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1768 lines
64 KiB
1768 lines
64 KiB
/* deflate.c -- compress data using the deflation algorithm |
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* Copyright (C) 1995-2005 Jean-loup Gailly. |
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* For conditions of distribution and use, see copyright notice in zlib.h |
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*/ |
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|
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/* |
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* ALGORITHM |
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* |
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* The "deflation" process depends on being able to identify portions |
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* of the input text which are identical to earlier input (within a |
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* sliding window trailing behind the input currently being processed). |
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* |
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* The most straightforward technique turns out to be the fastest for |
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* most input files: try all possible matches and select the longest. |
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* The key feature of this algorithm is that insertions into the string |
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* dictionary are very simple and thus fast, and deletions are avoided |
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* completely. Insertions are performed at each input character, whereas |
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* string matches are performed only when the previous match ends. So it |
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* is preferable to spend more time in matches to allow very fast string |
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* insertions and avoid deletions. The matching algorithm for small |
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* strings is inspired from that of Rabin & Karp. A brute force approach |
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* is used to find longer strings when a small match has been found. |
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* A similar algorithm is used in comic (by Jan-Mark Wams) and freeze |
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* (by Leonid Broukhis). |
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* A previous version of this file used a more sophisticated algorithm |
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* (by Fiala and Greene) which is guaranteed to run in linear amortized |
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* time, but has a larger average cost, uses more memory and is patented. |
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* However the F&G algorithm may be faster for some highly redundant |
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* files if the parameter max_chain_length (described below) is too large. |
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* |
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* ACKNOWLEDGEMENTS |
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* |
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* The idea of lazy evaluation of matches is due to Jan-Mark Wams, and |
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* I found it in 'freeze' written by Leonid Broukhis. |
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* Thanks to many people for bug reports and testing. |
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* |
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* REFERENCES |
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* |
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* Deutsch, L.P.,"DEFLATE Compressed Data Format Specification". |
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* Available in http://www.ietf.org/rfc/rfc1951.txt |
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* |
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* A description of the Rabin and Karp algorithm is given in the book |
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* "Algorithms" by R. Sedgewick, Addison-Wesley, p252. |
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* |
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* Fiala,E.R., and Greene,D.H. |
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* Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595 |
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* |
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*/ |
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|
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/* @(#) $Id$ */ |
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|
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#include "deflate.h" |
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|
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const char deflate_copyright[] = |
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" deflate 1.2.3.1 Copyright 1995-2005 Jean-loup Gailly "; |
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/* |
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If you use the zlib library in a product, an acknowledgment is welcome |
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in the documentation of your product. If for some reason you cannot |
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include such an acknowledgment, I would appreciate that you keep this |
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copyright string in the executable of your product. |
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*/ |
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|
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/* =========================================================================== |
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* Function prototypes. |
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*/ |
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typedef enum { |
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need_more, /* block not completed, need more input or more output */ |
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block_done, /* block flush performed */ |
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finish_started, /* finish started, need only more output at next deflate */ |
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finish_done /* finish done, accept no more input or output */ |
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} block_state; |
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|
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typedef block_state (*compress_func) OF((deflate_state *s, int flush)); |
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/* Compression function. Returns the block state after the call. */ |
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|
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local void fill_window OF((deflate_state *s)); |
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local block_state deflate_stored OF((deflate_state *s, int flush)); |
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local block_state deflate_fast OF((deflate_state *s, int flush)); |
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#ifndef FASTEST |
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local block_state deflate_slow OF((deflate_state *s, int flush)); |
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#endif |
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local void lm_init OF((deflate_state *s)); |
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local void putShortMSB OF((deflate_state *s, uInt b)); |
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local void flush_pending OF((z_streamp strm)); |
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local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size)); |
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#ifndef FASTEST |
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#ifdef ASMV |
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void match_init OF((void)); /* asm code initialization */ |
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uInt longest_match OF((deflate_state *s, IPos cur_match)); |
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#else |
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local uInt longest_match OF((deflate_state *s, IPos cur_match)); |
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#endif |
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#endif |
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local uInt longest_match_fast OF((deflate_state *s, IPos cur_match)); |
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|
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#ifdef DEBUG |
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local void check_match OF((deflate_state *s, IPos start, IPos match, |
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int length)); |
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#endif |
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|
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/* =========================================================================== |
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* Local data |
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*/ |
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|
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#define NIL 0 |
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/* Tail of hash chains */ |
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|
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#ifndef TOO_FAR |
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# define TOO_FAR 4096 |
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#endif |
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/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ |
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|
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#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1) |
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/* Minimum amount of lookahead, except at the end of the input file. |
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* See deflate.c for comments about the MIN_MATCH+1. |
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*/ |
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|
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/* Values for max_lazy_match, good_match and max_chain_length, depending on |
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* the desired pack level (0..9). The values given below have been tuned to |
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* exclude worst case performance for pathological files. Better values may be |
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* found for specific files. |
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*/ |
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typedef struct config_s { |
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ush good_length; /* reduce lazy search above this match length */ |
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ush max_lazy; /* do not perform lazy search above this match length */ |
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ush nice_length; /* quit search above this match length */ |
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ush max_chain; |
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compress_func func; |
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} config; |
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|
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#ifdef FASTEST |
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local const config configuration_table[2] = { |
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/* good lazy nice chain */ |
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/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ |
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/* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */ |
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#else |
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local const config configuration_table[10] = { |
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/* good lazy nice chain */ |
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/* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only */ |
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/* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches */ |
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/* 2 */ {4, 5, 16, 8, deflate_fast}, |
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/* 3 */ {4, 6, 32, 32, deflate_fast}, |
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|
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/* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches */ |
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/* 5 */ {8, 16, 32, 32, deflate_slow}, |
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/* 6 */ {8, 16, 128, 128, deflate_slow}, |
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/* 7 */ {8, 32, 128, 256, deflate_slow}, |
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/* 8 */ {32, 128, 258, 1024, deflate_slow}, |
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/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */ |
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#endif |
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|
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/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4 |
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* For deflate_fast() (levels <= 3) good is ignored and lazy has a different |
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* meaning. |
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*/ |
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|
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#define EQUAL 0 |
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/* result of memcmp for equal strings */ |
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|
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#ifndef NO_DUMMY_DECL |
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struct static_tree_desc_s {int dummy;}; /* for buggy compilers */ |
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#endif |
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|
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/* =========================================================================== |
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* Update a hash value with the given input byte |
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* IN assertion: all calls to to UPDATE_HASH are made with consecutive |
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* input characters, so that a running hash key can be computed from the |
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* previous key instead of complete recalculation each time. |
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*/ |
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#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask) |
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|
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/* =========================================================================== |
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* Insert string str in the dictionary and set match_head to the previous head |
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* of the hash chain (the most recent string with same hash key). Return |
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* the previous length of the hash chain. |
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* If this file is compiled with -DFASTEST, the compression level is forced |
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* to 1, and no hash chains are maintained. |
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* IN assertion: all calls to to INSERT_STRING are made with consecutive |
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* input characters and the first MIN_MATCH bytes of str are valid |
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* (except for the last MIN_MATCH-1 bytes of the input file). |
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*/ |
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#ifdef FASTEST |
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#define INSERT_STRING(s, str, match_head) \ |
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(UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ |
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match_head = s->head[s->ins_h], \ |
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s->head[s->ins_h] = (Pos)(str)) |
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#else |
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#define INSERT_STRING(s, str, match_head) \ |
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(UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \ |
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match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \ |
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s->head[s->ins_h] = (Pos)(str)) |
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#endif |
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|
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/* =========================================================================== |
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* Initialize the hash table (avoiding 64K overflow for 16 bit systems). |
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* prev[] will be initialized on the fly. |
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*/ |
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#define CLEAR_HASH(s) \ |
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s->head[s->hash_size-1] = NIL; \ |
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zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head)); |
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|
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/* ========================================================================= */ |
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int ZEXPORT deflateInit_(strm, level, version, stream_size) |
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z_streamp strm; |
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int level; |
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const char *version; |
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int stream_size; |
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{ |
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return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL, |
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Z_DEFAULT_STRATEGY, version, stream_size); |
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/* To do: ignore strm->next_in if we use it as window */ |
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} |
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|
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/* ========================================================================= */ |
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int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy, |
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version, stream_size) |
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z_streamp strm; |
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int level; |
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int method; |
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int windowBits; |
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int memLevel; |
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int strategy; |
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const char *version; |
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int stream_size; |
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{ |
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deflate_state *s; |
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int wrap = 1; |
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static const char my_version[] = ZLIB_VERSION; |
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|
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ushf *overlay; |
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/* We overlay pending_buf and d_buf+l_buf. This works since the average |
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* output size for (length,distance) codes is <= 24 bits. |
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*/ |
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|
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if (version == Z_NULL || version[0] != my_version[0] || |
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stream_size != sizeof(z_stream)) { |
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return Z_VERSION_ERROR; |
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} |
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if (strm == Z_NULL) return Z_STREAM_ERROR; |
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|
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strm->msg = Z_NULL; |
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if (strm->zalloc == (alloc_func)0) { |
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strm->zalloc = zcalloc; |
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strm->opaque = (voidpf)0; |
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} |
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if (strm->zfree == (free_func)0) strm->zfree = zcfree; |
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|
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#ifdef FASTEST |
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if (level != 0) level = 1; |
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#else |
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if (level == Z_DEFAULT_COMPRESSION) level = 6; |
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#endif |
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|
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if (windowBits < 0) { /* suppress zlib wrapper */ |
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wrap = 0; |
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windowBits = -windowBits; |
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} |
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#ifdef GZIP |
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else if (windowBits > 15) { |
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wrap = 2; /* write gzip wrapper instead */ |
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windowBits -= 16; |
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} |
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#endif |
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if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || |
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windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || |
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strategy < 0 || strategy > Z_FIXED) { |
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return Z_STREAM_ERROR; |
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} |
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if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ |
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s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); |
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if (s == Z_NULL) return Z_MEM_ERROR; |
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strm->state = (struct internal_state FAR *)s; |
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s->strm = strm; |
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|
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s->wrap = wrap; |
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s->gzhead = Z_NULL; |
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s->w_bits = windowBits; |
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s->w_size = 1 << s->w_bits; |
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s->w_mask = s->w_size - 1; |
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|
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s->hash_bits = memLevel + 7; |
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s->hash_size = 1 << s->hash_bits; |
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s->hash_mask = s->hash_size - 1; |
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s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); |
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s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); |
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s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); |
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s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); |
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|
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s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ |
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overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); |
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s->pending_buf = (uchf *) overlay; |
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s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); |
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|
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if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || |
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s->pending_buf == Z_NULL) { |
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s->status = FINISH_STATE; |
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strm->msg = (char*)ERR_MSG(Z_MEM_ERROR); |
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deflateEnd (strm); |
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return Z_MEM_ERROR; |
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} |
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s->d_buf = overlay + s->lit_bufsize/sizeof(ush); |
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s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; |
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|
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s->level = level; |
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s->strategy = strategy; |
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s->method = (Byte)method; |
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|
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return deflateReset(strm); |
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} |
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|
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/* ========================================================================= */ |
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int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength) |
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z_streamp strm; |
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const Bytef *dictionary; |
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uInt dictLength; |
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{ |
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deflate_state *s; |
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uInt length = dictLength; |
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uInt n; |
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IPos hash_head = 0; |
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|
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if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL || |
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strm->state->wrap == 2 || |
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(strm->state->wrap == 1 && strm->state->status != INIT_STATE)) |
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return Z_STREAM_ERROR; |
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|
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s = strm->state; |
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if (s->wrap) |
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strm->adler = adler32(strm->adler, dictionary, dictLength); |
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|
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if (length < MIN_MATCH) return Z_OK; |
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if (length > MAX_DIST(s)) { |
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length = MAX_DIST(s); |
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dictionary += dictLength - length; /* use the tail of the dictionary */ |
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} |
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zmemcpy(s->window, dictionary, length); |
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s->strstart = length; |
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s->block_start = (long)length; |
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|
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/* Insert all strings in the hash table (except for the last two bytes). |
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* s->lookahead stays null, so s->ins_h will be recomputed at the next |
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* call of fill_window. |
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*/ |
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s->ins_h = s->window[0]; |
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UPDATE_HASH(s, s->ins_h, s->window[1]); |
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for (n = 0; n <= length - MIN_MATCH; n++) { |
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INSERT_STRING(s, n, hash_head); |
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} |
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if (hash_head) hash_head = 0; /* to make compiler happy */ |
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return Z_OK; |
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} |
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|
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/* ========================================================================= */ |
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int ZEXPORT deflateReset (strm) |
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z_streamp strm; |
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{ |
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deflate_state *s; |
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|
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if (strm == Z_NULL || strm->state == Z_NULL || |
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strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) { |
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return Z_STREAM_ERROR; |
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} |
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|
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strm->total_in = strm->total_out = 0; |
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strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ |
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strm->data_type = Z_UNKNOWN; |
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|
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s = (deflate_state *)strm->state; |
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s->pending = 0; |
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s->pending_out = s->pending_buf; |
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|
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if (s->wrap < 0) { |
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s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ |
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} |
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s->status = s->wrap ? INIT_STATE : BUSY_STATE; |
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strm->adler = |
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#ifdef GZIP |
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s->wrap == 2 ? crc32(0L, Z_NULL, 0) : |
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#endif |
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adler32(0L, Z_NULL, 0); |
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s->last_flush = Z_NO_FLUSH; |
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|
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_tr_init(s); |
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lm_init(s); |
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|
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return Z_OK; |
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} |
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|
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/* ========================================================================= */ |
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int ZEXPORT deflateSetHeader (strm, head) |
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z_streamp strm; |
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gz_headerp head; |
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{ |
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if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
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if (strm->state->wrap != 2) return Z_STREAM_ERROR; |
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strm->state->gzhead = head; |
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return Z_OK; |
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} |
|
|
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/* ========================================================================= */ |
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int ZEXPORT deflatePrime (strm, bits, value) |
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z_streamp strm; |
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int bits; |
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int value; |
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{ |
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if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
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strm->state->bi_valid = bits; |
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strm->state->bi_buf = (ush)(value & ((1 << bits) - 1)); |
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return Z_OK; |
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} |
|
|
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/* ========================================================================= */ |
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int ZEXPORT deflateParams(strm, level, strategy) |
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z_streamp strm; |
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int level; |
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int strategy; |
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{ |
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deflate_state *s; |
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compress_func func; |
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int err = Z_OK; |
|
|
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if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
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s = strm->state; |
|
|
|
#ifdef FASTEST |
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if (level != 0) level = 1; |
|
#else |
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if (level == Z_DEFAULT_COMPRESSION) level = 6; |
|
#endif |
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if (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) { |
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return Z_STREAM_ERROR; |
|
} |
|
func = configuration_table[s->level].func; |
|
|
|
if (func != configuration_table[level].func && strm->total_in != 0) { |
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/* Flush the last buffer: */ |
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err = deflate(strm, Z_PARTIAL_FLUSH); |
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} |
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if (s->level != level) { |
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s->level = level; |
|
s->max_lazy_match = configuration_table[level].max_lazy; |
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s->good_match = configuration_table[level].good_length; |
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s->nice_match = configuration_table[level].nice_length; |
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s->max_chain_length = configuration_table[level].max_chain; |
|
} |
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s->strategy = strategy; |
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return err; |
|
} |
|
|
|
/* ========================================================================= */ |
|
int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain) |
|
z_streamp strm; |
|
int good_length; |
|
int max_lazy; |
|
int nice_length; |
|
int max_chain; |
|
{ |
|
deflate_state *s; |
|
|
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if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
|
s = strm->state; |
|
s->good_match = good_length; |
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s->max_lazy_match = max_lazy; |
|
s->nice_match = nice_length; |
|
s->max_chain_length = max_chain; |
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return Z_OK; |
|
} |
|
|
|
/* ========================================================================= |
|
* For the default windowBits of 15 and memLevel of 8, this function returns |
|
* a close to exact, as well as small, upper bound on the compressed size. |
|
* They are coded as constants here for a reason--if the #define's are |
|
* changed, then this function needs to be changed as well. The return |
|
* value for 15 and 8 only works for those exact settings. |
|
* |
|
* For any setting other than those defaults for windowBits and memLevel, |
|
* the value returned is a conservative worst case for the maximum expansion |
|
* resulting from using fixed blocks instead of stored blocks, which deflate |
|
* can emit on compressed data for some combinations of the parameters. |
|
* |
|
* This function could be more sophisticated to provide closer upper bounds for |
|
* every combination of windowBits and memLevel. But even the conservative |
|
* upper bound of about 14% expansion does not seem onerous for output buffer |
|
* allocation. |
|
*/ |
|
uLong ZEXPORT deflateBound(strm, sourceLen) |
|
z_streamp strm; |
|
uLong sourceLen; |
|
{ |
|
deflate_state *s; |
|
uLong complen, wraplen; |
|
Bytef *str; |
|
|
|
/* conservative upper bound for compressed data */ |
|
complen = sourceLen + |
|
((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5; |
|
|
|
/* if can't get parameters, return conservative bound plus zlib wrapper */ |
|
if (strm == Z_NULL || strm->state == Z_NULL) |
|
return complen + 6; |
|
|
|
/* compute wrapper length */ |
|
s = strm->state; |
|
switch (s->wrap) { |
|
case 0: /* raw deflate */ |
|
wraplen = 0; |
|
break; |
|
case 1: /* zlib wrapper */ |
|
wraplen = 6 + (s->strstart ? 4 : 0); |
|
break; |
|
case 2: /* gzip wrapper */ |
|
wraplen = 18; |
|
if (s->gzhead != NULL) { /* user-supplied gzip header */ |
|
if (s->gzhead->extra != NULL) |
|
wraplen += 2 + s->gzhead->extra_len; |
|
str = s->gzhead->name; |
|
if (str != NULL) |
|
do { |
|
wraplen++; |
|
} while (*str++); |
|
str = s->gzhead->comment; |
|
if (str != NULL) |
|
do { |
|
wraplen++; |
|
} while (*str++); |
|
if (s->gzhead->hcrc) |
|
wraplen += 2; |
|
} |
|
break; |
|
default: /* for compiler happiness */ |
|
wraplen = 6; |
|
} |
|
|
|
/* if not default parameters, return conservative bound */ |
|
if (s->w_bits != 15 || s->hash_bits != 8 + 7) |
|
return complen + wraplen; |
|
|
|
/* default settings: return tight bound for that case */ |
|
return compressBound(sourceLen) - 6 + wraplen; |
|
} |
|
|
|
/* ========================================================================= |
|
* Put a short in the pending buffer. The 16-bit value is put in MSB order. |
|
* IN assertion: the stream state is correct and there is enough room in |
|
* pending_buf. |
|
*/ |
|
local void putShortMSB (s, b) |
|
deflate_state *s; |
|
uInt b; |
|
{ |
|
put_byte(s, (Byte)(b >> 8)); |
|
put_byte(s, (Byte)(b & 0xff)); |
|
} |
|
|
|
/* ========================================================================= |
|
* Flush as much pending output as possible. All deflate() output goes |
|
* through this function so some applications may wish to modify it |
|
* to avoid allocating a large strm->next_out buffer and copying into it. |
|
* (See also read_buf()). |
|
*/ |
|
local void flush_pending(strm) |
|
z_streamp strm; |
|
{ |
|
unsigned len = strm->state->pending; |
|
|
|
if (len > strm->avail_out) len = strm->avail_out; |
|
if (len == 0) return; |
|
|
|
zmemcpy(strm->next_out, strm->state->pending_out, len); |
|
strm->next_out += len; |
|
strm->state->pending_out += len; |
|
strm->total_out += len; |
|
strm->avail_out -= len; |
|
strm->state->pending -= len; |
|
if (strm->state->pending == 0) { |
|
strm->state->pending_out = strm->state->pending_buf; |
|
} |
|
} |
|
|
|
/* ========================================================================= */ |
|
int ZEXPORT deflate (strm, flush) |
|
z_streamp strm; |
|
int flush; |
|
{ |
|
int old_flush; /* value of flush param for previous deflate call */ |
|
deflate_state *s; |
|
|
|
if (strm == Z_NULL || strm->state == Z_NULL || |
|
flush > Z_FINISH || flush < 0) { |
|
return Z_STREAM_ERROR; |
|
} |
|
s = strm->state; |
|
|
|
if (strm->next_out == Z_NULL || |
|
(strm->next_in == Z_NULL && strm->avail_in != 0) || |
|
(s->status == FINISH_STATE && flush != Z_FINISH)) { |
|
ERR_RETURN(strm, Z_STREAM_ERROR); |
|
} |
|
if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); |
|
|
|
s->strm = strm; /* just in case */ |
|
old_flush = s->last_flush; |
|
s->last_flush = flush; |
|
|
|
/* Write the header */ |
|
if (s->status == INIT_STATE) { |
|
#ifdef GZIP |
|
if (s->wrap == 2) { |
|
strm->adler = crc32(0L, Z_NULL, 0); |
|
put_byte(s, 31); |
|
put_byte(s, 139); |
|
put_byte(s, 8); |
|
if (s->gzhead == NULL) { |
|
put_byte(s, 0); |
|
put_byte(s, 0); |
|
put_byte(s, 0); |
|
put_byte(s, 0); |
|
put_byte(s, 0); |
|
put_byte(s, s->level == 9 ? 2 : |
|
(s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? |
|
4 : 0)); |
|
put_byte(s, OS_CODE); |
|
s->status = BUSY_STATE; |
|
} |
|
else { |
|
put_byte(s, (s->gzhead->text ? 1 : 0) + |
|
(s->gzhead->hcrc ? 2 : 0) + |
|
(s->gzhead->extra == Z_NULL ? 0 : 4) + |
|
(s->gzhead->name == Z_NULL ? 0 : 8) + |
|
(s->gzhead->comment == Z_NULL ? 0 : 16) |
|
); |
|
put_byte(s, (Byte)(s->gzhead->time & 0xff)); |
|
put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff)); |
|
put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff)); |
|
put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff)); |
|
put_byte(s, s->level == 9 ? 2 : |
|
(s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ? |
|
4 : 0)); |
|
put_byte(s, s->gzhead->os & 0xff); |
|
if (s->gzhead->extra != NULL) { |
|
put_byte(s, s->gzhead->extra_len & 0xff); |
|
put_byte(s, (s->gzhead->extra_len >> 8) & 0xff); |
|
} |
|
if (s->gzhead->hcrc) |
|
strm->adler = crc32(strm->adler, s->pending_buf, |
|
s->pending); |
|
s->gzindex = 0; |
|
s->status = EXTRA_STATE; |
|
} |
|
} |
|
else |
|
#endif |
|
{ |
|
uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; |
|
uInt level_flags; |
|
|
|
if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) |
|
level_flags = 0; |
|
else if (s->level < 6) |
|
level_flags = 1; |
|
else if (s->level == 6) |
|
level_flags = 2; |
|
else |
|
level_flags = 3; |
|
header |= (level_flags << 6); |
|
if (s->strstart != 0) header |= PRESET_DICT; |
|
header += 31 - (header % 31); |
|
|
|
s->status = BUSY_STATE; |
|
putShortMSB(s, header); |
|
|
|
/* Save the adler32 of the preset dictionary: */ |
|
if (s->strstart != 0) { |
|
putShortMSB(s, (uInt)(strm->adler >> 16)); |
|
putShortMSB(s, (uInt)(strm->adler & 0xffff)); |
|
} |
|
strm->adler = adler32(0L, Z_NULL, 0); |
|
} |
|
} |
|
#ifdef GZIP |
|
if (s->status == EXTRA_STATE) { |
|
if (s->gzhead->extra != NULL) { |
|
uInt beg = s->pending; /* start of bytes to update crc */ |
|
|
|
while (s->gzindex < (s->gzhead->extra_len & 0xffff)) { |
|
if (s->pending == s->pending_buf_size) { |
|
if (s->gzhead->hcrc && s->pending > beg) |
|
strm->adler = crc32(strm->adler, s->pending_buf + beg, |
|
s->pending - beg); |
|
flush_pending(strm); |
|
beg = s->pending; |
|
if (s->pending == s->pending_buf_size) |
|
break; |
|
} |
|
put_byte(s, s->gzhead->extra[s->gzindex]); |
|
s->gzindex++; |
|
} |
|
if (s->gzhead->hcrc && s->pending > beg) |
|
strm->adler = crc32(strm->adler, s->pending_buf + beg, |
|
s->pending - beg); |
|
if (s->gzindex == s->gzhead->extra_len) { |
|
s->gzindex = 0; |
|
s->status = NAME_STATE; |
|
} |
|
} |
|
else |
|
s->status = NAME_STATE; |
|
} |
|
if (s->status == NAME_STATE) { |
|
if (s->gzhead->name != NULL) { |
|
uInt beg = s->pending; /* start of bytes to update crc */ |
|
int val; |
|
|
|
do { |
|
if (s->pending == s->pending_buf_size) { |
|
if (s->gzhead->hcrc && s->pending > beg) |
|
strm->adler = crc32(strm->adler, s->pending_buf + beg, |
|
s->pending - beg); |
|
flush_pending(strm); |
|
beg = s->pending; |
|
if (s->pending == s->pending_buf_size) { |
|
val = 1; |
|
break; |
|
} |
|
} |
|
val = s->gzhead->name[s->gzindex++]; |
|
put_byte(s, val); |
|
} while (val != 0); |
|
if (s->gzhead->hcrc && s->pending > beg) |
|
strm->adler = crc32(strm->adler, s->pending_buf + beg, |
|
s->pending - beg); |
|
if (val == 0) { |
|
s->gzindex = 0; |
|
s->status = COMMENT_STATE; |
|
} |
|
} |
|
else |
|
s->status = COMMENT_STATE; |
|
} |
|
if (s->status == COMMENT_STATE) { |
|
if (s->gzhead->comment != NULL) { |
|
uInt beg = s->pending; /* start of bytes to update crc */ |
|
int val; |
|
|
|
do { |
|
if (s->pending == s->pending_buf_size) { |
|
if (s->gzhead->hcrc && s->pending > beg) |
|
strm->adler = crc32(strm->adler, s->pending_buf + beg, |
|
s->pending - beg); |
|
flush_pending(strm); |
|
beg = s->pending; |
|
if (s->pending == s->pending_buf_size) { |
|
val = 1; |
|
break; |
|
} |
|
} |
|
val = s->gzhead->comment[s->gzindex++]; |
|
put_byte(s, val); |
|
} while (val != 0); |
|
if (s->gzhead->hcrc && s->pending > beg) |
|
strm->adler = crc32(strm->adler, s->pending_buf + beg, |
|
s->pending - beg); |
|
if (val == 0) |
|
s->status = HCRC_STATE; |
|
} |
|
else |
|
s->status = HCRC_STATE; |
|
} |
|
if (s->status == HCRC_STATE) { |
|
if (s->gzhead->hcrc) { |
|
if (s->pending + 2 > s->pending_buf_size) |
|
flush_pending(strm); |
|
if (s->pending + 2 <= s->pending_buf_size) { |
|
put_byte(s, (Byte)(strm->adler & 0xff)); |
|
put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); |
|
strm->adler = crc32(0L, Z_NULL, 0); |
|
s->status = BUSY_STATE; |
|
} |
|
} |
|
else |
|
s->status = BUSY_STATE; |
|
} |
|
#endif |
|
|
|
/* Flush as much pending output as possible */ |
|
if (s->pending != 0) { |
|
flush_pending(strm); |
|
if (strm->avail_out == 0) { |
|
/* Since avail_out is 0, deflate will be called again with |
|
* more output space, but possibly with both pending and |
|
* avail_in equal to zero. There won't be anything to do, |
|
* but this is not an error situation so make sure we |
|
* return OK instead of BUF_ERROR at next call of deflate: |
|
*/ |
|
s->last_flush = -1; |
|
return Z_OK; |
|
} |
|
|
|
/* Make sure there is something to do and avoid duplicate consecutive |
|
* flushes. For repeated and useless calls with Z_FINISH, we keep |
|
* returning Z_STREAM_END instead of Z_BUF_ERROR. |
|
*/ |
|
} else if (strm->avail_in == 0 && flush <= old_flush && |
|
flush != Z_FINISH) { |
|
ERR_RETURN(strm, Z_BUF_ERROR); |
|
} |
|
|
|
/* User must not provide more input after the first FINISH: */ |
|
if (s->status == FINISH_STATE && strm->avail_in != 0) { |
|
ERR_RETURN(strm, Z_BUF_ERROR); |
|
} |
|
|
|
/* Start a new block or continue the current one. |
|
*/ |
|
if (strm->avail_in != 0 || s->lookahead != 0 || |
|
(flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { |
|
block_state bstate; |
|
|
|
bstate = (*(configuration_table[s->level].func))(s, flush); |
|
|
|
if (bstate == finish_started || bstate == finish_done) { |
|
s->status = FINISH_STATE; |
|
} |
|
if (bstate == need_more || bstate == finish_started) { |
|
if (strm->avail_out == 0) { |
|
s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ |
|
} |
|
return Z_OK; |
|
/* If flush != Z_NO_FLUSH && avail_out == 0, the next call |
|
* of deflate should use the same flush parameter to make sure |
|
* that the flush is complete. So we don't have to output an |
|
* empty block here, this will be done at next call. This also |
|
* ensures that for a very small output buffer, we emit at most |
|
* one empty block. |
|
*/ |
|
} |
|
if (bstate == block_done) { |
|
if (flush == Z_PARTIAL_FLUSH) { |
|
_tr_align(s); |
|
} else { /* FULL_FLUSH or SYNC_FLUSH */ |
|
_tr_stored_block(s, (char*)0, 0L, 0); |
|
/* For a full flush, this empty block will be recognized |
|
* as a special marker by inflate_sync(). |
|
*/ |
|
if (flush == Z_FULL_FLUSH) { |
|
CLEAR_HASH(s); /* forget history */ |
|
} |
|
} |
|
flush_pending(strm); |
|
if (strm->avail_out == 0) { |
|
s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */ |
|
return Z_OK; |
|
} |
|
} |
|
} |
|
Assert(strm->avail_out > 0, "bug2"); |
|
|
|
if (flush != Z_FINISH) return Z_OK; |
|
if (s->wrap <= 0) return Z_STREAM_END; |
|
|
|
/* Write the trailer */ |
|
#ifdef GZIP |
|
if (s->wrap == 2) { |
|
put_byte(s, (Byte)(strm->adler & 0xff)); |
|
put_byte(s, (Byte)((strm->adler >> 8) & 0xff)); |
|
put_byte(s, (Byte)((strm->adler >> 16) & 0xff)); |
|
put_byte(s, (Byte)((strm->adler >> 24) & 0xff)); |
|
put_byte(s, (Byte)(strm->total_in & 0xff)); |
|
put_byte(s, (Byte)((strm->total_in >> 8) & 0xff)); |
|
put_byte(s, (Byte)((strm->total_in >> 16) & 0xff)); |
|
put_byte(s, (Byte)((strm->total_in >> 24) & 0xff)); |
|
} |
|
else |
|
#endif |
|
{ |
|
putShortMSB(s, (uInt)(strm->adler >> 16)); |
|
putShortMSB(s, (uInt)(strm->adler & 0xffff)); |
|
} |
|
flush_pending(strm); |
|
/* If avail_out is zero, the application will call deflate again |
|
* to flush the rest. |
|
*/ |
|
if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ |
|
return s->pending != 0 ? Z_OK : Z_STREAM_END; |
|
} |
|
|
|
/* ========================================================================= */ |
|
int ZEXPORT deflateEnd (strm) |
|
z_streamp strm; |
|
{ |
|
int status; |
|
|
|
if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; |
|
|
|
status = strm->state->status; |
|
if (status != INIT_STATE && |
|
status != EXTRA_STATE && |
|
status != NAME_STATE && |
|
status != COMMENT_STATE && |
|
status != HCRC_STATE && |
|
status != BUSY_STATE && |
|
status != FINISH_STATE) { |
|
return Z_STREAM_ERROR; |
|
} |
|
|
|
/* Deallocate in reverse order of allocations: */ |
|
TRY_FREE(strm, strm->state->pending_buf); |
|
TRY_FREE(strm, strm->state->head); |
|
TRY_FREE(strm, strm->state->prev); |
|
TRY_FREE(strm, strm->state->window); |
|
|
|
ZFREE(strm, strm->state); |
|
strm->state = Z_NULL; |
|
|
|
return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK; |
|
} |
|
|
|
/* ========================================================================= |
|
* Copy the source state to the destination state. |
|
* To simplify the source, this is not supported for 16-bit MSDOS (which |
|
* doesn't have enough memory anyway to duplicate compression states). |
|
*/ |
|
int ZEXPORT deflateCopy (dest, source) |
|
z_streamp dest; |
|
z_streamp source; |
|
{ |
|
#ifdef MAXSEG_64K |
|
return Z_STREAM_ERROR; |
|
#else |
|
deflate_state *ds; |
|
deflate_state *ss; |
|
ushf *overlay; |
|
|
|
|
|
if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) { |
|
return Z_STREAM_ERROR; |
|
} |
|
|
|
ss = source->state; |
|
|
|
zmemcpy(dest, source, sizeof(z_stream)); |
|
|
|
ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); |
|
if (ds == Z_NULL) return Z_MEM_ERROR; |
|
dest->state = (struct internal_state FAR *) ds; |
|
zmemcpy(ds, ss, sizeof(deflate_state)); |
|
ds->strm = dest; |
|
|
|
ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte)); |
|
ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos)); |
|
ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); |
|
overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2); |
|
ds->pending_buf = (uchf *) overlay; |
|
|
|
if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL || |
|
ds->pending_buf == Z_NULL) { |
|
deflateEnd (dest); |
|
return Z_MEM_ERROR; |
|
} |
|
/* following zmemcpy do not work for 16-bit MSDOS */ |
|
zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte)); |
|
zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos)); |
|
zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos)); |
|
zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size); |
|
|
|
ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); |
|
ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush); |
|
ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize; |
|
|
|
ds->l_desc.dyn_tree = ds->dyn_ltree; |
|
ds->d_desc.dyn_tree = ds->dyn_dtree; |
|
ds->bl_desc.dyn_tree = ds->bl_tree; |
|
|
|
return Z_OK; |
|
#endif /* MAXSEG_64K */ |
|
} |
|
|
|
/* =========================================================================== |
|
* Read a new buffer from the current input stream, update the adler32 |
|
* and total number of bytes read. All deflate() input goes through |
|
* this function so some applications may wish to modify it to avoid |
|
* allocating a large strm->next_in buffer and copying from it. |
|
* (See also flush_pending()). |
|
*/ |
|
local int read_buf(strm, buf, size) |
|
z_streamp strm; |
|
Bytef *buf; |
|
unsigned size; |
|
{ |
|
unsigned len = strm->avail_in; |
|
|
|
if (len > size) len = size; |
|
if (len == 0) return 0; |
|
|
|
strm->avail_in -= len; |
|
|
|
if (strm->state->wrap == 1) { |
|
strm->adler = adler32(strm->adler, strm->next_in, len); |
|
} |
|
#ifdef GZIP |
|
else if (strm->state->wrap == 2) { |
|
strm->adler = crc32(strm->adler, strm->next_in, len); |
|
} |
|
#endif |
|
zmemcpy(buf, strm->next_in, len); |
|
strm->next_in += len; |
|
strm->total_in += len; |
|
|
|
return (int)len; |
|
} |
|
|
|
/* =========================================================================== |
|
* Initialize the "longest match" routines for a new zlib stream |
|
*/ |
|
local void lm_init (s) |
|
deflate_state *s; |
|
{ |
|
s->window_size = (ulg)2L*s->w_size; |
|
|
|
CLEAR_HASH(s); |
|
|
|
/* Set the default configuration parameters: |
|
*/ |
|
s->max_lazy_match = configuration_table[s->level].max_lazy; |
|
s->good_match = configuration_table[s->level].good_length; |
|
s->nice_match = configuration_table[s->level].nice_length; |
|
s->max_chain_length = configuration_table[s->level].max_chain; |
|
|
|
s->strstart = 0; |
|
s->block_start = 0L; |
|
s->lookahead = 0; |
|
s->match_length = s->prev_length = MIN_MATCH-1; |
|
s->match_available = 0; |
|
s->ins_h = 0; |
|
#ifndef FASTEST |
|
#ifdef ASMV |
|
match_init(); /* initialize the asm code */ |
|
#endif |
|
#endif |
|
} |
|
|
|
#ifndef FASTEST |
|
/* =========================================================================== |
|
* Set match_start to the longest match starting at the given string and |
|
* return its length. Matches shorter or equal to prev_length are discarded, |
|
* in which case the result is equal to prev_length and match_start is |
|
* garbage. |
|
* IN assertions: cur_match is the head of the hash chain for the current |
|
* string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1 |
|
* OUT assertion: the match length is not greater than s->lookahead. |
|
*/ |
|
#ifndef ASMV |
|
/* For 80x86 and 680x0, an optimized version will be provided in match.asm or |
|
* match.S. The code will be functionally equivalent. |
|
*/ |
|
local uInt longest_match(s, cur_match) |
|
deflate_state *s; |
|
IPos cur_match; /* current match */ |
|
{ |
|
unsigned chain_length = s->max_chain_length;/* max hash chain length */ |
|
register Bytef *scan = s->window + s->strstart; /* current string */ |
|
register Bytef *match; /* matched string */ |
|
register int len; /* length of current match */ |
|
int best_len = s->prev_length; /* best match length so far */ |
|
int nice_match = s->nice_match; /* stop if match long enough */ |
|
IPos limit = s->strstart > (IPos)MAX_DIST(s) ? |
|
s->strstart - (IPos)MAX_DIST(s) : NIL; |
|
/* Stop when cur_match becomes <= limit. To simplify the code, |
|
* we prevent matches with the string of window index 0. |
|
*/ |
|
Posf *prev = s->prev; |
|
uInt wmask = s->w_mask; |
|
|
|
#ifdef UNALIGNED_OK |
|
/* Compare two bytes at a time. Note: this is not always beneficial. |
|
* Try with and without -DUNALIGNED_OK to check. |
|
*/ |
|
register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1; |
|
register ush scan_start = *(ushf*)scan; |
|
register ush scan_end = *(ushf*)(scan+best_len-1); |
|
#else |
|
register Bytef *strend = s->window + s->strstart + MAX_MATCH; |
|
register Byte scan_end1 = scan[best_len-1]; |
|
register Byte scan_end = scan[best_len]; |
|
#endif |
|
|
|
/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. |
|
* It is easy to get rid of this optimization if necessary. |
|
*/ |
|
Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); |
|
|
|
/* Do not waste too much time if we already have a good match: */ |
|
if (s->prev_length >= s->good_match) { |
|
chain_length >>= 2; |
|
} |
|
/* Do not look for matches beyond the end of the input. This is necessary |
|
* to make deflate deterministic. |
|
*/ |
|
if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; |
|
|
|
Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); |
|
|
|
do { |
|
Assert(cur_match < s->strstart, "no future"); |
|
match = s->window + cur_match; |
|
|
|
/* Skip to next match if the match length cannot increase |
|
* or if the match length is less than 2. Note that the checks below |
|
* for insufficient lookahead only occur occasionally for performance |
|
* reasons. Therefore uninitialized memory will be accessed, and |
|
* conditional jumps will be made that depend on those values. |
|
* However the length of the match is limited to the lookahead, so |
|
* the output of deflate is not affected by the uninitialized values. |
|
*/ |
|
#if (defined(UNALIGNED_OK) && MAX_MATCH == 258) |
|
/* This code assumes sizeof(unsigned short) == 2. Do not use |
|
* UNALIGNED_OK if your compiler uses a different size. |
|
*/ |
|
if (*(ushf*)(match+best_len-1) != scan_end || |
|
*(ushf*)match != scan_start) continue; |
|
|
|
/* It is not necessary to compare scan[2] and match[2] since they are |
|
* always equal when the other bytes match, given that the hash keys |
|
* are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at |
|
* strstart+3, +5, ... up to strstart+257. We check for insufficient |
|
* lookahead only every 4th comparison; the 128th check will be made |
|
* at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is |
|
* necessary to put more guard bytes at the end of the window, or |
|
* to check more often for insufficient lookahead. |
|
*/ |
|
Assert(scan[2] == match[2], "scan[2]?"); |
|
scan++, match++; |
|
do { |
|
} while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
|
*(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
|
*(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
|
*(ushf*)(scan+=2) == *(ushf*)(match+=2) && |
|
scan < strend); |
|
/* The funny "do {}" generates better code on most compilers */ |
|
|
|
/* Here, scan <= window+strstart+257 */ |
|
Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); |
|
if (*scan == *match) scan++; |
|
|
|
len = (MAX_MATCH - 1) - (int)(strend-scan); |
|
scan = strend - (MAX_MATCH-1); |
|
|
|
#else /* UNALIGNED_OK */ |
|
|
|
if (match[best_len] != scan_end || |
|
match[best_len-1] != scan_end1 || |
|
*match != *scan || |
|
*++match != scan[1]) continue; |
|
|
|
/* The check at best_len-1 can be removed because it will be made |
|
* again later. (This heuristic is not always a win.) |
|
* It is not necessary to compare scan[2] and match[2] since they |
|
* are always equal when the other bytes match, given that |
|
* the hash keys are equal and that HASH_BITS >= 8. |
|
*/ |
|
scan += 2, match++; |
|
Assert(*scan == *match, "match[2]?"); |
|
|
|
/* We check for insufficient lookahead only every 8th comparison; |
|
* the 256th check will be made at strstart+258. |
|
*/ |
|
do { |
|
} while (*++scan == *++match && *++scan == *++match && |
|
*++scan == *++match && *++scan == *++match && |
|
*++scan == *++match && *++scan == *++match && |
|
*++scan == *++match && *++scan == *++match && |
|
scan < strend); |
|
|
|
Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); |
|
|
|
len = MAX_MATCH - (int)(strend - scan); |
|
scan = strend - MAX_MATCH; |
|
|
|
#endif /* UNALIGNED_OK */ |
|
|
|
if (len > best_len) { |
|
s->match_start = cur_match; |
|
best_len = len; |
|
if (len >= nice_match) break; |
|
#ifdef UNALIGNED_OK |
|
scan_end = *(ushf*)(scan+best_len-1); |
|
#else |
|
scan_end1 = scan[best_len-1]; |
|
scan_end = scan[best_len]; |
|
#endif |
|
} |
|
} while ((cur_match = prev[cur_match & wmask]) > limit |
|
&& --chain_length != 0); |
|
|
|
if ((uInt)best_len <= s->lookahead) return (uInt)best_len; |
|
return s->lookahead; |
|
} |
|
#endif /* ASMV */ |
|
#endif /* FASTEST */ |
|
|
|
/* --------------------------------------------------------------------------- |
|
* Optimized version for level == 1 or strategy == Z_RLE only |
|
*/ |
|
local uInt longest_match_fast(s, cur_match) |
|
deflate_state *s; |
|
IPos cur_match; /* current match */ |
|
{ |
|
register Bytef *scan = s->window + s->strstart; /* current string */ |
|
register Bytef *match; /* matched string */ |
|
register int len; /* length of current match */ |
|
register Bytef *strend = s->window + s->strstart + MAX_MATCH; |
|
|
|
/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16. |
|
* It is easy to get rid of this optimization if necessary. |
|
*/ |
|
Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever"); |
|
|
|
Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); |
|
|
|
Assert(cur_match < s->strstart, "no future"); |
|
|
|
match = s->window + cur_match; |
|
|
|
/* Return failure if the match length is less than 2: |
|
*/ |
|
if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1; |
|
|
|
/* The check at best_len-1 can be removed because it will be made |
|
* again later. (This heuristic is not always a win.) |
|
* It is not necessary to compare scan[2] and match[2] since they |
|
* are always equal when the other bytes match, given that |
|
* the hash keys are equal and that HASH_BITS >= 8. |
|
*/ |
|
scan += 2, match += 2; |
|
Assert(*scan == *match, "match[2]?"); |
|
|
|
/* We check for insufficient lookahead only every 8th comparison; |
|
* the 256th check will be made at strstart+258. |
|
*/ |
|
do { |
|
} while (*++scan == *++match && *++scan == *++match && |
|
*++scan == *++match && *++scan == *++match && |
|
*++scan == *++match && *++scan == *++match && |
|
*++scan == *++match && *++scan == *++match && |
|
scan < strend); |
|
|
|
Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan"); |
|
|
|
len = MAX_MATCH - (int)(strend - scan); |
|
|
|
if (len < MIN_MATCH) return MIN_MATCH - 1; |
|
|
|
s->match_start = cur_match; |
|
return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead; |
|
} |
|
|
|
#ifdef DEBUG |
|
/* =========================================================================== |
|
* Check that the match at match_start is indeed a match. |
|
*/ |
|
local void check_match(s, start, match, length) |
|
deflate_state *s; |
|
IPos start, match; |
|
int length; |
|
{ |
|
/* check that the match is indeed a match */ |
|
if (zmemcmp(s->window + match, |
|
s->window + start, length) != EQUAL) { |
|
fprintf(stderr, " start %u, match %u, length %d\n", |
|
start, match, length); |
|
do { |
|
fprintf(stderr, "%c%c", s->window[match++], s->window[start++]); |
|
} while (--length != 0); |
|
z_error("invalid match"); |
|
} |
|
if (z_verbose > 1) { |
|
fprintf(stderr,"\\[%d,%d]", start-match, length); |
|
do { putc(s->window[start++], stderr); } while (--length != 0); |
|
} |
|
} |
|
#else |
|
# define check_match(s, start, match, length) |
|
#endif /* DEBUG */ |
|
|
|
/* =========================================================================== |
|
* Fill the window when the lookahead becomes insufficient. |
|
* Updates strstart and lookahead. |
|
* |
|
* IN assertion: lookahead < MIN_LOOKAHEAD |
|
* OUT assertions: strstart <= window_size-MIN_LOOKAHEAD |
|
* At least one byte has been read, or avail_in == 0; reads are |
|
* performed for at least two bytes (required for the zip translate_eol |
|
* option -- not supported here). |
|
*/ |
|
local void fill_window(s) |
|
deflate_state *s; |
|
{ |
|
register unsigned n, m; |
|
register Posf *p; |
|
unsigned more; /* Amount of free space at the end of the window. */ |
|
uInt wsize = s->w_size; |
|
|
|
do { |
|
more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); |
|
|
|
/* Deal with !@#$% 64K limit: */ |
|
if (sizeof(int) <= 2) { |
|
if (more == 0 && s->strstart == 0 && s->lookahead == 0) { |
|
more = wsize; |
|
|
|
} else if (more == (unsigned)(-1)) { |
|
/* Very unlikely, but possible on 16 bit machine if |
|
* strstart == 0 && lookahead == 1 (input done a byte at time) |
|
*/ |
|
more--; |
|
} |
|
} |
|
|
|
/* If the window is almost full and there is insufficient lookahead, |
|
* move the upper half to the lower one to make room in the upper half. |
|
*/ |
|
if (s->strstart >= wsize+MAX_DIST(s)) { |
|
|
|
zmemcpy(s->window, s->window+wsize, (unsigned)wsize); |
|
s->match_start -= wsize; |
|
s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ |
|
s->block_start -= (long) wsize; |
|
|
|
/* Slide the hash table (could be avoided with 32 bit values |
|
at the expense of memory usage). We slide even when level == 0 |
|
to keep the hash table consistent if we switch back to level > 0 |
|
later. (Using level 0 permanently is not an optimal usage of |
|
zlib, so we don't care about this pathological case.) |
|
*/ |
|
/* %%% avoid this when Z_RLE */ |
|
n = s->hash_size; |
|
p = &s->head[n]; |
|
do { |
|
m = *--p; |
|
*p = (Pos)(m >= wsize ? m-wsize : NIL); |
|
} while (--n); |
|
|
|
n = wsize; |
|
#ifndef FASTEST |
|
p = &s->prev[n]; |
|
do { |
|
m = *--p; |
|
*p = (Pos)(m >= wsize ? m-wsize : NIL); |
|
/* If n is not on any hash chain, prev[n] is garbage but |
|
* its value will never be used. |
|
*/ |
|
} while (--n); |
|
#endif |
|
more += wsize; |
|
} |
|
if (s->strm->avail_in == 0) return; |
|
|
|
/* If there was no sliding: |
|
* strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 && |
|
* more == window_size - lookahead - strstart |
|
* => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1) |
|
* => more >= window_size - 2*WSIZE + 2 |
|
* In the BIG_MEM or MMAP case (not yet supported), |
|
* window_size == input_size + MIN_LOOKAHEAD && |
|
* strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD. |
|
* Otherwise, window_size == 2*WSIZE so more >= 2. |
|
* If there was sliding, more >= WSIZE. So in all cases, more >= 2. |
|
*/ |
|
Assert(more >= 2, "more < 2"); |
|
|
|
n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); |
|
s->lookahead += n; |
|
|
|
/* Initialize the hash value now that we have some input: */ |
|
if (s->lookahead >= MIN_MATCH) { |
|
s->ins_h = s->window[s->strstart]; |
|
UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); |
|
#if MIN_MATCH != 3 |
|
Call UPDATE_HASH() MIN_MATCH-3 more times |
|
#endif |
|
} |
|
/* If the whole input has less than MIN_MATCH bytes, ins_h is garbage, |
|
* but this is not important since only literal bytes will be emitted. |
|
*/ |
|
|
|
} while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); |
|
} |
|
|
|
/* =========================================================================== |
|
* Flush the current block, with given end-of-file flag. |
|
* IN assertion: strstart is set to the end of the current match. |
|
*/ |
|
#define FLUSH_BLOCK_ONLY(s, eof) { \ |
|
_tr_flush_block(s, (s->block_start >= 0L ? \ |
|
(charf *)&s->window[(unsigned)s->block_start] : \ |
|
(charf *)Z_NULL), \ |
|
(ulg)((long)s->strstart - s->block_start), \ |
|
(eof)); \ |
|
s->block_start = s->strstart; \ |
|
flush_pending(s->strm); \ |
|
Tracev((stderr,"[FLUSH]")); \ |
|
} |
|
|
|
/* Same but force premature exit if necessary. */ |
|
#define FLUSH_BLOCK(s, eof) { \ |
|
FLUSH_BLOCK_ONLY(s, eof); \ |
|
if (s->strm->avail_out == 0) return (eof) ? finish_started : need_more; \ |
|
} |
|
|
|
/* =========================================================================== |
|
* Copy without compression as much as possible from the input stream, return |
|
* the current block state. |
|
* This function does not insert new strings in the dictionary since |
|
* uncompressible data is probably not useful. This function is used |
|
* only for the level=0 compression option. |
|
* NOTE: this function should be optimized to avoid extra copying from |
|
* window to pending_buf. |
|
*/ |
|
local block_state deflate_stored(s, flush) |
|
deflate_state *s; |
|
int flush; |
|
{ |
|
/* Stored blocks are limited to 0xffff bytes, pending_buf is limited |
|
* to pending_buf_size, and each stored block has a 5 byte header: |
|
*/ |
|
ulg max_block_size = 0xffff; |
|
ulg max_start; |
|
|
|
if (max_block_size > s->pending_buf_size - 5) { |
|
max_block_size = s->pending_buf_size - 5; |
|
} |
|
|
|
/* Copy as much as possible from input to output: */ |
|
for (;;) { |
|
/* Fill the window as much as possible: */ |
|
if (s->lookahead <= 1) { |
|
|
|
Assert(s->strstart < s->w_size+MAX_DIST(s) || |
|
s->block_start >= (long)s->w_size, "slide too late"); |
|
|
|
fill_window(s); |
|
if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more; |
|
|
|
if (s->lookahead == 0) break; /* flush the current block */ |
|
} |
|
Assert(s->block_start >= 0L, "block gone"); |
|
|
|
s->strstart += s->lookahead; |
|
s->lookahead = 0; |
|
|
|
/* Emit a stored block if pending_buf will be full: */ |
|
max_start = s->block_start + max_block_size; |
|
if (s->strstart == 0 || (ulg)s->strstart >= max_start) { |
|
/* strstart == 0 is possible when wraparound on 16-bit machine */ |
|
s->lookahead = (uInt)(s->strstart - max_start); |
|
s->strstart = (uInt)max_start; |
|
FLUSH_BLOCK(s, 0); |
|
} |
|
/* Flush if we may have to slide, otherwise block_start may become |
|
* negative and the data will be gone: |
|
*/ |
|
if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) { |
|
FLUSH_BLOCK(s, 0); |
|
} |
|
} |
|
FLUSH_BLOCK(s, flush == Z_FINISH); |
|
return flush == Z_FINISH ? finish_done : block_done; |
|
} |
|
|
|
/* =========================================================================== |
|
* Compress as much as possible from the input stream, return the current |
|
* block state. |
|
* This function does not perform lazy evaluation of matches and inserts |
|
* new strings in the dictionary only for unmatched strings or for short |
|
* matches. It is used only for the fast compression options. |
|
*/ |
|
local block_state deflate_fast(s, flush) |
|
deflate_state *s; |
|
int flush; |
|
{ |
|
IPos hash_head = NIL; /* head of the hash chain */ |
|
int bflush; /* set if current block must be flushed */ |
|
|
|
for (;;) { |
|
/* Make sure that we always have enough lookahead, except |
|
* at the end of the input file. We need MAX_MATCH bytes |
|
* for the next match, plus MIN_MATCH bytes to insert the |
|
* string following the next match. |
|
*/ |
|
if (s->lookahead < MIN_LOOKAHEAD) { |
|
fill_window(s); |
|
if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { |
|
return need_more; |
|
} |
|
if (s->lookahead == 0) break; /* flush the current block */ |
|
} |
|
|
|
/* Insert the string window[strstart .. strstart+2] in the |
|
* dictionary, and set hash_head to the head of the hash chain: |
|
*/ |
|
if (s->lookahead >= MIN_MATCH) { |
|
INSERT_STRING(s, s->strstart, hash_head); |
|
} |
|
|
|
/* Find the longest match, discarding those <= prev_length. |
|
* At this point we have always match_length < MIN_MATCH |
|
*/ |
|
if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) { |
|
/* To simplify the code, we prevent matches with the string |
|
* of window index 0 (in particular we have to avoid a match |
|
* of the string with itself at the start of the input file). |
|
*/ |
|
#ifdef FASTEST |
|
if ((s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) || |
|
(s->strategy == Z_RLE && s->strstart - hash_head == 1)) { |
|
s->match_length = longest_match_fast (s, hash_head); |
|
} |
|
#else |
|
if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) { |
|
s->match_length = longest_match (s, hash_head); |
|
} else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { |
|
s->match_length = longest_match_fast (s, hash_head); |
|
} |
|
#endif |
|
/* longest_match() or longest_match_fast() sets match_start */ |
|
} |
|
if (s->match_length >= MIN_MATCH) { |
|
check_match(s, s->strstart, s->match_start, s->match_length); |
|
|
|
_tr_tally_dist(s, s->strstart - s->match_start, |
|
s->match_length - MIN_MATCH, bflush); |
|
|
|
s->lookahead -= s->match_length; |
|
|
|
/* Insert new strings in the hash table only if the match length |
|
* is not too large. This saves time but degrades compression. |
|
*/ |
|
#ifndef FASTEST |
|
if (s->match_length <= s->max_insert_length && |
|
s->lookahead >= MIN_MATCH) { |
|
s->match_length--; /* string at strstart already in table */ |
|
do { |
|
s->strstart++; |
|
INSERT_STRING(s, s->strstart, hash_head); |
|
/* strstart never exceeds WSIZE-MAX_MATCH, so there are |
|
* always MIN_MATCH bytes ahead. |
|
*/ |
|
} while (--s->match_length != 0); |
|
s->strstart++; |
|
} else |
|
#endif |
|
{ |
|
s->strstart += s->match_length; |
|
s->match_length = 0; |
|
s->ins_h = s->window[s->strstart]; |
|
UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); |
|
#if MIN_MATCH != 3 |
|
Call UPDATE_HASH() MIN_MATCH-3 more times |
|
#endif |
|
/* If lookahead < MIN_MATCH, ins_h is garbage, but it does not |
|
* matter since it will be recomputed at next deflate call. |
|
*/ |
|
} |
|
} else { |
|
/* No match, output a literal byte */ |
|
Tracevv((stderr,"%c", s->window[s->strstart])); |
|
_tr_tally_lit (s, s->window[s->strstart], bflush); |
|
s->lookahead--; |
|
s->strstart++; |
|
} |
|
if (bflush) FLUSH_BLOCK(s, 0); |
|
} |
|
FLUSH_BLOCK(s, flush == Z_FINISH); |
|
return flush == Z_FINISH ? finish_done : block_done; |
|
} |
|
|
|
#ifndef FASTEST |
|
/* =========================================================================== |
|
* Same as above, but achieves better compression. We use a lazy |
|
* evaluation for matches: a match is finally adopted only if there is |
|
* no better match at the next window position. |
|
*/ |
|
local block_state deflate_slow(s, flush) |
|
deflate_state *s; |
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int flush; |
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{ |
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IPos hash_head = NIL; /* head of hash chain */ |
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int bflush; /* set if current block must be flushed */ |
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|
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/* Process the input block. */ |
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for (;;) { |
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/* Make sure that we always have enough lookahead, except |
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* at the end of the input file. We need MAX_MATCH bytes |
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* for the next match, plus MIN_MATCH bytes to insert the |
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* string following the next match. |
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*/ |
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if (s->lookahead < MIN_LOOKAHEAD) { |
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fill_window(s); |
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if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { |
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return need_more; |
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} |
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if (s->lookahead == 0) break; /* flush the current block */ |
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} |
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|
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/* Insert the string window[strstart .. strstart+2] in the |
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* dictionary, and set hash_head to the head of the hash chain: |
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*/ |
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if (s->lookahead >= MIN_MATCH) { |
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INSERT_STRING(s, s->strstart, hash_head); |
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} |
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|
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/* Find the longest match, discarding those <= prev_length. |
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*/ |
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s->prev_length = s->match_length, s->prev_match = s->match_start; |
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s->match_length = MIN_MATCH-1; |
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|
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if (hash_head != NIL && s->prev_length < s->max_lazy_match && |
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s->strstart - hash_head <= MAX_DIST(s)) { |
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/* To simplify the code, we prevent matches with the string |
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* of window index 0 (in particular we have to avoid a match |
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* of the string with itself at the start of the input file). |
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*/ |
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if (s->strategy != Z_HUFFMAN_ONLY && s->strategy != Z_RLE) { |
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s->match_length = longest_match (s, hash_head); |
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} else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { |
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s->match_length = longest_match_fast (s, hash_head); |
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} |
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/* longest_match() or longest_match_fast() sets match_start */ |
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if (s->match_length <= 5 && (s->strategy == Z_FILTERED |
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#if TOO_FAR <= 32767 |
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|| (s->match_length == MIN_MATCH && |
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s->strstart - s->match_start > TOO_FAR) |
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#endif |
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)) { |
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|
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/* If prev_match is also MIN_MATCH, match_start is garbage |
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* but we will ignore the current match anyway. |
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*/ |
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s->match_length = MIN_MATCH-1; |
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} |
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} |
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/* If there was a match at the previous step and the current |
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* match is not better, output the previous match: |
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*/ |
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if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { |
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uInt max_insert = s->strstart + s->lookahead - MIN_MATCH; |
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/* Do not insert strings in hash table beyond this. */ |
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|
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check_match(s, s->strstart-1, s->prev_match, s->prev_length); |
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_tr_tally_dist(s, s->strstart -1 - s->prev_match, |
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s->prev_length - MIN_MATCH, bflush); |
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|
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/* Insert in hash table all strings up to the end of the match. |
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* strstart-1 and strstart are already inserted. If there is not |
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* enough lookahead, the last two strings are not inserted in |
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* the hash table. |
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*/ |
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s->lookahead -= s->prev_length-1; |
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s->prev_length -= 2; |
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do { |
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if (++s->strstart <= max_insert) { |
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INSERT_STRING(s, s->strstart, hash_head); |
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} |
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} while (--s->prev_length != 0); |
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s->match_available = 0; |
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s->match_length = MIN_MATCH-1; |
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s->strstart++; |
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if (bflush) FLUSH_BLOCK(s, 0); |
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|
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} else if (s->match_available) { |
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/* If there was no match at the previous position, output a |
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* single literal. If there was a match but the current match |
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* is longer, truncate the previous match to a single literal. |
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*/ |
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Tracevv((stderr,"%c", s->window[s->strstart-1])); |
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_tr_tally_lit(s, s->window[s->strstart-1], bflush); |
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if (bflush) { |
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FLUSH_BLOCK_ONLY(s, 0); |
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} |
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s->strstart++; |
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s->lookahead--; |
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if (s->strm->avail_out == 0) return need_more; |
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} else { |
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/* There is no previous match to compare with, wait for |
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* the next step to decide. |
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*/ |
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s->match_available = 1; |
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s->strstart++; |
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s->lookahead--; |
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} |
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} |
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Assert (flush != Z_NO_FLUSH, "no flush?"); |
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if (s->match_available) { |
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Tracevv((stderr,"%c", s->window[s->strstart-1])); |
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_tr_tally_lit(s, s->window[s->strstart-1], bflush); |
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s->match_available = 0; |
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} |
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FLUSH_BLOCK(s, flush == Z_FINISH); |
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return flush == Z_FINISH ? finish_done : block_done; |
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} |
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#endif /* FASTEST */ |
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|
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#if 0 |
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/* =========================================================================== |
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* For Z_RLE, simply look for runs of bytes, generate matches only of distance |
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* one. Do not maintain a hash table. (It will be regenerated if this run of |
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* deflate switches away from Z_RLE.) |
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*/ |
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local block_state deflate_rle(s, flush) |
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deflate_state *s; |
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int flush; |
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{ |
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int bflush; /* set if current block must be flushed */ |
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uInt run; /* length of run */ |
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uInt max; /* maximum length of run */ |
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uInt prev; /* byte at distance one to match */ |
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Bytef *scan; /* scan for end of run */ |
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|
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for (;;) { |
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/* Make sure that we always have enough lookahead, except |
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* at the end of the input file. We need MAX_MATCH bytes |
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* for the longest encodable run. |
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*/ |
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if (s->lookahead < MAX_MATCH) { |
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fill_window(s); |
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if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) { |
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return need_more; |
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} |
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if (s->lookahead == 0) break; /* flush the current block */ |
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} |
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|
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/* See how many times the previous byte repeats */ |
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run = 0; |
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if (s->strstart > 0) { /* if there is a previous byte, that is */ |
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max = s->lookahead < MAX_MATCH ? s->lookahead : MAX_MATCH; |
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scan = s->window + s->strstart - 1; |
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prev = *scan++; |
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do { |
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if (*scan++ != prev) |
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break; |
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} while (++run < max); |
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} |
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|
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/* Emit match if have run of MIN_MATCH or longer, else emit literal */ |
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if (run >= MIN_MATCH) { |
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check_match(s, s->strstart, s->strstart - 1, run); |
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_tr_tally_dist(s, 1, run - MIN_MATCH, bflush); |
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s->lookahead -= run; |
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s->strstart += run; |
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} else { |
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/* No match, output a literal byte */ |
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Tracevv((stderr,"%c", s->window[s->strstart])); |
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_tr_tally_lit (s, s->window[s->strstart], bflush); |
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s->lookahead--; |
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s->strstart++; |
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} |
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if (bflush) FLUSH_BLOCK(s, 0); |
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} |
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FLUSH_BLOCK(s, flush == Z_FINISH); |
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return flush == Z_FINISH ? finish_done : block_done; |
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} |
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#endif
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