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408 lines
16 KiB
408 lines
16 KiB
#ifndef DEFLATE_H_ |
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#define DEFLATE_H_ |
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/* deflate.h -- internal compression state |
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* Copyright (C) 1995-2016 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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/* WARNING: this file should *not* be used by applications. It is |
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part of the implementation of the compression library and is |
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subject to change. Applications should only use zlib.h. |
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*/ |
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#include "zutil.h" |
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#include "zendian.h" |
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#include "adler32_fold.h" |
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#include "crc32_fold.h" |
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/* define NO_GZIP when compiling if you want to disable gzip header and |
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trailer creation by deflate(). NO_GZIP would be used to avoid linking in |
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the crc code when it is not needed. For shared libraries, gzip encoding |
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should be left enabled. */ |
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#ifndef NO_GZIP |
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# define GZIP |
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#endif |
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/* =========================================================================== |
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* Internal compression state. |
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*/ |
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#define LENGTH_CODES 29 |
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/* number of length codes, not counting the special END_BLOCK code */ |
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#define LITERALS 256 |
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/* number of literal bytes 0..255 */ |
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#define L_CODES (LITERALS+1+LENGTH_CODES) |
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/* number of Literal or Length codes, including the END_BLOCK code */ |
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#define D_CODES 30 |
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/* number of distance codes */ |
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#define BL_CODES 19 |
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/* number of codes used to transfer the bit lengths */ |
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#define HEAP_SIZE (2*L_CODES+1) |
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/* maximum heap size */ |
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#define BIT_BUF_SIZE 64 |
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/* size of bit buffer in bi_buf */ |
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#define END_BLOCK 256 |
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/* end of block literal code */ |
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#define INIT_STATE 1 /* zlib header -> BUSY_STATE */ |
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#ifdef GZIP |
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# define GZIP_STATE 4 /* gzip header -> BUSY_STATE | EXTRA_STATE */ |
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# define EXTRA_STATE 5 /* gzip extra block -> NAME_STATE */ |
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# define NAME_STATE 6 /* gzip file name -> COMMENT_STATE */ |
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# define COMMENT_STATE 7 /* gzip comment -> HCRC_STATE */ |
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# define HCRC_STATE 8 /* gzip header CRC -> BUSY_STATE */ |
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#endif |
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#define BUSY_STATE 2 /* deflate -> FINISH_STATE */ |
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#define FINISH_STATE 3 /* stream complete */ |
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#ifdef GZIP |
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# define MAX_STATE HCRC_STATE |
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#else |
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# define MAX_STATE FINISH_STATE |
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#endif |
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/* Stream status */ |
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#define HASH_BITS 16u /* log2(HASH_SIZE) */ |
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#ifndef HASH_SIZE |
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# define HASH_SIZE 65536u /* number of elements in hash table */ |
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#endif |
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#define HASH_MASK (HASH_SIZE - 1u) /* HASH_SIZE-1 */ |
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/* Data structure describing a single value and its code string. */ |
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typedef struct ct_data_s { |
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union { |
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uint16_t freq; /* frequency count */ |
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uint16_t code; /* bit string */ |
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} fc; |
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union { |
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uint16_t dad; /* father node in Huffman tree */ |
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uint16_t len; /* length of bit string */ |
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} dl; |
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} ct_data; |
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#define Freq fc.freq |
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#define Code fc.code |
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#define Dad dl.dad |
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#define Len dl.len |
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typedef struct static_tree_desc_s static_tree_desc; |
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typedef struct tree_desc_s { |
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ct_data *dyn_tree; /* the dynamic tree */ |
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int max_code; /* largest code with non zero frequency */ |
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const static_tree_desc *stat_desc; /* the corresponding static tree */ |
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} tree_desc; |
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typedef uint16_t Pos; |
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/* A Pos is an index in the character window. We use short instead of int to |
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* save space in the various tables. |
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*/ |
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/* Type definitions for hash callbacks */ |
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typedef struct internal_state deflate_state; |
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typedef uint32_t (* update_hash_cb) (deflate_state *const s, uint32_t h, uint32_t val); |
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typedef void (* insert_string_cb) (deflate_state *const s, uint32_t str, uint32_t count); |
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typedef Pos (* quick_insert_string_cb)(deflate_state *const s, uint32_t str); |
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struct internal_state { |
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PREFIX3(stream) *strm; /* pointer back to this zlib stream */ |
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unsigned char *pending_buf; /* output still pending */ |
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unsigned char *pending_out; /* next pending byte to output to the stream */ |
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uint32_t pending_buf_size; /* size of pending_buf */ |
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uint32_t pending; /* nb of bytes in the pending buffer */ |
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int wrap; /* bit 0 true for zlib, bit 1 true for gzip */ |
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uint32_t gzindex; /* where in extra, name, or comment */ |
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PREFIX(gz_headerp) gzhead; /* gzip header information to write */ |
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int status; /* as the name implies */ |
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int last_flush; /* value of flush param for previous deflate call */ |
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int reproducible; /* Whether reproducible compression results are required. */ |
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int block_open; |
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/* Whether or not a block is currently open for the QUICK deflation scheme. |
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* This is set to 1 if there is an active block, or 0 if the block was just closed. |
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*/ |
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/* used by deflate.c: */ |
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unsigned int w_size; /* LZ77 window size (32K by default) */ |
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unsigned int w_bits; /* log2(w_size) (8..16) */ |
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unsigned int w_mask; /* w_size - 1 */ |
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unsigned int lookahead; /* number of valid bytes ahead in window */ |
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unsigned int high_water; |
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/* High water mark offset in window for initialized bytes -- bytes above |
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* this are set to zero in order to avoid memory check warnings when |
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* longest match routines access bytes past the input. This is then |
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* updated to the new high water mark. |
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*/ |
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unsigned int window_size; |
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/* Actual size of window: 2*wSize, except when the user input buffer |
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* is directly used as sliding window. |
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*/ |
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unsigned char *window; |
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/* Sliding window. Input bytes are read into the second half of the window, |
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* and move to the first half later to keep a dictionary of at least wSize |
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* bytes. With this organization, matches are limited to a distance of |
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* wSize-STD_MAX_MATCH bytes, but this ensures that IO is always |
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* performed with a length multiple of the block size. Also, it limits |
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* the window size to 64K, which is quite useful on MSDOS. |
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* To do: use the user input buffer as sliding window. |
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*/ |
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Pos *prev; |
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/* Link to older string with same hash index. To limit the size of this |
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* array to 64K, this link is maintained only for the last 32K strings. |
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* An index in this array is thus a window index modulo 32K. |
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*/ |
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Pos *head; /* Heads of the hash chains or 0. */ |
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uint32_t ins_h; /* hash index of string to be inserted */ |
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int block_start; |
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/* Window position at the beginning of the current output block. Gets |
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* negative when the window is moved backwards. |
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*/ |
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unsigned int match_length; /* length of best match */ |
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Pos prev_match; /* previous match */ |
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int match_available; /* set if previous match exists */ |
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unsigned int strstart; /* start of string to insert */ |
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unsigned int match_start; /* start of matching string */ |
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unsigned int prev_length; |
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/* Length of the best match at previous step. Matches not greater than this |
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* are discarded. This is used in the lazy match evaluation. |
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*/ |
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unsigned int max_chain_length; |
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/* To speed up deflation, hash chains are never searched beyond this length. |
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* A higher limit improves compression ratio but degrades the speed. |
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*/ |
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unsigned int max_lazy_match; |
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/* Attempt to find a better match only when the current match is strictly smaller |
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* than this value. This mechanism is used only for compression levels >= 4. |
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*/ |
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# define max_insert_length max_lazy_match |
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/* Insert new strings in the hash table only if the match length is not |
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* greater than this length. This saves time but degrades compression. |
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* max_insert_length is used only for compression levels <= 3. |
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*/ |
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update_hash_cb update_hash; |
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insert_string_cb insert_string; |
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quick_insert_string_cb quick_insert_string; |
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/* Hash function callbacks that can be configured depending on the deflate |
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* algorithm being used */ |
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int level; /* compression level (1..9) */ |
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int strategy; /* favor or force Huffman coding*/ |
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unsigned int good_match; |
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/* Use a faster search when the previous match is longer than this */ |
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int nice_match; /* Stop searching when current match exceeds this */ |
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struct crc32_fold_s ALIGNED_(16) crc_fold; |
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/* used by trees.c: */ |
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/* Didn't use ct_data typedef below to suppress compiler warning */ |
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struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */ |
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struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */ |
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struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */ |
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struct tree_desc_s l_desc; /* desc. for literal tree */ |
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struct tree_desc_s d_desc; /* desc. for distance tree */ |
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struct tree_desc_s bl_desc; /* desc. for bit length tree */ |
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uint16_t bl_count[MAX_BITS+1]; |
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/* number of codes at each bit length for an optimal tree */ |
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int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */ |
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int heap_len; /* number of elements in the heap */ |
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int heap_max; /* element of largest frequency */ |
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/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used. |
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* The same heap array is used to build all trees. |
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*/ |
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unsigned char depth[2*L_CODES+1]; |
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/* Depth of each subtree used as tie breaker for trees of equal frequency |
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*/ |
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unsigned int lit_bufsize; |
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/* Size of match buffer for literals/lengths. There are 4 reasons for |
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* limiting lit_bufsize to 64K: |
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* - frequencies can be kept in 16 bit counters |
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* - if compression is not successful for the first block, all input |
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* data is still in the window so we can still emit a stored block even |
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* when input comes from standard input. (This can also be done for |
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* all blocks if lit_bufsize is not greater than 32K.) |
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* - if compression is not successful for a file smaller than 64K, we can |
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* even emit a stored file instead of a stored block (saving 5 bytes). |
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* This is applicable only for zip (not gzip or zlib). |
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* - creating new Huffman trees less frequently may not provide fast |
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* adaptation to changes in the input data statistics. (Take for |
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* example a binary file with poorly compressible code followed by |
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* a highly compressible string table.) Smaller buffer sizes give |
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* fast adaptation but have of course the overhead of transmitting |
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* trees more frequently. |
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* - I can't count above 4 |
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*/ |
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unsigned char *sym_buf; /* buffer for distances and literals/lengths */ |
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unsigned int sym_next; /* running index in sym_buf */ |
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unsigned int sym_end; /* symbol table full when sym_next reaches this */ |
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unsigned long opt_len; /* bit length of current block with optimal trees */ |
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unsigned long static_len; /* bit length of current block with static trees */ |
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unsigned int matches; /* number of string matches in current block */ |
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unsigned int insert; /* bytes at end of window left to insert */ |
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/* compressed_len and bits_sent are only used if ZLIB_DEBUG is defined */ |
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unsigned long compressed_len; /* total bit length of compressed file mod 2^32 */ |
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unsigned long bits_sent; /* bit length of compressed data sent mod 2^32 */ |
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/* Reserved for future use and alignment purposes */ |
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char *reserved_p; |
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uint64_t bi_buf; |
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/* Output buffer. bits are inserted starting at the bottom (least significant bits). */ |
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int32_t bi_valid; |
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/* Number of valid bits in bi_buf. All bits above the last valid bit are always zero. */ |
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/* Reserved for future use and alignment purposes */ |
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int32_t reserved[11]; |
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} ALIGNED_(8); |
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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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/* Output a byte on the stream. |
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* IN assertion: there is enough room in pending_buf. |
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*/ |
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#define put_byte(s, c) { \ |
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s->pending_buf[s->pending++] = (unsigned char)(c); \ |
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} |
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/* =========================================================================== |
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* Output a short LSB first on the stream. |
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* IN assertion: there is enough room in pending_buf. |
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*/ |
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static inline void put_short(deflate_state *s, uint16_t w) { |
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#if BYTE_ORDER == BIG_ENDIAN |
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w = ZSWAP16(w); |
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#endif |
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memcpy(&s->pending_buf[s->pending], &w, sizeof(w)); |
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s->pending += 2; |
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} |
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/* =========================================================================== |
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* Output a short MSB first on the stream. |
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* IN assertion: there is enough room in pending_buf. |
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*/ |
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static inline void put_short_msb(deflate_state *s, uint16_t w) { |
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#if BYTE_ORDER == LITTLE_ENDIAN |
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w = ZSWAP16(w); |
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#endif |
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memcpy(&s->pending_buf[s->pending], &w, sizeof(w)); |
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s->pending += 2; |
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} |
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/* =========================================================================== |
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* Output a 32-bit unsigned int LSB first on the stream. |
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* IN assertion: there is enough room in pending_buf. |
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*/ |
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static inline void put_uint32(deflate_state *s, uint32_t dw) { |
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#if BYTE_ORDER == BIG_ENDIAN |
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dw = ZSWAP32(dw); |
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#endif |
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memcpy(&s->pending_buf[s->pending], &dw, sizeof(dw)); |
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s->pending += 4; |
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} |
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/* =========================================================================== |
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* Output a 32-bit unsigned int MSB first on the stream. |
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* IN assertion: there is enough room in pending_buf. |
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*/ |
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static inline void put_uint32_msb(deflate_state *s, uint32_t dw) { |
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#if BYTE_ORDER == LITTLE_ENDIAN |
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dw = ZSWAP32(dw); |
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#endif |
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memcpy(&s->pending_buf[s->pending], &dw, sizeof(dw)); |
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s->pending += 4; |
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} |
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/* =========================================================================== |
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* Output a 64-bit unsigned int LSB first on the stream. |
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* IN assertion: there is enough room in pending_buf. |
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*/ |
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static inline void put_uint64(deflate_state *s, uint64_t lld) { |
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#if BYTE_ORDER == BIG_ENDIAN |
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lld = ZSWAP64(lld); |
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#endif |
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memcpy(&s->pending_buf[s->pending], &lld, sizeof(lld)); |
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s->pending += 8; |
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} |
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#define MIN_LOOKAHEAD (STD_MAX_MATCH + STD_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 STD_MIN_MATCH+1. |
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*/ |
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#define MAX_DIST(s) ((s)->w_size - MIN_LOOKAHEAD) |
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/* In order to simplify the code, particularly on 16 bit machines, match |
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* distances are limited to MAX_DIST instead of WSIZE. |
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*/ |
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#define WIN_INIT STD_MAX_MATCH |
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/* Number of bytes after end of data in window to initialize in order to avoid |
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memory checker errors from longest match routines */ |
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void Z_INTERNAL PREFIX(fill_window)(deflate_state *s); |
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void Z_INTERNAL slide_hash_c(deflate_state *s); |
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/* in trees.c */ |
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void Z_INTERNAL zng_tr_init(deflate_state *s); |
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void Z_INTERNAL zng_tr_flush_block(deflate_state *s, char *buf, uint32_t stored_len, int last); |
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void Z_INTERNAL zng_tr_flush_bits(deflate_state *s); |
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void Z_INTERNAL zng_tr_align(deflate_state *s); |
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void Z_INTERNAL zng_tr_stored_block(deflate_state *s, char *buf, uint32_t stored_len, int last); |
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uint16_t Z_INTERNAL PREFIX(bi_reverse)(unsigned code, int len); |
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void Z_INTERNAL PREFIX(flush_pending)(PREFIX3(streamp) strm); |
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#define d_code(dist) ((dist) < 256 ? zng_dist_code[dist] : zng_dist_code[256+((dist)>>7)]) |
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/* Mapping from a distance to a distance code. dist is the distance - 1 and |
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* must not have side effects. zng_dist_code[256] and zng_dist_code[257] are never |
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* used. |
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*/ |
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/* Bit buffer and compress bits calculation debugging */ |
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#ifdef ZLIB_DEBUG |
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# define cmpr_bits_add(s, len) s->compressed_len += (len) |
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# define cmpr_bits_align(s) s->compressed_len = (s->compressed_len + 7) & ~7L |
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# define sent_bits_add(s, bits) s->bits_sent += (bits) |
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# define sent_bits_align(s) s->bits_sent = (s->bits_sent + 7) & ~7L |
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#else |
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# define cmpr_bits_add(s, len) Z_UNUSED(len) |
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# define cmpr_bits_align(s) |
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# define sent_bits_add(s, bits) Z_UNUSED(bits) |
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# define sent_bits_align(s) |
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#endif |
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#endif /* DEFLATE_H_ */
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