/* deflate.c -- compress data using the deflation algorithm * Copyright (C) 1995-2004 Jean-loup Gailly. * 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 1.2.2 Copyright 1995-2004 Jean-loup Gailly "; /* If you use the zlib library in a product, an acknowledgment is welcome in the documentation of your product. If for some reason you cannot include such an acknowledgment, I would appreciate that you keep this copyright 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 FASTEST local block_state deflate_slow OF((deflate_state *s, int flush)); #endif 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)); #ifndef FASTEST #ifdef ASMV void match_init OF((void)); /* asm code initialization */ uInt longest_match OF((deflate_state *s, IPos cur_match)); #else local uInt longest_match OF((deflate_state *s, IPos cur_match)); #endif #endif local uInt longest_match_fast OF((deflate_state *s, IPos cur_match)); #ifdef DEBUG local 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 */ #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. */ /* 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 FASTEST local 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 */ #else local 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_DECL struct 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)<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; 71 { 71 deflate_state *s; 71 int wrap = 1; 71 static const char my_version[] = ZLIB_VERSION; 71 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. */ 71 if (version == Z_NULL || version[0] != my_version[0] || stream_size != sizeof(z_stream)) { ###### return Z_VERSION_ERROR; } 71 if (strm == Z_NULL) return Z_STREAM_ERROR; 71 strm->msg = Z_NULL; 71 if (strm->zalloc == (alloc_func)0) { 71 strm->zalloc = zcalloc; 71 strm->opaque = (voidpf)0; } 71 if (strm->zfree == (free_func)0) strm->zfree = zcfree; #ifdef FASTEST if (level != 0) level = 1; #else 71 if (level == Z_DEFAULT_COMPRESSION) level = 6; #endif 71 if (windowBits < 0) { /* suppress zlib wrapper */ 29 wrap = 0; 29 windowBits = -windowBits; } #ifdef GZIP 42 else if (windowBits > 15) { ###### wrap = 2; /* write gzip wrapper instead */ ###### windowBits -= 16; } #endif 71 if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || strategy < 0 || strategy > Z_RLE) { 1 return Z_STREAM_ERROR; } 70 if (windowBits == 8) windowBits = 9; /* until 256-byte window bug fixed */ 70 s = (deflate_state *) ZALLOC(strm, 1, sizeof(deflate_state)); 70 if (s == Z_NULL) return Z_MEM_ERROR; 70 strm->state = (struct internal_state FAR *)s; 70 s->strm = strm; 70 s->wrap = wrap; 70 s->w_bits = windowBits; 70 s->w_size = 1 << s->w_bits; 70 s->w_mask = s->w_size - 1; 70 s->hash_bits = memLevel + 7; 70 s->hash_size = 1 << s->hash_bits; 70 s->hash_mask = s->hash_size - 1; 70 s->hash_shift = ((s->hash_bits+MIN_MATCH-1)/MIN_MATCH); 70 s->window = (Bytef *) ZALLOC(strm, s->w_size, 2*sizeof(Byte)); 70 s->prev = (Posf *) ZALLOC(strm, s->w_size, sizeof(Pos)); 70 s->head = (Posf *) ZALLOC(strm, s->hash_size, sizeof(Pos)); 70 s->lit_bufsize = 1 << (memLevel + 6); /* 16K elements by default */ 70 overlay = (ushf *) ZALLOC(strm, s->lit_bufsize, sizeof(ush)+2); 70 s->pending_buf = (uchf *) overlay; 70 s->pending_buf_size = (ulg)s->lit_bufsize * (sizeof(ush)+2L); 70 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; } 70 s->d_buf = overlay + s->lit_bufsize/sizeof(ush); 70 s->l_buf = s->pending_buf + (1+sizeof(ush))*s->lit_bufsize; 70 s->level = level; 70 s->strategy = strategy; 70 s->method = (Byte)method; 70 return deflateReset(strm); } /* ========================================================================= */ int ZEXPORT deflateSetDictionary (strm, dictionary, dictLength) z_streamp strm; const Bytef *dictionary; uInt dictLength; 1 { 1 deflate_state *s; 1 uInt length = dictLength; 1 uInt n; 1 IPos hash_head = 0; 1 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; 1 s = strm->state; 1 if (s->wrap) 1 strm->adler = adler32(strm->adler, dictionary, dictLength); 1 if (length < MIN_MATCH) return Z_OK; 1 if (length > MAX_DIST(s)) { ###### length = MAX_DIST(s); #ifndef USE_DICT_HEAD ###### dictionary += dictLength - length; /* use the tail of the dictionary */ #endif } 1 zmemcpy(s->window, dictionary, length); 1 s->strstart = length; 1 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. */ 1 s->ins_h = s->window[0]; 1 UPDATE_HASH(s, s->ins_h, s->window[1]); 4 for (n = 0; n <= length - MIN_MATCH; n++) { 3 INSERT_STRING(s, n, hash_head); } 1 if (hash_head) hash_head = 0; /* to make compiler happy */ 1 return Z_OK; } /* ========================================================================= */ int ZEXPORT deflateReset (strm) z_streamp strm; 70 { 70 deflate_state *s; 70 if (strm == Z_NULL || strm->state == Z_NULL || strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) { ###### return Z_STREAM_ERROR; } 70 strm->total_in = strm->total_out = 0; 70 strm->msg = Z_NULL; /* use zfree if we ever allocate msg dynamically */ 70 strm->data_type = Z_UNKNOWN; 70 s = (deflate_state *)strm->state; 70 s->pending = 0; 70 s->pending_out = s->pending_buf; 70 if (s->wrap < 0) { ###### s->wrap = -s->wrap; /* was made negative by deflate(..., Z_FINISH); */ } 70 s->status = s->wrap ? INIT_STATE : BUSY_STATE; 70 strm->adler = #ifdef GZIP s->wrap == 2 ? crc32(0L, Z_NULL, 0) : #endif adler32(0L, Z_NULL, 0); 70 s->last_flush = Z_NO_FLUSH; 70 _tr_init(s); 70 lm_init(s); 70 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; 4 { 4 deflate_state *s; 4 compress_func func; 4 int err = Z_OK; 4 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 4 s = strm->state; #ifdef FASTEST if (level != 0) level = 1; #else 4 if (level == Z_DEFAULT_COMPRESSION) level = 6; #endif 4 if (level < 0 || level > 9 || strategy < 0 || strategy > Z_RLE) { ###### return Z_STREAM_ERROR; } 4 func = configuration_table[s->level].func; 4 if (func != configuration_table[level].func && strm->total_in != 0) { /* Flush the last buffer: */ 3 err = deflate(strm, Z_PARTIAL_FLUSH); } 4 if (s->level != level) { 3 s->level = level; 3 s->max_lazy_match = configuration_table[level].max_lazy; 3 s->good_match = configuration_table[level].good_length; 3 s->nice_match = configuration_table[level].nice_length; 3 s->max_chain_length = configuration_table[level].max_chain; } 4 s->strategy = strategy; 4 return err; } /* ========================================================================= * 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, as well as wrap. * 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 destLen; /* conservative upper bound */ ###### destLen = sourceLen + ((sourceLen + 7) >> 3) + ((sourceLen + 63) >> 6) + 11; /* if can't get parameters, return conservative bound */ ###### if (strm == Z_NULL || strm->state == Z_NULL) ###### return destLen; /* if not default parameters, return conservative bound */ ###### s = strm->state; ###### if (s->w_bits != 15 || s->hash_bits != 8 + 7) ###### return destLen; /* default settings: return tight bound for that case */ ###### return compressBound(sourceLen); } /* ========================================================================= * 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; 125 { 125 put_byte(s, (Byte)(b >> 8)); 125 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; 178 { 178 unsigned len = strm->state->pending; 178 if (len > strm->avail_out) len = strm->avail_out; 178 if (len == 0) return; 178 zmemcpy(strm->next_out, strm->state->pending_out, len); 178 strm->next_out += len; 178 strm->state->pending_out += len; 178 strm->total_out += len; 178 strm->avail_out -= len; 178 strm->state->pending -= len; 178 if (strm->state->pending == 0) { 160 strm->state->pending_out = strm->state->pending_buf; } } /* ========================================================================= */ int ZEXPORT deflate (strm, flush) z_streamp strm; int flush; 287 { 287 int old_flush; /* value of flush param for previous deflate call */ 287 deflate_state *s; 287 if (strm == Z_NULL || strm->state == Z_NULL || flush > Z_FINISH || flush < 0) { ###### return Z_STREAM_ERROR; } 287 s = strm->state; 287 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); } 287 if (strm->avail_out == 0) ERR_RETURN(strm, Z_BUF_ERROR); 287 s->strm = strm; /* just in case */ 287 old_flush = s->last_flush; 287 s->last_flush = flush; /* Write the header */ 287 if (s->status == INIT_STATE) { #ifdef GZIP 41 if (s->wrap == 2) { ###### put_byte(s, 31); ###### put_byte(s, 139); ###### put_byte(s, 8); ###### 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, 255); ###### s->status = BUSY_STATE; ###### strm->adler = crc32(0L, Z_NULL, 0); } else #endif { 41 uInt header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; 41 uInt level_flags; 41 if (s->strategy >= Z_HUFFMAN_ONLY || s->level < 2) ###### level_flags = 0; 41 else if (s->level < 6) ###### level_flags = 1; 41 else if (s->level == 6) 37 level_flags = 2; else 4 level_flags = 3; 41 header |= (level_flags << 6); 41 if (s->strstart != 0) header |= PRESET_DICT; 41 header += 31 - (header % 31); 41 s->status = BUSY_STATE; 41 putShortMSB(s, header); /* Save the adler32 of the preset dictionary: */ 41 if (s->strstart != 0) { 1 putShortMSB(s, (uInt)(strm->adler >> 16)); 1 putShortMSB(s, (uInt)(strm->adler & 0xffff)); } 41 strm->adler = adler32(0L, Z_NULL, 0); } } /* Flush as much pending output as possible */ 287 if (s->pending != 0) { 59 flush_pending(strm); 59 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: */ 10 s->last_flush = -1; 10 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. */ 228 } 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: */ 277 if (s->status == FINISH_STATE && strm->avail_in != 0) { ###### ERR_RETURN(strm, Z_BUF_ERROR); } /* Start a new block or continue the current one. */ 277 if (strm->avail_in != 0 || s->lookahead != 0 || (flush != Z_NO_FLUSH && s->status != FINISH_STATE)) { 271 block_state bstate; 271 bstate = (*(configuration_table[s->level].func))(s, flush); 271 if (bstate == finish_started || bstate == finish_done) { 70 s->status = FINISH_STATE; } 271 if (bstate == need_more || bstate == finish_started) { 205 if (strm->avail_out == 0) { 9 s->last_flush = -1; /* avoid BUF_ERROR next call, see above */ } 205 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. */ } 66 if (bstate == block_done) { 2 if (flush == Z_PARTIAL_FLUSH) { 1 _tr_align(s); } else { /* FULL_FLUSH or SYNC_FLUSH */ 1 _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(). */ 1 if (flush == Z_FULL_FLUSH) { 1 CLEAR_HASH(s); /* forget history */ } } 2 flush_pending(strm); 2 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"); 72 if (flush != Z_FINISH) return Z_OK; 70 if (s->wrap <= 0) return Z_STREAM_END; /* Write the trailer */ #ifdef GZIP 41 if (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 { 41 putShortMSB(s, (uInt)(strm->adler >> 16)); 41 putShortMSB(s, (uInt)(strm->adler & 0xffff)); } 41 flush_pending(strm); /* If avail_out is zero, the application will call deflate again * to flush the rest. */ 41 if (s->wrap > 0) s->wrap = -s->wrap; /* write the trailer only once! */ 41 return s->pending != 0 ? Z_OK : Z_STREAM_END; } /* ========================================================================= */ int ZEXPORT deflateEnd (strm) z_streamp strm; 70 { 70 int status; 70 if (strm == Z_NULL || strm->state == Z_NULL) return Z_STREAM_ERROR; 70 status = strm->state->status; 70 if (status != INIT_STATE && status != BUSY_STATE && status != FINISH_STATE) { ###### return Z_STREAM_ERROR; } /* Deallocate in reverse order of allocations: */ 70 TRY_FREE(strm, strm->state->pending_buf); 70 TRY_FREE(strm, strm->state->head); 70 TRY_FREE(strm, strm->state->prev); 70 TRY_FREE(strm, strm->state->window); 70 ZFREE(strm, strm->state); 70 strm->state = Z_NULL; 70 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_64K return Z_STREAM_ERROR; #else ###### deflate_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; ###### *dest = *source; ###### ds = (deflate_state *) ZALLOC(dest, 1, sizeof(deflate_state)); ###### if (ds == Z_NULL) return Z_MEM_ERROR; ###### dest->state = (struct internal_state FAR *) ds; ###### *ds = *ss; ###### 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; 201 { 201 unsigned len = strm->avail_in; 201 if (len > size) len = size; 201 if (len == 0) return 0; 201 strm->avail_in -= len; 201 if (strm->state->wrap == 1) { 95 strm->adler = adler32(strm->adler, strm->next_in, len); } #ifdef GZIP 106 else if (strm->state->wrap == 2) { ###### strm->adler = crc32(strm->adler, strm->next_in, len); } #endif 201 zmemcpy(buf, strm->next_in, len); 201 strm->next_in += len; 201 strm->total_in += len; 201 return (int)len; } /* =========================================================================== * Initialize the "longest match" routines for a new zlib stream */ local void lm_init (s) deflate_state *s; 70 { 70 s->window_size = (ulg)2L*s->w_size; 70 CLEAR_HASH(s); /* Set the default configuration parameters: */ 70 s->max_lazy_match = configuration_table[s->level].max_lazy; 70 s->good_match = configuration_table[s->level].good_length; 70 s->nice_match = configuration_table[s->level].nice_length; 70 s->max_chain_length = configuration_table[s->level].max_chain; 70 s->strstart = 0; 70 s->block_start = 0L; 70 s->lookahead = 0; 70 s->match_length = s->prev_length = MIN_MATCH-1; 70 s->match_available = 0; 70 s->ins_h = 0; #ifdef ASMV match_init(); /* initialize the asm code */ #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 */ 11706 { 11706 unsigned chain_length = s->max_chain_length;/* max hash chain length */ 11706 register Bytef *scan = s->window + s->strstart; /* current string */ 11706 register Bytef *match; /* matched string */ 11706 register int len; /* length of current match */ 11706 int best_len = s->prev_length; /* best match length so far */ 11706 int nice_match = s->nice_match; /* stop if match long enough */ 11706 IPos limit = s->strstart > (IPos)MAX_DIST(s) ? 11706 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. */ 11706 Posf *prev = s->prev; 11706 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); #else 11706 register Bytef *strend = s->window + s->strstart + MAX_MATCH; 11706 register Byte scan_end1 = scan[best_len-1]; 11706 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: */ 11706 if (s->prev_length >= s->good_match) { 10 chain_length >>= 2; } /* Do not look for matches beyond the end of the input. This is necessary * to make deflate deterministic. */ 11706 if ((uInt)nice_match > s->lookahead) nice_match = s->lookahead; Assert((ulg)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); 27393 do { Assert(cur_match < s->strstart, "no future"); 27393 match = s->window + cur_match; /* Skip to next match if the match length cannot increase * or if the match length is less than 2: */ #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 */ 27393 if (match[best_len] != scan_end || match[best_len-1] != scan_end1 || *match != *scan || 11927 *++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. */ 11927 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. */ 42810 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"); 11927 len = MAX_MATCH - (int)(strend - scan); 11927 scan = strend - MAX_MATCH; #endif /* UNALIGNED_OK */ 11927 if (len > best_len) { 11920 s->match_start = cur_match; 11920 best_len = len; 11920 if (len >= nice_match) break; #ifdef UNALIGNED_OK scan_end = *(ushf*)(scan+best_len-1); #else 7926 scan_end1 = scan[best_len-1]; 7926 scan_end = scan[best_len]; #endif } 23399 } while ((cur_match = prev[cur_match & wmask]) > limit && --chain_length != 0); 11706 if ((uInt)best_len <= s->lookahead) return (uInt)best_len; 9 return s->lookahead; } #endif /* ASMV */ #endif /* FASTEST */ /* --------------------------------------------------------------------------- * Optimized version for level == 1 or strategy == Z_RLE only */ local uInt longest_match_fast(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; } #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; 2891 { 2891 register unsigned n, m; 2891 register Posf *p; 2891 unsigned more; /* Amount of free space at the end of the window. */ 2891 uInt wsize = s->w_size; 2891 do { 2891 more = (unsigned)(s->window_size -(ulg)s->lookahead -(ulg)s->strstart); /* Deal with !@#$% 64K limit: */ 2891 if (sizeof(int) <= 2) { 2891 if (more == 0 && s->strstart == 0 && s->lookahead == 0) { 2891 more = wsize; 2891 } else if (more == (unsigned)(-1)) { /* Very unlikely, but possible on 16 bit machine if * strstart == 0 && lookahead == 1 (input done a byte at time) */ 2891 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. */ 2891 if (s->strstart >= wsize+MAX_DIST(s)) { 4 zmemcpy(s->window, s->window+wsize, (unsigned)wsize); 4 s->match_start -= wsize; 4 s->strstart -= wsize; /* we now have strstart >= MAX_DIST */ 4 s->block_start -= (long) wsize; /* Slide the hash table (could be avoided with 32 bit values at the expense of memory usage). We slide even when level == 0 to keep the hash table consistent if we switch back to level > 0 later. (Using level 0 permanently is not an optimal usage of zlib, so we don't care about this pathological case.) */ 4 n = s->hash_size; 4 p = &s->head[n]; 229376 do { 229376 m = *--p; 229376 *p = (Pos)(m >= wsize ? m-wsize : NIL); 229376 } while (--n); 4 n = wsize; #ifndef FASTEST 4 p = &s->prev[n]; 131072 do { 131072 m = *--p; 131072 *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. */ 131072 } while (--n); #endif 4 more += wsize; } 2891 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"); 201 n = read_buf(s->strm, s->window + s->strstart + s->lookahead, more); 201 s->lookahead += n; /* Initialize the hash value now that we have some input: */ 201 if (s->lookahead >= MIN_MATCH) { 185 s->ins_h = s->window[s->strstart]; 185 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); #if MIN_MATCH != 3 Call 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. */ 201 } while (s->lookahead < MIN_LOOKAHEAD && s->strm->avail_in != 0); } /* =========================================================================== * 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, eof) { \ _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), \ (eof)); \ s->block_start = s->strstart; \ flush_pending(s->strm); \ Tracev((stderr,"[FLUSH]")); \ } /* Same but force premature exit if necessary. */ #define FLUSH_BLOCK(s, eof) { \ FLUSH_BLOCK_ONLY(s, eof); \ if (s->strm->avail_out == 0) return (eof) ? 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; 3 { /* Stored blocks are limited to 0xffff bytes, pending_buf is limited * to pending_buf_size, and each stored block has a 5 byte header: */ 3 ulg max_block_size = 0xffff; 3 ulg max_start; 3 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: */ 6 for (;;) { /* Fill the window as much as possible: */ 5 if (s->lookahead <= 1) { Assert(s->strstart < s->w_size+MAX_DIST(s) || s->block_start >= (long)s->w_size, "slide too late"); 5 fill_window(s); 5 if (s->lookahead == 0 && flush == Z_NO_FLUSH) return need_more; 4 if (s->lookahead == 0) break; /* flush the current block */ } Assert(s->block_start >= 0L, "block gone"); 3 s->strstart += s->lookahead; 3 s->lookahead = 0; /* Emit a stored block if pending_buf will be full: */ 3 max_start = s->block_start + max_block_size; 3 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: */ 3 if (s->strstart - (uInt)s->block_start >= MAX_DIST(s)) { 1 FLUSH_BLOCK(s, 0); } } 1 FLUSH_BLOCK(s, flush == Z_FINISH); 1 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; 61 { 61 IPos hash_head = NIL; /* head of the hash chain */ 67070 int bflush; /* set if current block must be flushed */ 67078 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. */ 67070 if (s->lookahead < MIN_LOOKAHEAD) { 639 fill_window(s); 639 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 53 return need_more; } 586 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: */ 67009 if (s->lookahead >= MIN_MATCH) { 67005 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 */ 67009 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). */ #ifdef FASTEST if ((s->strategy < Z_HUFFMAN_ONLY) || (s->strategy == Z_RLE && s->strstart - hash_head == 1)) { s->match_length = longest_match_fast (s, hash_head); } #else 61796 if (s->strategy < Z_HUFFMAN_ONLY) { 9562 s->match_length = longest_match (s, hash_head); 52234 } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { ###### s->match_length = longest_match_fast (s, hash_head); } #endif /* longest_match() or longest_match_fast() sets match_start */ } 67009 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, 8980 s->match_length - MIN_MATCH, bflush); 8980 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 FASTEST 8980 if (s->match_length <= s->max_insert_length && s->lookahead >= MIN_MATCH) { 3627 s->match_length--; /* string at strstart already in table */ 9112 do { 9112 s->strstart++; 9112 INSERT_STRING(s, s->strstart, hash_head); /* strstart never exceeds WSIZE-MAX_MATCH, so there are * always MIN_MATCH bytes ahead. */ 9112 } while (--s->match_length != 0); 3627 s->strstart++; } else #endif { 5353 s->strstart += s->match_length; 5353 s->match_length = 0; 5353 s->ins_h = s->window[s->strstart]; 5353 UPDATE_HASH(s, s->ins_h, s->window[s->strstart+1]); #if MIN_MATCH != 3 Call 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])); 58029 _tr_tally_lit (s, s->window[s->strstart], bflush); 58029 s->lookahead--; 58029 s->strstart++; } 67009 if (bflush) FLUSH_BLOCK(s, 0); } 8 FLUSH_BLOCK(s, flush == Z_FINISH); 7 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; 207 { 207 IPos hash_head = NIL; /* head of hash chain */ 27654 int bflush; /* set if current block must be flushed */ /* Process the input block. */ 28559 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. */ 27654 if (s->lookahead < MIN_LOOKAHEAD) { 2247 fill_window(s); 2247 if (s->lookahead < MIN_LOOKAHEAD && flush == Z_NO_FLUSH) { 142 return need_more; } 2105 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: */ 27447 if (s->lookahead >= MIN_MATCH) { 27353 INSERT_STRING(s, s->strstart, hash_head); } /* Find the longest match, discarding those <= prev_length. */ 27447 s->prev_length = s->match_length, s->prev_match = s->match_start; 27447 s->match_length = MIN_MATCH-1; 27447 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). */ 2144 if (s->strategy < Z_HUFFMAN_ONLY) { 2144 s->match_length = longest_match (s, hash_head); ###### } else if (s->strategy == Z_RLE && s->strstart - hash_head == 1) { ###### s->match_length = longest_match_fast (s, hash_head); } /* longest_match() or longest_match_fast() sets match_start */ 2144 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: */ 27447 if (s->prev_length >= MIN_MATCH && s->match_length <= s->prev_length) { 854 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, 854 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. */ 854 s->lookahead -= s->prev_length-1; 854 s->prev_length -= 2; 203847 do { 203847 if (++s->strstart <= max_insert) { 203827 INSERT_STRING(s, s->strstart, hash_head); } 203847 } while (--s->prev_length != 0); 854 s->match_available = 0; 854 s->match_length = MIN_MATCH-1; 854 s->strstart++; 854 if (bflush) FLUSH_BLOCK(s, 0); 26593 } 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])); 25688 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 25688 if (bflush) { ###### FLUSH_BLOCK_ONLY(s, 0); } 25688 s->strstart++; 25688 s->lookahead--; 25688 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. */ 905 s->match_available = 1; 905 s->strstart++; 905 s->lookahead--; } } Assert (flush != Z_NO_FLUSH, "no flush?"); 65 if (s->match_available) { Tracevv((stderr,"%c", s->window[s->strstart-1])); 51 _tr_tally_lit(s, s->window[s->strstart-1], bflush); 51 s->match_available = 0; } 65 FLUSH_BLOCK(s, flush == Z_FINISH); 58 return flush == Z_FINISH ? finish_done : block_done; } #endif /* FASTEST */