Provide more output starting at next_out and update next_out and avail_out
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265 accordingly. inflate() always provides as much output as possible
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266 (until there is no more input data or no more space in the output buffer).
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267
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268 Before the call of inflate(), the application should ensure that at least
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269 one of the actions is possible, by providing more input and/or consuming
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270 more output, and updating the next_* and avail_* values accordingly.
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271 The application can consume the uncompressed output when it wants, for
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272 example when the output buffer is full (avail_out == 0), or after each
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273 call of inflate().
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274
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275 If the parameter flush is set to Z_PARTIAL_FLUSH, inflate flushes as much
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276 output as possible to the output buffer. The flushing behavior of inflate is
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277 not specified for values of the flush parameter other than Z_PARTIAL_FLUSH
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278 and Z_FINISH, but the current implementation actually flushes as much output
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279 as possible anyway.
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280
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281 inflate() should normally be called until it returns Z_STREAM_END or an
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282 error. However if all decompression is to be performed in a single step
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283 (a single call of inflate), the parameter flush should be set to
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284 Z_FINISH. In this case all pending input is processed and all pending
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285 output is flushed; avail_out must be large enough to hold all the
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286 uncompressed data. (The size of the uncompressed data may have been saved
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287 by the compressor for this purpose.) The next operation on this stream must
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288 be inflateEnd to deallocate the decompression state. The use of Z_FINISH
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289 is never required, but can be used to inform inflate that a faster routine
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290 may be used for the single inflate() call.
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291
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292 inflate() returns Z_OK if some progress has been made (more input
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293 processed or more output produced), Z_STREAM_END if the end of the
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294 compressed data has been reached and all uncompressed output has been
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295 produced, Z_DATA_ERROR if the input data was corrupted, Z_STREAM_ERROR if
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296 the stream structure was inconsistent (for example if next_in or next_out
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297 was NULL), Z_MEM_ERROR if there was not enough memory, Z_BUF_ERROR if no
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298 progress is possible or if there was not enough room in the output buffer
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299 when Z_FINISH is used. In the Z_DATA_ERROR case, the application may then
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300 call inflateSync to look for a good compression block.
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301 */
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302
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303
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304 extern int inflateEnd OF((z_stream *strm));
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305 /*
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306 All dynamically allocated data structures for this stream are freed.
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307 This function discards any unprocessed input and does not flush any
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308 pending output.
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309
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310 inflateEnd returns Z_OK if success, Z_STREAM_ERROR if the stream state
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311 was inconsistent. In the error case, msg may be set but then points to a
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312 static string (which must not be deallocated).
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313 */
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314
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315 /* advanced functions */
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316
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317 /*
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318 The following functions are needed only in some special applications.
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319 */
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320
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321 extern int deflateInit2 OF((z_stream *strm,
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322 int level,
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323 int method,
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324 int windowBits,
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325 int memLevel,
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326 int strategy));
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327 /*
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328 This is another version of deflateInit with more compression options. The
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329 fields next_in, zalloc and zfree must be initialized before by the caller.
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330
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331 The method parameter is the compression method. It must be 8 in this
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332 version of the library. (Method 9 will allow a 64K history buffer and
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333 partial block flushes.)
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334
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335 The windowBits parameter is the base two logarithm of the window size
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336 (the size of the history buffer). It should be in the range 8..15 for this
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337 version of the library (the value 16 will be allowed for method 9). Larger
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338 values of this parameter result in better compression at the expense of
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339 memory usage. The default value is 15 if deflateInit is used instead.
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340
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341 The memLevel parameter specifies how much memory should be allocated
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342 for the internal compression state. memLevel=1 uses minimum memory but
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343 is slow and reduces compression ratio; memLevel=9 uses maximum memory
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344 for optimal speed. The default value is 8. See zconf.h for total memory
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345 usage as a function of windowBits and memLevel.
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346
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347 The strategy parameter is used to tune the compression algorithm. Use
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348 the value Z_DEFAULT_STRATEGY for normal data, Z_FILTERED for data
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349 produced by a filter (or predictor), or Z_HUFFMAN_ONLY to force Huffman
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350 encoding only (no string match). Filtered data consists mostly of small
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351 values with a somewhat random distribution. In this case, the
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352 compression algorithm is tuned to compress them better. The strategy
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353 parameter only affects the compression ratio but not the correctness of
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354 the compressed output even if it is not set appropriately.
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355
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356 If next_in is not null, the library will use this buffer to hold also
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357 some history information; the buffer must either hold the entire input
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358 data, or have at least 1<<(windowBits+1) bytes and be writable. If next_in
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359 is null, the library will allocate its own history buffer (and leave next_in
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360 null). next_out need not be provided here but must be provided by the
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361 application for the next call of deflate().
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362
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363 If the history buffer is provided by the application, next_in must
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364 must never be changed by the application since the compressor maintains
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365 information inside this buffer from call to call; the application
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366 must provide more input only by increasing avail_in. next_in is always
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367 reset by the library in this case.
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368
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369 deflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
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370 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
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371 an invalid method). msg is set to null if there is no error message.
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372 deflateInit2 does not perform any compression: this will be done by
|
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373 deflate().
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374 */
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375
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376 extern int deflateCopy OF((z_stream *dest,
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377 z_stream *source));
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|
378 /*
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|
|
379 Sets the destination stream as a complete copy of the source stream. If
|
|
|
380 the source stream is using an application-supplied history buffer, a new
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|
|
381 buffer is allocated for the destination stream. The compressed output
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|
|
382 buffer is always application-supplied. It's the responsibility of the
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|
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383 application to provide the correct values of next_out and avail_out for the
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|
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384 next call of deflate.
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|
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385
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386 This function is useful when several compression strategies will be
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387 tried, for example when there are several ways of pre-processing the input
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388 data with a filter. The streams that will be discarded should then be freed
|
|
|
389 by calling deflateEnd. Note that deflateCopy duplicates the internal
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|
390 compression state which can be quite large, so this strategy is slow and
|
|
|
391 can consume lots of memory.
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|
|
392
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|
|
393 deflateCopy returns Z_OK if success, Z_MEM_ERROR if there was not
|
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394 enough memory, Z_STREAM_ERROR if the source stream state was inconsistent
|
|
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395 (such as zalloc being NULL). msg is left unchanged in both source and
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396 destination.
|
|
|
397 */
|
|
|
398
|
|
|
399 extern int deflateReset OF((z_stream *strm));
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|
|
400 /*
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|
|
401 This function is equivalent to deflateEnd followed by deflateInit,
|
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|
402 but does not free and reallocate all the internal compression state.
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|
403 The stream will keep the same compression level and any other attributes
|
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404 that may have been set by deflateInit2.
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405
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406 deflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
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|
|
407 stream state was inconsistent (such as zalloc or state being NULL).
|
|
|
408 */
|
|
|
409
|
|
|
410 extern int inflateInit2 OF((z_stream *strm,
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|
411 int windowBits));
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|
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412 /*
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|
|
413 This is another version of inflateInit with more compression options. The
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414 fields next_out, zalloc and zfree must be initialized before by the caller.
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415
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|
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416 The windowBits parameter is the base two logarithm of the maximum window
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|
417 size (the size of the history buffer). It should be in the range 8..15 for
|
|
|
418 this version of the library (the value 16 will be allowed soon). The
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|
|
419 default value is 15 if inflateInit is used instead. If a compressed stream
|
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|
420 with a larger window size is given as input, inflate() will return with
|
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421 the error code Z_DATA_ERROR instead of trying to allocate a larger window.
|
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|
422
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|
423 If next_out is not null, the library will use this buffer for the history
|
|
|
424 buffer; the buffer must either be large enough to hold the entire output
|
|
|
425 data, or have at least 1<<windowBits bytes. If next_out is null, the
|
|
|
426 library will allocate its own buffer (and leave next_out null). next_in
|
|
|
427 need not be provided here but must be provided by the application for the
|
|
|
428 next call of inflate().
|
|
|
429
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|
|
430 If the history buffer is provided by the application, next_out must
|
|
|
431 never be changed by the application since the decompressor maintains
|
|
|
432 history information inside this buffer from call to call; the application
|
|
|
433 can only reset next_out to the beginning of the history buffer when
|
|
|
434 avail_out is zero and all output has been consumed.
|
|
|
435
|
|
|
436 inflateInit2 returns Z_OK if success, Z_MEM_ERROR if there was
|
|
|
437 not enough memory, Z_STREAM_ERROR if a parameter is invalid (such as
|
|
|
438 windowBits < 8). msg is set to null if there is no error message.
|
|
|
439 inflateInit2 does not perform any decompression: this will be done by
|
|
|
440 inflate().
|
|
|
441 */
|
|
|
442
|
|
|
443 extern int inflateSync OF((z_stream *strm));
|
|
|
444 /*
|
|
|
445 Skips invalid compressed data until the special marker (see deflate()
|
|
|
446 above) can be found, or until all available input is skipped. No output
|
|
|
447 is provided.
|
|
|
448
|
|
|
449 inflateSync returns Z_OK if the special marker has been found, Z_BUF_ERROR
|
|
|
450 if no more input was provided, Z_DATA_ERROR if no marker has been found,
|
|
|
451 or Z_STREAM_ERROR if the stream structure was inconsistent. In the success
|
|
|
452 case, the application may save the current current value of total_in which
|
|
|
453 indicates where valid compressed data was found. In the error case, the
|
|
|
454 application may repeatedly call inflateSync, providing more input each time,
|
|
|
455 until success or end of the input data.
|
|
|
456 */
|
|
|
457
|
|
|
458 extern int inflateReset OF((z_stream *strm));
|
|
|
459 /*
|
|
|
460 This function is equivalent to inflateEnd followed by inflateInit,
|
|
|
461 but does not free and reallocate all the internal decompression state.
|
|
|
462 The stream will keep attributes that may have been set by inflateInit2.
|
|
|
463
|
|
|
464 inflateReset returns Z_OK if success, or Z_STREAM_ERROR if the source
|
|
|
465 stream state was inconsistent (such as zalloc or state being NULL).
|
|
|
466 */
|
|
|
467
|
|
|
468
|
|
|
469 /* utility functions */
|
|
|
470
|
|
|
471 /*
|
|
|
472 The following utility functions are implemented on top of the
|
|
|
473 basic stream-oriented functions. To simplify the interface, some
|
|
|
474 default options are assumed (compression level, window size,
|
|
|
475 standard memory allocation functions). The source code of these
|
|
|
476 utility functions can easily be modified if you need special options.
|
|
|
477 */
|
|
|
478
|
|
|
479 extern int compress OF((Bytef *dest, uLongf *destLen,
|
|
|
480 Bytef *source, uLong sourceLen));
|
|
|
481 /*
|
|
|
482 Compresses the source buffer into the destination buffer. sourceLen is
|
|
|
483 the byte length of the source buffer. Upon entry, destLen is the total
|
|
|
484 size of the destination buffer, which must be at least 0.1% larger than
|
|
|
485 sourceLen plus 12 bytes. Upon exit, destLen is the actual size of the
|
|
|
486 compressed buffer.
|
|
|
487 This function can be used to compress a whole file at once if the
|
|
|
488 input file is mmap'ed.
|
|
|
489 compress returns Z_OK if success, Z_MEM_ERROR if there was not
|
|
|
490 enough memory, Z_BUF_ERROR if there was not enough room in the output
|
|
|
491 buffer.
|
|
|
492 */
|
|
|
493
|
|
|
494 extern int uncompress OF((Bytef *dest, uLongf *destLen,
|
|
|
495 Bytef *source, uLong sourceLen));
|
|
|
496 /*
|
|
|
497 Decompresses the source buffer into the destination buffer. sourceLen is
|
|
|
498 the byte length of the source buffer. Upon entry, destLen is the total
|
|
|
499 size of the destination buffer, which must be large enough to hold the
|
|
|
500 entire uncompressed data. (The size of the uncompressed data must have
|
|
|
501 been saved previously by the compressor and transmitted to the decompressor
|
|
|
502 by some mechanism outside the scope of this compression library.)
|
|
|
503 Upon exit, destLen is the actual size of the compressed buffer.
|
|
|
504 This function can be used to decompress a whole file at once if the
|
|
|
505 input file is mmap'ed.
|
|
|
506
|
|
|
507 uncompress returns Z_OK if success, Z_MEM_ERROR if there was not
|
|
|
508 enough memory, Z_BUF_ERROR if there was not enough room in the output
|
|
|
509 buffer, or Z_DATA_ERROR if the input data was corrupted.
|
|
|
510 */
|
|
|
511
|
|
|
512
|
|
|
513 typedef voidp gzFile;
|
|
|
514
|
|
|
515 extern gzFile gzopen OF((char *path, char *mode));
|
|
|
516 /*
|
|
|
517 Opens a gzip (.gz) file for reading or writing. The mode parameter
|
|
|
518 is as in fopen ("rb" or "wb") but can also include a compression level
|
|
|
519 ("wb9"). gzopen can be used to read a file which is not in gzip format;
|
|
|
520 in this case gzread will directly read from the file without decompression.
|
|
|
521 gzopen returns NULL if the file could not be opened or if there was
|
|
|
522 insufficient memory to allocate the (de)compression state; errno
|
|
|
523 can be checked to distinguish the two cases (if errno is zero, the
|
|
|
524 zlib error is Z_MEM_ERROR).
|
|
|
525 */
|
|
|
526
|
|
|
527 extern gzFile gzdopen OF((int fd, char *mode));
|
|
|
528 /*
|
|
|
529 gzdopen() associates a gzFile with the file descriptor fd. File
|
|
|
530 descriptors are obtained from calls like open, dup, creat, or pipe.
|
|
|
531 The mode parameter is as in fopen ("rb" or "wb").
|
|
|
532 gzdopen returns NULL if there was insufficient memory to allocate
|
|
|
533 the (de)compression state.
|
|
|
534 */
|
|
|
535
|
|
|
536 extern int gzread OF((gzFile file, voidp buf, unsigned len));
|
|
|
537 /*
|
|
|
538 Reads the given number of uncompressed bytes from the compressed file.
|
|
|
539 If the input file was not in gzip format, gzread copies the given number
|
|
|
540 of bytes into the buffer.
|
|
|
541 gzread returns the number of uncompressed bytes actually read (0 for
|
|
|
542 end of file, -1 for error). */
|
|
|
543
|
|
|
544 extern int gzwrite OF((gzFile file, voidp buf, unsigned len));
|
|
|
545 /*
|
|
|
546 Writes the given number of uncompressed bytes into the compressed file.
|
|
|
547 gzwrite returns the number of uncompressed bytes actually written
|
|
|
548 (0 in case of error).
|
|
|
549 */
|
|
|
550
|
|
|
551 extern int gzflush OF((gzFile file, int flush));
|
|
|
552 /*
|
|
|
553 Flushes all pending output into the compressed file. The parameter
|
|
|
554 flush is as in the deflate() function. The return value is the zlib
|
|
|
555 error number (see function gzerror below). gzflush returns Z_OK if
|
|
|
556 the flush parameter is Z_FINISH and all output could be flushed.
|
|
|
557 gzflush should be called only when strictly necessary because it can
|
|
|
558 degrade compression.
|
|
|
559 */
|
|
|
560
|
|
|
561 extern int gzclose OF((gzFile file));
|
|
|
562 /*
|
|
|
563 Flushes all pending output if necessary, closes the compressed file
|
|
|
564 and deallocates all the (de)compression state. The return value is the zlib
|
|
|
565 error number (see function gzerror below).
|
|
|
566 */
|
|
|
567
|
|
|
568 extern char* gzerror OF((gzFile file, int *errnum));
|
|
|
569 /*
|
|
|
570 Returns the error message for the last error which occurred on the
|
|
|
571 given compressed file. errnum is set to zlib error number. If an
|
|
|
572 error occurred in the file system and not in the compression library,
|
|
|
573 errnum is set to Z_ERRNO and the application may consult errno
|
|
|
574 to get the exact error code.
|
|
|
575 */
|
|
|
576
|
|
|
577 /* checksum functions */
|
|
|
578
|
|
|
579 /*
|
|
|
580 These functions are not related to compression but are exported
|
|
|
581 anyway because they might be useful in applications using the
|
|
|
582 compression library.
|
|
|
583 */
|
|
|
584
|
|
|
585 extern uLong adler32 OF((uLong adler, Bytef *buf, uInt len));
|
|
|
586
|
|
|
587 /*
|
|
|
588 Update a running Adler-32 checksum with the bytes buf[0..len-1] and
|
|
|
589 return the updated checksum. If buf is NULL, this function returns
|
|
|
590 the required initial value for the checksum.
|
|
|
591 An Adler-32 checksum is almost as reliable as a CRC32 but can be computed
|
|
|
592 much faster. Usage example:
|
|
|
593
|
|
|
594 uLong adler = adler32(0L, Z_NULL, 0);
|
|
|
595
|
|
|
596 while (read_buffer(buffer, length) != EOF) {
|
|
|
597 adler = adler32(adler, buffer, length);
|
|
|
598 }
|
|
|
599 if (adler != original_adler) error();
|
|
|
600 */
|
|
|
601
|
|
|
602 extern uLong crc32 OF((uLong crc, Bytef *buf, uInt len));
|
|
|
603 /*
|
|
|
604 Update a running crc with the bytes buf[0..len-1] and return the updated
|
|
|
605 crc. If buf is NULL, this function returns the required initial value
|
|
|
606 for the crc. Pre- and post-conditioning (one's complement) is performed
|
|
|
607 within this function so it shouldn't be done by the application.
|
|
|
608 Usage example:
|
|
|
609
|
|
|
610 uLong crc = crc32(0L, Z_NULL, 0);
|
|
|
611
|
|
|
612 while (read_buffer(buffer, length) != EOF) {
|
|
|
613 crc = crc32(crc, buffer, length);
|
|
|
614 }
|
|
|
615 if (crc != original_crc) error();
|
|
|
616 */
|
|
|
617
|
|
|
618 #ifndef _Z_UTIL_H
|
|
|
619 struct internal_state {int dummy;}; /* hack for buggy compilers */
|
|
|
620 #endif
|
|
|
621
|
|
|
622 #endif /* _ZLIB_H */
|
