1 /* vi: set sw=4 ts=4: */
3 * Gzip implementation for busybox
5 * Based on GNU gzip Copyright (C) 1992-1993 Jean-loup Gailly.
7 * Originally adjusted for busybox by Charles P. Wright <cpw@unix.asb.com>
8 * "this is a stripped down version of gzip I put into busybox, it does
9 * only standard in to standard out with -9 compression. It also requires
10 * the zcat module for some important functions."
12 * Adjusted further by Erik Andersen <andersen@codepoet.org> to support
13 * files as well as stdin/stdout, and to generally behave itself wrt
14 * command line handling.
16 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
18 /* TODO: full support for -v for DESKTOP
19 * "/usr/bin/gzip -v a bogus aa" should say:
20 a: 85.1% -- replaced with a.gz
21 gzip: bogus: No such file or directory
22 aa: 85.1% -- replaced with aa.gz
25 //config: bool "gzip (17 kb)"
28 //config: gzip is used to compress files.
29 //config: It's probably the most widely used UNIX compression program.
31 //config:config FEATURE_GZIP_LONG_OPTIONS
32 //config: bool "Enable long options"
34 //config: depends on GZIP && LONG_OPTS
36 //config:config GZIP_FAST
37 //config: int "Trade memory for speed (0:small,slow - 2:fast,big)"
40 //config: depends on GZIP
42 //config: Enable big memory options for gzip.
43 //config: 0: small buffers, small hash-tables
44 //config: 1: larger buffers, larger hash-tables
45 //config: 2: larger buffers, largest hash-tables
46 //config: Larger models may give slightly better compression
48 //config:config FEATURE_GZIP_LEVELS
49 //config: bool "Enable compression levels"
51 //config: depends on GZIP
53 //config: Enable support for compression levels 4-9. The default level
54 //config: is 6. If levels 1-3 are specified, 4 is used.
55 //config: If this option is not selected, -N options are ignored and -9
58 //config:config FEATURE_GZIP_DECOMPRESS
59 //config: bool "Enable decompression"
61 //config: depends on GZIP || GUNZIP || ZCAT
63 //config: Enable -d (--decompress) and -t (--test) options for gzip.
64 //config: This will be automatically selected if gunzip or zcat is
67 //applet:IF_GZIP(APPLET(gzip, BB_DIR_BIN, BB_SUID_DROP))
69 //kbuild:lib-$(CONFIG_GZIP) += gzip.o
71 //usage:#define gzip_trivial_usage
72 //usage: "[-cfk" IF_FEATURE_GZIP_DECOMPRESS("dt") IF_FEATURE_GZIP_LEVELS("123456789") "] [FILE]..."
73 //usage:#define gzip_full_usage "\n\n"
74 //usage: "Compress FILEs (or stdin)\n"
75 //usage: IF_FEATURE_GZIP_LEVELS(
76 //usage: "\n -1..9 Compression level"
78 //usage: IF_FEATURE_GZIP_DECOMPRESS(
79 //usage: "\n -d Decompress"
80 //usage: "\n -t Test file integrity"
82 //usage: "\n -c Write to stdout"
83 //usage: "\n -f Force"
84 //usage: "\n -k Keep input files"
86 //usage:#define gzip_example_usage
87 //usage: "$ ls -la /tmp/busybox*\n"
88 //usage: "-rw-rw-r-- 1 andersen andersen 1761280 Apr 14 17:47 /tmp/busybox.tar\n"
89 //usage: "$ gzip /tmp/busybox.tar\n"
90 //usage: "$ ls -la /tmp/busybox*\n"
91 //usage: "-rw-rw-r-- 1 andersen andersen 554058 Apr 14 17:49 /tmp/busybox.tar.gz\n"
94 #include "bb_archive.h"
96 /* ===========================================================================
99 /* Diagnostic functions */
102 # define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); }
103 # define Trace(x) fprintf x
104 # define Tracev(x) {if (verbose) fprintf x; }
105 # define Tracevv(x) {if (verbose > 1) fprintf x; }
106 # define Tracec(c,x) {if (verbose && (c)) fprintf x; }
107 # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; }
109 # define Assert(cond,msg)
114 # define Tracecv(c,x)
117 /* ===========================================================================
119 #if CONFIG_GZIP_FAST == 0
121 #elif CONFIG_GZIP_FAST == 1
123 #elif CONFIG_GZIP_FAST == 2
126 # error "Invalid CONFIG_GZIP_FAST value"
131 # define INBUFSIZ 0x2000 /* input buffer size */
133 # define INBUFSIZ 0x8000 /* input buffer size */
139 # define OUTBUFSIZ 8192 /* output buffer size */
141 # define OUTBUFSIZ 16384 /* output buffer size */
147 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
149 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
154 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
155 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
156 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
157 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
158 #define COMMENT 0x10 /* bit 4 set: file comment present */
159 #define RESERVED 0xC0 /* bit 6,7: reserved */
161 /* internal file attribute */
162 #define UNKNOWN 0xffff
167 # define WSIZE 0x8000 /* window size--must be a power of two, and */
168 #endif /* at least 32K for zip's deflate method */
171 #define MAX_MATCH 258
172 /* The minimum and maximum match lengths */
174 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
175 /* Minimum amount of lookahead, except at the end of the input file.
176 * See deflate.c for comments about the MIN_MATCH+1.
179 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
180 /* In order to simplify the code, particularly on 16 bit machines, match
181 * distances are limited to MAX_DIST instead of WSIZE.
185 # define MAX_PATH_LEN 1024 /* max pathname length */
188 #define seekable() 0 /* force sequential output */
189 #define translate_eol 0 /* no option -a yet */
194 #define INIT_BITS 9 /* Initial number of bits per code */
196 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
197 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
198 * It's a pity that old uncompress does not check bit 0x20. That makes
199 * extension of the format actually undesirable because old compress
200 * would just crash on the new format instead of giving a meaningful
201 * error message. It does check the number of bits, but it's more
202 * helpful to say "unsupported format, get a new version" than
203 * "can only handle 16 bits".
207 # define MAX_SUFFIX MAX_EXT_CHARS
209 # define MAX_SUFFIX 30
212 /* ===========================================================================
213 * Compile with MEDIUM_MEM to reduce the memory requirements or
214 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
215 * entire input file can be held in memory (not possible on 16 bit systems).
216 * Warning: defining these symbols affects HASH_BITS (see below) and thus
217 * affects the compression ratio. The compressed output
218 * is still correct, and might even be smaller in some cases.
221 # define HASH_BITS 13 /* Number of bits used to hash strings */
224 # define HASH_BITS 14
227 # define HASH_BITS 15
228 /* For portability to 16 bit machines, do not use values above 15. */
231 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
232 #define HASH_MASK (HASH_SIZE-1)
233 #define WMASK (WSIZE-1)
234 /* HASH_SIZE and WSIZE must be powers of two */
236 # define TOO_FAR 4096
238 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
240 /* ===========================================================================
241 * These types are not really 'char', 'short' and 'long'
244 typedef uint16_t ush;
245 typedef uint32_t ulg;
249 typedef unsigned IPos;
250 /* A Pos is an index in the character window. We use short instead of int to
251 * save space in the various tables. IPos is used only for parameter passing.
255 WINDOW_SIZE = 2 * WSIZE,
256 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
257 * input file length plus MIN_LOOKAHEAD.
260 #if !ENABLE_FEATURE_GZIP_LEVELS
262 max_chain_length = 4096,
263 /* To speed up deflation, hash chains are never searched beyond this length.
264 * A higher limit improves compression ratio but degrades the speed.
267 max_lazy_match = 258,
268 /* Attempt to find a better match only when the current match is strictly
269 * smaller than this value. This mechanism is used only for compression
273 max_insert_length = max_lazy_match,
274 /* Insert new strings in the hash table only if the match length
275 * is not greater than this length. This saves time but degrades compression.
276 * max_insert_length is used only for compression levels <= 3.
280 /* Use a faster search when the previous match is longer than this */
282 /* Values for max_lazy_match, good_match and max_chain_length, depending on
283 * the desired pack level (0..9). The values given below have been tuned to
284 * exclude worst case performance for pathological files. Better values may be
285 * found for specific files.
288 nice_match = 258, /* Stop searching when current match exceeds this */
289 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
290 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
293 #endif /* ENABLE_FEATURE_GZIP_LEVELS */
297 /* =========================================================================== */
298 /* global buffers, allocated once */
300 #define DECLARE(type, array, size) \
302 #define ALLOC(type, array, size) \
303 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type))
304 #define FREE(array) \
305 do { free(array); array = NULL; } while (0)
307 /* buffer for literals or lengths */
308 /* DECLARE(uch, l_buf, LIT_BUFSIZE); */
309 DECLARE(uch, l_buf, INBUFSIZ);
311 DECLARE(ush, d_buf, DIST_BUFSIZE);
312 DECLARE(uch, outbuf, OUTBUFSIZ);
314 /* Sliding window. Input bytes are read into the second half of the window,
315 * and move to the first half later to keep a dictionary of at least WSIZE
316 * bytes. With this organization, matches are limited to a distance of
317 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
318 * performed with a length multiple of the block size. Also, it limits
319 * the window size to 64K, which is quite useful on MSDOS.
320 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
321 * be less efficient).
323 DECLARE(uch, window, 2L * WSIZE);
325 /* Link to older string with same hash index. To limit the size of this
326 * array to 64K, this link is maintained only for the last 32K strings.
327 * An index in this array is thus a window index modulo 32K.
329 /* DECLARE(Pos, prev, WSIZE); */
330 DECLARE(ush, prev, 1L << BITS);
332 /* Heads of the hash chains or 0. */
333 /* DECLARE(Pos, head, 1<<HASH_BITS); */
334 #define head (G1.prev + WSIZE) /* hash head (see deflate.c) */
336 #if ENABLE_FEATURE_GZIP_LEVELS
337 unsigned max_chain_length;
338 unsigned max_lazy_match;
341 #define max_chain_length (G1.max_chain_length)
342 #define max_lazy_match (G1.max_lazy_match)
343 #define good_match (G1.good_match)
344 #define nice_match (G1.nice_match)
347 /* =========================================================================== */
348 /* all members below are zeroed out in pack_gzip() for each next file */
350 uint32_t crc; /* shift register contents */
351 /*uint32_t *crc_32_tab;*/
353 /* window position at the beginning of the current output block. Gets
354 * negative when the window is moved backwards.
358 unsigned ins_h; /* hash index of string to be inserted */
360 /* Number of bits by which ins_h and del_h must be shifted at each
361 * input step. It must be such that after MIN_MATCH steps, the oldest
362 * byte no longer takes part in the hash key, that is:
363 * H_SHIFT * MIN_MATCH >= HASH_BITS
365 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
367 /* Length of the best match at previous step. Matches not greater than this
368 * are discarded. This is used in the lazy match evaluation.
370 unsigned prev_length;
372 unsigned strstart; /* start of string to insert */
373 unsigned match_start; /* start of matching string */
374 unsigned lookahead; /* number of valid bytes ahead in window */
376 /* number of input bytes */
377 ulg isize; /* only 32 bits stored in .gz file */
379 /* bbox always use stdin/stdout */
380 #define ifd STDIN_FILENO /* input file descriptor */
381 #define ofd STDOUT_FILENO /* output file descriptor */
384 unsigned insize; /* valid bytes in l_buf */
386 unsigned outcnt; /* bytes in output buffer */
387 smallint eofile; /* flag set at end of input file */
389 /* ===========================================================================
390 * Local data used by the "bit string" routines.
393 /* Output buffer. bits are inserted starting at the bottom (least significant
396 unsigned bi_buf; /* was unsigned short */
399 #define BUF_SIZE (int)(8 * sizeof(G1.bi_buf))
401 /* Number of bits used within bi_buf. (bi_buf might be implemented on
402 * more than 16 bits on some systems.)
407 ulg bits_sent; /* bit length of the compressed data */
408 # define DEBUG_bits_sent(v) (void)(G1.bits_sent v)
410 # define DEBUG_bits_sent(v) ((void)0)
414 #define G1 (*(ptr_to_globals - 1))
416 /* ===========================================================================
417 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
418 * (used for the compressed data only)
420 static void flush_outbuf(void)
425 xwrite(ofd, (char *) G1.outbuf, G1.outcnt);
429 /* ===========================================================================
431 /* put_8bit is used for the compressed output */
432 #define put_8bit(c) \
434 G1.outbuf[G1.outcnt++] = (c); \
435 if (G1.outcnt == OUTBUFSIZ) \
439 /* Output a 16 bit value, lsb first */
440 static void put_16bit(ush w)
442 /* GCC 4.2.1 won't optimize out redundant loads of G1.outcnt
443 * (probably because of fear of aliasing with G1.outbuf[]
444 * stores), do it explicitly:
446 unsigned outcnt = G1.outcnt;
447 uch *dst = &G1.outbuf[outcnt];
449 #if BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN
450 if (outcnt < OUTBUFSIZ-2) {
452 ush *dst16 = (void*) dst;
453 *dst16 = w; /* unaligned LSB 16-bit store */
454 G1.outcnt = outcnt + 2;
459 G1.outcnt = ++outcnt;
463 if (outcnt < OUTBUFSIZ-2) {
466 G1.outcnt = outcnt + 2;
469 G1.outcnt = ++outcnt;
472 /* Slowpath: we will need to do flush_outbuf() */
473 if (outcnt == OUTBUFSIZ)
474 flush_outbuf(); /* here */
475 put_8bit(w); /* or here */
478 #define OPTIMIZED_PUT_32BIT (CONFIG_GZIP_FAST > 0 && BB_UNALIGNED_MEMACCESS_OK && BB_LITTLE_ENDIAN)
479 static void put_32bit(ulg n)
481 if (OPTIMIZED_PUT_32BIT) {
482 unsigned outcnt = G1.outcnt;
483 if (outcnt < OUTBUFSIZ-4) {
485 ulg *dst32 = (void*) &G1.outbuf[outcnt];
486 *dst32 = n; /* unaligned LSB 32-bit store */
487 //bb_error_msg("%p", dst32); // store alignment debugging
488 G1.outcnt = outcnt + 4;
495 static ALWAYS_INLINE void flush_outbuf_if_32bit_optimized(void)
497 /* If put_32bit() performs 32bit stores && it is used in send_bits() */
498 if (OPTIMIZED_PUT_32BIT && BUF_SIZE > 16)
502 /* ===========================================================================
503 * Run a set of bytes through the crc shift register. If s is a NULL
504 * pointer, then initialize the crc shift register contents instead.
505 * Return the current crc in either case.
507 static void updcrc(uch * s, unsigned n)
509 G1.crc = crc32_block_endian0(G1.crc, s, n, global_crc32_table /*G1.crc_32_tab*/);
512 /* ===========================================================================
513 * Read a new buffer from the current input file, perform end-of-line
514 * translation, and update the crc and input file size.
515 * IN assertion: size >= 2 (for end-of-line translation)
517 static unsigned file_read(void *buf, unsigned size)
521 Assert(G1.insize == 0, "l_buf not empty");
523 len = safe_read(ifd, buf, size);
524 if (len == (unsigned)(-1) || len == 0)
532 /* ===========================================================================
533 * Send a value on a given number of bits.
534 * IN assertion: length <= 16 and value fits in length bits.
536 static void send_bits(unsigned value, unsigned length)
541 Tracev((stderr, " l %2d v %4x ", length, value));
542 Assert(length > 0 && length <= 15, "invalid length");
543 DEBUG_bits_sent(+= length);
545 BUILD_BUG_ON(BUF_SIZE != 32 && BUF_SIZE != 16);
547 new_buf = G1.bi_buf | (value << G1.bi_valid);
548 /* NB: the above may sometimes do "<< 32" shift (undefined)
549 * if check below is changed to "length > BUF_SIZE" instead of >= */
550 length += G1.bi_valid;
552 /* If bi_buf is full */
553 if (length >= BUF_SIZE) {
554 /* ...use (valid) bits from bi_buf and
555 * (BUF_SIZE - bi_valid) bits from value,
556 * leaving (width - (BUF_SIZE-bi_valid)) unused bits in value.
558 value >>= (BUF_SIZE - G1.bi_valid);
559 if (BUF_SIZE == 32) {
568 G1.bi_valid = length;
571 /* ===========================================================================
572 * Reverse the first len bits of a code, using straightforward code (a faster
573 * method would use a table)
574 * IN assertion: 1 <= len <= 15
576 static unsigned bi_reverse(unsigned code, int len)
582 if (--len <= 0) return res;
588 /* ===========================================================================
589 * Write out any remaining bits in an incomplete byte.
591 static void bi_windup(void)
593 unsigned bits = G1.bi_buf;
594 int cnt = G1.bi_valid;
603 DEBUG_bits_sent(= (G1.bits_sent + 7) & ~7);
606 /* ===========================================================================
607 * Copy a stored block to the zip file, storing first the length and its
608 * one's complement if requested.
610 static void copy_block(char *buf, unsigned len, int header)
612 bi_windup(); /* align on byte boundary */
615 unsigned v = ((uint16_t)len) | ((~len) << 16);
617 DEBUG_bits_sent(+= 2 * 16);
619 DEBUG_bits_sent(+= (ulg) len << 3);
623 /* The above can 32-bit misalign outbuf */
624 if (G1.outcnt & 3) /* syscalls are expensive, is it really misaligned? */
625 flush_outbuf_if_32bit_optimized();
628 /* ===========================================================================
629 * Fill the window when the lookahead becomes insufficient.
630 * Updates strstart and lookahead, and sets eofile if end of input file.
631 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
632 * OUT assertions: at least one byte has been read, or eofile is set;
633 * file reads are performed for at least two bytes (required for the
634 * translate_eol option).
636 static void fill_window(void)
639 unsigned more = WINDOW_SIZE - G1.lookahead - G1.strstart;
640 /* Amount of free space at the end of the window. */
642 /* If the window is almost full and there is insufficient lookahead,
643 * move the upper half to the lower one to make room in the upper half.
645 if (more == (unsigned) -1) {
646 /* Very unlikely, but possible on 16 bit machine if strstart == 0
647 * and lookahead == 1 (input done one byte at time)
650 } else if (G1.strstart >= WSIZE + MAX_DIST) {
651 /* By the IN assertion, the window is not empty so we can't confuse
652 * more == 0 with more == 64K on a 16 bit machine.
654 Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
656 memcpy(G1.window, G1.window + WSIZE, WSIZE);
657 G1.match_start -= WSIZE;
658 G1.strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
660 G1.block_start -= WSIZE;
662 for (n = 0; n < HASH_SIZE; n++) {
664 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
666 for (n = 0; n < WSIZE; n++) {
668 G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
669 /* If n is not on any hash chain, prev[n] is garbage but
670 * its value will never be used.
675 /* At this point, more >= 2 */
677 n = file_read(G1.window + G1.strstart + G1.lookahead, more);
678 if (n == 0 || n == (unsigned) -1) {
685 /* Both users fill window with the same loop: */
686 static void fill_window_if_needed(void)
688 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
692 /* ===========================================================================
693 * Set match_start to the longest match starting at the given string and
694 * return its length. Matches shorter or equal to prev_length are discarded,
695 * in which case the result is equal to prev_length and match_start is
697 * IN assertions: cur_match is the head of the hash chain for the current
698 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
701 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
702 * match.s. The code is functionally equivalent, so you can use the C version
705 static int longest_match(IPos cur_match)
707 unsigned chain_length = max_chain_length; /* max hash chain length */
708 uch *scan = G1.window + G1.strstart; /* current string */
709 uch *match; /* matched string */
710 int len; /* length of current match */
711 int best_len = G1.prev_length; /* best match length so far */
712 IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0;
713 /* Stop when cur_match becomes <= limit. To simplify the code,
714 * we prevent matches with the string of window index 0.
717 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
718 * It is easy to get rid of this optimization if necessary.
720 #if HASH_BITS < 8 || MAX_MATCH != 258
721 # error Code too clever
723 uch *strend = G1.window + G1.strstart + MAX_MATCH;
724 uch scan_end1 = scan[best_len - 1];
725 uch scan_end = scan[best_len];
727 /* Do not waste too much time if we already have a good match: */
728 if (G1.prev_length >= good_match) {
731 Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
734 Assert(cur_match < G1.strstart, "no future");
735 match = G1.window + cur_match;
737 /* Skip to next match if the match length cannot increase
738 * or if the match length is less than 2:
740 if (match[best_len] != scan_end
741 || match[best_len - 1] != scan_end1
742 || *match != *scan || *++match != scan[1]
747 /* The check at best_len-1 can be removed because it will be made
748 * again later. (This heuristic is not always a win.)
749 * It is not necessary to compare scan[2] and match[2] since they
750 * are always equal when the other bytes match, given that
751 * the hash keys are equal and that HASH_BITS >= 8.
755 /* We check for insufficient lookahead only every 8th comparison;
756 * the 256th check will be made at strstart+258.
759 } while (*++scan == *++match && *++scan == *++match &&
760 *++scan == *++match && *++scan == *++match &&
761 *++scan == *++match && *++scan == *++match &&
762 *++scan == *++match && *++scan == *++match && scan < strend);
764 len = MAX_MATCH - (int) (strend - scan);
765 scan = strend - MAX_MATCH;
767 if (len > best_len) {
768 G1.match_start = cur_match;
770 if (len >= nice_match)
772 scan_end1 = scan[best_len - 1];
773 scan_end = scan[best_len];
775 } while ((cur_match = G1.prev[cur_match & WMASK]) > limit
776 && --chain_length != 0);
782 /* ===========================================================================
783 * Check that the match at match_start is indeed a match.
785 static void check_match(IPos start, IPos match, int length)
787 /* check that the match is indeed a match */
788 if (memcmp(G1.window + match, G1.window + start, length) != 0) {
789 bb_error_msg(" start %d, match %d, length %d", start, match, length);
790 bb_error_msg("invalid match");
793 bb_error_msg("\\[%d,%d]", start - match, length);
795 bb_putchar_stderr(G1.window[start++]);
796 } while (--length != 0);
800 # define check_match(start, match, length) ((void)0)
804 /* trees.c -- output deflated data using Huffman coding
805 * Copyright (C) 1992-1993 Jean-loup Gailly
806 * This is free software; you can redistribute it and/or modify it under the
807 * terms of the GNU General Public License, see the file COPYING.
811 * Encode various sets of source values using variable-length
815 * The PKZIP "deflation" process uses several Huffman trees. The more
816 * common source values are represented by shorter bit sequences.
818 * Each code tree is stored in the ZIP file in a compressed form
819 * which is itself a Huffman encoding of the lengths of
820 * all the code strings (in ascending order by source values).
821 * The actual code strings are reconstructed from the lengths in
822 * the UNZIP process, as described in the "application note"
823 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
827 * Data Compression: Techniques and Applications, pp. 53-55.
828 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
831 * Data Compression: Methods and Theory, pp. 49-50.
832 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
836 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
840 * Allocate the match buffer, initialize the various tables [and save
841 * the location of the internal file attribute (ascii/binary) and
842 * method (DEFLATE/STORE) -- deleted in bbox]
844 * void ct_tally(int dist, int lc);
845 * Save the match info and tally the frequency counts.
847 * ulg flush_block(char *buf, ulg stored_len, int eof)
848 * Determine the best encoding for the current block: dynamic trees,
849 * static trees or store, and output the encoded block to the zip
850 * file. Returns the total compressed length for the file so far.
854 /* All codes must not exceed MAX_BITS bits */
856 #define MAX_BL_BITS 7
857 /* Bit length codes must not exceed MAX_BL_BITS bits */
859 #define LENGTH_CODES 29
860 /* number of length codes, not counting the special END_BLOCK code */
863 /* number of literal bytes 0..255 */
865 #define END_BLOCK 256
866 /* end of block literal code */
868 #define L_CODES (LITERALS+1+LENGTH_CODES)
869 /* number of Literal or Length codes, including the END_BLOCK code */
872 /* number of distance codes */
875 /* number of codes used to transfer the bit lengths */
877 /* extra bits for each length code */
878 static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = {
879 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
883 /* extra bits for each distance code */
884 static const uint8_t extra_dbits[D_CODES] ALIGN1 = {
885 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
886 10, 10, 11, 11, 12, 12, 13, 13
889 /* extra bits for each bit length code */
890 static const uint8_t extra_blbits[BL_CODES] ALIGN1 = {
891 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
893 /* number of codes at each bit length for an optimal tree */
894 static const uint8_t bl_order[BL_CODES] ALIGN1 = {
895 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
897 #define STORED_BLOCK 0
898 #define STATIC_TREES 1
900 /* The three kinds of block type */
904 # define LIT_BUFSIZE 0x2000
907 # define LIT_BUFSIZE 0x4000
909 # define LIT_BUFSIZE 0x8000
914 # define DIST_BUFSIZE LIT_BUFSIZE
916 /* Sizes of match buffers for literals/lengths and distances. There are
917 * 4 reasons for limiting LIT_BUFSIZE to 64K:
918 * - frequencies can be kept in 16 bit counters
919 * - if compression is not successful for the first block, all input data is
920 * still in the window so we can still emit a stored block even when input
921 * comes from standard input. (This can also be done for all blocks if
922 * LIT_BUFSIZE is not greater than 32K.)
923 * - if compression is not successful for a file smaller than 64K, we can
924 * even emit a stored file instead of a stored block (saving 5 bytes).
925 * - creating new Huffman trees less frequently may not provide fast
926 * adaptation to changes in the input data statistics. (Take for
927 * example a binary file with poorly compressible code followed by
928 * a highly compressible string table.) Smaller buffer sizes give
929 * fast adaptation but have of course the overhead of transmitting trees
931 * - I can't count above 4
932 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
933 * memory at the expense of compression). Some optimizations would be possible
934 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
937 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
939 /* repeat a zero length 3-10 times (3 bits of repeat count) */
940 #define REPZ_11_138 18
941 /* repeat a zero length 11-138 times (7 bits of repeat count) */
943 /* ===========================================================================
945 /* Data structure describing a single value and its code string. */
946 typedef struct ct_data {
948 ush freq; /* frequency count */
949 ush code; /* bit string */
952 ush dad; /* father node in Huffman tree */
953 ush len; /* length of bit string */
962 #define HEAP_SIZE (2*L_CODES + 1)
963 /* maximum heap size */
965 typedef struct tree_desc {
966 ct_data *dyn_tree; /* the dynamic tree */
967 ct_data *static_tree; /* corresponding static tree or NULL */
968 const uint8_t *extra_bits; /* extra bits for each code or NULL */
969 int extra_base; /* base index for extra_bits */
970 int elems; /* max number of elements in the tree */
971 int max_length; /* max bit length for the codes */
972 int max_code; /* largest code with non zero frequency */
977 ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
978 int heap_len; /* number of elements in the heap */
979 int heap_max; /* element of largest frequency */
981 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
982 * The same heap array is used to build all trees.
985 ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
986 ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
988 ct_data static_ltree[L_CODES + 2];
990 /* The static literal tree. Since the bit lengths are imposed, there is no
991 * need for the L_CODES extra codes used during heap construction. However
992 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
996 ct_data static_dtree[D_CODES];
998 /* The static distance tree. (Actually a trivial tree since all codes use
1002 ct_data bl_tree[2 * BL_CODES + 1];
1004 /* Huffman tree for the bit lengths */
1010 ush bl_count[MAX_BITS + 1];
1012 /* The lengths of the bit length codes are sent in order of decreasing
1013 * probability, to avoid transmitting the lengths for unused bit length codes.
1016 uch depth[2 * L_CODES + 1];
1018 /* Depth of each subtree used as tie breaker for trees of equal frequency */
1020 uch length_code[MAX_MATCH - MIN_MATCH + 1];
1022 /* length code for each normalized match length (0 == MIN_MATCH) */
1026 /* distance codes. The first 256 values correspond to the distances
1027 * 3 .. 258, the last 256 values correspond to the top 8 bits of
1028 * the 15 bit distances.
1031 int base_length[LENGTH_CODES];
1033 /* First normalized length for each code (0 = MIN_MATCH) */
1035 int base_dist[D_CODES];
1037 /* First normalized distance for each code (0 = distance of 1) */
1039 uch flag_buf[LIT_BUFSIZE / 8];
1041 /* flag_buf is a bit array distinguishing literals from lengths in
1042 * l_buf, thus indicating the presence or absence of a distance.
1045 unsigned last_lit; /* running index in l_buf */
1046 unsigned last_dist; /* running index in d_buf */
1047 unsigned last_flags; /* running index in flag_buf */
1048 uch flags; /* current flags not yet saved in flag_buf */
1049 uch flag_bit; /* current bit used in flags */
1051 /* bits are filled in flags starting at bit 0 (least significant).
1052 * Note: these flags are overkill in the current code since we don't
1053 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
1056 ulg opt_len; /* bit length of current block with optimal trees */
1057 ulg static_len; /* bit length of current block with static trees */
1059 // ulg compressed_len; /* total bit length of compressed file */
1062 #define G2ptr ((struct globals2*)(ptr_to_globals))
1065 /* ===========================================================================
1068 /* Send a code of the given tree. c and tree must not have side effects */
1069 # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
1071 # define SEND_CODE(c, tree) \
1073 if (verbose > 1) bb_error_msg("\ncd %3d ", (c)); \
1074 send_bits(tree[c].Code, tree[c].Len); \
1078 #define D_CODE(dist) \
1079 ((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)])
1080 /* Mapping from a distance to a distance code. dist is the distance - 1 and
1081 * must not have side effects. dist_code[256] and dist_code[257] are never
1083 * The arguments must not have side effects.
1086 /* ===========================================================================
1087 * Initialize a new block.
1089 static void init_block(void)
1091 int n; /* iterates over tree elements */
1093 /* Initialize the trees. */
1094 for (n = 0; n < L_CODES; n++)
1095 G2.dyn_ltree[n].Freq = 0;
1096 for (n = 0; n < D_CODES; n++)
1097 G2.dyn_dtree[n].Freq = 0;
1098 for (n = 0; n < BL_CODES; n++)
1099 G2.bl_tree[n].Freq = 0;
1101 G2.dyn_ltree[END_BLOCK].Freq = 1;
1102 G2.opt_len = G2.static_len = 0;
1103 G2.last_lit = G2.last_dist = G2.last_flags = 0;
1108 /* ===========================================================================
1109 * Restore the heap property by moving down the tree starting at node k,
1110 * exchanging a node with the smallest of its two sons if necessary, stopping
1111 * when the heap property is re-established (each father smaller than its
1115 /* Compares to subtrees, using the tree depth as tie breaker when
1116 * the subtrees have equal frequency. This minimizes the worst case length. */
1117 #define SMALLER(tree, n, m) \
1118 (tree[n].Freq < tree[m].Freq \
1119 || (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))
1121 static void pqdownheap(ct_data * tree, int k)
1124 int j = k << 1; /* left son of k */
1126 while (j <= G2.heap_len) {
1127 /* Set j to the smallest of the two sons: */
1128 if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j]))
1131 /* Exit if v is smaller than both sons */
1132 if (SMALLER(tree, v, G2.heap[j]))
1135 /* Exchange v with the smallest son */
1136 G2.heap[k] = G2.heap[j];
1139 /* And continue down the tree, setting j to the left son of k */
1145 /* ===========================================================================
1146 * Compute the optimal bit lengths for a tree and update the total bit length
1147 * for the current block.
1148 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1149 * above are the tree nodes sorted by increasing frequency.
1150 * OUT assertions: the field len is set to the optimal bit length, the
1151 * array bl_count contains the frequencies for each bit length.
1152 * The length opt_len is updated; static_len is also updated if stree is
1155 static void gen_bitlen(tree_desc * desc)
1157 ct_data *tree = desc->dyn_tree;
1158 const uint8_t *extra = desc->extra_bits;
1159 int base = desc->extra_base;
1160 int max_code = desc->max_code;
1161 int max_length = desc->max_length;
1162 ct_data *stree = desc->static_tree;
1163 int h; /* heap index */
1164 int n, m; /* iterate over the tree elements */
1165 int bits; /* bit length */
1166 int xbits; /* extra bits */
1167 ush f; /* frequency */
1168 int overflow = 0; /* number of elements with bit length too large */
1170 for (bits = 0; bits <= MAX_BITS; bits++)
1171 G2.bl_count[bits] = 0;
1173 /* In a first pass, compute the optimal bit lengths (which may
1174 * overflow in the case of the bit length tree).
1176 tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */
1178 for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
1180 bits = tree[tree[n].Dad].Len + 1;
1181 if (bits > max_length) {
1185 tree[n].Len = (ush) bits;
1186 /* We overwrite tree[n].Dad which is no longer needed */
1189 continue; /* not a leaf node */
1191 G2.bl_count[bits]++;
1194 xbits = extra[n - base];
1196 G2.opt_len += (ulg) f *(bits + xbits);
1199 G2.static_len += (ulg) f * (stree[n].Len + xbits);
1204 Trace((stderr, "\nbit length overflow\n"));
1205 /* This happens for example on obj2 and pic of the Calgary corpus */
1207 /* Find the first bit length which could increase: */
1209 bits = max_length - 1;
1210 while (G2.bl_count[bits] == 0)
1212 G2.bl_count[bits]--; /* move one leaf down the tree */
1213 G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1214 G2.bl_count[max_length]--;
1215 /* The brother of the overflow item also moves one step up,
1216 * but this does not affect bl_count[max_length]
1219 } while (overflow > 0);
1221 /* Now recompute all bit lengths, scanning in increasing frequency.
1222 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1223 * lengths instead of fixing only the wrong ones. This idea is taken
1224 * from 'ar' written by Haruhiko Okumura.)
1226 for (bits = max_length; bits != 0; bits--) {
1227 n = G2.bl_count[bits];
1232 if (tree[m].Len != (unsigned) bits) {
1233 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
1234 G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
1242 /* ===========================================================================
1243 * Generate the codes for a given tree and bit counts (which need not be
1245 * IN assertion: the array bl_count contains the bit length statistics for
1246 * the given tree and the field len is set for all tree elements.
1247 * OUT assertion: the field code is set for all tree elements of non
1250 static void gen_codes(ct_data * tree, int max_code)
1252 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1253 ush code = 0; /* running code value */
1254 int bits; /* bit index */
1255 int n; /* code index */
1257 /* The distribution counts are first used to generate the code values
1258 * without bit reversal.
1260 for (bits = 1; bits <= MAX_BITS; bits++) {
1261 next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1;
1263 /* Check that the bit counts in bl_count are consistent. The last code
1266 Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1267 "inconsistent bit counts");
1268 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1270 for (n = 0; n <= max_code; n++) {
1271 int len = tree[n].Len;
1275 /* Now reverse the bits */
1276 tree[n].Code = bi_reverse(next_code[len]++, len);
1278 Tracec(tree != G2.static_ltree,
1279 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1280 (n > ' ' ? n : ' '), len, tree[n].Code,
1281 next_code[len] - 1));
1285 /* ===========================================================================
1286 * Construct one Huffman tree and assigns the code bit strings and lengths.
1287 * Update the total bit length for the current block.
1288 * IN assertion: the field freq is set for all tree elements.
1289 * OUT assertions: the fields len and code are set to the optimal bit length
1290 * and corresponding code. The length opt_len is updated; static_len is
1291 * also updated if stree is not null. The field max_code is set.
1294 /* Remove the smallest element from the heap and recreate the heap with
1295 * one less element. Updates heap and heap_len. */
1298 /* Index within the heap array of least frequent node in the Huffman tree */
1300 #define PQREMOVE(tree, top) \
1302 top = G2.heap[SMALLEST]; \
1303 G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \
1304 pqdownheap(tree, SMALLEST); \
1307 static void build_tree(tree_desc * desc)
1309 ct_data *tree = desc->dyn_tree;
1310 ct_data *stree = desc->static_tree;
1311 int elems = desc->elems;
1312 int n, m; /* iterate over heap elements */
1313 int max_code = -1; /* largest code with non zero frequency */
1314 int node = elems; /* next internal node of the tree */
1316 /* Construct the initial heap, with least frequent element in
1317 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1318 * heap[0] is not used.
1321 G2.heap_max = HEAP_SIZE;
1323 for (n = 0; n < elems; n++) {
1324 if (tree[n].Freq != 0) {
1325 G2.heap[++G2.heap_len] = max_code = n;
1332 /* The pkzip format requires that at least one distance code exists,
1333 * and that at least one bit should be sent even if there is only one
1334 * possible code. So to avoid special checks later on we force at least
1335 * two codes of non zero frequency.
1337 while (G2.heap_len < 2) {
1338 int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0);
1344 G2.static_len -= stree[new].Len;
1345 /* new is 0 or 1 so it does not have extra bits */
1347 desc->max_code = max_code;
1349 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1350 * establish sub-heaps of increasing lengths:
1352 for (n = G2.heap_len / 2; n >= 1; n--)
1353 pqdownheap(tree, n);
1355 /* Construct the Huffman tree by repeatedly combining the least two
1359 PQREMOVE(tree, n); /* n = node of least frequency */
1360 m = G2.heap[SMALLEST]; /* m = node of next least frequency */
1362 G2.heap[--G2.heap_max] = n; /* keep the nodes sorted by frequency */
1363 G2.heap[--G2.heap_max] = m;
1365 /* Create a new node father of n and m */
1366 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1367 G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1;
1368 tree[n].Dad = tree[m].Dad = (ush) node;
1370 if (tree == G2.bl_tree) {
1371 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1372 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1375 /* and insert the new node in the heap */
1376 G2.heap[SMALLEST] = node++;
1377 pqdownheap(tree, SMALLEST);
1378 } while (G2.heap_len >= 2);
1380 G2.heap[--G2.heap_max] = G2.heap[SMALLEST];
1382 /* At this point, the fields freq and dad are set. We can now
1383 * generate the bit lengths.
1385 gen_bitlen((tree_desc *) desc);
1387 /* The field len is now set, we can generate the bit codes */
1388 gen_codes((ct_data *) tree, max_code);
1391 /* ===========================================================================
1392 * Scan a literal or distance tree to determine the frequencies of the codes
1393 * in the bit length tree. Updates opt_len to take into account the repeat
1394 * counts. (The contribution of the bit length codes will be added later
1395 * during the construction of bl_tree.)
1397 static void scan_tree(ct_data * tree, int max_code)
1399 int n; /* iterates over all tree elements */
1400 int prevlen = -1; /* last emitted length */
1401 int curlen; /* length of current code */
1402 int nextlen = tree[0].Len; /* length of next code */
1403 int count = 0; /* repeat count of the current code */
1404 int max_count = 7; /* max repeat count */
1405 int min_count = 4; /* min repeat count */
1411 tree[max_code + 1].Len = 0xffff; /* guard */
1413 for (n = 0; n <= max_code; n++) {
1415 nextlen = tree[n + 1].Len;
1416 if (++count < max_count && curlen == nextlen)
1419 if (count < min_count) {
1420 G2.bl_tree[curlen].Freq += count;
1421 } else if (curlen != 0) {
1422 if (curlen != prevlen)
1423 G2.bl_tree[curlen].Freq++;
1424 G2.bl_tree[REP_3_6].Freq++;
1425 } else if (count <= 10) {
1426 G2.bl_tree[REPZ_3_10].Freq++;
1428 G2.bl_tree[REPZ_11_138].Freq++;
1438 } else if (curlen == nextlen) {
1445 /* ===========================================================================
1446 * Send a literal or distance tree in compressed form, using the codes in
1449 static void send_tree(ct_data * tree, int max_code)
1451 int n; /* iterates over all tree elements */
1452 int prevlen = -1; /* last emitted length */
1453 int curlen; /* length of current code */
1454 int nextlen = tree[0].Len; /* length of next code */
1455 int count = 0; /* repeat count of the current code */
1456 int max_count = 7; /* max repeat count */
1457 int min_count = 4; /* min repeat count */
1459 /* tree[max_code+1].Len = -1; *//* guard already set */
1461 max_count = 138, min_count = 3;
1463 for (n = 0; n <= max_code; n++) {
1465 nextlen = tree[n + 1].Len;
1466 if (++count < max_count && curlen == nextlen) {
1468 } else if (count < min_count) {
1470 SEND_CODE(curlen, G2.bl_tree);
1472 } else if (curlen != 0) {
1473 if (curlen != prevlen) {
1474 SEND_CODE(curlen, G2.bl_tree);
1477 Assert(count >= 3 && count <= 6, " 3_6?");
1478 SEND_CODE(REP_3_6, G2.bl_tree);
1479 send_bits(count - 3, 2);
1480 } else if (count <= 10) {
1481 SEND_CODE(REPZ_3_10, G2.bl_tree);
1482 send_bits(count - 3, 3);
1484 SEND_CODE(REPZ_11_138, G2.bl_tree);
1485 send_bits(count - 11, 7);
1492 } else if (curlen == nextlen) {
1502 /* ===========================================================================
1503 * Construct the Huffman tree for the bit lengths and return the index in
1504 * bl_order of the last bit length code to send.
1506 static int build_bl_tree(void)
1508 int max_blindex; /* index of last bit length code of non zero freq */
1510 /* Determine the bit length frequencies for literal and distance trees */
1511 scan_tree(G2.dyn_ltree, G2.l_desc.max_code);
1512 scan_tree(G2.dyn_dtree, G2.d_desc.max_code);
1514 /* Build the bit length tree: */
1515 build_tree(&G2.bl_desc);
1516 /* opt_len now includes the length of the tree representations, except
1517 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1520 /* Determine the number of bit length codes to send. The pkzip format
1521 * requires that at least 4 bit length codes be sent. (appnote.txt says
1522 * 3 but the actual value used is 4.)
1524 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1525 if (G2.bl_tree[bl_order[max_blindex]].Len != 0)
1528 /* Update opt_len to include the bit length tree and counts */
1529 G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1530 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", (long)G2.opt_len, (long)G2.static_len));
1535 /* ===========================================================================
1536 * Send the header for a block using dynamic Huffman trees: the counts, the
1537 * lengths of the bit length codes, the literal tree and the distance tree.
1538 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1540 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1542 int rank; /* index in bl_order */
1544 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1545 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1546 && blcodes <= BL_CODES, "too many codes");
1547 Tracev((stderr, "\nbl counts: "));
1548 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1549 send_bits(dcodes - 1, 5);
1550 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1551 for (rank = 0; rank < blcodes; rank++) {
1552 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1553 send_bits(G2.bl_tree[bl_order[rank]].Len, 3);
1555 Tracev((stderr, "\nbl tree: sent %ld", (long)G1.bits_sent));
1557 send_tree((ct_data *) G2.dyn_ltree, lcodes - 1); /* send the literal tree */
1558 Tracev((stderr, "\nlit tree: sent %ld", (long)G1.bits_sent));
1560 send_tree((ct_data *) G2.dyn_dtree, dcodes - 1); /* send the distance tree */
1561 Tracev((stderr, "\ndist tree: sent %ld", (long)G1.bits_sent));
1564 /* ===========================================================================
1565 * Save the match info and tally the frequency counts. Return true if
1566 * the current block must be flushed.
1568 static int ct_tally(int dist, int lc)
1570 G1.l_buf[G2.last_lit++] = lc;
1572 /* lc is the unmatched char */
1573 G2.dyn_ltree[lc].Freq++;
1575 /* Here, lc is the match length - MIN_MATCH */
1576 dist--; /* dist = match distance - 1 */
1577 Assert((ush) dist < (ush) MAX_DIST
1578 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
1579 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
1582 G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++;
1583 G2.dyn_dtree[D_CODE(dist)].Freq++;
1585 G1.d_buf[G2.last_dist++] = dist;
1586 G2.flags |= G2.flag_bit;
1590 /* Output the flags if they fill a byte: */
1591 if ((G2.last_lit & 7) == 0) {
1592 G2.flag_buf[G2.last_flags++] = G2.flags;
1596 /* Try to guess if it is profitable to stop the current block here */
1597 if ((G2.last_lit & 0xfff) == 0) {
1598 /* Compute an upper bound for the compressed length */
1599 ulg out_length = G2.last_lit * 8L;
1600 ulg in_length = (ulg) G1.strstart - G1.block_start;
1603 for (dcode = 0; dcode < D_CODES; dcode++) {
1604 out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
1608 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1609 G2.last_lit, G2.last_dist,
1610 (long)in_length, (long)out_length,
1611 100L - out_length * 100L / in_length));
1612 if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2)
1615 return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE);
1616 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1617 * on 16 bit machines and because stored blocks are restricted to
1622 /* ===========================================================================
1623 * Send the block data compressed using the given Huffman trees
1625 static void compress_block(ct_data * ltree, ct_data * dtree)
1627 unsigned dist; /* distance of matched string */
1628 int lc; /* match length or unmatched char (if dist == 0) */
1629 unsigned lx = 0; /* running index in l_buf */
1630 unsigned dx = 0; /* running index in d_buf */
1631 unsigned fx = 0; /* running index in flag_buf */
1632 uch flag = 0; /* current flags */
1633 unsigned code; /* the code to send */
1634 int extra; /* number of extra bits to send */
1636 if (G2.last_lit != 0) do {
1638 flag = G2.flag_buf[fx++];
1639 lc = G1.l_buf[lx++];
1640 if ((flag & 1) == 0) {
1641 SEND_CODE(lc, ltree); /* send a literal byte */
1642 Tracecv(lc > ' ', (stderr, " '%c' ", lc));
1644 /* Here, lc is the match length - MIN_MATCH */
1645 code = G2.length_code[lc];
1646 SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
1647 extra = extra_lbits[code];
1649 lc -= G2.base_length[code];
1650 send_bits(lc, extra); /* send the extra length bits */
1652 dist = G1.d_buf[dx++];
1653 /* Here, dist is the match distance - 1 */
1654 code = D_CODE(dist);
1655 Assert(code < D_CODES, "bad d_code");
1657 SEND_CODE(code, dtree); /* send the distance code */
1658 extra = extra_dbits[code];
1660 dist -= G2.base_dist[code];
1661 send_bits(dist, extra); /* send the extra distance bits */
1663 } /* literal or match pair ? */
1665 } while (lx < G2.last_lit);
1667 SEND_CODE(END_BLOCK, ltree);
1670 /* ===========================================================================
1671 * Determine the best encoding for the current block: dynamic trees, static
1672 * trees or store, and output the encoded block to the zip file. This function
1673 * returns the total compressed length for the file so far.
1675 static void flush_block(char *buf, ulg stored_len, int eof)
1677 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1678 int max_blindex; /* index of last bit length code of non zero freq */
1680 G2.flag_buf[G2.last_flags] = G2.flags; /* Save the flags for the last 8 items */
1682 /* Construct the literal and distance trees */
1683 build_tree(&G2.l_desc);
1684 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", (long)G2.opt_len, (long)G2.static_len));
1686 build_tree(&G2.d_desc);
1687 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", (long)G2.opt_len, (long)G2.static_len));
1688 /* At this point, opt_len and static_len are the total bit lengths of
1689 * the compressed block data, excluding the tree representations.
1692 /* Build the bit length tree for the above two trees, and get the index
1693 * in bl_order of the last bit length code to send.
1695 max_blindex = build_bl_tree();
1697 /* Determine the best encoding. Compute first the block length in bytes */
1698 opt_lenb = (G2.opt_len + 3 + 7) >> 3;
1699 static_lenb = (G2.static_len + 3 + 7) >> 3;
1702 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
1703 (unsigned long)opt_lenb, (unsigned long)G2.opt_len,
1704 (unsigned long)static_lenb, (unsigned long)G2.static_len,
1705 (unsigned long)stored_len,
1706 G2.last_lit, G2.last_dist));
1708 if (static_lenb <= opt_lenb)
1709 opt_lenb = static_lenb;
1711 /* If compression failed and this is the first and last block,
1712 * and if the zip file can be seeked (to rewrite the local header),
1713 * the whole file is transformed into a stored file:
1715 // seekable() is constant FALSE in busybox, and G2.compressed_len is disabled
1716 // (this was the only user)
1717 // if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) {
1718 // /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
1720 // bb_error_msg("block vanished");
1722 // G2.compressed_len = stored_len << 3;
1723 // copy_block(buf, (unsigned) stored_len, 0); /* without header */
1725 if (stored_len + 4 <= opt_lenb && buf != NULL) {
1726 /* 4: two words for the lengths */
1727 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1728 * Otherwise we can't have processed more than WSIZE input bytes since
1729 * the last block flush, because compression would have been
1730 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1731 * transform a block into a stored block.
1733 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
1734 // G2.compressed_len = ((G2.compressed_len + 3 + 7) & ~7L)
1735 // + ((stored_len + 4) << 3);
1736 copy_block(buf, (unsigned) stored_len, 1); /* with header */
1738 if (static_lenb == opt_lenb) {
1739 send_bits((STATIC_TREES << 1) + eof, 3);
1740 compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree);
1741 // G2.compressed_len += 3 + G2.static_len;
1743 send_bits((DYN_TREES << 1) + eof, 3);
1744 send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1,
1746 compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree);
1747 // G2.compressed_len += 3 + G2.opt_len;
1749 // Assert(G2.compressed_len == G1.bits_sent, "bad compressed size");
1754 // G2.compressed_len += 7; /* align on byte boundary */
1756 // Tracev((stderr, "\ncomprlen %lu(%lu) ",
1757 // (unsigned long)G2.compressed_len >> 3,
1758 // (unsigned long)G2.compressed_len - 7 * eof));
1760 return; /* was "return G2.compressed_len >> 3;" */
1763 /* ===========================================================================
1764 * Update a hash value with the given input byte
1765 * IN assertion: all calls to UPDATE_HASH are made with consecutive
1766 * input characters, so that a running hash key can be computed from the
1767 * previous key instead of complete recalculation each time.
1769 #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
1771 /* ===========================================================================
1772 * Same as above, but achieves better compression. We use a lazy
1773 * evaluation for matches: a match is finally adopted only if there is
1774 * no better match at the next window position.
1776 * Processes a new input file and return its compressed length. Sets
1777 * the compressed length, crc, deflate flags and internal file
1781 /* Flush the current block, with given end-of-file flag.
1782 * IN assertion: strstart is set to the end of the current match. */
1783 #define FLUSH_BLOCK(eof) \
1785 G1.block_start >= 0L \
1786 ? (char*)&G1.window[(unsigned)G1.block_start] \
1788 (ulg)G1.strstart - G1.block_start, \
1792 /* Insert string s in the dictionary and set match_head to the previous head
1793 * of the hash chain (the most recent string with same hash key). Return
1794 * the previous length of the hash chain.
1795 * IN assertion: all calls to INSERT_STRING are made with consecutive
1796 * input characters and the first MIN_MATCH bytes of s are valid
1797 * (except for the last MIN_MATCH-1 bytes of the input file). */
1798 #define INSERT_STRING(s, match_head) \
1800 UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \
1801 G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \
1802 head[G1.ins_h] = (s); \
1805 static NOINLINE void deflate(void)
1807 IPos hash_head; /* head of hash chain */
1808 IPos prev_match; /* previous match */
1809 int flush; /* set if current block must be flushed */
1810 int match_available = 0; /* set if previous match exists */
1811 unsigned match_length = MIN_MATCH - 1; /* length of best match */
1813 /* Process the input block. */
1814 while (G1.lookahead != 0) {
1815 /* Insert the string window[strstart .. strstart+2] in the
1816 * dictionary, and set hash_head to the head of the hash chain:
1818 INSERT_STRING(G1.strstart, hash_head);
1820 /* Find the longest match, discarding those <= prev_length.
1822 G1.prev_length = match_length;
1823 prev_match = G1.match_start;
1824 match_length = MIN_MATCH - 1;
1826 if (hash_head != 0 && G1.prev_length < max_lazy_match
1827 && G1.strstart - hash_head <= MAX_DIST
1829 /* To simplify the code, we prevent matches with the string
1830 * of window index 0 (in particular we have to avoid a match
1831 * of the string with itself at the start of the input file).
1833 match_length = longest_match(hash_head);
1834 /* longest_match() sets match_start */
1835 if (match_length > G1.lookahead)
1836 match_length = G1.lookahead;
1838 /* Ignore a length 3 match if it is too distant: */
1839 if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) {
1840 /* If prev_match is also MIN_MATCH, G1.match_start is garbage
1841 * but we will ignore the current match anyway.
1846 /* If there was a match at the previous step and the current
1847 * match is not better, output the previous match:
1849 if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) {
1850 check_match(G1.strstart - 1, prev_match, G1.prev_length);
1851 flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH);
1853 /* Insert in hash table all strings up to the end of the match.
1854 * strstart-1 and strstart are already inserted.
1856 G1.lookahead -= G1.prev_length - 1;
1857 G1.prev_length -= 2;
1860 INSERT_STRING(G1.strstart, hash_head);
1861 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1862 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
1863 * these bytes are garbage, but it does not matter since the
1864 * next lookahead bytes will always be emitted as literals.
1866 } while (--G1.prev_length != 0);
1867 match_available = 0;
1868 match_length = MIN_MATCH - 1;
1872 G1.block_start = G1.strstart;
1874 } else if (match_available) {
1875 /* If there was no match at the previous position, output a
1876 * single literal. If there was a match but the current match
1877 * is longer, truncate the previous match to a single literal.
1879 Tracevv((stderr, "%c", G1.window[G1.strstart - 1]));
1880 if (ct_tally(0, G1.window[G1.strstart - 1])) {
1882 G1.block_start = G1.strstart;
1887 /* There is no previous match to compare with, wait for
1888 * the next step to decide.
1890 match_available = 1;
1894 Assert(G1.strstart <= G1.isize && G1.lookahead <= G1.isize, "a bit too far");
1896 /* Make sure that we always have enough lookahead, except
1897 * at the end of the input file. We need MAX_MATCH bytes
1898 * for the next match, plus MIN_MATCH bytes to insert the
1899 * string following the next match.
1901 fill_window_if_needed();
1903 if (match_available)
1904 ct_tally(0, G1.window[G1.strstart - 1]);
1906 FLUSH_BLOCK(1); /* eof */
1909 /* ===========================================================================
1910 * Initialize the bit string routines.
1912 static void bi_init(void)
1914 //G1.bi_buf = 0; // globals are zeroed in pack_gzip()
1915 //G1.bi_valid = 0; // globals are zeroed in pack_gzip()
1916 //DEBUG_bits_sent(= 0L); // globals are zeroed in pack_gzip()
1919 /* ===========================================================================
1920 * Initialize the "longest match" routines for a new file
1922 static void lm_init(unsigned *flags16p)
1926 /* Initialize the hash table. */
1927 memset(head, 0, HASH_SIZE * sizeof(*head));
1928 /* prev will be initialized on the fly */
1930 /* speed options for the general purpose bit flag */
1931 *flags16p |= 2; /* FAST 4, SLOW 2 */
1932 /* ??? reduce max_chain_length for binary files */
1934 //G1.strstart = 0; // globals are zeroed in pack_gzip()
1935 //G1.block_start = 0L; // globals are zeroed in pack_gzip()
1937 G1.lookahead = file_read(G1.window,
1938 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
1940 if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) {
1945 //G1.eofile = 0; // globals are zeroed in pack_gzip()
1947 /* Make sure that we always have enough lookahead. This is important
1948 * if input comes from a device such as a tty.
1950 fill_window_if_needed();
1952 //G1.ins_h = 0; // globals are zeroed in pack_gzip()
1953 for (j = 0; j < MIN_MATCH - 1; j++)
1954 UPDATE_HASH(G1.ins_h, G1.window[j]);
1955 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
1956 * not important since only literal bytes will be emitted.
1960 /* ===========================================================================
1961 * Allocate the match buffer, initialize the various tables and save the
1962 * location of the internal file attribute (ascii/binary) and method
1964 * One callsite in zip()
1966 static void ct_init(void)
1968 int n; /* iterates over tree elements */
1969 int length; /* length value */
1970 int code; /* code value */
1971 int dist; /* distance index */
1973 // //G2.compressed_len = 0L; // globals are zeroed in pack_gzip()
1976 if (G2.static_dtree[0].Len != 0)
1977 return; /* ct_init already called */
1980 /* Initialize the mapping length (0..255) -> length code (0..28) */
1982 for (code = 0; code < LENGTH_CODES - 1; code++) {
1983 G2.base_length[code] = length;
1984 for (n = 0; n < (1 << extra_lbits[code]); n++) {
1985 G2.length_code[length++] = code;
1988 Assert(length == 256, "ct_init: length != 256");
1989 /* Note that the length 255 (match length 258) can be represented
1990 * in two different ways: code 284 + 5 bits or code 285, so we
1991 * overwrite length_code[255] to use the best encoding:
1993 G2.length_code[length - 1] = code;
1995 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
1997 for (code = 0; code < 16; code++) {
1998 G2.base_dist[code] = dist;
1999 for (n = 0; n < (1 << extra_dbits[code]); n++) {
2000 G2.dist_code[dist++] = code;
2003 Assert(dist == 256, "ct_init: dist != 256");
2004 dist >>= 7; /* from now on, all distances are divided by 128 */
2005 for (; code < D_CODES; code++) {
2006 G2.base_dist[code] = dist << 7;
2007 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
2008 G2.dist_code[256 + dist++] = code;
2011 Assert(dist == 256, "ct_init: 256+dist != 512");
2013 /* Construct the codes of the static literal tree */
2014 //for (n = 0; n <= MAX_BITS; n++) // globals are zeroed in pack_gzip()
2015 // G2.bl_count[n] = 0;
2019 G2.static_ltree[n++].Len = 8;
2022 //G2.bl_count[8] = 143 + 1;
2024 G2.static_ltree[n++].Len = 9;
2027 //G2.bl_count[9] = 255 - 143;
2029 G2.static_ltree[n++].Len = 7;
2032 //G2.bl_count[7] = 279 - 255;
2034 G2.static_ltree[n++].Len = 8;
2037 //G2.bl_count[8] += 287 - 279;
2038 G2.bl_count[7] = 279 - 255;
2039 G2.bl_count[8] = (143 + 1) + (287 - 279);
2040 G2.bl_count[9] = 255 - 143;
2041 /* Codes 286 and 287 do not exist, but we must include them in the
2042 * tree construction to get a canonical Huffman tree (longest code
2045 gen_codes((ct_data *) G2.static_ltree, L_CODES + 1);
2047 /* The static distance tree is trivial: */
2048 for (n = 0; n < D_CODES; n++) {
2049 G2.static_dtree[n].Len = 5;
2050 G2.static_dtree[n].Code = bi_reverse(n, 5);
2053 /* Initialize the first block of the first file: */
2057 /* ===========================================================================
2058 * Deflate in to out.
2059 * IN assertions: the input and output buffers are cleared.
2061 static void zip(void)
2063 unsigned deflate_flags;
2065 //G1.outcnt = 0; // globals are zeroed in pack_gzip()
2067 /* Write the header to the gzip file. See algorithm.doc for the format */
2068 /* magic header for gzip files: 1F 8B */
2069 /* compression method: 8 (DEFLATED) */
2070 /* general flags: 0 */
2071 put_32bit(0x00088b1f);
2072 put_32bit(0); /* Unix timestamp */
2074 /* Write deflated file to zip file */
2079 deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
2080 lm_init(&deflate_flags);
2082 put_16bit(deflate_flags | 0x300); /* extra flags. OS id = 3 (Unix) */
2084 /* The above 32-bit misaligns outbuf (10 bytes are stored), flush it */
2085 flush_outbuf_if_32bit_optimized();
2089 /* Write the crc and uncompressed size */
2091 put_32bit(G1.isize);
2096 /* ======================================================================== */
2098 IF_DESKTOP(long long) int FAST_FUNC pack_gzip(transformer_state_t *xstate UNUSED_PARAM)
2100 /* Reinit G1.xxx except pointers to allocated buffers, and entire G2 */
2101 memset(&G1.crc, 0, (sizeof(G1) - offsetof(struct globals, crc)) + sizeof(G2));
2103 /* Clear input and output buffers */
2111 G2.l_desc.dyn_tree = G2.dyn_ltree;
2112 G2.l_desc.static_tree = G2.static_ltree;
2113 G2.l_desc.extra_bits = extra_lbits;
2114 G2.l_desc.extra_base = LITERALS + 1;
2115 G2.l_desc.elems = L_CODES;
2116 G2.l_desc.max_length = MAX_BITS;
2117 //G2.l_desc.max_code = 0;
2118 G2.d_desc.dyn_tree = G2.dyn_dtree;
2119 G2.d_desc.static_tree = G2.static_dtree;
2120 G2.d_desc.extra_bits = extra_dbits;
2121 //G2.d_desc.extra_base = 0;
2122 G2.d_desc.elems = D_CODES;
2123 G2.d_desc.max_length = MAX_BITS;
2124 //G2.d_desc.max_code = 0;
2125 G2.bl_desc.dyn_tree = G2.bl_tree;
2126 //G2.bl_desc.static_tree = NULL;
2127 G2.bl_desc.extra_bits = extra_blbits,
2128 //G2.bl_desc.extra_base = 0;
2129 G2.bl_desc.elems = BL_CODES;
2130 G2.bl_desc.max_length = MAX_BL_BITS;
2131 //G2.bl_desc.max_code = 0;
2134 /* Saving of timestamp is disabled. Why?
2135 * - it is not Y2038-safe.
2136 * - some people want deterministic results
2137 * (normally they'd use -n, but our -n is a nop).
2139 * Per RFC 1952, gzfile.time=0 is "no timestamp".
2140 * If users will demand this to be reinstated,
2141 * implement -n "don't save timestamp".
2145 fstat(STDIN_FILENO, &s);
2153 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2154 static const char gzip_longopts[] ALIGN1 =
2155 "stdout\0" No_argument "c"
2156 "to-stdout\0" No_argument "c"
2157 "force\0" No_argument "f"
2158 "verbose\0" No_argument "v"
2159 #if ENABLE_FEATURE_GZIP_DECOMPRESS
2160 "decompress\0" No_argument "d"
2161 "uncompress\0" No_argument "d"
2162 "test\0" No_argument "t"
2164 "quiet\0" No_argument "q"
2165 "fast\0" No_argument "1"
2166 "best\0" No_argument "9"
2167 "no-name\0" No_argument "n"
2172 * Linux kernel build uses gzip -d -n. We accept and ignore -n.
2175 * gzip: do not save the original file name and time stamp.
2176 * (The original name is always saved if the name had to be truncated.)
2177 * gunzip: do not restore the original file name/time even if present
2178 * (remove only the gzip suffix from the compressed file name).
2179 * This option is the default when decompressing.
2181 * gzip: always save the original file name and time stamp (this is the default)
2182 * gunzip: restore the original file name and time stamp if present.
2185 int gzip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
2186 #if ENABLE_FEATURE_GZIP_DECOMPRESS
2187 int gzip_main(int argc, char **argv)
2189 int gzip_main(int argc UNUSED_PARAM, char **argv)
2193 #if ENABLE_FEATURE_GZIP_LEVELS
2194 static const struct {
2196 uint8_t chain_shift;
2199 } gzip_level_config[6] = {
2200 {4, 4, 4/2, 16/2}, /* Level 4 */
2201 {8, 5, 16/2, 32/2}, /* Level 5 */
2202 {8, 7, 16/2, 128/2}, /* Level 6 */
2203 {8, 8, 32/2, 128/2}, /* Level 7 */
2204 {32, 10, 128/2, 258/2}, /* Level 8 */
2205 {32, 12, 258/2, 258/2}, /* Level 9 */
2209 SET_PTR_TO_GLOBALS((char *)xzalloc(sizeof(struct globals)+sizeof(struct globals2))
2210 + sizeof(struct globals));
2212 /* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */
2213 #if ENABLE_FEATURE_GZIP_LONG_OPTIONS
2214 opt = getopt32long(argv, BBUNPK_OPTSTR IF_FEATURE_GZIP_DECOMPRESS("dt") "n123456789", gzip_longopts);
2216 opt = getopt32(argv, BBUNPK_OPTSTR IF_FEATURE_GZIP_DECOMPRESS("dt") "n123456789");
2218 #if ENABLE_FEATURE_GZIP_DECOMPRESS /* gunzip_main may not be visible... */
2219 if (opt & (BBUNPK_OPT_DECOMPRESS|BBUNPK_OPT_TEST)) /* -d and/or -t */
2220 return gunzip_main(argc, argv);
2222 #if ENABLE_FEATURE_GZIP_LEVELS
2223 opt >>= (BBUNPK_OPTSTRLEN IF_FEATURE_GZIP_DECOMPRESS(+ 2) + 1); /* drop cfkvq[dt]n bits */
2225 opt = 1 << 6; /* default: 6 */
2226 opt = ffs(opt >> 4); /* Maps -1..-4 to [0], -5 to [1] ... -9 to [5] */
2227 max_chain_length = 1 << gzip_level_config[opt].chain_shift;
2228 good_match = gzip_level_config[opt].good;
2229 max_lazy_match = gzip_level_config[opt].lazy2 * 2;
2230 nice_match = gzip_level_config[opt].nice2 * 2;
2232 option_mask32 &= BBUNPK_OPTSTRMASK; /* retain only -cfkvq */
2234 /* Allocate all global buffers (for DYN_ALLOC option) */
2235 ALLOC(uch, G1.l_buf, INBUFSIZ);
2236 ALLOC(uch, G1.outbuf, OUTBUFSIZ);
2237 ALLOC(ush, G1.d_buf, DIST_BUFSIZE);
2238 ALLOC(uch, G1.window, 2L * WSIZE);
2239 ALLOC(ush, G1.prev, 1L << BITS);
2241 /* Initialize the CRC32 table */
2242 global_crc32_new_table_le();
2245 return bbunpack(argv, pack_gzip, append_ext, "gz");