/* deflate.c -- compress data using the deflation algorithm * Copyright (C) 1995-2023 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://tools.ietf.org/html/rfc1951 * * 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 1.3 Copyright 1995-2023 Jean-loup Gailly and Mark Adler "; /* 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. */ 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)(deflate_state *s, int flush); /* Compression function. Returns the block state after the call. */ static int deflateStateCheck(z_streamp strm); static void fill_window(deflate_state *s); static block_state deflate_stored(deflate_state *s, int flush); static block_state deflate_fast(deflate_state *s, int flush); static block_state deflate_slow(deflate_state *s, int flush); static block_state deflate_rle(deflate_state *s, int flush); static block_state deflate_huff(deflate_state *s, int flush); static void lm_init(deflate_state *s); static void putShortMSB(deflate_state *s, uint32_t b); static void flush_pending(z_streamp strm); static int read_buf(z_streamp strm, uint8_t *buf, uint32_t size); #ifdef ZLIB_DEBUG static void check_match(deflate_state *s, IPos start, IPos match, int length); #endif /* =========================================================================== * Local data */ #define NIL 0 /* Tail of hash chains */ #define ACTUAL_MIN_MATCH 4 /* 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 { uint16_t good_length; /* reduce lazy search above this match length */ uint16_t max_lazy; /* do not perform lazy search above this match length */ uint16_t nice_length; /* quit search above this match length */ uint16_t max_chain; compress_func func; } config; static 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 */ /* 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. */ /* rank Z_BLOCK between Z_NO_FLUSH and Z_PARTIAL_FLUSH */ #define RANK(f) (((f) * 2) - ((f) > 4 ? 9 : 0)) #ifdef __aarch64__ #include #include static uint32_t hash_func(deflate_state *s, void* str) { return __crc32cw(0, *(uint32_t*)str) & s->hash_mask; } #elif defined __x86_64__ || defined _M_AMD64 #include static uint32_t hash_func(deflate_state *s, void* str) { return _mm_crc32_u32(0, *(uint32_t*)str) & s->hash_mask; } #else #error "Only 64-bit Intel and ARM architectures are supported" #endif /* =========================================================================== * Insert string str in the dictionary and return the previous head * of the hash chain (the most recent string with same hash key). * IN assertion: ACTUAL_MIN_MATCH bytes of str are valid * (except for the last ACTUAL_MIN_MATCH-1 bytes of the input file). */ static Pos insert_string(deflate_state *s, Pos str) { Pos match_head; s->ins_h = hash_func(s, &s->window[str]); match_head = s->prev[(str) & s->w_mask] = s->head[s->ins_h]; s->head[s->ins_h] = (Pos)str; return match_head; } static void bulk_insert_str(deflate_state *s, Pos startpos, uint32_t count) { uint32_t idx; for (idx = 0; idx < count; idx++) { s->ins_h = hash_func(s, &s->window[startpos + idx]); s->prev[(startpos + idx) & s->w_mask] = s->head[s->ins_h]; s->head[s->ins_h] = (Pos)(startpos + idx); } } /* =========================================================================== * Initialize the hash table prev[] will be initialized on the fly. */ #define CLEAR_HASH(s) \ zmemzero((uint8_t *)s->head, (unsigned)(s->hash_size)*sizeof(*s->head)); /* ========================================================================= */ int ZEXPORT deflateInit_(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_(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; 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) { #ifdef Z_SOLO return Z_STREAM_ERROR; #else strm->zalloc = zcalloc; strm->opaque = (voidpf)0; #endif } if (strm->zfree == (free_func)0) #ifdef Z_SOLO return Z_STREAM_ERROR; #else strm->zfree = zcfree; #endif if (level == Z_DEFAULT_COMPRESSION) level = 6; if (windowBits < 0) { /* suppress zlib wrapper */ wrap = 0; if (windowBits < -15) return Z_STREAM_ERROR; windowBits = -windowBits; } else if (windowBits > 15) { wrap = 2; /* write gzip wrapper instead */ windowBits -= 16; } if (memLevel < 1 || memLevel > MAX_MEM_LEVEL || method != Z_DEFLATED || windowBits < 8 || windowBits > 15 || level < 0 || level > 9 || strategy < 0 || strategy > Z_FIXED || (windowBits == 8 && wrap != 1)) { 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 *)s; s->strm = strm; s->status = INIT_STATE; /* to pass state test in deflateReset() */ 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->window = (uint8_t *) ZALLOC(strm, s->w_size, 2*sizeof(uint8_t)); s->prev = (Pos *) ZALLOC(strm, s->w_size, sizeof(Pos)); s->head = (Pos *) 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 */ /* We overlay pending_buf and sym_buf. This works since the average size * for length/distance pairs over any compressed block is assured to be 31 * bits or less. * * Analysis: The longest fixed codes are a length code of 8 bits plus 5 * extra bits, for lengths 131 to 257. The longest fixed distance codes are * 5 bits plus 13 extra bits, for distances 16385 to 32768. The longest * possible fixed-codes length/distance pair is then 31 bits total. * * sym_buf starts one-fourth of the way into pending_buf. So there are * three bytes in sym_buf for every four bytes in pending_buf. Each symbol * in sym_buf is three bytes -- two for the distance and one for the * literal/length. As each symbol is consumed, the pointer to the next * sym_buf value to read moves forward three bytes. From that symbol, up to * 31 bits are written to pending_buf. The closest the written pending_buf * bits gets to the next sym_buf symbol to read is just before the last * code is written. At that time, 31*(n - 2) bits have been written, just * after 24*(n - 2) bits have been consumed from sym_buf. sym_buf starts at * 8*n bits into pending_buf. (Note that the symbol buffer fills when n - 1 * symbols are written.) The closest the writing gets to what is unread is * then n + 14 bits. Here n is lit_bufsize, which is 16384 by default, and * can range from 128 to 32768. * * Therefore, at a minimum, there are 142 bits of space between what is * written and what is read in the overlain buffers, so the symbols cannot * be overwritten by the compressed data. That space is actually 139 bits, * due to the three-bit fixed-code block header. * * That covers the case where either Z_FIXED is specified, forcing fixed * codes, or when the use of fixed codes is chosen, because that choice * results in a smaller compressed block than dynamic codes. That latter * condition then assures that the above analysis also covers all dynamic * blocks. A dynamic-code block will only be chosen to be emitted if it has * fewer bits than a fixed-code block would for the same set of symbols. * Therefore its average symbol length is assured to be less than 31. So * the compressed data for a dynamic block also cannot overwrite the * symbols from which it is being constructed. */ s->pending_buf = (uint8_t *) ZALLOC(strm, s->lit_bufsize, 4); s->pending_buf_size = (uint64_t)s->lit_bufsize * 4; if (s->window == Z_NULL || s->prev == Z_NULL || s->head == Z_NULL || s->pending_buf == Z_NULL) { s->status = FINISH_STATE; strm->msg = ERR_MSG(Z_MEM_ERROR); deflateEnd (strm); return Z_MEM_ERROR; } s->sym_buf = s->pending_buf + s->lit_bufsize; s->sym_end = (s->lit_bufsize - 1) * 3; /* We avoid equality with lit_bufsize*3 because of wraparound at 64K * on 16 bit machines and because stored blocks are restricted to * 64K-1 bytes. */ s->level = level; s->strategy = strategy; s->method = (uint8_t)method; return deflateReset(strm); } /* ========================================================================= * Check for a valid deflate stream state. Return 0 if ok, 1 if not. */ static int deflateStateCheck(z_streamp strm) { deflate_state *s; if (strm == Z_NULL || strm->zalloc == (alloc_func)0 || strm->zfree == (free_func)0) return 1; s = strm->state; if (s == Z_NULL || s->strm != strm || (s->status != INIT_STATE && s->status != EXTRA_STATE && s->status != NAME_STATE && s->status != COMMENT_STATE && s->status != HCRC_STATE && s->status != BUSY_STATE && s->status != FINISH_STATE)) return 1; return 0; } /* ========================================================================= */ int ZEXPORT deflateSetDictionary (z_streamp strm, const uint8_t *dictionary, uint32_t dictLength) { deflate_state *s; uint32_t str, n; int wrap; uint32_t avail; z_const uint8_t *next; if (deflateStateCheck(strm) || dictionary == Z_NULL) return Z_STREAM_ERROR; s = strm->state; wrap = s->wrap; if (wrap == 2 || (wrap == 1 && s->status != INIT_STATE) || s->lookahead) return Z_STREAM_ERROR; /* when using zlib wrappers, compute Adler-32 for provided dictionary */ if (wrap == 1) strm->adler = adler32(strm->adler, dictionary, dictLength); s->wrap = 0; /* avoid computing Adler-32 in read_buf */ /* if dictionary would fill window, just replace the history */ if (dictLength >= s->w_size) { if (wrap == 0) { /* already empty otherwise */ CLEAR_HASH(s); s->strstart = 0; s->block_start = 0L; s->insert = 0; } dictionary += dictLength - s->w_size; /* use the tail */ dictLength = s->w_size; } /* insert dictionary into window and hash */ avail = strm->avail_in; next = strm->next_in; strm->avail_in = dictLength; strm->next_in = (z_const uint8_t*)dictionary; fill_window(s); while (s->lookahead >= ACTUAL_MIN_MATCH) { str = s->strstart; n = s->lookahead - (ACTUAL_MIN_MATCH-1); bulk_insert_str(s, str, n); s->strstart = str + n; s->lookahead = ACTUAL_MIN_MATCH-1; fill_window(s); } s->strstart += s->lookahead; s->block_start = (long)s->strstart; s->insert = s->lookahead; s->lookahead = 0; s->match_length = s->prev_length = ACTUAL_MIN_MATCH-1; s->match_available = 0; strm->next_in = next; strm->avail_in = avail; s->wrap = wrap; return Z_OK; } /* ========================================================================= */ int ZEXPORT deflateResetKeep(z_streamp strm) { deflate_state *s; if (deflateStateCheck(strm)) { 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 = s->wrap == 2 ? crc32(0L, Z_NULL, 0) : adler32(0L, Z_NULL, 0); s->last_flush = -2; _tr_init(s); return Z_OK; } /* ========================================================================= */ int ZEXPORT deflateReset(z_streamp strm) { int ret; ret = deflateResetKeep(strm); if (ret == Z_OK) lm_init(strm->state); return ret; } /* ========================================================================= */ int ZEXPORT deflateSetHeader(z_streamp strm, gz_headerp head) { if (deflateStateCheck(strm) || strm->state->wrap != 2) return Z_STREAM_ERROR; strm->state->gzhead = head; return Z_OK; } /* ========================================================================= */ int ZEXPORT deflatePending(z_streamp strm, unsigned *pending, int *bits) { if (deflateStateCheck(strm)) return Z_STREAM_ERROR; if (pending != Z_NULL) *pending = strm->state->pending; if (bits != Z_NULL) *bits = strm->state->bi_valid; return Z_OK; } /* ========================================================================= */ int ZEXPORT deflatePrime(z_streamp strm, int bits, int value) { deflate_state *s; int put; if (deflateStateCheck(strm)) return Z_STREAM_ERROR; s = strm->state; if ((uint8_t *)(s->sym_buf) < s->pending_out + ((Buf_size + 7) >> 3)) return Z_BUF_ERROR; do { put = Buf_size - s->bi_valid; if (put > bits) put = bits; s->bi_buf |= (uint16_t)((value & ((1 << put) - 1)) << s->bi_valid); s->bi_valid += put; _tr_flush_bits(s); value >>= put; bits -= put; } while (bits); return Z_OK; } /* ========================================================================= */ int ZEXPORT deflateParams(z_streamp strm, int level, int strategy) { deflate_state *s; compress_func func; if (deflateStateCheck(strm)) return Z_STREAM_ERROR; s = strm->state; if (level == Z_DEFAULT_COMPRESSION) level = 6; if (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) && s->last_flush != -2) { /* Flush the last buffer: */ int err = deflate(strm, Z_BLOCK); if (err == Z_STREAM_ERROR) return err; if (strm->avail_in || (s->strstart - s->block_start) + s->lookahead) return Z_BUF_ERROR; } 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 Z_OK; } /* ========================================================================= */ int ZEXPORT deflateTune(z_streamp strm, int good_length, int max_lazy, int nice_length, int max_chain) { deflate_state *s; if (deflateStateCheck(strm)) 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. */ uint64_t ZEXPORT deflateBound(z_streamp strm, uint64_t sourceLen) { deflate_state *s; uint64_t complen, wraplen; uint8_t *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 (deflateStateCheck(strm)) 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. */ static void putShortMSB (deflate_state *s, uint32_t b) { put_byte(s, (uint8_t)(b >> 8)); put_byte(s, (uint8_t)(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()). */ static void flush_pending(z_streamp strm) { uint32_t len; deflate_state *s = strm->state; _tr_flush_bits(s); len = s->pending; if (len > strm->avail_out) len = strm->avail_out; if (len == 0) return; zmemcpy(strm->next_out, s->pending_out, len); strm->next_out += len; s->pending_out += len; strm->total_out += len; strm->avail_out -= len; s->pending -= len; if (s->pending == 0) { s->pending_out = s->pending_buf; } } /* ========================================================================= */ int ZEXPORT deflate(z_streamp strm, int flush) { int old_flush; /* value of flush param for previous deflate call */ deflate_state *s; if (deflateStateCheck(strm) || flush > Z_BLOCK || flush < 0) { return Z_STREAM_ERROR; } s = strm->state; if (strm->next_out == Z_NULL || (strm->avail_in != 0 && strm->next_in == Z_NULL) || (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) { if (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, (uint8_t)(s->gzhead->time & 0xff)); put_byte(s, (uint8_t)((s->gzhead->time >> 8) & 0xff)); put_byte(s, (uint8_t)((s->gzhead->time >> 16) & 0xff)); put_byte(s, (uint8_t)((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 { uint32_t header = (Z_DEFLATED + ((s->w_bits-8)<<4)) << 8; uint32_t 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; else level_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, (uint32_t)(strm->adler >> 16)); putShortMSB(s, (uint32_t)(strm->adler & 0xffff)); } strm->adler = adler32(0L, Z_NULL, 0); } } if (s->status == EXTRA_STATE) { if (s->gzhead->extra != Z_NULL) { uint32_t 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; } } else s->status = NAME_STATE; } if (s->status == NAME_STATE) { if (s->gzhead->name != Z_NULL) { uint32_t 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; } } else s->status = COMMENT_STATE; } if (s->status == COMMENT_STATE) { if (s->gzhead->comment != Z_NULL) { uint32_t 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; } else s->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, (uint8_t)(strm->adler & 0xff)); put_byte(s, (uint8_t)((strm->adler >> 8) & 0xff)); strm->adler = crc32(0L, Z_NULL, 0); s->status = BUSY_STATE; } } else s->status = BUSY_STATE; } /* 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 && RANK(flush) <= RANK(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->level == 0 ? deflate_stored(s, flush) : 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, (uint8_t*)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; s->insert = 0; } } } 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 */ if (s->wrap == 2) { put_byte(s, (uint8_t)(strm->adler & 0xff)); put_byte(s, (uint8_t)((strm->adler >> 8) & 0xff)); put_byte(s, (uint8_t)((strm->adler >> 16) & 0xff)); put_byte(s, (uint8_t)((strm->adler >> 24) & 0xff)); put_byte(s, (uint8_t)(strm->total_in & 0xff)); put_byte(s, (uint8_t)((strm->total_in >> 8) & 0xff)); put_byte(s, (uint8_t)((strm->total_in >> 16) & 0xff)); put_byte(s, (uint8_t)((strm->total_in >> 24) & 0xff)); } else { putShortMSB(s, (uint32_t)(strm->adler >> 16)); putShortMSB(s, (uint32_t)(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(z_streamp strm) { int status; if (deflateStateCheck(strm)) return Z_STREAM_ERROR; status = strm->state->status; /* 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(z_streamp dest, z_streamp source) { deflate_state *ds; deflate_state *ss; if (deflateStateCheck(source) || dest == Z_NULL) { return Z_STREAM_ERROR; } ss = source->state; zmemcpy((voidpf)dest, (voidpf)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 *) ds; zmemcpy((voidpf)ds, (voidpf)ss, sizeof(deflate_state)); ds->strm = dest; ds->window = (uint8_t *) ZALLOC(dest, ds->w_size, 2*sizeof(uint8_t)); ds->prev = (Pos *) ZALLOC(dest, ds->w_size, sizeof(Pos)); ds->head = (Pos *) ZALLOC(dest, ds->hash_size, sizeof(Pos)); ds->pending_buf = (uint8_t *) ZALLOC(dest, ds->lit_bufsize, sizeof(uint16_t)+2); 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(uint8_t)); zmemcpy((voidpf)ds->prev, (voidpf)ss->prev, ds->w_size * sizeof(Pos)); zmemcpy((voidpf)ds->head, (voidpf)ss->head, ds->hash_size * sizeof(Pos)); zmemcpy(ds->pending_buf, ss->pending_buf, (uint32_t)ds->pending_buf_size); ds->pending_out = ds->pending_buf + (ss->pending_out - ss->pending_buf); ds->sym_buf = ds->pending_buf + 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; } /* =========================================================================== * 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()). */ static int read_buf(z_streamp strm, uint8_t *buf, uint32_t size) { uint32_t len = strm->avail_in; if (len > size) len = size; if (len == 0) return 0; strm->avail_in -= len; zmemcpy(buf, strm->next_in, len); if (strm->state->wrap == 1) { strm->adler = adler32(strm->adler, buf, len); } else if (strm->state->wrap == 2) { strm->adler = crc32(strm->adler, buf, len); } strm->next_in += len; strm->total_in += len; return (int)len; } /* =========================================================================== * Initialize the "longest match" routines for a new zlib stream */ static void lm_init (deflate_state *s) { s->window_size = (uint64_t)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->insert = 0; s->match_length = s->prev_length = ACTUAL_MIN_MATCH-1; s->match_available = 0; s->ins_h = 0; } /* longest_match() with minor change to improve performance (in terms of * execution time). * * The pristine longest_match() function is sketched bellow (strip the * then-clause of the "#ifdef UNALIGNED_OK"-directive) * * ------------------------------------------------------------ * uInt longest_match(...) { * ... * do { * match = s->window + cur_match; //s0 * if (*(ushf*)(match+best_len-1) != scan_end || //s1 * *(ushf*)match != scan_start) continue; //s2 * ... * * 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); //s3 * * ... * } while(cond); //s4 * * ------------------------------------------------------------- * * The change include: * * 1) The hottest statements of the function is: s0, s1 and s4. Pull them * together to form a new loop. The benefit is two-fold: * * o. Ease the compiler to yield good code layout: the conditional-branch * corresponding to s1 and its biased target s4 become very close (likely, * fit in the same cache-line), hence improving instruction-fetching * efficiency. * * o. Ease the compiler to promote "s->window" into register. "s->window" * is loop-invariant; it is supposed to be promoted into register and keep * the value throughout the entire loop. However, there are many such * loop-invariant, and x86-family has small register file; "s->window" is * likely to be chosen as register-allocation victim such that its value * is reloaded from memory in every single iteration. By forming a new loop, * "s->window" is loop-invariant of that newly created tight loop. It is * lot easier for compiler to promote this quantity to register and keep * its value throughout the entire small loop. * * 2) Transfrom s3 such that it examines sizeof(long)-byte-match at a time. * This is done by: * ------------------------------------------------ * v1 = load from "scan" by sizeof(long) bytes * v2 = load from "match" by sizeof(lnog) bytes * v3 = v1 xor v2 * match-bit = little-endian-machine(yes-for-x86) ? * count-trailing-zero(v3) : * count-leading-zero(v3); * * match-byte = match-bit/8 * * "scan" and "match" advance if necessary * ------------------------------------------------- */ static uint32_t longest_match(deflate_state *s, IPos cur_match /* current match */) { uint32_t chain_length = s->max_chain_length; /* max hash chain length */ register uint8_t *scan = s->window + s->strstart; /* current string */ register uint8_t *match; /* matched string */ register int len; /* length of current match */ int best_len = (s->prev_length == 0) ? ACTUAL_MIN_MATCH-1 : 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. */ Pos *prev = s->prev; uint32_t wmask = s->w_mask; register uint8_t *strend = s->window + s->strstart + MAX_MATCH; /* We optimize for a minimal match of four bytes */ register uint32_t scan_start = *(uint32_t*)scan; register uint32_t scan_end = *(uint32_t*)(scan+best_len-3); /* 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 ((uint32_t)nice_match > s->lookahead) nice_match = s->lookahead; Assert((uint64_t)s->strstart <= s->window_size-MIN_LOOKAHEAD, "need lookahead"); do { int cont ; Assert(cur_match < s->strstart, "no future"); /* 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. */ cont = 1; do { match = s->window + cur_match; if (likely(*(uint32_t*)(match+best_len-3) != scan_end) || (*(uint32_t*)match != scan_start)) { if ((cur_match = prev[cur_match & wmask]) > limit && --chain_length != 0) { continue; } else cont = 0; } break; } while (1); if (!cont) break; scan += 4, match+=4; do { uint64_t sv = *(uint64_t*)(void*)scan; uint64_t mv = *(uint64_t*)(void*)match; uint64_t xor = sv ^ mv; if (xor) { int match_byte = __builtin_ctzl(xor) / 8; scan += match_byte; match += match_byte; break; } else { scan += 8; match += 8; } } while (scan < strend); if (scan > strend) scan = strend; Assert(scan <= s->window+(uint32_t)(s->window_size-1), "wild scan"); len = MAX_MATCH - (int)(strend - scan); scan = strend - MAX_MATCH; if (len > best_len) { s->match_start = cur_match; best_len = len; if (len >= nice_match) break; scan_end = *(uint32_t*)(scan+best_len-3); } } while ((cur_match = prev[cur_match & wmask]) > limit && --chain_length != 0); if ((uint32_t)best_len <= s->lookahead) return (uint32_t)best_len; return s->lookahead; } #ifdef ZLIB_DEBUG #define EQUAL 0 /* result of memcmp for equal strings */ /* =========================================================================== * Check that the match at match_start is indeed a match. */ static void check_match(deflate_state *s, IPos start, IPos 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 /* ZLIB_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). */ static void fill_window(deflate_state *s) { register uint32_t n, m; register Pos *p; uint32_t more; /* Amount of free space at the end of the window. */ uint32_t wsize = s->w_size; Assert(s->lookahead < MIN_LOOKAHEAD, "already enough lookahead"); do { more = (unsigned)(s->window_size -(uint64_t)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)) { int i; zmemcpy(s->window, s->window+wsize, (unsigned)wsize); s->match_start -= wsize; s->strstart -= wsize; s->block_start -= (int64_t) wsize; n = s->hash_size; #ifdef __aarch64__ uint16x8_t W; uint16_t *q ; W = vmovq_n_u16(wsize); q = (uint16_t*)s->head; for(i=0; iprev; for(i=0; ihead; for(i=0; iprev; for(i=0; istrm->avail_in == 0) break; /* 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 + s->insert >= ACTUAL_MIN_MATCH) { uint32_t str = s->strstart - s->insert; uint32_t ins_h = s->window[str]; while (s->insert) { ins_h = hash_func(s, &s->window[str]); s->prev[str & s->w_mask] = s->head[ins_h]; s->head[ins_h] = (Pos)str; str++; s->insert--; if (s->lookahead + s->insert < ACTUAL_MIN_MATCH) break; } s->ins_h = ins_h; } /* If the whole input has less than ACTUAL_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) { uint64_t curr = s->strstart + (ulg)(s->lookahead); uint64_t 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 < (uint64_t)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 = (uint64_t)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; } } Assert((uint64_t)s->strstart <= s->window_size - MIN_LOOKAHEAD, "not enough room for search"); } /* =========================================================================== * 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 ? \ (uint8_t *)&s->window[(uint64_t)s->block_start] : \ (uint8_t *)Z_NULL), \ (uint64_t)((int64_t)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. */ static block_state deflate_stored(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: */ uint64_t max_block_size = 0xffff; uint64_t max_start; if (max_block_size > s->pending_buf_size - 6) { max_block_size = s->pending_buf_size - 6; } /* 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 >= (int64_t)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 || (uint64_t)s->strstart >= max_start) { /* strstart == 0 is possible when wraparound on 16-bit machine */ s->lookahead = (uint32_t)(s->strstart - max_start); s->strstart = (uint32_t)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 - (uint32_t)s->block_start >= MAX_DIST(s)) { FLUSH_BLOCK(s, 0); } } s->insert = 0; if (flush == Z_FINISH) { FLUSH_BLOCK(s, 1); return finish_done; } if ((int64_t)s->strstart > s->block_start) FLUSH_BLOCK(s, 0); return 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. */ static block_state deflate_fast(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 ACTUAL_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 >= ACTUAL_MIN_MATCH) { hash_head = insert_string(s, s->strstart); } /* Find the longest match, discarding those <= prev_length. * At this point we have always match_length < ACTUAL_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 >= ACTUAL_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. */ if (s->match_length <= s->max_insert_length && s->lookahead >= ACTUAL_MIN_MATCH) { s->match_length--; /* string at strstart already in table */ do { s->strstart++; hash_head = insert_string(s, s->strstart); /* strstart never exceeds WSIZE-MAX_MATCH, so there are * always ACTUAL_MIN_MATCH bytes ahead. */ } while (--s->match_length != 0); s->strstart++; } else { s->strstart += s->match_length; s->match_length = 0; /* If lookahead < ACTUAL_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); } s->insert = s->strstart < ACTUAL_MIN_MATCH-1 ? s->strstart : ACTUAL_MIN_MATCH-1; if (flush == Z_FINISH) { FLUSH_BLOCK(s, 1); return finish_done; } if (s->sym_next) FLUSH_BLOCK(s, 0); return block_done; } /* =========================================================================== * 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. */ static block_state deflate_slow(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 ACTUAL_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+3] in the * dictionary, and set hash_head to the head of the hash chain: */ hash_head = NIL; if (s->lookahead >= ACTUAL_MIN_MATCH) { hash_head = insert_string(s, s->strstart); } /* Find the longest match, discarding those <= prev_length. */ s->prev_length = s->match_length, s->prev_match = s->match_start; s->match_length = ACTUAL_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 prev_match is also ACTUAL_MIN_MATCH, match_start is garbage * but we will ignore the current match anyway. */ s->match_length = ACTUAL_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 >= ACTUAL_MIN_MATCH && s->match_length <= s->prev_length) { uint32_t mov_fwd ; uint32_t insert_cnt ; uint32_t max_insert = s->strstart + s->lookahead - ACTUAL_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; mov_fwd = s->prev_length - 2; insert_cnt = mov_fwd; if (unlikely(insert_cnt > max_insert - s->strstart)) insert_cnt = max_insert - s->strstart; bulk_insert_str(s, s->strstart + 1, insert_cnt); s->prev_length = ACTUAL_MIN_MATCH-1; s->match_available = 0; s->match_length = ACTUAL_MIN_MATCH-1; s->strstart += mov_fwd + 1; 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; } s->insert = s->strstart < ACTUAL_MIN_MATCH-1 ? s->strstart : ACTUAL_MIN_MATCH-1; if (flush == Z_FINISH) { FLUSH_BLOCK(s, 1); return finish_done; } if (s->sym_next) FLUSH_BLOCK(s, 0); return block_done; } /* =========================================================================== * 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.) */ static block_state deflate_rle(deflate_state *s, int flush) { int bflush; /* set if current block must be flushed */ uint32_t prev; /* byte at distance one to match */ uint8_t *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 run, plus one for the unrolled loop. */ 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 >= ACTUAL_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; } Assert(scan <= s->window+(uint32_t)(s->window_size-1), "wild scan"); } /* Emit match if have run of ACTUAL_MIN_MATCH or longer, else emit literal */ if (s->match_length >= ACTUAL_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); } s->insert = 0; if (flush == Z_FINISH) { FLUSH_BLOCK(s, 1); return finish_done; } if (s->sym_next) FLUSH_BLOCK(s, 0); return 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.) */ static block_state deflate_huff(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); } s->insert = 0; if (flush == Z_FINISH) { FLUSH_BLOCK(s, 1); return finish_done; } if (s->sym_next) FLUSH_BLOCK(s, 0); return block_done; }