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/* deflate.h -- internal compression state* Copyright (C) 1995-2010 Jean-loup Gailly* For conditions of distribution and use, see copyright notice in zlib.h*//* WARNING: this file should *not* be used by applications. It ispart of the implementation of the compression library and issubject to change. Applications should only use zlib.h.*//* @(#) $Id$ */#ifndef DEFLATE_H#define DEFLATE_H#include "zutil.h"/* define NO_GZIP when compiling if you want to disable gzip header andtrailer creation by deflate(). NO_GZIP would be used to avoid linking inthe crc code when it is not needed. For shared libraries, gzip encodingshould be left enabled. */#ifndef NO_GZIP# define GZIP#endif/* ===========================================================================* Internal compression state.*/#define LENGTH_CODES 29/* number of length codes, not counting the special END_BLOCK code */#define LITERALS 256/* number of literal bytes 0..255 */#define L_CODES (LITERALS+1+LENGTH_CODES)/* number of Literal or Length codes, including the END_BLOCK code */#define D_CODES 30/* number of distance codes */#define BL_CODES 19/* number of codes used to transfer the bit lengths */#define HEAP_SIZE (2*L_CODES+1)/* maximum heap size */#define MAX_BITS 15/* All codes must not exceed MAX_BITS bits */#define INIT_STATE 42#define EXTRA_STATE 69#define NAME_STATE 73#define COMMENT_STATE 91#define HCRC_STATE 103#define BUSY_STATE 113#define FINISH_STATE 666/* Stream status *//* Data structure describing a single value and its code string. */typedef struct ct_data_s {union {ush freq; /* frequency count */ush code; /* bit string */} fc;union {ush dad; /* father node in Huffman tree */ush len; /* length of bit string */} dl;} FAR ct_data;#define Freq fc.freq#define Code fc.code#define Dad dl.dad#define Len dl.lentypedef struct static_tree_desc_s static_tree_desc;typedef struct tree_desc_s {ct_data *dyn_tree; /* the dynamic tree */int max_code; /* largest code with non zero frequency */static_tree_desc *stat_desc; /* the corresponding static tree */} FAR tree_desc;typedef ush Pos;typedef Pos FAR Posf;typedef unsigned IPos;/* A Pos is an index in the character window. We use short instead of int to* save space in the various tables. IPos is used only for parameter passing.*/typedef struct internal_state {z_streamp strm; /* pointer back to this zlib stream */int status; /* as the name implies */Bytef *pending_buf; /* output still pending */ulg pending_buf_size; /* size of pending_buf */Bytef *pending_out; /* next pending byte to output to the stream */uInt pending; /* nb of bytes in the pending buffer */int wrap; /* bit 0 true for zlib, bit 1 true for gzip */gz_headerp gzhead; /* gzip header information to write */uInt gzindex; /* where in extra, name, or comment */Byte method; /* STORED (for zip only) or DEFLATED */int last_flush; /* value of flush param for previous deflate call *//* used by deflate.c: */uInt w_size; /* LZ77 window size (32K by default) */uInt w_bits; /* log2(w_size) (8..16) */uInt w_mask; /* w_size - 1 */Bytef *window;/* Sliding window. Input bytes are read into the second half of the window,* and move to the first half later to keep a dictionary of at least wSize* bytes. With this organization, matches are limited to a distance of* wSize-MAX_MATCH bytes, but this ensures that IO is always* performed with a length multiple of the block size. Also, it limits* the window size to 64K, which is quite useful on MSDOS.* To do: use the user input buffer as sliding window.*/ulg window_size;/* Actual size of window: 2*wSize, except when the user input buffer* is directly used as sliding window.*/Posf *prev;/* Link to older string with same hash index. To limit the size of this* array to 64K, this link is maintained only for the last 32K strings.* An index in this array is thus a window index modulo 32K.*/Posf *head; /* Heads of the hash chains or NIL. */uInt ins_h; /* hash index of string to be inserted */uInt hash_size; /* number of elements in hash table */uInt hash_bits; /* log2(hash_size) */uInt hash_mask; /* hash_size-1 */uInt hash_shift;/* Number of bits by which ins_h must be shifted at each input* step. It must be such that after MIN_MATCH steps, the oldest* byte no longer takes part in the hash key, that is:* hash_shift * MIN_MATCH >= hash_bits*/long block_start;/* Window position at the beginning of the current output block. Gets* negative when the window is moved backwards.*/uInt match_length; /* length of best match */IPos prev_match; /* previous match */int match_available; /* set if previous match exists */uInt strstart; /* start of string to insert */uInt match_start; /* start of matching string */uInt lookahead; /* number of valid bytes ahead in window */uInt prev_length;/* Length of the best match at previous step. Matches not greater than this* are discarded. This is used in the lazy match evaluation.*/uInt max_chain_length;/* To speed up deflation, hash chains are never searched beyond this* length. A higher limit improves compression ratio but degrades the* speed.*/uInt max_lazy_match;/* Attempt to find a better match only when the current match is strictly* smaller than this value. This mechanism is used only for compression* levels >= 4.*/# define max_insert_length max_lazy_match/* Insert new strings in the hash table only if the match length is not* greater than this length. This saves time but degrades compression.* max_insert_length is used only for compression levels <= 3.*/int level; /* compression level (1..9) */int strategy; /* favor or force Huffman coding*/uInt good_match;/* Use a faster search when the previous match is longer than this */int nice_match; /* Stop searching when current match exceeds this *//* used by trees.c: *//* Didn't use ct_data typedef below to supress compiler warning */struct ct_data_s dyn_ltree[HEAP_SIZE]; /* literal and length tree */struct ct_data_s dyn_dtree[2*D_CODES+1]; /* distance tree */struct ct_data_s bl_tree[2*BL_CODES+1]; /* Huffman tree for bit lengths */struct tree_desc_s l_desc; /* desc. for literal tree */struct tree_desc_s d_desc; /* desc. for distance tree */struct tree_desc_s bl_desc; /* desc. for bit length tree */ush bl_count[MAX_BITS+1];/* number of codes at each bit length for an optimal tree */int heap[2*L_CODES+1]; /* heap used to build the Huffman trees */int heap_len; /* number of elements in the heap */int heap_max; /* element of largest frequency *//* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.* The same heap array is used to build all trees.*/uch depth[2*L_CODES+1];/* Depth of each subtree used as tie breaker for trees of equal frequency*/uchf *l_buf; /* buffer for literals or lengths */uInt lit_bufsize;/* Size of match buffer for literals/lengths. There are 4 reasons for* limiting lit_bufsize to 64K:* - frequencies can be kept in 16 bit counters* - if compression is not successful for the first block, all input* data is still in the window so we can still emit a stored block even* when input comes from standard input. (This can also be done for* all blocks if lit_bufsize is not greater than 32K.)* - if compression is not successful for a file smaller than 64K, we can* even emit a stored file instead of a stored block (saving 5 bytes).* This is applicable only for zip (not gzip or zlib).* - creating new Huffman trees less frequently may not provide fast* adaptation to changes in the input data statistics. (Take for* example a binary file with poorly compressible code followed by* a highly compressible string table.) Smaller buffer sizes give* fast adaptation but have of course the overhead of transmitting* trees more frequently.* - I can't count above 4*/uInt last_lit; /* running index in l_buf */ushf *d_buf;/* Buffer for distances. To simplify the code, d_buf and l_buf have* the same number of elements. To use different lengths, an extra flag* array would be necessary.*/ulg opt_len; /* bit length of current block with optimal trees */ulg static_len; /* bit length of current block with static trees */uInt matches; /* number of string matches in current block */int last_eob_len; /* bit length of EOB code for last block */#ifdef DEBUGulg compressed_len; /* total bit length of compressed file mod 2^32 */ulg bits_sent; /* bit length of compressed data sent mod 2^32 */#endifush bi_buf;/* Output buffer. bits are inserted starting at the bottom (least* significant bits).*/int bi_valid;/* Number of valid bits in bi_buf. All bits above the last valid bit* are always zero.*/ulg high_water;/* High water mark offset in window for initialized bytes -- bytes above* this are set to zero in order to avoid memory check warnings when* longest match routines access bytes past the input. This is then* updated to the new high water mark.*/} FAR deflate_state;/* Output a byte on the stream.* IN assertion: there is enough room in pending_buf.*/#define put_byte(s, c) {s->pending_buf[s->pending++] = (c);}#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)/* Minimum amount of lookahead, except at the end of the input file.* See deflate.c for comments about the MIN_MATCH+1.*/#define MAX_DIST(s) ((s)->w_size-MIN_LOOKAHEAD)/* In order to simplify the code, particularly on 16 bit machines, match* distances are limited to MAX_DIST instead of WSIZE.*/#define WIN_INIT MAX_MATCH/* Number of bytes after end of data in window to initialize in order to avoidmemory checker errors from longest match routines *//* in trees.c */void ZLIB_INTERNAL _tr_init OF((deflate_state *s));int ZLIB_INTERNAL _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc));void ZLIB_INTERNAL _tr_flush_block OF((deflate_state *s, charf *buf,ulg stored_len, int last));void ZLIB_INTERNAL _tr_align OF((deflate_state *s));void ZLIB_INTERNAL _tr_stored_block OF((deflate_state *s, charf *buf,ulg stored_len, int last));#define d_code(dist) \((dist) < 256 ? _dist_code[dist] : _dist_code[256+((dist)>>7)])/* Mapping from a distance to a distance code. dist is the distance - 1 and* must not have side effects. _dist_code[256] and _dist_code[257] are never* used.*/#ifndef DEBUG/* Inline versions of _tr_tally for speed: */#if defined(GEN_TREES_H) || !defined(STDC)extern uch ZLIB_INTERNAL _length_code[];extern uch ZLIB_INTERNAL _dist_code[];#elseextern const uch ZLIB_INTERNAL _length_code[];extern const uch ZLIB_INTERNAL _dist_code[];#endif# define _tr_tally_lit(s, c, flush) \{ uch cc = (c); \s->d_buf[s->last_lit] = 0; \s->l_buf[s->last_lit++] = cc; \s->dyn_ltree[cc].Freq++; \flush = (s->last_lit == s->lit_bufsize-1); \}# define _tr_tally_dist(s, distance, length, flush) \{ uch len = (length); \ush dist = (distance); \s->d_buf[s->last_lit] = dist; \s->l_buf[s->last_lit++] = len; \dist--; \s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \s->dyn_dtree[d_code(dist)].Freq++; \flush = (s->last_lit == s->lit_bufsize-1); \}#else# define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c)# define _tr_tally_dist(s, distance, length, flush) \flush = _tr_tally(s, distance, length)#endif#endif /* DEFLATE_H */