| /* deflate.h -- internal compression state |
| * Copyright (C) 1995-2018 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 is |
| part of the implementation of the compression library and is |
| subject 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 and |
| trailer creation by deflate(). NO_GZIP would be used to avoid linking in |
| the crc code when it is not needed. For shared libraries, gzip encoding |
| should 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 Buf_size 16 |
| /* size of bit buffer in bi_buf */ |
| |
| #define INIT_STATE 42 /* zlib header -> BUSY_STATE */ |
| #ifdef GZIP |
| # define GZIP_STATE 57 /* gzip header -> BUSY_STATE | EXTRA_STATE */ |
| #endif |
| #define EXTRA_STATE 69 /* gzip extra block -> NAME_STATE */ |
| #define NAME_STATE 73 /* gzip file name -> COMMENT_STATE */ |
| #define COMMENT_STATE 91 /* gzip comment -> HCRC_STATE */ |
| #define HCRC_STATE 103 /* gzip header CRC -> BUSY_STATE */ |
| #define BUSY_STATE 113 /* deflate -> FINISH_STATE */ |
| #define FINISH_STATE 666 /* stream complete */ |
| /* 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 */ |
| const 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 */ |
| ulg 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 */ |
| ulg gzindex; /* where in extra, name, or comment */ |
| Byte method; /* can only be 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 suppress 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 *sym_buf; /* buffer for distances and literals/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 sym_next; /* running index in sym_buf */ |
| uInt sym_end; /* symbol table full when sym_next reaches this */ |
| |
| 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 */ |
| uInt insert; /* bytes at end of window left to insert */ |
| |
| #ifdef ZLIB_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. |
| */ |
| |
| 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++] = (Bytef)(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 avoid |
| memory 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_flush_bits OF((deflate_state *s)); |
| 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 ZLIB_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[]; |
| #else |
| extern 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->sym_buf[s->sym_next++] = 0; \ |
| s->sym_buf[s->sym_next++] = 0; \ |
| s->sym_buf[s->sym_next++] = cc; \ |
| s->dyn_ltree[cc].Freq++; \ |
| flush = (s->sym_next == s->sym_end); \ |
| } |
| # define _tr_tally_dist(s, distance, length, flush) \ |
| { uch len = (uch)(length); \ |
| ush dist = (ush)(distance); \ |
| s->sym_buf[s->sym_next++] = (uch)dist; \ |
| s->sym_buf[s->sym_next++] = (uch)(dist >> 8); \ |
| s->sym_buf[s->sym_next++] = len; \ |
| dist--; \ |
| s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ |
| s->dyn_dtree[d_code(dist)].Freq++; \ |
| flush = (s->sym_next == s->sym_end); \ |
| } |
| #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 */ |
