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 tarball for details.
19 /* big objects in bss:
21 * 00000074 b base_length
22 * 00000078 b base_dist
23 * 00000078 b static_dtree
25 * 000000f4 b dyn_dtree
26 * 00000100 b length_code
27 * 00000200 b dist_code
31 * 00000480 b static_ltree
32 * 000008f4 b dyn_ltree
35 /* TODO: full support for -v for DESKTOP
36 * "/usr/bin/gzip -v a bogus aa" should say:
37 a: 85.1% -- replaced with a.gz
38 gzip: bogus: No such file or directory
39 aa: 85.1% -- replaced with aa.gz
45 /* ===========================================================================
48 /* Diagnostic functions */
50 # define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); }
51 # define Trace(x) fprintf x
52 # define Tracev(x) {if (verbose) fprintf x; }
53 # define Tracevv(x) {if (verbose > 1) fprintf x; }
54 # define Tracec(c,x) {if (verbose && (c)) fprintf x; }
55 # define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; }
57 # define Assert(cond,msg)
66 /* ===========================================================================
72 # define INBUFSIZ 0x2000 /* input buffer size */
74 # define INBUFSIZ 0x8000 /* input buffer size */
80 # define OUTBUFSIZ 8192 /* output buffer size */
82 # define OUTBUFSIZ 16384 /* output buffer size */
88 # define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
90 # define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
95 #define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
96 #define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
97 #define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
98 #define ORIG_NAME 0x08 /* bit 3 set: original file name present */
99 #define COMMENT 0x10 /* bit 4 set: file comment present */
100 #define RESERVED 0xC0 /* bit 6,7: reserved */
102 /* internal file attribute */
103 #define UNKNOWN 0xffff
108 # define WSIZE 0x8000 /* window size--must be a power of two, and */
109 #endif /* at least 32K for zip's deflate method */
112 #define MAX_MATCH 258
113 /* The minimum and maximum match lengths */
115 #define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
116 /* Minimum amount of lookahead, except at the end of the input file.
117 * See deflate.c for comments about the MIN_MATCH+1.
120 #define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
121 /* In order to simplify the code, particularly on 16 bit machines, match
122 * distances are limited to MAX_DIST instead of WSIZE.
126 # define MAX_PATH_LEN 1024 /* max pathname length */
129 #define seekable() 0 /* force sequential output */
130 #define translate_eol 0 /* no option -a yet */
135 #define INIT_BITS 9 /* Initial number of bits per code */
137 #define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
138 /* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
139 * It's a pity that old uncompress does not check bit 0x20. That makes
140 * extension of the format actually undesirable because old compress
141 * would just crash on the new format instead of giving a meaningful
142 * error message. It does check the number of bits, but it's more
143 * helpful to say "unsupported format, get a new version" than
144 * "can only handle 16 bits".
148 # define MAX_SUFFIX MAX_EXT_CHARS
150 # define MAX_SUFFIX 30
154 /* ===========================================================================
155 * Compile with MEDIUM_MEM to reduce the memory requirements or
156 * with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
157 * entire input file can be held in memory (not possible on 16 bit systems).
158 * Warning: defining these symbols affects HASH_BITS (see below) and thus
159 * affects the compression ratio. The compressed output
160 * is still correct, and might even be smaller in some cases.
164 # define HASH_BITS 13 /* Number of bits used to hash strings */
167 # define HASH_BITS 14
170 # define HASH_BITS 15
171 /* For portability to 16 bit machines, do not use values above 15. */
174 #define HASH_SIZE (unsigned)(1<<HASH_BITS)
175 #define HASH_MASK (HASH_SIZE-1)
176 #define WMASK (WSIZE-1)
177 /* HASH_SIZE and WSIZE must be powers of two */
179 # define TOO_FAR 4096
181 /* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
184 /* ===========================================================================
185 * These types are not really 'char', 'short' and 'long'
188 typedef uint16_t ush;
189 typedef uint32_t ulg;
193 typedef unsigned IPos;
194 /* A Pos is an index in the character window. We use short instead of int to
195 * save space in the various tables. IPos is used only for parameter passing.
199 WINDOW_SIZE = 2 * WSIZE,
200 /* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
201 * input file length plus MIN_LOOKAHEAD.
204 max_chain_length = 4096,
205 /* To speed up deflation, hash chains are never searched beyond this length.
206 * A higher limit improves compression ratio but degrades the speed.
209 max_lazy_match = 258,
210 /* Attempt to find a better match only when the current match is strictly
211 * smaller than this value. This mechanism is used only for compression
215 max_insert_length = max_lazy_match,
216 /* Insert new strings in the hash table only if the match length
217 * is not greater than this length. This saves time but degrades compression.
218 * max_insert_length is used only for compression levels <= 3.
222 /* Use a faster search when the previous match is longer than this */
224 /* Values for max_lazy_match, good_match and max_chain_length, depending on
225 * the desired pack level (0..9). The values given below have been tuned to
226 * exclude worst case performance for pathological files. Better values may be
227 * found for specific files.
230 nice_match = 258, /* Stop searching when current match exceeds this */
231 /* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
232 * For deflate_fast() (levels <= 3) good is ignored and lazy has a different
242 /* window position at the beginning of the current output block. Gets
243 * negative when the window is moved backwards.
245 unsigned ins_h; /* hash index of string to be inserted */
247 #define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
248 /* Number of bits by which ins_h and del_h must be shifted at each
249 * input step. It must be such that after MIN_MATCH steps, the oldest
250 * byte no longer takes part in the hash key, that is:
251 * H_SHIFT * MIN_MATCH >= HASH_BITS
254 unsigned prev_length;
256 /* Length of the best match at previous step. Matches not greater than this
257 * are discarded. This is used in the lazy match evaluation.
260 unsigned strstart; /* start of string to insert */
261 unsigned match_start; /* start of matching string */
262 unsigned lookahead; /* number of valid bytes ahead in window */
264 /* ===========================================================================
266 #define DECLARE(type, array, size) \
268 #define ALLOC(type, array, size) \
269 array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type));
270 #define FREE(array) \
271 do { free(array); array = NULL; } while (0)
275 /* buffer for literals or lengths */
276 /* DECLARE(uch, l_buf, LIT_BUFSIZE); */
277 DECLARE(uch, l_buf, INBUFSIZ);
279 DECLARE(ush, d_buf, DIST_BUFSIZE);
280 DECLARE(uch, outbuf, OUTBUFSIZ);
282 /* Sliding window. Input bytes are read into the second half of the window,
283 * and move to the first half later to keep a dictionary of at least WSIZE
284 * bytes. With this organization, matches are limited to a distance of
285 * WSIZE-MAX_MATCH bytes, but this ensures that IO is always
286 * performed with a length multiple of the block size. Also, it limits
287 * the window size to 64K, which is quite useful on MSDOS.
288 * To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
289 * be less efficient).
291 DECLARE(uch, window, 2L * WSIZE);
293 /* Link to older string with same hash index. To limit the size of this
294 * array to 64K, this link is maintained only for the last 32K strings.
295 * An index in this array is thus a window index modulo 32K.
297 /* DECLARE(Pos, prev, WSIZE); */
298 DECLARE(ush, prev, 1L << BITS);
300 /* Heads of the hash chains or 0. */
301 /* DECLARE(Pos, head, 1<<HASH_BITS); */
302 #define head (G1.prev + WSIZE) /* hash head (see deflate.c) */
304 /* number of input bytes */
305 ulg isize; /* only 32 bits stored in .gz file */
307 /* bbox always use stdin/stdout */
308 #define ifd STDIN_FILENO /* input file descriptor */
309 #define ofd STDOUT_FILENO /* output file descriptor */
312 unsigned insize; /* valid bytes in l_buf */
314 unsigned outcnt; /* bytes in output buffer */
316 smallint eofile; /* flag set at end of input file */
318 /* ===========================================================================
319 * Local data used by the "bit string" routines.
322 unsigned short bi_buf;
324 /* Output buffer. bits are inserted starting at the bottom (least significant
329 #define BUF_SIZE (8 * sizeof(G1.bi_buf))
330 /* Number of bits used within bi_buf. (bi_buf might be implemented on
331 * more than 16 bits on some systems.)
336 /* Current input function. Set to mem_read for in-memory compression */
339 ulg bits_sent; /* bit length of the compressed data */
342 uint32_t *crc_32_tab;
343 uint32_t crc; /* shift register contents */
346 #define G1 (*(ptr_to_globals - 1))
349 /* ===========================================================================
350 * Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
351 * (used for the compressed data only)
353 static void flush_outbuf(void)
358 xwrite(ofd, (char *) G1.outbuf, G1.outcnt);
363 /* ===========================================================================
365 /* put_8bit is used for the compressed output */
366 #define put_8bit(c) \
368 G1.outbuf[G1.outcnt++] = (c); \
369 if (G1.outcnt == OUTBUFSIZ) flush_outbuf(); \
372 /* Output a 16 bit value, lsb first */
373 static void put_16bit(ush w)
375 if (G1.outcnt < OUTBUFSIZ - 2) {
376 G1.outbuf[G1.outcnt++] = w;
377 G1.outbuf[G1.outcnt++] = w >> 8;
384 static void put_32bit(ulg n)
390 /* ===========================================================================
391 * Clear input and output buffers
393 static void clear_bufs(void)
403 /* ===========================================================================
404 * Run a set of bytes through the crc shift register. If s is a NULL
405 * pointer, then initialize the crc shift register contents instead.
406 * Return the current crc in either case.
408 static uint32_t updcrc(uch * s, unsigned n)
412 c = G1.crc_32_tab[(uch)(c ^ *s++)] ^ (c >> 8);
420 /* ===========================================================================
421 * Read a new buffer from the current input file, perform end-of-line
422 * translation, and update the crc and input file size.
423 * IN assertion: size >= 2 (for end-of-line translation)
425 static unsigned file_read(void *buf, unsigned size)
429 Assert(G1.insize == 0, "l_buf not empty");
431 len = safe_read(ifd, buf, size);
432 if (len == (unsigned)(-1) || len == 0)
441 /* ===========================================================================
442 * Send a value on a given number of bits.
443 * IN assertion: length <= 16 and value fits in length bits.
445 static void send_bits(int value, int length)
448 Tracev((stderr, " l %2d v %4x ", length, value));
449 Assert(length > 0 && length <= 15, "invalid length");
450 G1.bits_sent += length;
452 /* If not enough room in bi_buf, use (valid) bits from bi_buf and
453 * (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
454 * unused bits in value.
456 if (G1.bi_valid > (int) BUF_SIZE - length) {
457 G1.bi_buf |= (value << G1.bi_valid);
458 put_16bit(G1.bi_buf);
459 G1.bi_buf = (ush) value >> (BUF_SIZE - G1.bi_valid);
460 G1.bi_valid += length - BUF_SIZE;
462 G1.bi_buf |= value << G1.bi_valid;
463 G1.bi_valid += length;
468 /* ===========================================================================
469 * Reverse the first len bits of a code, using straightforward code (a faster
470 * method would use a table)
471 * IN assertion: 1 <= len <= 15
473 static unsigned bi_reverse(unsigned code, int len)
479 if (--len <= 0) return res;
486 /* ===========================================================================
487 * Write out any remaining bits in an incomplete byte.
489 static void bi_windup(void)
491 if (G1.bi_valid > 8) {
492 put_16bit(G1.bi_buf);
493 } else if (G1.bi_valid > 0) {
499 G1.bits_sent = (G1.bits_sent + 7) & ~7;
504 /* ===========================================================================
505 * Copy a stored block to the zip file, storing first the length and its
506 * one's complement if requested.
508 static void copy_block(char *buf, unsigned len, int header)
510 bi_windup(); /* align on byte boundary */
516 G1.bits_sent += 2 * 16;
520 G1.bits_sent += (ulg) len << 3;
528 /* ===========================================================================
529 * Fill the window when the lookahead becomes insufficient.
530 * Updates strstart and lookahead, and sets eofile if end of input file.
531 * IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
532 * OUT assertions: at least one byte has been read, or eofile is set;
533 * file reads are performed for at least two bytes (required for the
534 * translate_eol option).
536 static void fill_window(void)
539 unsigned more = WINDOW_SIZE - G1.lookahead - G1.strstart;
540 /* Amount of free space at the end of the window. */
542 /* If the window is almost full and there is insufficient lookahead,
543 * move the upper half to the lower one to make room in the upper half.
545 if (more == (unsigned) -1) {
546 /* Very unlikely, but possible on 16 bit machine if strstart == 0
547 * and lookahead == 1 (input done one byte at time)
550 } else if (G1.strstart >= WSIZE + MAX_DIST) {
551 /* By the IN assertion, the window is not empty so we can't confuse
552 * more == 0 with more == 64K on a 16 bit machine.
554 Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
556 memcpy(G1.window, G1.window + WSIZE, WSIZE);
557 G1.match_start -= WSIZE;
558 G1.strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
560 G1.block_start -= WSIZE;
562 for (n = 0; n < HASH_SIZE; n++) {
564 head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
566 for (n = 0; n < WSIZE; n++) {
568 G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
569 /* If n is not on any hash chain, prev[n] is garbage but
570 * its value will never be used.
575 /* At this point, more >= 2 */
577 n = file_read(G1.window + G1.strstart + G1.lookahead, more);
578 if (n == 0 || n == (unsigned) -1) {
587 /* ===========================================================================
588 * Set match_start to the longest match starting at the given string and
589 * return its length. Matches shorter or equal to prev_length are discarded,
590 * in which case the result is equal to prev_length and match_start is
592 * IN assertions: cur_match is the head of the hash chain for the current
593 * string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
596 /* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
597 * match.s. The code is functionally equivalent, so you can use the C version
600 static int longest_match(IPos cur_match)
602 unsigned chain_length = max_chain_length; /* max hash chain length */
603 uch *scan = G1.window + G1.strstart; /* current string */
604 uch *match; /* matched string */
605 int len; /* length of current match */
606 int best_len = G1.prev_length; /* best match length so far */
607 IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0;
608 /* Stop when cur_match becomes <= limit. To simplify the code,
609 * we prevent matches with the string of window index 0.
612 /* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
613 * It is easy to get rid of this optimization if necessary.
615 #if HASH_BITS < 8 || MAX_MATCH != 258
616 # error Code too clever
618 uch *strend = G1.window + G1.strstart + MAX_MATCH;
619 uch scan_end1 = scan[best_len - 1];
620 uch scan_end = scan[best_len];
622 /* Do not waste too much time if we already have a good match: */
623 if (G1.prev_length >= good_match) {
626 Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
629 Assert(cur_match < G1.strstart, "no future");
630 match = G1.window + cur_match;
632 /* Skip to next match if the match length cannot increase
633 * or if the match length is less than 2:
635 if (match[best_len] != scan_end ||
636 match[best_len - 1] != scan_end1 ||
637 *match != *scan || *++match != scan[1])
640 /* The check at best_len-1 can be removed because it will be made
641 * again later. (This heuristic is not always a win.)
642 * It is not necessary to compare scan[2] and match[2] since they
643 * are always equal when the other bytes match, given that
644 * the hash keys are equal and that HASH_BITS >= 8.
648 /* We check for insufficient lookahead only every 8th comparison;
649 * the 256th check will be made at strstart+258.
652 } while (*++scan == *++match && *++scan == *++match &&
653 *++scan == *++match && *++scan == *++match &&
654 *++scan == *++match && *++scan == *++match &&
655 *++scan == *++match && *++scan == *++match && scan < strend);
657 len = MAX_MATCH - (int) (strend - scan);
658 scan = strend - MAX_MATCH;
660 if (len > best_len) {
661 G1.match_start = cur_match;
663 if (len >= nice_match)
665 scan_end1 = scan[best_len - 1];
666 scan_end = scan[best_len];
668 } while ((cur_match = G1.prev[cur_match & WMASK]) > limit
669 && --chain_length != 0);
676 /* ===========================================================================
677 * Check that the match at match_start is indeed a match.
679 static void check_match(IPos start, IPos match, int length)
681 /* check that the match is indeed a match */
682 if (memcmp(G1.window + match, G1.window + start, length) != 0) {
683 bb_error_msg(" start %d, match %d, length %d", start, match, length);
684 bb_error_msg("invalid match");
687 bb_error_msg("\\[%d,%d]", start - match, length);
689 fputc(G1.window[start++], stderr);
690 } while (--length != 0);
694 # define check_match(start, match, length) ((void)0)
698 /* trees.c -- output deflated data using Huffman coding
699 * Copyright (C) 1992-1993 Jean-loup Gailly
700 * This is free software; you can redistribute it and/or modify it under the
701 * terms of the GNU General Public License, see the file COPYING.
705 * Encode various sets of source values using variable-length
709 * The PKZIP "deflation" process uses several Huffman trees. The more
710 * common source values are represented by shorter bit sequences.
712 * Each code tree is stored in the ZIP file in a compressed form
713 * which is itself a Huffman encoding of the lengths of
714 * all the code strings (in ascending order by source values).
715 * The actual code strings are reconstructed from the lengths in
716 * the UNZIP process, as described in the "application note"
717 * (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
721 * Data Compression: Techniques and Applications, pp. 53-55.
722 * Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
725 * Data Compression: Methods and Theory, pp. 49-50.
726 * Computer Science Press, 1988. ISBN 0-7167-8156-5.
730 * Addison-Wesley, 1983. ISBN 0-201-06672-6.
734 * Allocate the match buffer, initialize the various tables [and save
735 * the location of the internal file attribute (ascii/binary) and
736 * method (DEFLATE/STORE) -- deleted in bbox]
738 * void ct_tally(int dist, int lc);
739 * Save the match info and tally the frequency counts.
741 * ulg flush_block(char *buf, ulg stored_len, int eof)
742 * Determine the best encoding for the current block: dynamic trees,
743 * static trees or store, and output the encoded block to the zip
744 * file. Returns the total compressed length for the file so far.
748 /* All codes must not exceed MAX_BITS bits */
750 #define MAX_BL_BITS 7
751 /* Bit length codes must not exceed MAX_BL_BITS bits */
753 #define LENGTH_CODES 29
754 /* number of length codes, not counting the special END_BLOCK code */
757 /* number of literal bytes 0..255 */
759 #define END_BLOCK 256
760 /* end of block literal code */
762 #define L_CODES (LITERALS+1+LENGTH_CODES)
763 /* number of Literal or Length codes, including the END_BLOCK code */
766 /* number of distance codes */
769 /* number of codes used to transfer the bit lengths */
771 /* extra bits for each length code */
772 static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = {
773 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
777 /* extra bits for each distance code */
778 static const uint8_t extra_dbits[D_CODES] ALIGN1 = {
779 0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
780 10, 10, 11, 11, 12, 12, 13, 13
783 /* extra bits for each bit length code */
784 static const uint8_t extra_blbits[BL_CODES] ALIGN1 = {
785 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
787 /* number of codes at each bit length for an optimal tree */
788 static const uint8_t bl_order[BL_CODES] ALIGN1 = {
789 16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
791 #define STORED_BLOCK 0
792 #define STATIC_TREES 1
794 /* The three kinds of block type */
798 # define LIT_BUFSIZE 0x2000
801 # define LIT_BUFSIZE 0x4000
803 # define LIT_BUFSIZE 0x8000
808 # define DIST_BUFSIZE LIT_BUFSIZE
810 /* Sizes of match buffers for literals/lengths and distances. There are
811 * 4 reasons for limiting LIT_BUFSIZE to 64K:
812 * - frequencies can be kept in 16 bit counters
813 * - if compression is not successful for the first block, all input data is
814 * still in the window so we can still emit a stored block even when input
815 * comes from standard input. (This can also be done for all blocks if
816 * LIT_BUFSIZE is not greater than 32K.)
817 * - if compression is not successful for a file smaller than 64K, we can
818 * even emit a stored file instead of a stored block (saving 5 bytes).
819 * - creating new Huffman trees less frequently may not provide fast
820 * adaptation to changes in the input data statistics. (Take for
821 * example a binary file with poorly compressible code followed by
822 * a highly compressible string table.) Smaller buffer sizes give
823 * fast adaptation but have of course the overhead of transmitting trees
825 * - I can't count above 4
826 * The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
827 * memory at the expense of compression). Some optimizations would be possible
828 * if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
831 /* repeat previous bit length 3-6 times (2 bits of repeat count) */
833 /* repeat a zero length 3-10 times (3 bits of repeat count) */
834 #define REPZ_11_138 18
835 /* repeat a zero length 11-138 times (7 bits of repeat count) */
837 /* ===========================================================================
839 /* Data structure describing a single value and its code string. */
840 typedef struct ct_data {
842 ush freq; /* frequency count */
843 ush code; /* bit string */
846 ush dad; /* father node in Huffman tree */
847 ush len; /* length of bit string */
856 #define HEAP_SIZE (2*L_CODES + 1)
857 /* maximum heap size */
859 typedef struct tree_desc {
860 ct_data *dyn_tree; /* the dynamic tree */
861 ct_data *static_tree; /* corresponding static tree or NULL */
862 const uint8_t *extra_bits; /* extra bits for each code or NULL */
863 int extra_base; /* base index for extra_bits */
864 int elems; /* max number of elements in the tree */
865 int max_length; /* max bit length for the codes */
866 int max_code; /* largest code with non zero frequency */
871 ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
872 int heap_len; /* number of elements in the heap */
873 int heap_max; /* element of largest frequency */
875 /* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
876 * The same heap array is used to build all trees.
879 ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
880 ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
882 ct_data static_ltree[L_CODES + 2];
884 /* The static literal tree. Since the bit lengths are imposed, there is no
885 * need for the L_CODES extra codes used during heap construction. However
886 * The codes 286 and 287 are needed to build a canonical tree (see ct_init
890 ct_data static_dtree[D_CODES];
892 /* The static distance tree. (Actually a trivial tree since all codes use
896 ct_data bl_tree[2 * BL_CODES + 1];
898 /* Huffman tree for the bit lengths */
904 ush bl_count[MAX_BITS + 1];
906 /* The lengths of the bit length codes are sent in order of decreasing
907 * probability, to avoid transmitting the lengths for unused bit length codes.
910 uch depth[2 * L_CODES + 1];
912 /* Depth of each subtree used as tie breaker for trees of equal frequency */
914 uch length_code[MAX_MATCH - MIN_MATCH + 1];
916 /* length code for each normalized match length (0 == MIN_MATCH) */
920 /* distance codes. The first 256 values correspond to the distances
921 * 3 .. 258, the last 256 values correspond to the top 8 bits of
922 * the 15 bit distances.
925 int base_length[LENGTH_CODES];
927 /* First normalized length for each code (0 = MIN_MATCH) */
929 int base_dist[D_CODES];
931 /* First normalized distance for each code (0 = distance of 1) */
933 uch flag_buf[LIT_BUFSIZE / 8];
935 /* flag_buf is a bit array distinguishing literals from lengths in
936 * l_buf, thus indicating the presence or absence of a distance.
939 unsigned last_lit; /* running index in l_buf */
940 unsigned last_dist; /* running index in d_buf */
941 unsigned last_flags; /* running index in flag_buf */
942 uch flags; /* current flags not yet saved in flag_buf */
943 uch flag_bit; /* current bit used in flags */
945 /* bits are filled in flags starting at bit 0 (least significant).
946 * Note: these flags are overkill in the current code since we don't
947 * take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
950 ulg opt_len; /* bit length of current block with optimal trees */
951 ulg static_len; /* bit length of current block with static trees */
953 ulg compressed_len; /* total bit length of compressed file */
956 #define G2ptr ((struct globals2*)(ptr_to_globals))
960 /* ===========================================================================
962 static void gen_codes(ct_data * tree, int max_code);
963 static void build_tree(tree_desc * desc);
964 static void scan_tree(ct_data * tree, int max_code);
965 static void send_tree(ct_data * tree, int max_code);
966 static int build_bl_tree(void);
967 static void send_all_trees(int lcodes, int dcodes, int blcodes);
968 static void compress_block(ct_data * ltree, ct_data * dtree);
972 /* Send a code of the given tree. c and tree must not have side effects */
973 # define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
975 # define SEND_CODE(c, tree) \
977 if (verbose > 1) bb_error_msg("\ncd %3d ",(c)); \
978 send_bits(tree[c].Code, tree[c].Len); \
982 #define D_CODE(dist) \
983 ((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)])
984 /* Mapping from a distance to a distance code. dist is the distance - 1 and
985 * must not have side effects. dist_code[256] and dist_code[257] are never
987 * The arguments must not have side effects.
991 /* ===========================================================================
992 * Initialize a new block.
994 static void init_block(void)
996 int n; /* iterates over tree elements */
998 /* Initialize the trees. */
999 for (n = 0; n < L_CODES; n++)
1000 G2.dyn_ltree[n].Freq = 0;
1001 for (n = 0; n < D_CODES; n++)
1002 G2.dyn_dtree[n].Freq = 0;
1003 for (n = 0; n < BL_CODES; n++)
1004 G2.bl_tree[n].Freq = 0;
1006 G2.dyn_ltree[END_BLOCK].Freq = 1;
1007 G2.opt_len = G2.static_len = 0;
1008 G2.last_lit = G2.last_dist = G2.last_flags = 0;
1014 /* ===========================================================================
1015 * Restore the heap property by moving down the tree starting at node k,
1016 * exchanging a node with the smallest of its two sons if necessary, stopping
1017 * when the heap property is re-established (each father smaller than its
1021 /* Compares to subtrees, using the tree depth as tie breaker when
1022 * the subtrees have equal frequency. This minimizes the worst case length. */
1023 #define SMALLER(tree, n, m) \
1024 (tree[n].Freq < tree[m].Freq \
1025 || (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))
1027 static void pqdownheap(ct_data * tree, int k)
1030 int j = k << 1; /* left son of k */
1032 while (j <= G2.heap_len) {
1033 /* Set j to the smallest of the two sons: */
1034 if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j]))
1037 /* Exit if v is smaller than both sons */
1038 if (SMALLER(tree, v, G2.heap[j]))
1041 /* Exchange v with the smallest son */
1042 G2.heap[k] = G2.heap[j];
1045 /* And continue down the tree, setting j to the left son of k */
1052 /* ===========================================================================
1053 * Compute the optimal bit lengths for a tree and update the total bit length
1054 * for the current block.
1055 * IN assertion: the fields freq and dad are set, heap[heap_max] and
1056 * above are the tree nodes sorted by increasing frequency.
1057 * OUT assertions: the field len is set to the optimal bit length, the
1058 * array bl_count contains the frequencies for each bit length.
1059 * The length opt_len is updated; static_len is also updated if stree is
1062 static void gen_bitlen(tree_desc * desc)
1064 ct_data *tree = desc->dyn_tree;
1065 const uint8_t *extra = desc->extra_bits;
1066 int base = desc->extra_base;
1067 int max_code = desc->max_code;
1068 int max_length = desc->max_length;
1069 ct_data *stree = desc->static_tree;
1070 int h; /* heap index */
1071 int n, m; /* iterate over the tree elements */
1072 int bits; /* bit length */
1073 int xbits; /* extra bits */
1074 ush f; /* frequency */
1075 int overflow = 0; /* number of elements with bit length too large */
1077 for (bits = 0; bits <= MAX_BITS; bits++)
1078 G2.bl_count[bits] = 0;
1080 /* In a first pass, compute the optimal bit lengths (which may
1081 * overflow in the case of the bit length tree).
1083 tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */
1085 for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
1087 bits = tree[tree[n].Dad].Len + 1;
1088 if (bits > max_length) {
1092 tree[n].Len = (ush) bits;
1093 /* We overwrite tree[n].Dad which is no longer needed */
1096 continue; /* not a leaf node */
1098 G2.bl_count[bits]++;
1101 xbits = extra[n - base];
1103 G2.opt_len += (ulg) f *(bits + xbits);
1106 G2.static_len += (ulg) f * (stree[n].Len + xbits);
1111 Trace((stderr, "\nbit length overflow\n"));
1112 /* This happens for example on obj2 and pic of the Calgary corpus */
1114 /* Find the first bit length which could increase: */
1116 bits = max_length - 1;
1117 while (G2.bl_count[bits] == 0)
1119 G2.bl_count[bits]--; /* move one leaf down the tree */
1120 G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
1121 G2.bl_count[max_length]--;
1122 /* The brother of the overflow item also moves one step up,
1123 * but this does not affect bl_count[max_length]
1126 } while (overflow > 0);
1128 /* Now recompute all bit lengths, scanning in increasing frequency.
1129 * h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
1130 * lengths instead of fixing only the wrong ones. This idea is taken
1131 * from 'ar' written by Haruhiko Okumura.)
1133 for (bits = max_length; bits != 0; bits--) {
1134 n = G2.bl_count[bits];
1139 if (tree[m].Len != (unsigned) bits) {
1140 Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
1141 G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
1150 /* ===========================================================================
1151 * Generate the codes for a given tree and bit counts (which need not be
1153 * IN assertion: the array bl_count contains the bit length statistics for
1154 * the given tree and the field len is set for all tree elements.
1155 * OUT assertion: the field code is set for all tree elements of non
1158 static void gen_codes(ct_data * tree, int max_code)
1160 ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
1161 ush code = 0; /* running code value */
1162 int bits; /* bit index */
1163 int n; /* code index */
1165 /* The distribution counts are first used to generate the code values
1166 * without bit reversal.
1168 for (bits = 1; bits <= MAX_BITS; bits++) {
1169 next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1;
1171 /* Check that the bit counts in bl_count are consistent. The last code
1174 Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
1175 "inconsistent bit counts");
1176 Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
1178 for (n = 0; n <= max_code; n++) {
1179 int len = tree[n].Len;
1183 /* Now reverse the bits */
1184 tree[n].Code = bi_reverse(next_code[len]++, len);
1186 Tracec(tree != G2.static_ltree,
1187 (stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
1188 (isgraph(n) ? n : ' '), len, tree[n].Code,
1189 next_code[len] - 1));
1194 /* ===========================================================================
1195 * Construct one Huffman tree and assigns the code bit strings and lengths.
1196 * Update the total bit length for the current block.
1197 * IN assertion: the field freq is set for all tree elements.
1198 * OUT assertions: the fields len and code are set to the optimal bit length
1199 * and corresponding code. The length opt_len is updated; static_len is
1200 * also updated if stree is not null. The field max_code is set.
1203 /* Remove the smallest element from the heap and recreate the heap with
1204 * one less element. Updates heap and heap_len. */
1207 /* Index within the heap array of least frequent node in the Huffman tree */
1209 #define PQREMOVE(tree, top) \
1211 top = G2.heap[SMALLEST]; \
1212 G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \
1213 pqdownheap(tree, SMALLEST); \
1216 static void build_tree(tree_desc * desc)
1218 ct_data *tree = desc->dyn_tree;
1219 ct_data *stree = desc->static_tree;
1220 int elems = desc->elems;
1221 int n, m; /* iterate over heap elements */
1222 int max_code = -1; /* largest code with non zero frequency */
1223 int node = elems; /* next internal node of the tree */
1225 /* Construct the initial heap, with least frequent element in
1226 * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
1227 * heap[0] is not used.
1230 G2.heap_max = HEAP_SIZE;
1232 for (n = 0; n < elems; n++) {
1233 if (tree[n].Freq != 0) {
1234 G2.heap[++G2.heap_len] = max_code = n;
1241 /* The pkzip format requires that at least one distance code exists,
1242 * and that at least one bit should be sent even if there is only one
1243 * possible code. So to avoid special checks later on we force at least
1244 * two codes of non zero frequency.
1246 while (G2.heap_len < 2) {
1247 int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0);
1253 G2.static_len -= stree[new].Len;
1254 /* new is 0 or 1 so it does not have extra bits */
1256 desc->max_code = max_code;
1258 /* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
1259 * establish sub-heaps of increasing lengths:
1261 for (n = G2.heap_len / 2; n >= 1; n--)
1262 pqdownheap(tree, n);
1264 /* Construct the Huffman tree by repeatedly combining the least two
1268 PQREMOVE(tree, n); /* n = node of least frequency */
1269 m = G2.heap[SMALLEST]; /* m = node of next least frequency */
1271 G2.heap[--G2.heap_max] = n; /* keep the nodes sorted by frequency */
1272 G2.heap[--G2.heap_max] = m;
1274 /* Create a new node father of n and m */
1275 tree[node].Freq = tree[n].Freq + tree[m].Freq;
1276 G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1;
1277 tree[n].Dad = tree[m].Dad = (ush) node;
1279 if (tree == G2.bl_tree) {
1280 bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
1281 node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
1284 /* and insert the new node in the heap */
1285 G2.heap[SMALLEST] = node++;
1286 pqdownheap(tree, SMALLEST);
1288 } while (G2.heap_len >= 2);
1290 G2.heap[--G2.heap_max] = G2.heap[SMALLEST];
1292 /* At this point, the fields freq and dad are set. We can now
1293 * generate the bit lengths.
1295 gen_bitlen((tree_desc *) desc);
1297 /* The field len is now set, we can generate the bit codes */
1298 gen_codes((ct_data *) tree, max_code);
1302 /* ===========================================================================
1303 * Scan a literal or distance tree to determine the frequencies of the codes
1304 * in the bit length tree. Updates opt_len to take into account the repeat
1305 * counts. (The contribution of the bit length codes will be added later
1306 * during the construction of bl_tree.)
1308 static void scan_tree(ct_data * tree, int max_code)
1310 int n; /* iterates over all tree elements */
1311 int prevlen = -1; /* last emitted length */
1312 int curlen; /* length of current code */
1313 int nextlen = tree[0].Len; /* length of next code */
1314 int count = 0; /* repeat count of the current code */
1315 int max_count = 7; /* max repeat count */
1316 int min_count = 4; /* min repeat count */
1322 tree[max_code + 1].Len = 0xffff; /* guard */
1324 for (n = 0; n <= max_code; n++) {
1326 nextlen = tree[n + 1].Len;
1327 if (++count < max_count && curlen == nextlen)
1330 if (count < min_count) {
1331 G2.bl_tree[curlen].Freq += count;
1332 } else if (curlen != 0) {
1333 if (curlen != prevlen)
1334 G2.bl_tree[curlen].Freq++;
1335 G2.bl_tree[REP_3_6].Freq++;
1336 } else if (count <= 10) {
1337 G2.bl_tree[REPZ_3_10].Freq++;
1339 G2.bl_tree[REPZ_11_138].Freq++;
1349 } else if (curlen == nextlen) {
1357 /* ===========================================================================
1358 * Send a literal or distance tree in compressed form, using the codes in
1361 static void send_tree(ct_data * tree, int max_code)
1363 int n; /* iterates over all tree elements */
1364 int prevlen = -1; /* last emitted length */
1365 int curlen; /* length of current code */
1366 int nextlen = tree[0].Len; /* length of next code */
1367 int count = 0; /* repeat count of the current code */
1368 int max_count = 7; /* max repeat count */
1369 int min_count = 4; /* min repeat count */
1371 /* tree[max_code+1].Len = -1; *//* guard already set */
1373 max_count = 138, min_count = 3;
1375 for (n = 0; n <= max_code; n++) {
1377 nextlen = tree[n + 1].Len;
1378 if (++count < max_count && curlen == nextlen) {
1380 } else if (count < min_count) {
1382 SEND_CODE(curlen, G2.bl_tree);
1384 } else if (curlen != 0) {
1385 if (curlen != prevlen) {
1386 SEND_CODE(curlen, G2.bl_tree);
1389 Assert(count >= 3 && count <= 6, " 3_6?");
1390 SEND_CODE(REP_3_6, G2.bl_tree);
1391 send_bits(count - 3, 2);
1392 } else if (count <= 10) {
1393 SEND_CODE(REPZ_3_10, G2.bl_tree);
1394 send_bits(count - 3, 3);
1396 SEND_CODE(REPZ_11_138, G2.bl_tree);
1397 send_bits(count - 11, 7);
1404 } else if (curlen == nextlen) {
1415 /* ===========================================================================
1416 * Construct the Huffman tree for the bit lengths and return the index in
1417 * bl_order of the last bit length code to send.
1419 static int build_bl_tree(void)
1421 int max_blindex; /* index of last bit length code of non zero freq */
1423 /* Determine the bit length frequencies for literal and distance trees */
1424 scan_tree(G2.dyn_ltree, G2.l_desc.max_code);
1425 scan_tree(G2.dyn_dtree, G2.d_desc.max_code);
1427 /* Build the bit length tree: */
1428 build_tree(&G2.bl_desc);
1429 /* opt_len now includes the length of the tree representations, except
1430 * the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
1433 /* Determine the number of bit length codes to send. The pkzip format
1434 * requires that at least 4 bit length codes be sent. (appnote.txt says
1435 * 3 but the actual value used is 4.)
1437 for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
1438 if (G2.bl_tree[bl_order[max_blindex]].Len != 0)
1441 /* Update opt_len to include the bit length tree and counts */
1442 G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
1443 Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1449 /* ===========================================================================
1450 * Send the header for a block using dynamic Huffman trees: the counts, the
1451 * lengths of the bit length codes, the literal tree and the distance tree.
1452 * IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
1454 static void send_all_trees(int lcodes, int dcodes, int blcodes)
1456 int rank; /* index in bl_order */
1458 Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
1459 Assert(lcodes <= L_CODES && dcodes <= D_CODES
1460 && blcodes <= BL_CODES, "too many codes");
1461 Tracev((stderr, "\nbl counts: "));
1462 send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
1463 send_bits(dcodes - 1, 5);
1464 send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
1465 for (rank = 0; rank < blcodes; rank++) {
1466 Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
1467 send_bits(G2.bl_tree[bl_order[rank]].Len, 3);
1469 Tracev((stderr, "\nbl tree: sent %ld", G1.bits_sent));
1471 send_tree((ct_data *) G2.dyn_ltree, lcodes - 1); /* send the literal tree */
1472 Tracev((stderr, "\nlit tree: sent %ld", G1.bits_sent));
1474 send_tree((ct_data *) G2.dyn_dtree, dcodes - 1); /* send the distance tree */
1475 Tracev((stderr, "\ndist tree: sent %ld", G1.bits_sent));
1479 /* ===========================================================================
1480 * Save the match info and tally the frequency counts. Return true if
1481 * the current block must be flushed.
1483 static int ct_tally(int dist, int lc)
1485 G1.l_buf[G2.last_lit++] = lc;
1487 /* lc is the unmatched char */
1488 G2.dyn_ltree[lc].Freq++;
1490 /* Here, lc is the match length - MIN_MATCH */
1491 dist--; /* dist = match distance - 1 */
1492 Assert((ush) dist < (ush) MAX_DIST
1493 && (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
1494 && (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
1497 G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++;
1498 G2.dyn_dtree[D_CODE(dist)].Freq++;
1500 G1.d_buf[G2.last_dist++] = dist;
1501 G2.flags |= G2.flag_bit;
1505 /* Output the flags if they fill a byte: */
1506 if ((G2.last_lit & 7) == 0) {
1507 G2.flag_buf[G2.last_flags++] = G2.flags;
1511 /* Try to guess if it is profitable to stop the current block here */
1512 if ((G2.last_lit & 0xfff) == 0) {
1513 /* Compute an upper bound for the compressed length */
1514 ulg out_length = G2.last_lit * 8L;
1515 ulg in_length = (ulg) G1.strstart - G1.block_start;
1518 for (dcode = 0; dcode < D_CODES; dcode++) {
1519 out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
1523 "\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
1524 G2.last_lit, G2.last_dist, in_length, out_length,
1525 100L - out_length * 100L / in_length));
1526 if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2)
1529 return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE);
1530 /* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
1531 * on 16 bit machines and because stored blocks are restricted to
1536 /* ===========================================================================
1537 * Send the block data compressed using the given Huffman trees
1539 static void compress_block(ct_data * ltree, ct_data * dtree)
1541 unsigned dist; /* distance of matched string */
1542 int lc; /* match length or unmatched char (if dist == 0) */
1543 unsigned lx = 0; /* running index in l_buf */
1544 unsigned dx = 0; /* running index in d_buf */
1545 unsigned fx = 0; /* running index in flag_buf */
1546 uch flag = 0; /* current flags */
1547 unsigned code; /* the code to send */
1548 int extra; /* number of extra bits to send */
1550 if (G2.last_lit != 0) do {
1552 flag = G2.flag_buf[fx++];
1553 lc = G1.l_buf[lx++];
1554 if ((flag & 1) == 0) {
1555 SEND_CODE(lc, ltree); /* send a literal byte */
1556 Tracecv(isgraph(lc), (stderr, " '%c' ", lc));
1558 /* Here, lc is the match length - MIN_MATCH */
1559 code = G2.length_code[lc];
1560 SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
1561 extra = extra_lbits[code];
1563 lc -= G2.base_length[code];
1564 send_bits(lc, extra); /* send the extra length bits */
1566 dist = G1.d_buf[dx++];
1567 /* Here, dist is the match distance - 1 */
1568 code = D_CODE(dist);
1569 Assert(code < D_CODES, "bad d_code");
1571 SEND_CODE(code, dtree); /* send the distance code */
1572 extra = extra_dbits[code];
1574 dist -= G2.base_dist[code];
1575 send_bits(dist, extra); /* send the extra distance bits */
1577 } /* literal or match pair ? */
1579 } while (lx < G2.last_lit);
1581 SEND_CODE(END_BLOCK, ltree);
1585 /* ===========================================================================
1586 * Determine the best encoding for the current block: dynamic trees, static
1587 * trees or store, and output the encoded block to the zip file. This function
1588 * returns the total compressed length for the file so far.
1590 static ulg flush_block(char *buf, ulg stored_len, int eof)
1592 ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
1593 int max_blindex; /* index of last bit length code of non zero freq */
1595 G2.flag_buf[G2.last_flags] = G2.flags; /* Save the flags for the last 8 items */
1597 /* Construct the literal and distance trees */
1598 build_tree(&G2.l_desc);
1599 Tracev((stderr, "\nlit data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1601 build_tree(&G2.d_desc);
1602 Tracev((stderr, "\ndist data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
1603 /* At this point, opt_len and static_len are the total bit lengths of
1604 * the compressed block data, excluding the tree representations.
1607 /* Build the bit length tree for the above two trees, and get the index
1608 * in bl_order of the last bit length code to send.
1610 max_blindex = build_bl_tree();
1612 /* Determine the best encoding. Compute first the block length in bytes */
1613 opt_lenb = (G2.opt_len + 3 + 7) >> 3;
1614 static_lenb = (G2.static_len + 3 + 7) >> 3;
1617 "\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
1618 opt_lenb, G2.opt_len, static_lenb, G2.static_len, stored_len,
1619 G2.last_lit, G2.last_dist));
1621 if (static_lenb <= opt_lenb)
1622 opt_lenb = static_lenb;
1624 /* If compression failed and this is the first and last block,
1625 * and if the zip file can be seeked (to rewrite the local header),
1626 * the whole file is transformed into a stored file:
1628 if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) {
1629 /* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
1631 bb_error_msg("block vanished");
1633 copy_block(buf, (unsigned) stored_len, 0); /* without header */
1634 G2.compressed_len = stored_len << 3;
1636 } else if (stored_len + 4 <= opt_lenb && buf != NULL) {
1637 /* 4: two words for the lengths */
1638 /* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
1639 * Otherwise we can't have processed more than WSIZE input bytes since
1640 * the last block flush, because compression would have been
1641 * successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
1642 * transform a block into a stored block.
1644 send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
1645 G2.compressed_len = (G2.compressed_len + 3 + 7) & ~7L;
1646 G2.compressed_len += (stored_len + 4) << 3;
1648 copy_block(buf, (unsigned) stored_len, 1); /* with header */
1650 } else if (static_lenb == opt_lenb) {
1651 send_bits((STATIC_TREES << 1) + eof, 3);
1652 compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree);
1653 G2.compressed_len += 3 + G2.static_len;
1655 send_bits((DYN_TREES << 1) + eof, 3);
1656 send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1,
1658 compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree);
1659 G2.compressed_len += 3 + G2.opt_len;
1661 Assert(G2.compressed_len == G1.bits_sent, "bad compressed size");
1666 G2.compressed_len += 7; /* align on byte boundary */
1668 Tracev((stderr, "\ncomprlen %lu(%lu) ", G2.compressed_len >> 3,
1669 G2.compressed_len - 7 * eof));
1671 return G2.compressed_len >> 3;
1675 /* ===========================================================================
1676 * Update a hash value with the given input byte
1677 * IN assertion: all calls to to UPDATE_HASH are made with consecutive
1678 * input characters, so that a running hash key can be computed from the
1679 * previous key instead of complete recalculation each time.
1681 #define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
1684 /* ===========================================================================
1685 * Same as above, but achieves better compression. We use a lazy
1686 * evaluation for matches: a match is finally adopted only if there is
1687 * no better match at the next window position.
1689 * Processes a new input file and return its compressed length. Sets
1690 * the compressed length, crc, deflate flags and internal file
1694 /* Flush the current block, with given end-of-file flag.
1695 * IN assertion: strstart is set to the end of the current match. */
1696 #define FLUSH_BLOCK(eof) \
1698 G1.block_start >= 0L \
1699 ? (char*)&G1.window[(unsigned)G1.block_start] \
1701 (ulg)G1.strstart - G1.block_start, \
1705 /* Insert string s in the dictionary and set match_head to the previous head
1706 * of the hash chain (the most recent string with same hash key). Return
1707 * the previous length of the hash chain.
1708 * IN assertion: all calls to to INSERT_STRING are made with consecutive
1709 * input characters and the first MIN_MATCH bytes of s are valid
1710 * (except for the last MIN_MATCH-1 bytes of the input file). */
1711 #define INSERT_STRING(s, match_head) \
1713 UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \
1714 G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \
1715 head[G1.ins_h] = (s); \
1718 static ulg deflate(void)
1720 IPos hash_head; /* head of hash chain */
1721 IPos prev_match; /* previous match */
1722 int flush; /* set if current block must be flushed */
1723 int match_available = 0; /* set if previous match exists */
1724 unsigned match_length = MIN_MATCH - 1; /* length of best match */
1726 /* Process the input block. */
1727 while (G1.lookahead != 0) {
1728 /* Insert the string window[strstart .. strstart+2] in the
1729 * dictionary, and set hash_head to the head of the hash chain:
1731 INSERT_STRING(G1.strstart, hash_head);
1733 /* Find the longest match, discarding those <= prev_length.
1735 G1.prev_length = match_length;
1736 prev_match = G1.match_start;
1737 match_length = MIN_MATCH - 1;
1739 if (hash_head != 0 && G1.prev_length < max_lazy_match
1740 && G1.strstart - hash_head <= MAX_DIST
1742 /* To simplify the code, we prevent matches with the string
1743 * of window index 0 (in particular we have to avoid a match
1744 * of the string with itself at the start of the input file).
1746 match_length = longest_match(hash_head);
1747 /* longest_match() sets match_start */
1748 if (match_length > G1.lookahead)
1749 match_length = G1.lookahead;
1751 /* Ignore a length 3 match if it is too distant: */
1752 if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) {
1753 /* If prev_match is also MIN_MATCH, G1.match_start is garbage
1754 * but we will ignore the current match anyway.
1759 /* If there was a match at the previous step and the current
1760 * match is not better, output the previous match:
1762 if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) {
1763 check_match(G1.strstart - 1, prev_match, G1.prev_length);
1764 flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH);
1766 /* Insert in hash table all strings up to the end of the match.
1767 * strstart-1 and strstart are already inserted.
1769 G1.lookahead -= G1.prev_length - 1;
1770 G1.prev_length -= 2;
1773 INSERT_STRING(G1.strstart, hash_head);
1774 /* strstart never exceeds WSIZE-MAX_MATCH, so there are
1775 * always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
1776 * these bytes are garbage, but it does not matter since the
1777 * next lookahead bytes will always be emitted as literals.
1779 } while (--G1.prev_length != 0);
1780 match_available = 0;
1781 match_length = MIN_MATCH - 1;
1785 G1.block_start = G1.strstart;
1787 } else if (match_available) {
1788 /* If there was no match at the previous position, output a
1789 * single literal. If there was a match but the current match
1790 * is longer, truncate the previous match to a single literal.
1792 Tracevv((stderr, "%c", G1.window[G1.strstart - 1]));
1793 if (ct_tally(0, G1.window[G1.strstart - 1])) {
1795 G1.block_start = G1.strstart;
1800 /* There is no previous match to compare with, wait for
1801 * the next step to decide.
1803 match_available = 1;
1807 Assert(G1.strstart <= G1.isize && lookahead <= G1.isize, "a bit too far");
1809 /* Make sure that we always have enough lookahead, except
1810 * at the end of the input file. We need MAX_MATCH bytes
1811 * for the next match, plus MIN_MATCH bytes to insert the
1812 * string following the next match.
1814 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1817 if (match_available)
1818 ct_tally(0, G1.window[G1.strstart - 1]);
1820 return FLUSH_BLOCK(1); /* eof */
1824 /* ===========================================================================
1825 * Initialize the bit string routines.
1827 static void bi_init(void)
1837 /* ===========================================================================
1838 * Initialize the "longest match" routines for a new file
1840 static void lm_init(ush * flagsp)
1844 /* Initialize the hash table. */
1845 memset(head, 0, HASH_SIZE * sizeof(*head));
1846 /* prev will be initialized on the fly */
1848 /* speed options for the general purpose bit flag */
1849 *flagsp |= 2; /* FAST 4, SLOW 2 */
1850 /* ??? reduce max_chain_length for binary files */
1853 G1.block_start = 0L;
1855 G1.lookahead = file_read(G1.window,
1856 sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
1858 if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) {
1864 /* Make sure that we always have enough lookahead. This is important
1865 * if input comes from a device such as a tty.
1867 while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
1871 for (j = 0; j < MIN_MATCH - 1; j++)
1872 UPDATE_HASH(G1.ins_h, G1.window[j]);
1873 /* If lookahead < MIN_MATCH, ins_h is garbage, but this is
1874 * not important since only literal bytes will be emitted.
1879 /* ===========================================================================
1880 * Allocate the match buffer, initialize the various tables and save the
1881 * location of the internal file attribute (ascii/binary) and method
1883 * One callsite in zip()
1885 static void ct_init(void)
1887 int n; /* iterates over tree elements */
1888 int length; /* length value */
1889 int code; /* code value */
1890 int dist; /* distance index */
1892 G2.compressed_len = 0L;
1895 if (G2.static_dtree[0].Len != 0)
1896 return; /* ct_init already called */
1899 /* Initialize the mapping length (0..255) -> length code (0..28) */
1901 for (code = 0; code < LENGTH_CODES - 1; code++) {
1902 G2.base_length[code] = length;
1903 for (n = 0; n < (1 << extra_lbits[code]); n++) {
1904 G2.length_code[length++] = code;
1907 Assert(length == 256, "ct_init: length != 256");
1908 /* Note that the length 255 (match length 258) can be represented
1909 * in two different ways: code 284 + 5 bits or code 285, so we
1910 * overwrite length_code[255] to use the best encoding:
1912 G2.length_code[length - 1] = code;
1914 /* Initialize the mapping dist (0..32K) -> dist code (0..29) */
1916 for (code = 0; code < 16; code++) {
1917 G2.base_dist[code] = dist;
1918 for (n = 0; n < (1 << extra_dbits[code]); n++) {
1919 G2.dist_code[dist++] = code;
1922 Assert(dist == 256, "ct_init: dist != 256");
1923 dist >>= 7; /* from now on, all distances are divided by 128 */
1924 for (; code < D_CODES; code++) {
1925 G2.base_dist[code] = dist << 7;
1926 for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
1927 G2.dist_code[256 + dist++] = code;
1930 Assert(dist == 256, "ct_init: 256+dist != 512");
1932 /* Construct the codes of the static literal tree */
1933 /* already zeroed - it's in bss
1934 for (n = 0; n <= MAX_BITS; n++)
1935 G2.bl_count[n] = 0; */
1939 G2.static_ltree[n++].Len = 8;
1943 G2.static_ltree[n++].Len = 9;
1947 G2.static_ltree[n++].Len = 7;
1951 G2.static_ltree[n++].Len = 8;
1954 /* Codes 286 and 287 do not exist, but we must include them in the
1955 * tree construction to get a canonical Huffman tree (longest code
1958 gen_codes((ct_data *) G2.static_ltree, L_CODES + 1);
1960 /* The static distance tree is trivial: */
1961 for (n = 0; n < D_CODES; n++) {
1962 G2.static_dtree[n].Len = 5;
1963 G2.static_dtree[n].Code = bi_reverse(n, 5);
1966 /* Initialize the first block of the first file: */
1971 /* ===========================================================================
1972 * Deflate in to out.
1973 * IN assertions: the input and output buffers are cleared.
1976 static void zip(ulg time_stamp)
1978 ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
1982 /* Write the header to the gzip file. See algorithm.doc for the format */
1983 /* magic header for gzip files: 1F 8B */
1984 /* compression method: 8 (DEFLATED) */
1985 /* general flags: 0 */
1986 put_32bit(0x00088b1f);
1987 put_32bit(time_stamp);
1989 /* Write deflated file to zip file */
1994 lm_init(&deflate_flags);
1996 put_8bit(deflate_flags); /* extra flags */
1997 put_8bit(3); /* OS identifier = 3 (Unix) */
2001 /* Write the crc and uncompressed size */
2003 put_32bit(G1.isize);
2009 /* ======================================================================== */
2011 char* make_new_name_gzip(char *filename)
2013 return xasprintf("%s.gz", filename);
2017 USE_DESKTOP(long long) int pack_gzip(void)
2023 fstat(STDIN_FILENO, &s);
2028 int gzip_main(int argc, char **argv);
2029 int gzip_main(int argc, char **argv)
2033 /* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */
2034 opt = getopt32(argv, "cfv" USE_GUNZIP("d") "q123456789" );
2035 option_mask32 &= 0x7; /* Clear -d, ignore -q, -0..9 */
2036 //if (opt & 0x1) // -c
2037 //if (opt & 0x2) // -f
2038 //if (opt & 0x4) // -v
2039 #if ENABLE_GUNZIP /* gunzip_main may not be visible... */
2040 if (opt & 0x8) { // -d
2041 return gunzip_main(argc, argv);
2046 PTR_TO_GLOBALS = xzalloc(sizeof(struct globals) + sizeof(struct globals2))
2047 + sizeof(struct globals);
2048 G2.l_desc.dyn_tree = G2.dyn_ltree;
2049 G2.l_desc.static_tree = G2.static_ltree;
2050 G2.l_desc.extra_bits = extra_lbits;
2051 G2.l_desc.extra_base = LITERALS + 1;
2052 G2.l_desc.elems = L_CODES;
2053 G2.l_desc.max_length = MAX_BITS;
2054 //G2.l_desc.max_code = 0;
2056 G2.d_desc.dyn_tree = G2.dyn_dtree;
2057 G2.d_desc.static_tree = G2.static_dtree;
2058 G2.d_desc.extra_bits = extra_dbits;
2059 //G2.d_desc.extra_base = 0;
2060 G2.d_desc.elems = D_CODES;
2061 G2.d_desc.max_length = MAX_BITS;
2062 //G2.d_desc.max_code = 0;
2064 G2.bl_desc.dyn_tree = G2.bl_tree;
2065 //G2.bl_desc.static_tree = NULL;
2066 G2.bl_desc.extra_bits = extra_blbits,
2067 //G2.bl_desc.extra_base = 0;
2068 G2.bl_desc.elems = BL_CODES;
2069 G2.bl_desc.max_length = MAX_BL_BITS;
2070 //G2.bl_desc.max_code = 0;
2072 /* Allocate all global buffers (for DYN_ALLOC option) */
2073 ALLOC(uch, G1.l_buf, INBUFSIZ);
2074 ALLOC(uch, G1.outbuf, OUTBUFSIZ);
2075 ALLOC(ush, G1.d_buf, DIST_BUFSIZE);
2076 ALLOC(uch, G1.window, 2L * WSIZE);
2077 ALLOC(ush, G1.prev, 1L << BITS);
2079 /* Initialise the CRC32 table */
2080 G1.crc_32_tab = crc32_filltable(NULL, 0);
2082 return bbunpack(argv, make_new_name_gzip, pack_gzip);