X-Git-Url: https://git.gag.com/?a=blobdiff_plain;f=deflate.c;h=951d7af4e895b2285d1617c05a4940c6b7b336b6;hb=92249085071a973e2c0621b0415b93d2e48bb00d;hp=bb8a749ac5a08dabd589cbd999f9b2a3f6dddfba;hpb=1bbb35416d8da71e8146a4cb4f2dbab7b24cff39;p=debian%2Fgzip diff --git a/deflate.c b/deflate.c index bb8a749..951d7af 100644 --- a/deflate.c +++ b/deflate.c @@ -1,6 +1,6 @@ /* deflate.c -- compress data using the deflation algorithm - Copyright (C) 1999, 2006, 2009-2013 Free Software Foundation, Inc. + Copyright (C) 1999, 2006, 2009-2018 Free Software Foundation, Inc. Copyright (C) 1992-1993 Jean-loup Gailly This program is free software; you can redistribute it and/or modify @@ -80,6 +80,7 @@ #include "tailor.h" #include "gzip.h" #include "lzw.h" /* just for consistency checking */ +#include "verify.h" /* =========================================================================== * Configuration parameters @@ -132,11 +133,11 @@ /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */ #ifndef RSYNC_WIN -# define RSYNC_WIN 8192 +# define RSYNC_WIN 4096 #endif -/* Size of rsync window, must be < MAX_DIST */ +verify(RSYNC_WIN < MAX_DIST); -#define RSYNC_SUM_MATCH(sum) (((sum) & (RSYNC_WIN - 1)) == 0) +#define RSYNC_SUM_MATCH(sum) ((sum) % RSYNC_WIN == 0) /* Whether window sum matches magic value */ /* =========================================================================== @@ -317,7 +318,7 @@ void lm_init (pack_level, flags) compr_level = pack_level; /* Initialize the hash table. */ -#if defined(MAXSEG_64K) && HASH_BITS == 15 +#if defined MAXSEG_64K && HASH_BITS == 15 for (j = 0; j < HASH_SIZE; j++) head[j] = NIL; #else memzero((char*)head, HASH_SIZE*sizeof(*head)); @@ -428,7 +429,7 @@ longest_match(IPos 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) +#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. */ @@ -564,8 +565,8 @@ local void fill_window() memcpy((char*)window, (char*)window+WSIZE, (unsigned)WSIZE); match_start -= WSIZE; strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */ - if (rsync_chunk_end != 0xFFFFFFFFUL) - rsync_chunk_end -= WSIZE; + if (rsync_chunk_end != 0xFFFFFFFFUL) + rsync_chunk_end -= WSIZE; block_start -= (long) WSIZE; @@ -595,28 +596,31 @@ local void fill_window() } } -local void rsync_roll(unsigned start, unsigned num) +/* With an initial offset of START, advance rsync's rolling checksum + by NUM bytes. */ +local void rsync_roll(unsigned int start, unsigned int num) { unsigned i; if (start < RSYNC_WIN) { - /* before window fills. */ - for (i = start; i < RSYNC_WIN; i++) { - if (i == start + num) return; - rsync_sum += (ulg)window[i]; - } - num -= (RSYNC_WIN - start); - start = RSYNC_WIN; + /* before window fills. */ + for (i = start; i < RSYNC_WIN; i++) { + if (i == start + num) + return; + rsync_sum += (ulg)window[i]; + } + num -= (RSYNC_WIN - start); + start = RSYNC_WIN; } /* buffer after window full */ for (i = start; i < start+num; i++) { - /* New character in */ - rsync_sum += (ulg)window[i]; - /* Old character out */ - rsync_sum -= (ulg)window[i - RSYNC_WIN]; - if (rsync_chunk_end == 0xFFFFFFFFUL && RSYNC_SUM_MATCH(rsync_sum)) - rsync_chunk_end = i; + /* New character in */ + rsync_sum += (ulg)window[i]; + /* Old character out */ + rsync_sum -= (ulg)window[i - RSYNC_WIN]; + if (rsync_chunk_end == 0xFFFFFFFFUL && RSYNC_SUM_MATCH(rsync_sum)) + rsync_chunk_end = i; } } @@ -643,7 +647,7 @@ local void rsync_roll(unsigned start, unsigned num) local off_t deflate_fast() { IPos hash_head; /* head of the hash chain */ - int flush = 0; /* set if current block must be flushed, 2=>and padded */ + int flush = 0; /* set if current block must be flushed, 2=>and padded */ unsigned match_length = 0; /* length of best match */ prev_length = MIN_MATCH-1; @@ -673,8 +677,8 @@ local off_t deflate_fast() lookahead -= match_length; - RSYNC_ROLL(strstart, match_length); - /* Insert new strings in the hash table only if the match length + RSYNC_ROLL(strstart, 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 (match_length <= max_insert_length) { @@ -702,13 +706,13 @@ local off_t deflate_fast() /* No match, output a literal byte */ Tracevv((stderr,"%c",window[strstart])); flush = ct_tally (0, window[strstart]); - RSYNC_ROLL(strstart, 1); + RSYNC_ROLL(strstart, 1); lookahead--; strstart++; } if (rsync && strstart > rsync_chunk_end) { - flush = 2; rsync_chunk_end = 0xFFFFFFFFUL; + flush = 2; } if (flush) FLUSH_BLOCK(0), block_start = strstart; @@ -783,7 +787,7 @@ off_t deflate() */ lookahead -= prev_length-1; prev_length -= 2; - RSYNC_ROLL(strstart, prev_length+1); + RSYNC_ROLL(strstart, prev_length+1); do { strstart++; INSERT_STRING(strstart, hash_head); @@ -797,10 +801,10 @@ off_t deflate() match_length = MIN_MATCH-1; strstart++; - if (rsync && strstart > rsync_chunk_end) { - rsync_chunk_end = 0xFFFFFFFFUL; - flush = 2; - } + if (rsync && strstart > rsync_chunk_end) { + rsync_chunk_end = 0xFFFFFFFFUL; + flush = 2; + } if (flush) FLUSH_BLOCK(0), block_start = strstart; } else if (match_available) { /* If there was no match at the previous position, output a @@ -808,26 +812,28 @@ off_t deflate() * is longer, truncate the previous match to a single literal. */ Tracevv((stderr,"%c",window[strstart-1])); - flush = ct_tally (0, window[strstart-1]); - if (rsync && strstart > rsync_chunk_end) { - rsync_chunk_end = 0xFFFFFFFFUL; - flush = 2; - } + flush = ct_tally (0, window[strstart-1]); + if (rsync && strstart > rsync_chunk_end) { + rsync_chunk_end = 0xFFFFFFFFUL; + flush = 2; + } if (flush) FLUSH_BLOCK(0), block_start = strstart; - RSYNC_ROLL(strstart, 1); + RSYNC_ROLL(strstart, 1); strstart++; lookahead--; } else { /* There is no previous match to compare with, wait for * the next step to decide. */ - if (rsync && strstart > rsync_chunk_end) { - rsync_chunk_end = 0xFFFFFFFFUL; - flush = 2; - FLUSH_BLOCK(0), block_start = strstart; - } + if (rsync && strstart > rsync_chunk_end) { + /* Reset huffman tree */ + rsync_chunk_end = 0xFFFFFFFFUL; + flush = 2; + FLUSH_BLOCK(0), block_start = strstart; + } + match_available = 1; - RSYNC_ROLL(strstart, 1); + RSYNC_ROLL(strstart, 1); strstart++; lookahead--; }