/* * Copyright (C) 1995-2002 Jean-loup Gailly * For conditions of distribution and use, see copyright notice in zlib.h */ /** * \file deflate.h * Internal compression state. */ /* WARNING: this file should *not* be used by applications. It is part of the implementation of the compression library and is subject to change. Applications should only use zlib.h. */ #ifndef _DEFLATE_H #define _DEFLATE_H #include "zutil.h" /* =========================================================================== * 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 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.len typedef 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 */ int pending; /*!< nb of bytes in the pending buffer */ int noheader; /*!< suppress zlib header and adler32 */ Byte data_type; /*!< UNKNOWN, BINARY or ASCII */ 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 DEBUG ulg compressed_len; /*!< total bit length of compressed file mod 2^32 */ ulg bits_sent; /*!< bit length of compressed data sent mod 2^32 */ #endif ush 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. */ } 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. */ /* in trees.c */ void _tr_init OF((deflate_state *s)) /*@globals internalState @*/ /*@modifies *s, internalState @*/; int _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc)) /*@modifies *s @*/; void _tr_flush_block OF((deflate_state *s, charf *buf, ulg stored_len, int eof)) /*@modifies *s @*/; void _tr_align OF((deflate_state *s)) /*@modifies *s @*/; void _tr_stored_block OF((deflate_state *s, /*@null@*/ charf *buf, ulg stored_len, int eof)) /*@modifies *s @*/; #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) /*@unchecked@*/ extern uch _length_code[]; /*@unchecked@*/ extern uch _dist_code[]; #else /*@unchecked@*/ extern const uch _length_code[]; /*@unchecked@*/ extern const uch _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