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/* deflate.c -- compress data using the deflation algorithm* Copyright (C) 1995-2010 Jean-loup Gailly and Mark Adler* For conditions of distribution and use, see copyright notice in zlib.h*//** ALGORITHM** The "deflation" process depends on being able to identify portions* of the input text which are identical to earlier input (within a* sliding window trailing behind the input currently being processed).** The most straightforward technique turns out to be the fastest for* most input files: try all possible matches and select the longest.* The key feature of this algorithm is that insertions into the string* dictionary are very simple and thus fast, and deletions are avoided* completely. Insertions are performed at each input character, whereas* string matches are performed only when the previous match ends. So it* is preferable to spend more time in matches to allow very fast string* insertions and avoid deletions. The matching algorithm for small* strings is inspired from that of Rabin & Karp. A brute force approach* is used to find longer strings when a small match has been found.* A similar algorithm is used in comic (by Jan-Mark Wams) and freeze* (by Leonid Broukhis).* A previous version of this file used a more sophisticated algorithm* (by Fiala and Greene) which is guaranteed to run in linear amortized* time, but has a larger average cost, uses more memory and is patented.* However the F&G algorithm may be faster for some highly redundant* files if the parameter max_chain_length (described below) is too large.** ACKNOWLEDGEMENTS** The idea of lazy evaluation of matches is due to Jan-Mark Wams, and* I found it in 'freeze' written by Leonid Broukhis.* Thanks to many people for bug reports and testing.** REFERENCES** Deutsch, L.P.,"DEFLATE Compressed Data Format Specification".* Available in http://www.ietf.org/rfc/rfc1951.txt** A description of the Rabin and Karp algorithm is given in the book* "Algorithms" by R. Sedgewick, Addison-Wesley, p252.** Fiala,E.R., and Greene,D.H.* Data Compression with Finite Windows, Comm.ACM, 32,4 (1989) 490-595**//* @(#) $Id$ */#include "deflate.h"const char deflate_copyright[] =" deflate 1.2.5 Copyright 1995-2010 Jean-loup Gailly and Mark Adler ";/*If you use the zlib library in a product, an acknowledgment is welcomein the documentation of your product. If for some reason you cannotinclude such an acknowledgment, I would appreciate that you keep thiscopyright string in the executable of your product.*//* ===========================================================================* Function prototypes.*/typedef enum {need_more, /* block not completed, need more input or more output */block_done, /* block flush performed */finish_started, /* finish started, need only more output at next deflate */finish_done /* finish done, accept no more input or output */} block_state;typedef block_state (*compress_func) OF((deflate_state *s, int flush));/* Compression function. Returns the block state after the call. */local void fill_window OF((deflate_state *s));local block_state deflate_stored OF((deflate_state *s, int flush));local block_state deflate_fast OF((deflate_state *s, int flush));#ifndef FASTESTlocal block_state deflate_slow OF((deflate_state *s, int flush));#endiflocal block_state deflate_rle OF((deflate_state *s, int flush));local block_state deflate_huff OF((deflate_state *s, int flush));local void lm_init OF((deflate_state *s));local void putShortMSB OF((deflate_state *s, uInt b));local void flush_pending OF((z_streamp strm));local int read_buf OF((z_streamp strm, Bytef *buf, unsigned size));#ifdef ASMVvoid match_init OF((void)); /* asm code initialization */uInt longest_match OF((deflate_state *s, IPos cur_match));#elselocal uInt longest_match OF((deflate_state *s, IPos cur_match));#endif#ifdef DEBUGlocal void check_match OF((deflate_state *s, IPos start, IPos match,int length));#endif/* ===========================================================================* Local data*/#define NIL 0/* Tail of hash chains */#ifndef TOO_FAR# define TOO_FAR 4096#endif/* Matches of length 3 are discarded if their distance exceeds TOO_FAR *//* Values for max_lazy_match, good_match and max_chain_length, depending on* the desired pack level (0..9). The values given below have been tuned to* exclude worst case performance for pathological files. Better values may be* found for specific files.*/typedef struct config_s {ush good_length; /* reduce lazy search above this match length */ush max_lazy; /* do not perform lazy search above this match length */ush nice_length; /* quit search above this match length */ush max_chain;compress_func func;} config;#ifdef FASTESTlocal const config configuration_table[2] = {/* good lazy nice chain *//* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only *//* 1 */ {4, 4, 8, 4, deflate_fast}}; /* max speed, no lazy matches */#elselocal const config configuration_table[10] = {/* good lazy nice chain *//* 0 */ {0, 0, 0, 0, deflate_stored}, /* store only *//* 1 */ {4, 4, 8, 4, deflate_fast}, /* max speed, no lazy matches *//* 2 */ {4, 5, 16, 8, deflate_fast},/* 3 */ {4, 6, 32, 32, deflate_fast},/* 4 */ {4, 4, 16, 16, deflate_slow}, /* lazy matches *//* 5 */ {8, 16, 32, 32, deflate_slow},/* 6 */ {8, 16, 128, 128, deflate_slow},/* 7 */ {8, 32, 128, 256, deflate_slow},/* 8 */ {32, 128, 258, 1024, deflate_slow},/* 9 */ {32, 258, 258, 4096, deflate_slow}}; /* max compression */#endif/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4* For deflate_fast() (levels <= 3) good is ignored and lazy has a different* meaning.*/#define EQUAL 0/* result of memcmp for equal strings */#ifndef NO_DUMMY_DECLstruct static_tree_desc_s {int dummy;}; /* for buggy compilers */#endif/* ===========================================================================* Update a hash value with the given input byte* IN assertion: all calls to to UPDATE_HASH are made with consecutive* input characters, so that a running hash key can be computed from the* previous key instead of complete recalculation each time.*/#define UPDATE_HASH(s,h,c) (h = (((h)<<s->hash_shift) ^ (c)) & s->hash_mask)/* ===========================================================================* Insert string str in the dictionary and set match_head to the previous head* of the hash chain (the most recent string with same hash key). Return* the previous length of the hash chain.* If this file is compiled with -DFASTEST, the compression level is forced* to 1, and no hash chains are maintained.* IN assertion: all calls to to INSERT_STRING are made with consecutive* input characters and the first MIN_MATCH bytes of str are valid* (except for the last MIN_MATCH-1 bytes of the input file).*/#ifdef FASTEST#define INSERT_STRING(s, str, match_head) \(UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \match_head = s->head[s->ins_h], \s->head[s->ins_h] = (Pos)(str))#else#define INSERT_STRING(s, str, match_head) \(UPDATE_HASH(s, s->ins_h, s->window[(str) + (MIN_MATCH-1)]), \match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h], \s->head[s->ins_h] = (Pos)(str))#endif/* ===========================================================================* Initialize the hash table (avoiding 64K overflow for 16 bit systems).* prev[] will be initialized on the fly.*/#define CLEAR_HASH(s) \s->head[s->hash_size-1] = NIL; \zmemzero((Bytef *)s->head, (unsigned)(s->hash_size-1)*sizeof(*s->head));/* ========================================================================= */int ZEXPORT deflateInit_(strm, level, version, stream_size)z_streamp strm;int level;const char *version;int stream_size;{return deflateInit2_(strm, level, Z_DEFLATED, MAX_WBITS, DEF_MEM_LEVEL,Z_DEFAULT_STRATEGY, version, stream_size);/* To do: ignore strm->next_in if we use it as window */}/* ========================================================================= */int ZEXPORT deflateInit2_(strm, level, method, windowBits, memLevel, strategy,version, stream_size)z_streamp strm;int level;int method;int windowBits;int memLevel;int strategy;const char *version;int stream_size;{deflate_state *s;int wrap = 1;static const char my_version[] = ZLIB_VERSION;ushf *overlay;/* We overlay pending_buf and d_buf+l_buf. This works since the average* output size for (length,distance) codes is <= 24 bits.*/if (version == Z_NULL || version[0] != my_version[0] ||stream_size != sizeof(z_stream)) {return Z_VERSION_ERROR;}if (strm == Z_NULL) return Z_STREAM_ERROR;strm->msg = Z_NULL;if (strm->zalloc == (alloc_func)0) {strm->zalloc = zcalloc;strm->opaque = (voidpf)0;}if (strm->zfree == (free_func)0) strm->zfree = zcfree;#ifdef FASTESTif (level != 0) level = 1;#elseif (level == Z_DEFAULT_COMPRESSION) level = 6;#endifif (windowBits < 0) { /* suppress zlib wrapper */wrap = 0;windowBits = -windowBits;}#ifdef GZIPelse if (windowBits > 15) {wrap = 2; /* write gzip wrapper instead */windowBits -= 16;}#endifif (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED ||windowBits < 8 || windowBits > 15 || level < 0 || level > 9 ||strategy < 0 || strategy > Z_FIXED) {return Z_STREAM_ERROR;}if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state));if (s == Z_NULL) return Z_MEM_ERROR;strm->state = (struct internal_state FAR *)s;s->strm = strm;s->wrap = wrap;s->gzhead = Z_NULL;s->w_bits = windowBits;s->w_size = 1 << s->w_bits;s->w_mask = s->w_size - 1;s->hash_bits = memLevel + 7;s->hash_size = 1 << s->hash_bits;s->hash_mask = s->hash_size - 1;s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH);s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte));s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos));s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos));s->high_water = 0; /* nothing written to s->window yet */s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2);s->pending_buf = (uchf *) overlay;s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L);if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL ||s->pending_buf == Z_NULL) {s->status = FINISH_STATE;strm->msg = (char*)ERR_MSG(Z_MEM_ERROR);deflateEnd (strm);return Z_MEM_ERROR;}s->d_buf = overlay + s->lit_bufsize/sizeof(ush);s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize;s->level = level;s->strategy = strategy;s->method = (Byte)method;return deflateReset(strm);}/* ========================================================================= */int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength)z_streamp strm;const Bytef *dictionary;uInt dictLength;{deflate_state *s;uInt length = dictLength;uInt n;IPos hash_head = 0;if (strm == Z_NULL || strm->state == Z_NULL || dictionary == Z_NULL ||strm->state->wrap == 2 ||(strm->state->wrap == 1 && strm->state->status != INIT_STATE))return Z_STREAM_ERROR;s = strm->state;if (s->wrap)strm->adler = adler32(strm->adler, dictionary, dictLength);if (length < MIN_MATCH) return Z_OK;if (length > s->w_size) {length = s->w_size;dictionary += dictLength - length; /* use the tail of the dictionary */}zmemcpy(s->window, dictionary, length);s->strstart = length;s->block_start = (long)length;/* Insert all strings in the hash table (except for the last two bytes).* s->lookahead stays null, so s->ins_h will be recomputed at the next* call of fill_window.*/s->ins_h = s->window[0];UPDATE_HASH(s, s->ins_h, s->window[1]);for (n = 0; n <= length - MIN_MATCH; n++) {INSERT_STRING(s, n, hash_head);}if (hash_head) hash_head = 0; /* to make compiler happy */return Z_OK;}/* ========================================================================= */int ZEXPORT deflateReset (strm)z_streamp strm;{deflate_state *s;if (strm == Z_NULL || strm->state == Z_NULL ||strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) {return Z_STREAM_ERROR;}strm->total_in = strm->total_out = 0;strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */strm->data_type = Z_UNKNOWN;s = (deflate_state *)strm->state;s->pending = 0;s->pending_out = s->pending_buf;if (s->wrap < 0) {s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */}s->status = s->wrap ? INIT_STATE : BUSY_STATE;strm->adler =#ifdef GZIPs->wrap == 2 ? crc32(0L, Z_NULL, 0) :#endifadler32(0L, Z_NULL, 0);s->last_flush = Z_NO_FLUSH;_tr_init(s);lm_init(s);return Z_OK;}/* ========================================================================= */int ZEXPORT deflateSetHeader (strm, head)z_streamp strm;gz_headerp head;{if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;if (strm->state->wrap != 2) return Z_STREAM_ERROR;strm->state->gzhead = head;return Z_OK;}/* ========================================================================= */int ZEXPORT deflatePrime (strm, bits, value)z_streamp strm;int bits;int value;{if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;strm->state->bi_valid = bits;strm->state->bi_buf = (ush)(value & ((1 << bits) - 1));return Z_OK;}/* ========================================================================= */int ZEXPORT deflateParams(strm, level, strategy)z_streamp strm;int level;int strategy;{deflate_state *s;compress_func func;int err = Z_OK;if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;s = strm->state;#ifdef FASTESTif (level != 0) level = 1;#elseif (level == Z_DEFAULT_COMPRESSION) level = 6;#endifif (level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED) {return Z_STREAM_ERROR;}func = configuration_table[s->level].func;if ((strategy != s->strategy || func != configuration_table[level].func) &&strm->total_in != 0) {/* Flush the last buffer: */err = deflate(strm, Z_BLOCK);}if (s->level != level) {s->level = level;s->max_lazy_match = configuration_table[level].max_lazy;s->good_match = configuration_table[level].good_length;s->nice_match = configuration_table[level].nice_length;s->max_chain_length = configuration_table[level].max_chain;}s->strategy = strategy;return err;}/* ========================================================================= */int ZEXPORT deflateTune(strm, good_length, max_lazy, nice_length, max_chain)z_streamp strm;int good_length;int max_lazy;int nice_length;int max_chain;{deflate_state *s;if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;s = strm->state;s->good_match = good_length;s->max_lazy_match = max_lazy;s->nice_match = nice_length;s->max_chain_length = max_chain;return Z_OK;}/* =========================================================================* For the default windowBits of 15 and memLevel of 8, this function returns* a close to exact, as well as small, upper bound on the compressed size.* They are coded as constants here for a reason--if the #define's are* changed, then this function needs to be changed as well. The return* value for 15 and 8 only works for those exact settings.** For any setting other than those defaults for windowBits and memLevel,* the value returned is a conservative worst case for the maximum expansion* resulting from using fixed blocks instead of stored blocks, which deflate* can emit on compressed data for some combinations of the parameters.** This function could be more sophisticated to provide closer upper bounds for* every combination of windowBits and memLevel. But even the conservative* upper bound of about 14% expansion does not seem onerous for output buffer* allocation.*/uLong ZEXPORT deflateBound(strm, sourceLen)z_streamp strm;uLong sourceLen;{deflate_state *s;uLong complen, wraplen;Bytef *str;/* conservative upper bound for compressed data */complen = sourceLen +((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 5;/* if can't get parameters, return conservative bound plus zlib wrapper */if (strm == Z_NULL || strm->state == Z_NULL)return complen + 6;/* compute wrapper length */s = strm->state;switch (s->wrap) {case 0: /* raw deflate */wraplen = 0;break;case 1: /* zlib wrapper */wraplen = 6 + (s->strstart ? 4 : 0);break;case 2: /* gzip wrapper */wraplen = 18;if (s->gzhead != Z_NULL) { /* user-supplied gzip header */if (s->gzhead->extra != Z_NULL)wraplen += 2 + s->gzhead->extra_len;str = s->gzhead->name;if (str != Z_NULL)do {wraplen++;} while (*str++);str = s->gzhead->comment;if (str != Z_NULL)do {wraplen++;} while (*str++);if (s->gzhead->hcrc)wraplen += 2;}break;default: /* for compiler happiness */wraplen = 6;}/* if not default parameters, return conservative bound */if (s->w_bits != 15 || s->hash_bits != 8 + 7)return complen + wraplen;/* default settings: return tight bound for that case */return sourceLen + (sourceLen >> 12) + (sourceLen >> 14) +(sourceLen >> 25) + 13 - 6 + wraplen;}/* =========================================================================* Put a short in the pending buffer. The 16-bit value is put in MSB order.* IN assertion: the stream state is correct and there is enough room in* pending_buf.*/local void putShortMSB (s, b)deflate_state *s;uInt b;{put_byte(s, (Byte)(b >> 8));put_byte(s, (Byte)(b & 0xff));}/* =========================================================================* Flush as much pending output as possible. All deflate() output goes* through this function so some applications may wish to modify it* to avoid allocating a large strm->next_out buffer and copying into it.* (See also read_buf()).*/local void flush_pending(strm)z_streamp strm;{unsigned len = strm->state->pending;if (len > strm->avail_out) len = strm->avail_out;if (len == 0) return;zmemcpy(strm->next_out, strm->state->pending_out, len);strm->next_out += len;strm->state->pending_out += len;strm->total_out += len;strm->avail_out -= len;strm->state->pending -= len;if (strm->state->pending == 0) {strm->state->pending_out = strm->state->pending_buf;}}/* ========================================================================= */int ZEXPORT deflate (strm, flush)z_streamp strm;int flush;{int old_flush; /* value of flush param for previous deflate call */deflate_state *s;if (strm == Z_NULL || strm->state == Z_NULL ||flush > Z_BLOCK || flush < 0) {return Z_STREAM_ERROR;}s = strm->state;if (strm->next_out == Z_NULL ||(strm->next_in == Z_NULL && strm->avail_in != 0) ||(s->status == FINISH_STATE && flush != Z_FINISH)) {ERR_RETURN(strm, Z_STREAM_ERROR);}if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR);s->strm = strm; /* just in case */old_flush = s->last_flush;s->last_flush = flush;/* Write the header */if (s->status == INIT_STATE) {#ifdef GZIPif (s->wrap == 2) {strm->adler = crc32(0L, Z_NULL, 0);put_byte(s, 31);put_byte(s, 139);put_byte(s, 8);if (s->gzhead == Z_NULL) {put_byte(s, 0);put_byte(s, 0);put_byte(s, 0);put_byte(s, 0);put_byte(s, 0);put_byte(s, s->level == 9 ? 2 :(s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?4 : 0));put_byte(s, OS_CODE);s->status = BUSY_STATE;}else {put_byte(s, (s->gzhead->text ? 1 : 0) +(s->gzhead->hcrc ? 2 : 0) +(s->gzhead->extra == Z_NULL ? 0 : 4) +(s->gzhead->name == Z_NULL ? 0 : 8) +(s->gzhead->comment == Z_NULL ? 0 : 16));put_byte(s, (Byte)(s->gzhead->time & 0xff));put_byte(s, (Byte)((s->gzhead->time >> 8) & 0xff));put_byte(s, (Byte)((s->gzhead->time >> 16) & 0xff));put_byte(s, (Byte)((s->gzhead->time >> 24) & 0xff));put_byte(s, s->level == 9 ? 2 :(s->strategy >= Z_HUFFMAN_ONLY || s->level < 2 ?4 : 0));put_byte(s, s->gzhead->os & 0xff);if (s->gzhead->extra != Z_NULL) {put_byte(s, s->gzhead->extra_len & 0xff);put_byte(s, (s->gzhead->extra_len >> 8) & 0xff);}if (s->gzhead->hcrc)strm->adler = crc32(strm->adler, s->pending_buf,s->pending);s->gzindex = 0;s->status = EXTRA_STATE;}}else#endif{uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8;uInt level_flags;if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2)level_flags = 0;else if (s->level < 6)level_flags = 1;else if (s->level == 6)level_flags = 2;elselevel_flags = 3;header |= (level_flags << 6);if (s->strstart != 0) header |= PRESET_DICT;header += 31 - (header % 31);s->status = BUSY_STATE;putShortMSB(s, header);/* Save the adler32 of the preset dictionary: */if (s->strstart != 0) {putShortMSB(s, (uInt)(strm->adler >> 16));putShortMSB(s, (uInt)(strm->adler & 0xffff));}strm->adler = adler32(0L, Z_NULL, 0);}}#ifdef GZIPif (s->status == EXTRA_STATE) {if (s->gzhead->extra != Z_NULL) {uInt beg = s->pending; /* start of bytes to update crc */while (s->gzindex < (s->gzhead->extra_len & 0xffff)) {if (s->pending == s->pending_buf_size) {if (s->gzhead->hcrc && s->pending > beg)strm->adler = crc32(strm->adler, s->pending_buf + beg,s->pending - beg);flush_pending(strm);beg = s->pending;if (s->pending == s->pending_buf_size)break;}put_byte(s, s->gzhead->extra[s->gzindex]);s->gzindex++;}if (s->gzhead->hcrc && s->pending > beg)strm->adler = crc32(strm->adler, s->pending_buf + beg,s->pending - beg);if (s->gzindex == s->gzhead->extra_len) {s->gzindex = 0;s->status = NAME_STATE;}}elses->status = NAME_STATE;}if (s->status == NAME_STATE) {if (s->gzhead->name != Z_NULL) {uInt beg = s->pending; /* start of bytes to update crc */int val;do {if (s->pending == s->pending_buf_size) {if (s->gzhead->hcrc && s->pending > beg)strm->adler = crc32(strm->adler, s->pending_buf + beg,s->pending - beg);flush_pending(strm);beg = s->pending;if (s->pending == s->pending_buf_size) {val = 1;break;}}val = s->gzhead->name[s->gzindex++];put_byte(s, val);} while (val != 0);if (s->gzhead->hcrc && s->pending > beg)strm->adler = crc32(strm->adler, s->pending_buf + beg,s->pending - beg);if (val == 0) {s->gzindex = 0;s->status = COMMENT_STATE;}}elses->status = COMMENT_STATE;}if (s->status == COMMENT_STATE) {if (s->gzhead->comment != Z_NULL) {uInt beg = s->pending; /* start of bytes to update crc */int val;do {if (s->pending == s->pending_buf_size) {if (s->gzhead->hcrc && s->pending > beg)strm->adler = crc32(strm->adler, s->pending_buf + beg,s->pending - beg);flush_pending(strm);beg = s->pending;if (s->pending == s->pending_buf_size) {val = 1;break;}}val = s->gzhead->comment[s->gzindex++];put_byte(s, val);} while (val != 0);if (s->gzhead->hcrc && s->pending > beg)strm->adler = crc32(strm->adler, s->pending_buf + beg,s->pending - beg);if (val == 0)s->status = HCRC_STATE;}elses->status = HCRC_STATE;}if (s->status == HCRC_STATE) {if (s->gzhead->hcrc) {if (s->pending + 2 > s->pending_buf_size)flush_pending(strm);if (s->pending + 2 <= s->pending_buf_size) {put_byte(s, (Byte)(strm->adler & 0xff));put_byte(s, (Byte)((strm->adler >> 8) & 0xff));strm->adler = crc32(0L, Z_NULL, 0);s->status = BUSY_STATE;}}elses->status = BUSY_STATE;}#endif/* Flush as much pending output as possible */if (s->pending != 0) {flush_pending(strm);if (strm->avail_out == 0) {/* Since avail_out is 0, deflate will be called again with* more output space, but possibly with both pending and* avail_in equal to zero. There won't be anything to do,* but this is not an error situation so make sure we* return OK instead of BUF_ERROR at next call of deflate:*/s->last_flush = -1;return Z_OK;}/* Make sure there is something to do and avoid duplicate consecutive* flushes. For repeated and useless calls with Z_FINISH, we keep* returning Z_STREAM_END instead of Z_BUF_ERROR.*/} else if (strm->avail_in == 0 && flush <= old_flush &&flush != Z_FINISH) {ERR_RETURN(strm, Z_BUF_ERROR);}/* User must not provide more input after the first FINISH: */if (s->status == FINISH_STATE && strm->avail_in != 0) {ERR_RETURN(strm, Z_BUF_ERROR);}/* Start a new block or continue the current one.*/if (strm->avail_in != 0 || s->lookahead != 0 ||(flush != Z_NO_FLUSH && s->status != FINISH_STATE)) {block_state bstate;bstate = s->strategy == Z_HUFFMAN_ONLY ? deflate_huff(s, flush) :(s->strategy == Z_RLE ? deflate_rle(s, flush) :(*(configuration_table[s->level].func))(s, flush));if (bstate == finish_started || bstate == finish_done) {s->status = FINISH_STATE;}if (bstate == need_more || bstate == finish_started) {if (strm->avail_out == 0) {s->last_flush = -1; /* avoid BUF_ERROR next call, see above */}return Z_OK;/* If flush != Z_NO_FLUSH && avail_out == 0, the next call* of deflate should use the same flush parameter to make sure* that the flush is complete. So we don't have to output an* empty block here, this will be done at next call. This also* ensures that for a very small output buffer, we emit at most* one empty block.*/}if (bstate == block_done) {if (flush == Z_PARTIAL_FLUSH) {_tr_align(s);} else if (flush != Z_BLOCK) { /* FULL_FLUSH or SYNC_FLUSH */_tr_stored_block(s, (char*)0, 0L, 0);/* For a full flush, this empty block will be recognized* as a special marker by inflate_sync().*/if (flush == Z_FULL_FLUSH) {CLEAR_HASH(s); /* forget history */if (s->lookahead == 0) {s->strstart = 0;s->block_start = 0L;}}}flush_pending(strm);if (strm->avail_out == 0) {s->last_flush = -1; /* avoid BUF_ERROR at next call, see above */return Z_OK;}}}Assert(strm->avail_out > 0, "bug2");if (flush != Z_FINISH) return Z_OK;if (s->wrap <= 0) return Z_STREAM_END;/* Write the trailer */#ifdef GZIPif (s->wrap == 2) {put_byte(s, (Byte)(strm->adler & 0xff));put_byte(s, (Byte)((strm->adler >> 8) & 0xff));put_byte(s, (Byte)((strm->adler >> 16) & 0xff));put_byte(s, (Byte)((strm->adler >> 24) & 0xff));put_byte(s, (Byte)(strm->total_in & 0xff));put_byte(s, (Byte)((strm->total_in >> 8) & 0xff));put_byte(s, (Byte)((strm->total_in >> 16) & 0xff));put_byte(s, (Byte)((strm->total_in >> 24) & 0xff));}else#endif{putShortMSB(s, (uInt)(strm->adler >> 16));putShortMSB(s, (uInt)(strm->adler & 0xffff));}flush_pending(strm);/* If avail_out is zero, the application will call deflate again* to flush the rest.*/if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */return s->pending != 0 ? Z_OK : Z_STREAM_END;}/* ========================================================================= */int ZEXPORT deflateEnd (strm)z_streamp strm;{int status;if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR;status = strm->state->status;if (status != INIT_STATE &&status != EXTRA_STATE &&status != NAME_STATE &&status != COMMENT_STATE &&status != HCRC_STATE &&status != BUSY_STATE &&status != FINISH_STATE) {return Z_STREAM_ERROR;}/* Deallocate in reverse order of allocations: */TRY_FREE(strm, strm->state->pending_buf);TRY_FREE(strm, strm->state->head);TRY_FREE(strm, strm->state->prev);TRY_FREE(strm, strm->state->window);ZFREE(strm, strm->state);strm->state = Z_NULL;return status == BUSY_STATE ? Z_DATA_ERROR : Z_OK;}/* =========================================================================* Copy the source state to the destination state.* To simplify the source, this is not supported for 16-bit MSDOS (which* doesn't have enough memory anyway to duplicate compression states).*/int ZEXPORT deflateCopy (dest, source)z_streamp dest;z_streamp source;{#ifdef MAXSEG_64Kreturn Z_STREAM_ERROR;#elsedeflate_state *ds;deflate_state *ss;ushf *overlay;if (source == Z_NULL || dest == Z_NULL || source->state == Z_NULL) {return Z_STREAM_ERROR;}ss = source->state;zmemcpy(dest, source, sizeof(z_stream));ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state));if (ds == Z_NULL) return Z_MEM_ERROR;dest->state = (struct internal_state FAR *) ds;zmemcpy(ds, ss, sizeof(deflate_state));ds->strm = dest;ds->window = (Bytef *) ZALLOC(dest, ds->w_size, 2*sizeof(Byte));ds->prev = (Posf *) ZALLOC(dest, ds->w_size, sizeof(Pos));ds->head = (Posf *) ZALLOC(dest, ds->hash_size, sizeof(Pos));overlay = (ushf *) ZALLOC(dest, ds->lit_bufsize, sizeof(ush)+2);ds->pending_buf = (uchf *) overlay;if (ds->window == Z_NULL || ds->prev == Z_NULL || ds->head == Z_NULL ||ds->pending_buf == Z_NULL) {deflateEnd (dest);return Z_MEM_ERROR;}/* following zmemcpy do not work for 16-bit MSDOS */zmemcpy(ds->window, ss->window, ds->w_size * 2 * sizeof(Byte));zmemcpy(ds->prev, ss->prev, ds->w_size * sizeof(Pos));zmemcpy(ds->head, ss->head, ds->hash_size * sizeof(Pos));zmemcpy(ds->pending_buf, ss->pending_buf, (uInt)ds->pending_buf_size);ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf);ds->d_buf = overlay + ds->lit_bufsize/sizeof(ush);ds->l_buf = ds->pending_buf + (1+sizeof(ush))*ds->lit_bufsize;ds->l_desc.dyn_tree = ds->dyn_ltree;ds->d_desc.dyn_tree = ds->dyn_dtree;ds->bl_desc.dyn_tree = ds->bl_tree;return Z_OK;#endif /* MAXSEG_64K */}/* ===========================================================================* Read a new buffer from the current input stream, update the adler32* and total number of bytes read. All deflate() input goes through* this function so some applications may wish to modify it to avoid* allocating a large strm->next_in buffer and copying from it.* (See also flush_pending()).*/local int read_buf(strm, buf, size)z_streamp strm;Bytef *buf;unsigned size;{unsigned len = strm->avail_in;if (len > size) len = size;if (len == 0) return 0;strm->avail_in -= len;if (strm->state->wrap == 1) {strm->adler = adler32(strm->adler, strm->next_in, len);}#ifdef GZIPelse if (strm->state->wrap == 2) {strm->adler = crc32(strm->adler, strm->next_in, len);}#endifzmemcpy(buf, strm->next_in, len);strm->next_in += len;strm->total_in += len;return (int)len;}/* ===========================================================================* Initialize the "longest match" routines for a new zlib stream*/local void lm_init (s)deflate_state *s;{s->window_size = (ulg)2L*s->w_size;CLEAR_HASH(s);/* Set the default configuration parameters:*/s->max_lazy_match = configuration_table[s->level].max_lazy;s->good_match = configuration_table[s->level].good_length;s->nice_match = configuration_table[s->level].nice_length;s->max_chain_length = configuration_table[s->level].max_chain;s->strstart = 0;s->block_start = 0L;s->lookahead = 0;s->match_length = s->prev_length = MIN_MATCH-1;s->match_available = 0;s->ins_h = 0;#ifndef FASTEST#ifdef ASMVmatch_init(); /* initialize the asm code */#endif#endif}#ifndef FASTEST/* ===========================================================================* Set match_start to the longest match starting at the given string and* return its length. Matches shorter or equal to prev_length are discarded,* in which case the result is equal to prev_length and match_start is* garbage.* IN assertions: cur_match is the head of the hash chain for the current* string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1* OUT assertion: the match length is not greater than s->lookahead.*/#ifndef ASMV/* For 80x86 and 680x0, an optimized version will be provided in match.asm or* match.S. The code will be functionally equivalent.*/local uInt longest_match(s, cur_match)deflate_state *s;IPos cur_match; /* current match */{unsigned chain_length = s->max_chain_length;/* max hash chain length */register Bytef *scan = s->window + s->strstart; /* current string */register Bytef *match; /* matched string */register int len; /* length of current match */int best_len = s->prev_length; /* best match length so far */int nice_match = s->nice_match; /* stop if match long enough */IPos limit = s->strstart > (IPos)MAX_DIST(s) ?s->strstart - (IPos)MAX_DIST(s) : NIL;/* Stop when cur_match becomes <= limit. To simplify the code,* we prevent matches with the string of window index 0.*/Posf *prev = s->prev;uInt wmask = s->w_mask;#ifdef UNALIGNED_OK/* Compare two bytes at a time. Note: this is not always beneficial.* Try with and without -DUNALIGNED_OK to check.*/register Bytef *strend = s->window + s->strstart + MAX_MATCH - 1;register ush scan_start = *(ushf*)scan;register ush scan_end = *(ushf*)(scan+best_len-1);#elseregister Bytef *strend = s->window + s->strstart + MAX_MATCH;register Byte scan_end1 = scan[best_len-1];register Byte scan_end = scan[best_len];#endif/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.* It is easy to get rid of this optimization if necessary.*/Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");/* Do not waste too much time if we already have a good match: */if (s->prev_length >= s->good_match) {chain_length >>= 2;}/* Do not look for matches beyond the end of the input. This is necessary* to make deflate deterministic.*/if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead;Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");do {Assert(cur_match < s->strstart, "no future");match = s->window + cur_match;/* Skip to next match if the match length cannot increase* or if the match length is less than 2. Note that the checks below* for insufficient lookahead only occur occasionally for performance* reasons. Therefore uninitialized memory will be accessed, and* conditional jumps will be made that depend on those values.* However the length of the match is limited to the lookahead, so* the output of deflate is not affected by the uninitialized values.*/#if (defined(UNALIGNED_OK) && MAX_MATCH == 258)/* This code assumes sizeof(unsigned short) == 2. Do not use* UNALIGNED_OK if your compiler uses a different size.*/if (*(ushf*)(match+best_len-1) != scan_end ||*(ushf*)match != scan_start) continue;/* It is not necessary to compare scan[2] and match[2] since they are* always equal when the other bytes match, given that the hash keys* are equal and that HASH_BITS >= 8. Compare 2 bytes at a time at* strstart+3, +5, ... up to strstart+257. We check for insufficient* lookahead only every 4th comparison; the 128th check will be made* at strstart+257. If MAX_MATCH-2 is not a multiple of 8, it is* necessary to put more guard bytes at the end of the window, or* to check more often for insufficient lookahead.*/Assert(scan[2] == match[2], "scan[2]?");scan++, match++;do {} while (*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&*(ushf*)(scan+=2) == *(ushf*)(match+=2) &&scan < strend);/* The funny "do {}" generates better code on most compilers *//* Here, scan <= window+strstart+257 */Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");if (*scan == *match) scan++;len = (MAX_MATCH - 1) - (int)(strend-scan);scan = strend - (MAX_MATCH-1);#else /* UNALIGNED_OK */if (match[best_len] != scan_end ||match[best_len-1] != scan_end1 ||*match != *scan ||*++match != scan[1]) continue;/* The check at best_len-1 can be removed because it will be made* again later. (This heuristic is not always a win.)* It is not necessary to compare scan[2] and match[2] since they* are always equal when the other bytes match, given that* the hash keys are equal and that HASH_BITS >= 8.*/scan += 2, match++;Assert(*scan == *match, "match[2]?");/* We check for insufficient lookahead only every 8th comparison;* the 256th check will be made at strstart+258.*/do {} while (*++scan == *++match && *++scan == *++match &&*++scan == *++match && *++scan == *++match &&*++scan == *++match && *++scan == *++match &&*++scan == *++match && *++scan == *++match &&scan < strend);Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");len = MAX_MATCH - (int)(strend - scan);scan = strend - MAX_MATCH;#endif /* UNALIGNED_OK */if (len > best_len) {s->match_start = cur_match;best_len = len;if (len >= nice_match) break;#ifdef UNALIGNED_OKscan_end = *(ushf*)(scan+best_len-1);#elsescan_end1 = scan[best_len-1];scan_end = scan[best_len];#endif}} while ((cur_match = prev[cur_match & wmask]) > limit&& --chain_length != 0);if ((uInt)best_len <= s->lookahead) return (uInt)best_len;return s->lookahead;}#endif /* ASMV */#else /* FASTEST *//* ---------------------------------------------------------------------------* Optimized version for FASTEST only*/local uInt longest_match(s, cur_match)deflate_state *s;IPos cur_match; /* current match */{register Bytef *scan = s->window + s->strstart; /* current string */register Bytef *match; /* matched string */register int len; /* length of current match */register Bytef *strend = s->window + s->strstart + MAX_MATCH;/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.* It is easy to get rid of this optimization if necessary.*/Assert(s->hash_bits >= 8 && MAX_MATCH == 258, "Code too clever");Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead");Assert(cur_match < s->strstart, "no future");match = s->window + cur_match;/* Return failure if the match length is less than 2:*/if (match[0] != scan[0] || match[1] != scan[1]) return MIN_MATCH-1;/* The check at best_len-1 can be removed because it will be made* again later. (This heuristic is not always a win.)* It is not necessary to compare scan[2] and match[2] since they* are always equal when the other bytes match, given that* the hash keys are equal and that HASH_BITS >= 8.*/scan += 2, match += 2;Assert(*scan == *match, "match[2]?");/* We check for insufficient lookahead only every 8th comparison;* the 256th check will be made at strstart+258.*/do {} while (*++scan == *++match && *++scan == *++match &&*++scan == *++match && *++scan == *++match &&*++scan == *++match && *++scan == *++match &&*++scan == *++match && *++scan == *++match &&scan < strend);Assert(scan <= s->window+(unsigned)(s->window_size-1), "wild scan");len = MAX_MATCH - (int)(strend - scan);if (len < MIN_MATCH) return MIN_MATCH - 1;s->match_start = cur_match;return (uInt)len <= s->lookahead ? (uInt)len : s->lookahead;}#endif /* FASTEST */#ifdef DEBUG/* ===========================================================================* Check that the match at match_start is indeed a match.*/local void check_match(s, start, match, length)deflate_state *s;IPos start, match;int length;{/* check that the match is indeed a match */if (zmemcmp(s->window + match,s->window + start, length) != EQUAL) {fprintf(stderr, " start %u, match %u, length %d\n",start, match, length);do {fprintf(stderr, "%c%c", s->window[match++], s->window[start++]);} while (--length != 0);z_error("invalid match");}if (z_verbose > 1) {fprintf(stderr,"\\[%d,%d]", start-match, length);do { putc(s->window[start++], stderr); } while (--length != 0);}}#else# define check_match(s, start, match, length)#endif /* DEBUG *//* ===========================================================================* Fill the window when the lookahead becomes insufficient.* Updates strstart and lookahead.** IN assertion: lookahead < MIN_LOOKAHEAD* OUT assertions: strstart <= window_size-MIN_LOOKAHEAD* At least one byte has been read, or avail_in == 0; reads are* performed for at least two bytes (required for the zip translate_eol* option -- not supported here).*/local void fill_window(s)deflate_state *s;{register unsigned n, m;register Posf *p;unsigned more; /* Amount of free space at the end of the window. */uInt wsize = s->w_size;do {more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart);/* Deal with !@#$% 64K limit: */if (sizeof(int) <= 2) {if (more == 0 && s->strstart == 0 && s->lookahead == 0) {more = wsize;} else if (more == (unsigned)(-1)) {/* Very unlikely, but possible on 16 bit machine if* strstart == 0 && lookahead == 1 (input done a byte at time)*/more--;}}/* If the window is almost full and there is insufficient lookahead,* move the upper half to the lower one to make room in the upper half.*/if (s->strstart >= wsize+MAX_DIST(s)) {zmemcpy(s->window, s->window+wsize, (unsigned)wsize);s->match_start -= wsize;s->strstart -= wsize; /* we now have strstart >= MAX_DIST */s->block_start -= (long) wsize;/* Slide the hash table (could be avoided with 32 bit valuesat the expense of memory usage). We slide even when level == 0to keep the hash table consistent if we switch back to level > 0later. (Using level 0 permanently is not an optimal usage ofzlib, so we don't care about this pathological case.)*/n = s->hash_size;p = &s->head[n];do {m = *--p;*p = (Pos)(m >= wsize ? m-wsize : NIL);} while (--n);n = wsize;#ifndef FASTESTp = &s->prev[n];do {m = *--p;*p = (Pos)(m >= wsize ? m-wsize : NIL);/* If n is not on any hash chain, prev[n] is garbage but* its value will never be used.*/} while (--n);#endifmore += wsize;}if (s->strm->avail_in == 0) return;/* If there was no sliding:* strstart <= WSIZE+MAX_DIST-1 && lookahead <= MIN_LOOKAHEAD - 1 &&* more == window_size - lookahead - strstart* => more >= window_size - (MIN_LOOKAHEAD-1 + WSIZE + MAX_DIST-1)* => more >= window_size - 2*WSIZE + 2* In the BIG_MEM or MMAP case (not yet supported),* window_size == input_size + MIN_LOOKAHEAD &&* strstart + s->lookahead <= input_size => more >= MIN_LOOKAHEAD.* Otherwise, window_size == 2*WSIZE so more >= 2.* If there was sliding, more >= WSIZE. So in all cases, more >= 2.*/Assert(more >= 2, "more < 2");n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more);s->lookahead += n;/* Initialize the hash value now that we have some input: */if (s->lookahead >= MIN_MATCH) {s->ins_h = s->window[s->strstart];UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);#if MIN_MATCH != 3Call UPDATE_HASH() MIN_MATCH-3 more times#endif}/* If the whole input has less than MIN_MATCH bytes, ins_h is garbage,* but this is not important since only literal bytes will be emitted.*/} while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0);/* If the WIN_INIT bytes after the end of the current data have never been* written, then zero those bytes in order to avoid memory check reports of* the use of uninitialized (or uninitialised as Julian writes) bytes by* the longest match routines. Update the high water mark for the next* time through here. WIN_INIT is set to MAX_MATCH since the longest match* routines allow scanning to strstart + MAX_MATCH, ignoring lookahead.*/if (s->high_water < s->window_size) {ulg curr = s->strstart + (ulg)(s->lookahead);ulg init;if (s->high_water < curr) {/* Previous high water mark below current data -- zero WIN_INIT* bytes or up to end of window, whichever is less.*/init = s->window_size - curr;if (init > WIN_INIT)init = WIN_INIT;zmemzero(s->window + curr, (unsigned)init);s->high_water = curr + init;}else if (s->high_water < (ulg)curr + WIN_INIT) {/* High water mark at or above current data, but below current data* plus WIN_INIT -- zero out to current data plus WIN_INIT, or up* to end of window, whichever is less.*/init = (ulg)curr + WIN_INIT - s->high_water;if (init > s->window_size - s->high_water)init = s->window_size - s->high_water;zmemzero(s->window + s->high_water, (unsigned)init);s->high_water += init;}}}/* ===========================================================================* Flush the current block, with given end-of-file flag.* IN assertion: strstart is set to the end of the current match.*/#define FLUSH_BLOCK_ONLY(s, last) { \_tr_flush_block(s, (s->block_start >= 0L ? \(charf *)&s->window[(unsigned)s->block_start] : \(charf *)Z_NULL), \(ulg)((long)s->strstart - s->block_start), \(last)); \s->block_start = s->strstart; \flush_pending(s->strm); \Tracev((stderr,"[FLUSH]")); \}/* Same but force premature exit if necessary. */#define FLUSH_BLOCK(s, last) { \FLUSH_BLOCK_ONLY(s, last); \if (s->strm->avail_out == 0) return (last) ? finish_started : need_more; \}/* ===========================================================================* Copy without compression as much as possible from the input stream, return* the current block state.* This function does not insert new strings in the dictionary since* uncompressible data is probably not useful. This function is used* only for the level=0 compression option.* NOTE: this function should be optimized to avoid extra copying from* window to pending_buf.*/local block_state deflate_stored(s, flush)deflate_state *s;int flush;{/* Stored blocks are limited to 0xffff bytes, pending_buf is limited* to pending_buf_size, and each stored block has a 5 byte header:*/ulg max_block_size = 0xffff;ulg max_start;if (max_block_size > s->pending_buf_size - 5) {max_block_size = s->pending_buf_size - 5;}/* Copy as much as possible from input to output: */for (;;) {/* Fill the window as much as possible: */if (s->lookahead <= 1) {Assert(s->strstart < s->w_size+MAX_DIST(s) ||s->block_start >= (long)s->w_size, "slide too late");fill_window(s);if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more;if (s->lookahead == 0) break; /* flush the current block */}Assert(s->block_start >= 0L, "block gone");s->strstart += s->lookahead;s->lookahead = 0;/* Emit a stored block if pending_buf will be full: */max_start = s->block_start + max_block_size;if (s->strstart == 0 || (ulg)s->strstart >= max_start) {/* strstart == 0 is possible when wraparound on 16-bit machine */s->lookahead = (uInt)(s->strstart - max_start);s->strstart = (uInt)max_start;FLUSH_BLOCK(s, 0);}/* Flush if we may have to slide, otherwise block_start may become* negative and the data will be gone:*/if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) {FLUSH_BLOCK(s, 0);}}FLUSH_BLOCK(s, flush == Z_FINISH);return flush == Z_FINISH ? finish_done : block_done;}/* ===========================================================================* Compress as much as possible from the input stream, return the current* block state.* This function does not perform lazy evaluation of matches and inserts* new strings in the dictionary only for unmatched strings or for short* matches. It is used only for the fast compression options.*/local block_state deflate_fast(s, flush)deflate_state *s;int flush;{IPos hash_head; /* head of the hash chain */int bflush; /* set if current block must be flushed */for (;;) {/* Make sure that we always have enough lookahead, except* at the end of the input file. We need MAX_MATCH bytes* for the next match, plus MIN_MATCH bytes to insert the* string following the next match.*/if (s->lookahead < MIN_LOOKAHEAD) {fill_window(s);if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {return need_more;}if (s->lookahead == 0) break; /* flush the current block */}/* Insert the string window[strstart .. strstart+2] in the* dictionary, and set hash_head to the head of the hash chain:*/hash_head = NIL;if (s->lookahead >= MIN_MATCH) {INSERT_STRING(s, s->strstart, hash_head);}/* Find the longest match, discarding those <= prev_length.* At this point we have always match_length < MIN_MATCH*/if (hash_head != NIL && s->strstart - hash_head <= MAX_DIST(s)) {/* To simplify the code, we prevent matches with the string* of window index 0 (in particular we have to avoid a match* of the string with itself at the start of the input file).*/s->match_length = longest_match (s, hash_head);/* longest_match() sets match_start */}if (s->match_length >= MIN_MATCH) {check_match(s, s->strstart, s->match_start, s->match_length);_tr_tally_dist(s, s->strstart - s->match_start,s->match_length - MIN_MATCH, bflush);s->lookahead -= s->match_length;/* Insert new strings in the hash table only if the match length* is not too large. This saves time but degrades compression.*/#ifndef FASTESTif (s->match_length <= s->max_insert_length &&s->lookahead >= MIN_MATCH) {s->match_length--; /* string at strstart already in table */do {s->strstart++;INSERT_STRING(s, s->strstart, hash_head);/* strstart never exceeds WSIZE-MAX_MATCH, so there are* always MIN_MATCH bytes ahead.*/} while (--s->match_length != 0);s->strstart++;} else#endif{s->strstart += s->match_length;s->match_length = 0;s->ins_h = s->window[s->strstart];UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]);#if MIN_MATCH != 3Call UPDATE_HASH() MIN_MATCH-3 more times#endif/* If lookahead < MIN_MATCH, ins_h is garbage, but it does not* matter since it will be recomputed at next deflate call.*/}} else {/* No match, output a literal byte */Tracevv((stderr,"%c", s->window[s->strstart]));_tr_tally_lit (s, s->window[s->strstart], bflush);s->lookahead--;s->strstart++;}if (bflush) FLUSH_BLOCK(s, 0);}FLUSH_BLOCK(s, flush == Z_FINISH);return flush == Z_FINISH ? finish_done : block_done;}#ifndef FASTEST/* ===========================================================================* Same as above, but achieves better compression. We use a lazy* evaluation for matches: a match is finally adopted only if there is* no better match at the next window position.*/local block_state deflate_slow(s, flush)deflate_state *s;int flush;{IPos hash_head; /* head of hash chain */int bflush; /* set if current block must be flushed *//* Process the input block. */for (;;) {/* Make sure that we always have enough lookahead, except* at the end of the input file. We need MAX_MATCH bytes* for the next match, plus MIN_MATCH bytes to insert the* string following the next match.*/if (s->lookahead < MIN_LOOKAHEAD) {fill_window(s);if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) {return need_more;}if (s->lookahead == 0) break; /* flush the current block */}/* Insert the string window[strstart .. strstart+2] in the* dictionary, and set hash_head to the head of the hash chain:*/hash_head = NIL;if (s->lookahead >= MIN_MATCH) {INSERT_STRING(s, s->strstart, hash_head);}/* Find the longest match, discarding those <= prev_length.*/s->prev_length = s->match_length, s->prev_match = s->match_start;s->match_length = MIN_MATCH-1;if (hash_head != NIL && s->prev_length < s->max_lazy_match &&s->strstart - hash_head <= MAX_DIST(s)) {/* To simplify the code, we prevent matches with the string* of window index 0 (in particular we have to avoid a match* of the string with itself at the start of the input file).*/s->match_length = longest_match (s, hash_head);/* longest_match() sets match_start */if (s->match_length <= 5 && (s->strategy == Z_FILTERED#if TOO_FAR <= 32767|| (s->match_length == MIN_MATCH &&s->strstart - s->match_start > TOO_FAR)#endif)) {/* If prev_match is also MIN_MATCH, match_start is garbage* but we will ignore the current match anyway.*/s->match_length = MIN_MATCH-1;}}/* If there was a match at the previous step and the current* match is not better, output the previous match:*/if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) {uInt max_insert = s->strstart + s->lookahead - MIN_MATCH;/* Do not insert strings in hash table beyond this. */check_match(s, s->strstart-1, s->prev_match, s->prev_length);_tr_tally_dist(s, s->strstart -1 - s->prev_match,s->prev_length - MIN_MATCH, bflush);/* Insert in hash table all strings up to the end of the match.* strstart-1 and strstart are already inserted. If there is not* enough lookahead, the last two strings are not inserted in* the hash table.*/s->lookahead -= s->prev_length-1;s->prev_length -= 2;do {if (++s->strstart <= max_insert) {INSERT_STRING(s, s->strstart, hash_head);}} while (--s->prev_length != 0);s->match_available = 0;s->match_length = MIN_MATCH-1;s->strstart++;if (bflush) FLUSH_BLOCK(s, 0);} else if (s->match_available) {/* If there was no match at the previous position, output a* single literal. If there was a match but the current match* is longer, truncate the previous match to a single literal.*/Tracevv((stderr,"%c", s->window[s->strstart-1]));_tr_tally_lit(s, s->window[s->strstart-1], bflush);if (bflush) {FLUSH_BLOCK_ONLY(s, 0);}s->strstart++;s->lookahead--;if (s->strm->avail_out == 0) return need_more;} else {/* There is no previous match to compare with, wait for* the next step to decide.*/s->match_available = 1;s->strstart++;s->lookahead--;}}Assert (flush != Z_NO_FLUSH, "no flush?");if (s->match_available) {Tracevv((stderr,"%c", s->window[s->strstart-1]));_tr_tally_lit(s, s->window[s->strstart-1], bflush);s->match_available = 0;}FLUSH_BLOCK(s, flush == Z_FINISH);return flush == Z_FINISH ? finish_done : block_done;}#endif /* FASTEST *//* ===========================================================================* For Z_RLE, simply look for runs of bytes, generate matches only of distance* one. Do not maintain a hash table. (It will be regenerated if this run of* deflate switches away from Z_RLE.)*/local block_state deflate_rle(s, flush)deflate_state *s;int flush;{int bflush; /* set if current block must be flushed */uInt prev; /* byte at distance one to match */Bytef *scan, *strend; /* scan goes up to strend for length of run */for (;;) {/* Make sure that we always have enough lookahead, except* at the end of the input file. We need MAX_MATCH bytes* for the longest encodable run.*/if (s->lookahead < MAX_MATCH) {fill_window(s);if (s->lookahead < MAX_MATCH && flush == Z_NO_FLUSH) {return need_more;}if (s->lookahead == 0) break; /* flush the current block */}/* See how many times the previous byte repeats */s->match_length = 0;if (s->lookahead >= MIN_MATCH && s->strstart > 0) {scan = s->window + s->strstart - 1;prev = *scan;if (prev == *++scan && prev == *++scan && prev == *++scan) {strend = s->window + s->strstart + MAX_MATCH;do {} while (prev == *++scan && prev == *++scan &&prev == *++scan && prev == *++scan &&prev == *++scan && prev == *++scan &&prev == *++scan && prev == *++scan &&scan < strend);s->match_length = MAX_MATCH - (int)(strend - scan);if (s->match_length > s->lookahead)s->match_length = s->lookahead;}}/* Emit match if have run of MIN_MATCH or longer, else emit literal */if (s->match_length >= MIN_MATCH) {check_match(s, s->strstart, s->strstart - 1, s->match_length);_tr_tally_dist(s, 1, s->match_length - MIN_MATCH, bflush);s->lookahead -= s->match_length;s->strstart += s->match_length;s->match_length = 0;} else {/* No match, output a literal byte */Tracevv((stderr,"%c", s->window[s->strstart]));_tr_tally_lit (s, s->window[s->strstart], bflush);s->lookahead--;s->strstart++;}if (bflush) FLUSH_BLOCK(s, 0);}FLUSH_BLOCK(s, flush == Z_FINISH);return flush == Z_FINISH ? finish_done : block_done;}/* ===========================================================================* For Z_HUFFMAN_ONLY, do not look for matches. Do not maintain a hash table.* (It will be regenerated if this run of deflate switches away from Huffman.)*/local block_state deflate_huff(s, flush)deflate_state *s;int flush;{int bflush; /* set if current block must be flushed */for (;;) {/* Make sure that we have a literal to write. */if (s->lookahead == 0) {fill_window(s);if (s->lookahead == 0) {if (flush == Z_NO_FLUSH)return need_more;break; /* flush the current block */}}/* Output a literal byte */s->match_length = 0;Tracevv((stderr,"%c", s->window[s->strstart]));_tr_tally_lit (s, s->window[s->strstart], bflush);s->lookahead--;s->strstart++;if (bflush) FLUSH_BLOCK(s, 0);}FLUSH_BLOCK(s, flush == Z_FINISH);return flush == Z_FINISH ? finish_done : block_done;}