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/* deflate.h -- internal compression state |
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* Copyright (C) 1995-2012 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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|
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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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|
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/* @(#) $Id$ */ |
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|
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#ifndef DEFLATE_H |
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#define DEFLATE_H |
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|
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#include "zutil.h" |
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|
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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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/* =========================================================================== |
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* Internal compression state. |
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*/ |
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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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|
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#define LITERALS 256 |
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/* number of literal bytes 0..255 */ |
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|
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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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|
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#define D_CODES 30 |
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/* number of distance codes */ |
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|
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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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|
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#define HEAP_SIZE (2*L_CODES+1) |
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/* maximum heap size */ |
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|
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#define MAX_BITS 15 |
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/* All codes must not exceed MAX_BITS bits */ |
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|
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#define Buf_size 16 |
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/* size of bit buffer in bi_buf */ |
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|
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#define INIT_STATE 42 |
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#define EXTRA_STATE 69 |
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#define NAME_STATE 73 |
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#define COMMENT_STATE 91 |
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#define HCRC_STATE 103 |
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#define BUSY_STATE 113 |
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#define FINISH_STATE 666 |
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/* Stream status */ |
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|
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|
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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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ush freq; /* frequency count */ |
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ush code; /* bit string */ |
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} fc; |
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union { |
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ush dad; /* father node in Huffman tree */ |
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ush len; /* length of bit string */ |
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} dl; |
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} FAR ct_data; |
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|
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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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|
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typedef struct static_tree_desc_s static_tree_desc; |
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|
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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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static_tree_desc *stat_desc; /* the corresponding static tree */ |
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} FAR tree_desc; |
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|
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typedef ush Pos; |
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typedef Pos FAR Posf; |
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typedef unsigned IPos; |
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|
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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. IPos is used only for parameter passing. |
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*/ |
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|
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typedef struct internal_state { |
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z_streamp strm; /* pointer back to this zlib stream */ |
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int status; /* as the name implies */ |
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Bytef *pending_buf; /* output still pending */ |
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ulg pending_buf_size; /* size of pending_buf */ |
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Bytef *pending_out; /* next pending byte to output to the stream */ |
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uInt 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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gz_headerp gzhead; /* gzip header information to write */ |
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uInt gzindex; /* where in extra, name, or comment */ |
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Byte method; /* can only be DEFLATED */ |
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int last_flush; /* value of flush param for previous deflate call */ |
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|
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/* used by deflate.c: */ |
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|
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uInt w_size; /* LZ77 window size (32K by default) */ |
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uInt w_bits; /* log2(w_size) (8..16) */ |
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uInt w_mask; /* w_size - 1 */ |
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|
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Bytef *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-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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|
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ulg 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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|
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Posf *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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|
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Posf *head; /* Heads of the hash chains or NIL. */ |
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|
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uInt ins_h; /* hash index of string to be inserted */ |
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uInt hash_size; /* number of elements in hash table */ |
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uInt hash_bits; /* log2(hash_size) */ |
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uInt hash_mask; /* hash_size-1 */ |
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|
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uInt hash_shift; |
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/* Number of bits by which ins_h must be shifted at each input |
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* step. It must be such that after MIN_MATCH steps, the oldest |
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* byte no longer takes part in the hash key, that is: |
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* hash_shift * MIN_MATCH >= hash_bits |
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*/ |
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|
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long 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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|
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uInt match_length; /* length of best match */ |
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IPos prev_match; /* previous match */ |
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int match_available; /* set if previous match exists */ |
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uInt strstart; /* start of string to insert */ |
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uInt match_start; /* start of matching string */ |
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uInt lookahead; /* number of valid bytes ahead in window */ |
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|
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uInt 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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|
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uInt max_chain_length; |
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/* To speed up deflation, hash chains are never searched beyond this |
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* length. A higher limit improves compression ratio but degrades the |
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* speed. |
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*/ |
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|
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uInt max_lazy_match; |
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/* Attempt to find a better match only when the current match is strictly |
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* smaller than this value. This mechanism is used only for compression |
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* 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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|
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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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|
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uInt good_match; |
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/* Use a faster search when the previous match is longer than this */ |
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|
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int nice_match; /* Stop searching when current match exceeds this */ |
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|
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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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|
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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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|
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ush bl_count[MAX_BITS+1]; |
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/* number of codes at each bit length for an optimal tree */ |
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|
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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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|
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uch 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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|
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uchf *l_buf; /* buffer for literals or lengths */ |
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|
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uInt 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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|
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uInt last_lit; /* running index in l_buf */ |
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|
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ushf *d_buf; |
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/* Buffer for distances. To simplify the code, d_buf and l_buf have |
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* the same number of elements. To use different lengths, an extra flag |
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* array would be necessary. |
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*/ |
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|
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ulg opt_len; /* bit length of current block with optimal trees */ |
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ulg static_len; /* bit length of current block with static trees */ |
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uInt matches; /* number of string matches in current block */ |
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uInt insert; /* bytes at end of window left to insert */ |
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|
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#ifdef DEBUG |
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ulg compressed_len; /* total bit length of compressed file mod 2^32 */ |
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ulg bits_sent; /* bit length of compressed data sent mod 2^32 */ |
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#endif |
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|
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ush bi_buf; |
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/* Output buffer. bits are inserted starting at the bottom (least |
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* significant bits). |
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*/ |
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int bi_valid; |
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/* Number of valid bits in bi_buf. All bits above the last valid bit |
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* are always zero. |
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*/ |
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|
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ulg 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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|
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} FAR deflate_state; |
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|
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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) {s->pending_buf[s->pending++] = (c);} |
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|
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|
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#define MIN_LOOKAHEAD (MAX_MATCH+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 MIN_MATCH+1. |
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*/ |
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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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|
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#define WIN_INIT 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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|
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/* in trees.c */ |
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void ZLIB_INTERNAL _tr_init OF((deflate_state *s)); |
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int ZLIB_INTERNAL _tr_tally OF((deflate_state *s, unsigned dist, unsigned lc)); |
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void ZLIB_INTERNAL _tr_flush_block OF((deflate_state *s, charf *buf, |
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ulg stored_len, int last)); |
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void ZLIB_INTERNAL _tr_flush_bits OF((deflate_state *s)); |
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void ZLIB_INTERNAL _tr_align OF((deflate_state *s)); |
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void ZLIB_INTERNAL _tr_stored_block OF((deflate_state *s, charf *buf, |
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ulg stored_len, int last)); |
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|
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#define d_code(dist) \ |
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((dist) < 256 ? _dist_code[dist] : _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. _dist_code[256] and _dist_code[257] are never |
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* used. |
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*/ |
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|
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#ifndef DEBUG |
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/* Inline versions of _tr_tally for speed: */ |
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|
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#if defined(GEN_TREES_H) || !defined(STDC) |
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extern uch ZLIB_INTERNAL _length_code[]; |
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extern uch ZLIB_INTERNAL _dist_code[]; |
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#else |
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extern const uch ZLIB_INTERNAL _length_code[]; |
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extern const uch ZLIB_INTERNAL _dist_code[]; |
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#endif |
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|
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# define _tr_tally_lit(s, c, flush) \ |
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{ uch cc = (c); \ |
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s->d_buf[s->last_lit] = 0; \ |
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s->l_buf[s->last_lit++] = cc; \ |
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s->dyn_ltree[cc].Freq++; \ |
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flush = (s->last_lit == s->lit_bufsize-1); \ |
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} |
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# define _tr_tally_dist(s, distance, length, flush) \ |
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{ uch len = (length); \ |
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ush dist = (distance); \ |
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s->d_buf[s->last_lit] = dist; \ |
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s->l_buf[s->last_lit++] = len; \ |
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dist--; \ |
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s->dyn_ltree[_length_code[len]+LITERALS+1].Freq++; \ |
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s->dyn_dtree[d_code(dist)].Freq++; \ |
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flush = (s->last_lit == s->lit_bufsize-1); \ |
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} |
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#else |
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# define _tr_tally_lit(s, c, flush) flush = _tr_tally(s, 0, c) |
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# define _tr_tally_dist(s, distance, length, flush) \ |
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flush = _tr_tally(s, distance, length) |
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#endif |
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|
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#endif /* DEFLATE_H */ |
