/* deflate.h -- internal compression state * Copyright (C) 1995-1998 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: deflate.h,v 1.1 2000/04/01 21:46:23 johan Exp $ */#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.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 */    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));int  _tr_tally        OF((deflate_state *s, unsigned dist, unsigned lc));void _tr_flush_block  OF((deflate_state *s, charf *buf, ulg stored_len,			  int eof));void _tr_align        OF((deflate_state *s));void _tr_stored_block OF((deflate_state *s, charf *buf, ulg stored_len,                          int eof));#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 _length_code[];  extern uch _dist_code[];#else  extern const uch _length_code[];  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