| /* deflate.h -- internal compression state | |
| * Copyright (C) 1995-2012 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. | |
| */ | |
| /* @(#) $Id$ */ | |
| /* 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. */ | |
| /* =========================================================================== | |
| * Internal compression state. | |
| */ | |
| /* number of length codes, not counting the special END_BLOCK code */ | |
| /* number of literal bytes 0..255 */ | |
| /* number of Literal or Length codes, including the END_BLOCK code */ | |
| /* number of distance codes */ | |
| /* number of codes used to transfer the bit lengths */ | |
| /* maximum heap size */ | |
| /* All codes must not exceed MAX_BITS bits */ | |
| /* size of bit buffer in bi_buf */ | |
| /* 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; | |
| 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 */ | |
| 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; /* 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. | |
| */ | |
| /* 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 *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 */ | |
| uInt insert; /* bytes at end of window left to insert */ | |
| ulg compressed_len; /* total bit length of compressed file mod 2^32 */ | |
| ulg bits_sent; /* bit length of compressed data sent mod 2^32 */ | |
| 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. | |
| */ | |
| /* Minimum amount of lookahead, except at the end of the input file. | |
| * See deflate.c for comments about the MIN_MATCH+1. | |
| */ | |
| /* In order to simplify the code, particularly on 16 bit machines, match | |
| * distances are limited to MAX_DIST instead of WSIZE. | |
| */ | |
| /* 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)); | |
| /* 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. | |
| */ | |
| /* Inline versions of _tr_tally for speed: */ | |
| extern uch ZLIB_INTERNAL _length_code[]; | |
| extern uch ZLIB_INTERNAL _dist_code[]; | |
| extern const uch ZLIB_INTERNAL _length_code[]; | |
| extern const uch ZLIB_INTERNAL _dist_code[]; | |