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hush/archival/gzip.c

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/* vi: set sw=4 ts=4: */
/*
* Gzip implementation for busybox
*
* Based on GNU gzip Copyright (C) 1992-1993 Jean-loup Gailly.
*
* Originally adjusted for busybox by Charles P. Wright <cpw@unix.asb.com>
* "this is a stripped down version of gzip I put into busybox, it does
* only standard in to standard out with -9 compression. It also requires
* the zcat module for some important functions."
*
* Adjusted further by Erik Andersen <andersen@codepoet.org> to support
* files as well as stdin/stdout, and to generally behave itself wrt
* command line handling.
*
* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
*/
/* big objects in bss:
* 00000020 b bl_count
* 00000074 b base_length
* 00000078 b base_dist
* 00000078 b static_dtree
* 0000009c b bl_tree
* 000000f4 b dyn_dtree
* 00000100 b length_code
* 00000200 b dist_code
* 0000023d b depth
* 00000400 b flag_buf
* 0000047a b heap
* 00000480 b static_ltree
* 000008f4 b dyn_ltree
*/
/* TODO: full support for -v for DESKTOP
* "/usr/bin/gzip -v a bogus aa" should say:
a: 85.1% -- replaced with a.gz
gzip: bogus: No such file or directory
aa: 85.1% -- replaced with aa.gz
*/
#include "libbb.h"
/* ===========================================================================
*/
//#define DEBUG 1
/* Diagnostic functions */
#ifdef DEBUG
# define Assert(cond,msg) { if (!(cond)) bb_error_msg(msg); }
# define Trace(x) fprintf x
# define Tracev(x) {if (verbose) fprintf x; }
# define Tracevv(x) {if (verbose > 1) fprintf x; }
# define Tracec(c,x) {if (verbose && (c)) fprintf x; }
# define Tracecv(c,x) {if (verbose > 1 && (c)) fprintf x; }
#else
# define Assert(cond,msg)
# define Trace(x)
# define Tracev(x)
# define Tracevv(x)
# define Tracec(c,x)
# define Tracecv(c,x)
#endif
/* ===========================================================================
*/
#define SMALL_MEM
#ifndef INBUFSIZ
# ifdef SMALL_MEM
# define INBUFSIZ 0x2000 /* input buffer size */
# else
# define INBUFSIZ 0x8000 /* input buffer size */
# endif
#endif
#ifndef OUTBUFSIZ
# ifdef SMALL_MEM
# define OUTBUFSIZ 8192 /* output buffer size */
# else
# define OUTBUFSIZ 16384 /* output buffer size */
# endif
#endif
#ifndef DIST_BUFSIZE
# ifdef SMALL_MEM
# define DIST_BUFSIZE 0x2000 /* buffer for distances, see trees.c */
# else
# define DIST_BUFSIZE 0x8000 /* buffer for distances, see trees.c */
# endif
#endif
/* gzip flag byte */
#define ASCII_FLAG 0x01 /* bit 0 set: file probably ascii text */
#define CONTINUATION 0x02 /* bit 1 set: continuation of multi-part gzip file */
#define EXTRA_FIELD 0x04 /* bit 2 set: extra field present */
#define ORIG_NAME 0x08 /* bit 3 set: original file name present */
#define COMMENT 0x10 /* bit 4 set: file comment present */
#define RESERVED 0xC0 /* bit 6,7: reserved */
/* internal file attribute */
#define UNKNOWN 0xffff
#define BINARY 0
#define ASCII 1
#ifndef WSIZE
# define WSIZE 0x8000 /* window size--must be a power of two, and */
#endif /* at least 32K for zip's deflate method */
#define MIN_MATCH 3
#define MAX_MATCH 258
/* The minimum and maximum match lengths */
#define MIN_LOOKAHEAD (MAX_MATCH+MIN_MATCH+1)
/* Minimum amount of lookahead, except at the end of the input file.
* See deflate.c for comments about the MIN_MATCH+1.
*/
#define MAX_DIST (WSIZE-MIN_LOOKAHEAD)
/* In order to simplify the code, particularly on 16 bit machines, match
* distances are limited to MAX_DIST instead of WSIZE.
*/
#ifndef MAX_PATH_LEN
# define MAX_PATH_LEN 1024 /* max pathname length */
#endif
#define seekable() 0 /* force sequential output */
#define translate_eol 0 /* no option -a yet */
#ifndef BITS
# define BITS 16
#endif
#define INIT_BITS 9 /* Initial number of bits per code */
#define BIT_MASK 0x1f /* Mask for 'number of compression bits' */
/* Mask 0x20 is reserved to mean a fourth header byte, and 0x40 is free.
* It's a pity that old uncompress does not check bit 0x20. That makes
* extension of the format actually undesirable because old compress
* would just crash on the new format instead of giving a meaningful
* error message. It does check the number of bits, but it's more
* helpful to say "unsupported format, get a new version" than
* "can only handle 16 bits".
*/
#ifdef MAX_EXT_CHARS
# define MAX_SUFFIX MAX_EXT_CHARS
#else
# define MAX_SUFFIX 30
#endif
/* ===========================================================================
* Compile with MEDIUM_MEM to reduce the memory requirements or
* with SMALL_MEM to use as little memory as possible. Use BIG_MEM if the
* entire input file can be held in memory (not possible on 16 bit systems).
* Warning: defining these symbols affects HASH_BITS (see below) and thus
* affects the compression ratio. The compressed output
* is still correct, and might even be smaller in some cases.
*/
#ifdef SMALL_MEM
# define HASH_BITS 13 /* Number of bits used to hash strings */
#endif
#ifdef MEDIUM_MEM
# define HASH_BITS 14
#endif
#ifndef HASH_BITS
# define HASH_BITS 15
/* For portability to 16 bit machines, do not use values above 15. */
#endif
#define HASH_SIZE (unsigned)(1<<HASH_BITS)
#define HASH_MASK (HASH_SIZE-1)
#define WMASK (WSIZE-1)
/* HASH_SIZE and WSIZE must be powers of two */
#ifndef TOO_FAR
# define TOO_FAR 4096
#endif
/* Matches of length 3 are discarded if their distance exceeds TOO_FAR */
/* ===========================================================================
* These types are not really 'char', 'short' and 'long'
*/
typedef uint8_t uch;
typedef uint16_t ush;
typedef uint32_t ulg;
typedef int32_t lng;
typedef ush Pos;
typedef unsigned IPos;
/* A Pos is an index in the character window. We use short instead of int to
* save space in the various tables. IPos is used only for parameter passing.
*/
enum {
WINDOW_SIZE = 2 * WSIZE,
/* window size, 2*WSIZE except for MMAP or BIG_MEM, where it is the
* input file length plus MIN_LOOKAHEAD.
*/
max_chain_length = 4096,
/* To speed up deflation, hash chains are never searched beyond this length.
* A higher limit improves compression ratio but degrades the speed.
*/
max_lazy_match = 258,
/* Attempt to find a better match only when the current match is strictly
* smaller than this value. This mechanism is used only for compression
* levels >= 4.
*/
max_insert_length = max_lazy_match,
/* Insert new strings in the hash table only if the match length
* is not greater than this length. This saves time but degrades compression.
* max_insert_length is used only for compression levels <= 3.
*/
good_match = 32,
/* Use a faster search when the previous match is longer than this */
/* Values for max_lazy_match, good_match and max_chain_length, depending on
* the desired pack level (0..9). The values given below have been tuned to
* exclude worst case performance for pathological files. Better values may be
* found for specific files.
*/
nice_match = 258, /* Stop searching when current match exceeds this */
/* Note: the deflate() code requires max_lazy >= MIN_MATCH and max_chain >= 4
* For deflate_fast() (levels <= 3) good is ignored and lazy has a different
* meaning.
*/
};
struct globals {
lng block_start;
/* window position at the beginning of the current output block. Gets
* negative when the window is moved backwards.
*/
unsigned ins_h; /* hash index of string to be inserted */
#define H_SHIFT ((HASH_BITS+MIN_MATCH-1) / MIN_MATCH)
/* Number of bits by which ins_h and del_h must be shifted at each
* input step. It must be such that after MIN_MATCH steps, the oldest
* byte no longer takes part in the hash key, that is:
* H_SHIFT * MIN_MATCH >= HASH_BITS
*/
unsigned prev_length;
/* Length of the best match at previous step. Matches not greater than this
* are discarded. This is used in the lazy match evaluation.
*/
unsigned strstart; /* start of string to insert */
unsigned match_start; /* start of matching string */
unsigned lookahead; /* number of valid bytes ahead in window */
/* ===========================================================================
*/
#define DECLARE(type, array, size) \
type * array
#define ALLOC(type, array, size) \
array = xzalloc((size_t)(((size)+1L)/2) * 2*sizeof(type));
#define FREE(array) \
do { free(array); array = NULL; } while (0)
/* global buffers */
/* buffer for literals or lengths */
/* DECLARE(uch, l_buf, LIT_BUFSIZE); */
DECLARE(uch, l_buf, INBUFSIZ);
DECLARE(ush, d_buf, DIST_BUFSIZE);
DECLARE(uch, outbuf, OUTBUFSIZ);
/* Sliding window. Input bytes are read into the second half of the window,
* and move to the first half later to keep a dictionary of at least WSIZE
* bytes. With this organization, matches are limited to a distance of
* WSIZE-MAX_MATCH bytes, but this ensures that IO is always
* performed with a length multiple of the block size. Also, it limits
* the window size to 64K, which is quite useful on MSDOS.
* To do: limit the window size to WSIZE+BSZ if SMALL_MEM (the code would
* be less efficient).
*/
DECLARE(uch, window, 2L * WSIZE);
/* Link to older string with same hash index. To limit the size of this
* array to 64K, this link is maintained only for the last 32K strings.
* An index in this array is thus a window index modulo 32K.
*/
/* DECLARE(Pos, prev, WSIZE); */
DECLARE(ush, prev, 1L << BITS);
/* Heads of the hash chains or 0. */
/* DECLARE(Pos, head, 1<<HASH_BITS); */
#define head (G1.prev + WSIZE) /* hash head (see deflate.c) */
/* number of input bytes */
ulg isize; /* only 32 bits stored in .gz file */
/* bbox always use stdin/stdout */
#define ifd STDIN_FILENO /* input file descriptor */
#define ofd STDOUT_FILENO /* output file descriptor */
#ifdef DEBUG
unsigned insize; /* valid bytes in l_buf */
#endif
unsigned outcnt; /* bytes in output buffer */
smallint eofile; /* flag set at end of input file */
/* ===========================================================================
* Local data used by the "bit string" routines.
*/
unsigned short bi_buf;
/* Output buffer. bits are inserted starting at the bottom (least significant
* bits).
*/
#undef BUF_SIZE
#define BUF_SIZE (8 * sizeof(G1.bi_buf))
/* Number of bits used within bi_buf. (bi_buf might be implemented on
* more than 16 bits on some systems.)
*/
int bi_valid;
/* Current input function. Set to mem_read for in-memory compression */
#ifdef DEBUG
ulg bits_sent; /* bit length of the compressed data */
#endif
uint32_t *crc_32_tab;
uint32_t crc; /* shift register contents */
};
#define G1 (*(ptr_to_globals - 1))
/* ===========================================================================
* Write the output buffer outbuf[0..outcnt-1] and update bytes_out.
* (used for the compressed data only)
*/
static void flush_outbuf(void)
{
if (G1.outcnt == 0)
return;
xwrite(ofd, (char *) G1.outbuf, G1.outcnt);
G1.outcnt = 0;
}
/* ===========================================================================
*/
/* put_8bit is used for the compressed output */
#define put_8bit(c) \
do { \
G1.outbuf[G1.outcnt++] = (c); \
if (G1.outcnt == OUTBUFSIZ) flush_outbuf(); \
} while (0)
/* Output a 16 bit value, lsb first */
static void put_16bit(ush w)
{
if (G1.outcnt < OUTBUFSIZ - 2) {
G1.outbuf[G1.outcnt++] = w;
G1.outbuf[G1.outcnt++] = w >> 8;
} else {
put_8bit(w);
put_8bit(w >> 8);
}
}
static void put_32bit(ulg n)
{
put_16bit(n);
put_16bit(n >> 16);
}
/* ===========================================================================
* Clear input and output buffers
*/
static void clear_bufs(void)
{
G1.outcnt = 0;
#ifdef DEBUG
G1.insize = 0;
#endif
G1.isize = 0;
}
/* ===========================================================================
* Run a set of bytes through the crc shift register. If s is a NULL
* pointer, then initialize the crc shift register contents instead.
* Return the current crc in either case.
*/
static uint32_t updcrc(uch * s, unsigned n)
{
uint32_t c = G1.crc;
while (n) {
c = G1.crc_32_tab[(uch)(c ^ *s++)] ^ (c >> 8);
n--;
}
G1.crc = c;
return c;
}
/* ===========================================================================
* Read a new buffer from the current input file, perform end-of-line
* translation, and update the crc and input file size.
* IN assertion: size >= 2 (for end-of-line translation)
*/
static unsigned file_read(void *buf, unsigned size)
{
unsigned len;
Assert(G1.insize == 0, "l_buf not empty");
len = safe_read(ifd, buf, size);
if (len == (unsigned)(-1) || len == 0)
return len;
updcrc(buf, len);
G1.isize += len;
return len;
}
/* ===========================================================================
* Send a value on a given number of bits.
* IN assertion: length <= 16 and value fits in length bits.
*/
static void send_bits(int value, int length)
{
#ifdef DEBUG
Tracev((stderr, " l %2d v %4x ", length, value));
Assert(length > 0 && length <= 15, "invalid length");
G1.bits_sent += length;
#endif
/* If not enough room in bi_buf, use (valid) bits from bi_buf and
* (16 - bi_valid) bits from value, leaving (width - (16-bi_valid))
* unused bits in value.
*/
if (G1.bi_valid > (int) BUF_SIZE - length) {
G1.bi_buf |= (value << G1.bi_valid);
put_16bit(G1.bi_buf);
G1.bi_buf = (ush) value >> (BUF_SIZE - G1.bi_valid);
G1.bi_valid += length - BUF_SIZE;
} else {
G1.bi_buf |= value << G1.bi_valid;
G1.bi_valid += length;
}
}
/* ===========================================================================
* Reverse the first len bits of a code, using straightforward code (a faster
* method would use a table)
* IN assertion: 1 <= len <= 15
*/
static unsigned bi_reverse(unsigned code, int len)
{
unsigned res = 0;
while (1) {
res |= code & 1;
if (--len <= 0) return res;
code >>= 1;
res <<= 1;
}
}
/* ===========================================================================
* Write out any remaining bits in an incomplete byte.
*/
static void bi_windup(void)
{
if (G1.bi_valid > 8) {
put_16bit(G1.bi_buf);
} else if (G1.bi_valid > 0) {
put_8bit(G1.bi_buf);
}
G1.bi_buf = 0;
G1.bi_valid = 0;
#ifdef DEBUG
G1.bits_sent = (G1.bits_sent + 7) & ~7;
#endif
}
/* ===========================================================================
* Copy a stored block to the zip file, storing first the length and its
* one's complement if requested.
*/
static void copy_block(char *buf, unsigned len, int header)
{
bi_windup(); /* align on byte boundary */
if (header) {
put_16bit(len);
put_16bit(~len);
#ifdef DEBUG
G1.bits_sent += 2 * 16;
#endif
}
#ifdef DEBUG
G1.bits_sent += (ulg) len << 3;
#endif
while (len--) {
put_8bit(*buf++);
}
}
/* ===========================================================================
* Fill the window when the lookahead becomes insufficient.
* Updates strstart and lookahead, and sets eofile if end of input file.
* IN assertion: lookahead < MIN_LOOKAHEAD && strstart + lookahead > 0
* OUT assertions: at least one byte has been read, or eofile is set;
* file reads are performed for at least two bytes (required for the
* translate_eol option).
*/
static void fill_window(void)
{
unsigned n, m;
unsigned more = WINDOW_SIZE - G1.lookahead - G1.strstart;
/* Amount of free space at the end of the window. */
/* If the window is almost full and there is insufficient lookahead,
* move the upper half to the lower one to make room in the upper half.
*/
if (more == (unsigned) -1) {
/* Very unlikely, but possible on 16 bit machine if strstart == 0
* and lookahead == 1 (input done one byte at time)
*/
more--;
} else if (G1.strstart >= WSIZE + MAX_DIST) {
/* By the IN assertion, the window is not empty so we can't confuse
* more == 0 with more == 64K on a 16 bit machine.
*/
Assert(WINDOW_SIZE == 2 * WSIZE, "no sliding with BIG_MEM");
memcpy(G1.window, G1.window + WSIZE, WSIZE);
G1.match_start -= WSIZE;
G1.strstart -= WSIZE; /* we now have strstart >= MAX_DIST: */
G1.block_start -= WSIZE;
for (n = 0; n < HASH_SIZE; n++) {
m = head[n];
head[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
}
for (n = 0; n < WSIZE; n++) {
m = G1.prev[n];
G1.prev[n] = (Pos) (m >= WSIZE ? m - WSIZE : 0);
/* If n is not on any hash chain, prev[n] is garbage but
* its value will never be used.
*/
}
more += WSIZE;
}
/* At this point, more >= 2 */
if (!G1.eofile) {
n = file_read(G1.window + G1.strstart + G1.lookahead, more);
if (n == 0 || n == (unsigned) -1) {
G1.eofile = 1;
} else {
G1.lookahead += n;
}
}
}
/* ===========================================================================
* Set match_start to the longest match starting at the given string and
* return its length. Matches shorter or equal to prev_length are discarded,
* in which case the result is equal to prev_length and match_start is
* garbage.
* IN assertions: cur_match is the head of the hash chain for the current
* string (strstart) and its distance is <= MAX_DIST, and prev_length >= 1
*/
/* For MSDOS, OS/2 and 386 Unix, an optimized version is in match.asm or
* match.s. The code is functionally equivalent, so you can use the C version
* if desired.
*/
static int longest_match(IPos cur_match)
{
unsigned chain_length = max_chain_length; /* max hash chain length */
uch *scan = G1.window + G1.strstart; /* current string */
uch *match; /* matched string */
int len; /* length of current match */
int best_len = G1.prev_length; /* best match length so far */
IPos limit = G1.strstart > (IPos) MAX_DIST ? G1.strstart - (IPos) MAX_DIST : 0;
/* Stop when cur_match becomes <= limit. To simplify the code,
* we prevent matches with the string of window index 0.
*/
/* The code is optimized for HASH_BITS >= 8 and MAX_MATCH-2 multiple of 16.
* It is easy to get rid of this optimization if necessary.
*/
#if HASH_BITS < 8 || MAX_MATCH != 258
# error Code too clever
#endif
uch *strend = G1.window + G1.strstart + MAX_MATCH;
uch scan_end1 = scan[best_len - 1];
uch scan_end = scan[best_len];
/* Do not waste too much time if we already have a good match: */
if (G1.prev_length >= good_match) {
chain_length >>= 2;
}
Assert(G1.strstart <= WINDOW_SIZE - MIN_LOOKAHEAD, "insufficient lookahead");
do {
Assert(cur_match < G1.strstart, "no future");
match = G1.window + cur_match;
/* Skip to next match if the match length cannot increase
* or if the match length is less than 2:
*/
if (match[best_len] != scan_end ||
match[best_len - 1] != scan_end1 ||
*match != *scan || *++match != scan[1])
continue;
/* The check at best_len-1 can be removed because it will be made
* again later. (This heuristic is not always a win.)
* It is not necessary to compare scan[2] and match[2] since they
* are always equal when the other bytes match, given that
* the hash keys are equal and that HASH_BITS >= 8.
*/
scan += 2, match++;
/* We check for insufficient lookahead only every 8th comparison;
* the 256th check will be made at strstart+258.
*/
do {
} while (*++scan == *++match && *++scan == *++match &&
*++scan == *++match && *++scan == *++match &&
*++scan == *++match && *++scan == *++match &&
*++scan == *++match && *++scan == *++match && scan < strend);
len = MAX_MATCH - (int) (strend - scan);
scan = strend - MAX_MATCH;
if (len > best_len) {
G1.match_start = cur_match;
best_len = len;
if (len >= nice_match)
break;
scan_end1 = scan[best_len - 1];
scan_end = scan[best_len];
}
} while ((cur_match = G1.prev[cur_match & WMASK]) > limit
&& --chain_length != 0);
return best_len;
}
#ifdef DEBUG
/* ===========================================================================
* Check that the match at match_start is indeed a match.
*/
static void check_match(IPos start, IPos match, int length)
{
/* check that the match is indeed a match */
if (memcmp(G1.window + match, G1.window + start, length) != 0) {
bb_error_msg(" start %d, match %d, length %d", start, match, length);
bb_error_msg("invalid match");
}
if (verbose > 1) {
bb_error_msg("\\[%d,%d]", start - match, length);
do {
fputc(G1.window[start++], stderr);
} while (--length != 0);
}
}
#else
# define check_match(start, match, length) ((void)0)
#endif
/* trees.c -- output deflated data using Huffman coding
* Copyright (C) 1992-1993 Jean-loup Gailly
* This is free software; you can redistribute it and/or modify it under the
* terms of the GNU General Public License, see the file COPYING.
*/
/* PURPOSE
* Encode various sets of source values using variable-length
* binary code trees.
*
* DISCUSSION
* The PKZIP "deflation" process uses several Huffman trees. The more
* common source values are represented by shorter bit sequences.
*
* Each code tree is stored in the ZIP file in a compressed form
* which is itself a Huffman encoding of the lengths of
* all the code strings (in ascending order by source values).
* The actual code strings are reconstructed from the lengths in
* the UNZIP process, as described in the "application note"
* (APPNOTE.TXT) distributed as part of PKWARE's PKZIP program.
*
* REFERENCES
* Lynch, Thomas J.
* Data Compression: Techniques and Applications, pp. 53-55.
* Lifetime Learning Publications, 1985. ISBN 0-534-03418-7.
*
* Storer, James A.
* Data Compression: Methods and Theory, pp. 49-50.
* Computer Science Press, 1988. ISBN 0-7167-8156-5.
*
* Sedgewick, R.
* Algorithms, p290.
* Addison-Wesley, 1983. ISBN 0-201-06672-6.
*
* INTERFACE
* void ct_init()
* Allocate the match buffer, initialize the various tables [and save
* the location of the internal file attribute (ascii/binary) and
* method (DEFLATE/STORE) -- deleted in bbox]
*
* void ct_tally(int dist, int lc);
* Save the match info and tally the frequency counts.
*
* ulg flush_block(char *buf, ulg stored_len, int eof)
* Determine the best encoding for the current block: dynamic trees,
* static trees or store, and output the encoded block to the zip
* file. Returns the total compressed length for the file so far.
*/
#define MAX_BITS 15
/* All codes must not exceed MAX_BITS bits */
#define MAX_BL_BITS 7
/* Bit length codes must not exceed MAX_BL_BITS bits */
#define LENGTH_CODES 29
/* number of length codes, not counting the special END_BLOCK code */
#define LITERALS 256
/* number of literal bytes 0..255 */
#define END_BLOCK 256
/* end of block literal code */
#define L_CODES (LITERALS+1+LENGTH_CODES)
/* number of Literal or Length codes, including the END_BLOCK code */
#define D_CODES 30
/* number of distance codes */
#define BL_CODES 19
/* number of codes used to transfer the bit lengths */
/* extra bits for each length code */
static const uint8_t extra_lbits[LENGTH_CODES] ALIGN1 = {
0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4,
4, 4, 5, 5, 5, 5, 0
};
/* extra bits for each distance code */
static const uint8_t extra_dbits[D_CODES] ALIGN1 = {
0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6, 7, 7, 8, 8, 9, 9,
10, 10, 11, 11, 12, 12, 13, 13
};
/* extra bits for each bit length code */
static const uint8_t extra_blbits[BL_CODES] ALIGN1 = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 7 };
/* number of codes at each bit length for an optimal tree */
static const uint8_t bl_order[BL_CODES] ALIGN1 = {
16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15 };
#define STORED_BLOCK 0
#define STATIC_TREES 1
#define DYN_TREES 2
/* The three kinds of block type */
#ifndef LIT_BUFSIZE
# ifdef SMALL_MEM
# define LIT_BUFSIZE 0x2000
# else
# ifdef MEDIUM_MEM
# define LIT_BUFSIZE 0x4000
# else
# define LIT_BUFSIZE 0x8000
# endif
# endif
#endif
#ifndef DIST_BUFSIZE
# define DIST_BUFSIZE LIT_BUFSIZE
#endif
/* Sizes of match buffers for literals/lengths and distances. There are
* 4 reasons for limiting LIT_BUFSIZE to 64K:
* - frequencies can be kept in 16 bit counters
* - if compression is not successful for the first block, all input data is
* still in the window so we can still emit a stored block even when input
* comes from standard input. (This can also be done for all blocks if
* LIT_BUFSIZE is not greater than 32K.)
* - if compression is not successful for a file smaller than 64K, we can
* even emit a stored file instead of a stored block (saving 5 bytes).
* - creating new Huffman trees less frequently may not provide fast
* adaptation to changes in the input data statistics. (Take for
* example a binary file with poorly compressible code followed by
* a highly compressible string table.) Smaller buffer sizes give
* fast adaptation but have of course the overhead of transmitting trees
* more frequently.
* - I can't count above 4
* The current code is general and allows DIST_BUFSIZE < LIT_BUFSIZE (to save
* memory at the expense of compression). Some optimizations would be possible
* if we rely on DIST_BUFSIZE == LIT_BUFSIZE.
*/
#define REP_3_6 16
/* repeat previous bit length 3-6 times (2 bits of repeat count) */
#define REPZ_3_10 17
/* repeat a zero length 3-10 times (3 bits of repeat count) */
#define REPZ_11_138 18
/* repeat a zero length 11-138 times (7 bits of repeat count) */
/* ===========================================================================
*/
/* Data structure describing a single value and its code string. */
typedef struct ct_data {
union {
ush freq; /* frequency count */
ush code; /* bit string */
} fc;
union {
ush dad; /* father node in Huffman tree */
ush len; /* length of bit string */
} dl;
} ct_data;
#define Freq fc.freq
#define Code fc.code
#define Dad dl.dad
#define Len dl.len
#define HEAP_SIZE (2*L_CODES + 1)
/* maximum heap size */
typedef struct tree_desc {
ct_data *dyn_tree; /* the dynamic tree */
ct_data *static_tree; /* corresponding static tree or NULL */
const uint8_t *extra_bits; /* extra bits for each code or NULL */
int extra_base; /* base index for extra_bits */
int elems; /* max number of elements in the tree */
int max_length; /* max bit length for the codes */
int max_code; /* largest code with non zero frequency */
} tree_desc;
struct globals2 {
ush heap[HEAP_SIZE]; /* heap used to build the Huffman trees */
int heap_len; /* number of elements in the heap */
int heap_max; /* element of largest frequency */
/* The sons of heap[n] are heap[2*n] and heap[2*n+1]. heap[0] is not used.
* The same heap array is used to build all trees.
*/
ct_data dyn_ltree[HEAP_SIZE]; /* literal and length tree */
ct_data dyn_dtree[2 * D_CODES + 1]; /* distance tree */
ct_data static_ltree[L_CODES + 2];
/* The static literal tree. Since the bit lengths are imposed, there is no
* need for the L_CODES extra codes used during heap construction. However
* The codes 286 and 287 are needed to build a canonical tree (see ct_init
* below).
*/
ct_data static_dtree[D_CODES];
/* The static distance tree. (Actually a trivial tree since all codes use
* 5 bits.)
*/
ct_data bl_tree[2 * BL_CODES + 1];
/* Huffman tree for the bit lengths */
tree_desc l_desc;
tree_desc d_desc;
tree_desc bl_desc;
ush bl_count[MAX_BITS + 1];
/* The lengths of the bit length codes are sent in order of decreasing
* probability, to avoid transmitting the lengths for unused bit length codes.
*/
uch depth[2 * L_CODES + 1];
/* Depth of each subtree used as tie breaker for trees of equal frequency */
uch length_code[MAX_MATCH - MIN_MATCH + 1];
/* length code for each normalized match length (0 == MIN_MATCH) */
uch dist_code[512];
/* distance codes. The first 256 values correspond to the distances
* 3 .. 258, the last 256 values correspond to the top 8 bits of
* the 15 bit distances.
*/
int base_length[LENGTH_CODES];
/* First normalized length for each code (0 = MIN_MATCH) */
int base_dist[D_CODES];
/* First normalized distance for each code (0 = distance of 1) */
uch flag_buf[LIT_BUFSIZE / 8];
/* flag_buf is a bit array distinguishing literals from lengths in
* l_buf, thus indicating the presence or absence of a distance.
*/
unsigned last_lit; /* running index in l_buf */
unsigned last_dist; /* running index in d_buf */
unsigned last_flags; /* running index in flag_buf */
uch flags; /* current flags not yet saved in flag_buf */
uch flag_bit; /* current bit used in flags */
/* bits are filled in flags starting at bit 0 (least significant).
* Note: these flags are overkill in the current code since we don't
* take advantage of DIST_BUFSIZE == LIT_BUFSIZE.
*/
ulg opt_len; /* bit length of current block with optimal trees */
ulg static_len; /* bit length of current block with static trees */
ulg compressed_len; /* total bit length of compressed file */
};
#define G2ptr ((struct globals2*)(ptr_to_globals))
#define G2 (*G2ptr)
/* ===========================================================================
*/
static void gen_codes(ct_data * tree, int max_code);
static void build_tree(tree_desc * desc);
static void scan_tree(ct_data * tree, int max_code);
static void send_tree(ct_data * tree, int max_code);
static int build_bl_tree(void);
static void send_all_trees(int lcodes, int dcodes, int blcodes);
static void compress_block(ct_data * ltree, ct_data * dtree);
#ifndef DEBUG
/* Send a code of the given tree. c and tree must not have side effects */
# define SEND_CODE(c, tree) send_bits(tree[c].Code, tree[c].Len)
#else
# define SEND_CODE(c, tree) \
{ \
if (verbose > 1) bb_error_msg("\ncd %3d ",(c)); \
send_bits(tree[c].Code, tree[c].Len); \
}
#endif
#define D_CODE(dist) \
((dist) < 256 ? G2.dist_code[dist] : G2.dist_code[256 + ((dist)>>7)])
/* Mapping from a distance to a distance code. dist is the distance - 1 and
* must not have side effects. dist_code[256] and dist_code[257] are never
* used.
* The arguments must not have side effects.
*/
/* ===========================================================================
* Initialize a new block.
*/
static void init_block(void)
{
int n; /* iterates over tree elements */
/* Initialize the trees. */
for (n = 0; n < L_CODES; n++)
G2.dyn_ltree[n].Freq = 0;
for (n = 0; n < D_CODES; n++)
G2.dyn_dtree[n].Freq = 0;
for (n = 0; n < BL_CODES; n++)
G2.bl_tree[n].Freq = 0;
G2.dyn_ltree[END_BLOCK].Freq = 1;
G2.opt_len = G2.static_len = 0;
G2.last_lit = G2.last_dist = G2.last_flags = 0;
G2.flags = 0;
G2.flag_bit = 1;
}
/* ===========================================================================
* Restore the heap property by moving down the tree starting at node k,
* exchanging a node with the smallest of its two sons if necessary, stopping
* when the heap property is re-established (each father smaller than its
* two sons).
*/
/* Compares to subtrees, using the tree depth as tie breaker when
* the subtrees have equal frequency. This minimizes the worst case length. */
#define SMALLER(tree, n, m) \
(tree[n].Freq < tree[m].Freq \
|| (tree[n].Freq == tree[m].Freq && G2.depth[n] <= G2.depth[m]))
static void pqdownheap(ct_data * tree, int k)
{
int v = G2.heap[k];
int j = k << 1; /* left son of k */
while (j <= G2.heap_len) {
/* Set j to the smallest of the two sons: */
if (j < G2.heap_len && SMALLER(tree, G2.heap[j + 1], G2.heap[j]))
j++;
/* Exit if v is smaller than both sons */
if (SMALLER(tree, v, G2.heap[j]))
break;
/* Exchange v with the smallest son */
G2.heap[k] = G2.heap[j];
k = j;
/* And continue down the tree, setting j to the left son of k */
j <<= 1;
}
G2.heap[k] = v;
}
/* ===========================================================================
* Compute the optimal bit lengths for a tree and update the total bit length
* for the current block.
* IN assertion: the fields freq and dad are set, heap[heap_max] and
* above are the tree nodes sorted by increasing frequency.
* OUT assertions: the field len is set to the optimal bit length, the
* array bl_count contains the frequencies for each bit length.
* The length opt_len is updated; static_len is also updated if stree is
* not null.
*/
static void gen_bitlen(tree_desc * desc)
{
ct_data *tree = desc->dyn_tree;
const uint8_t *extra = desc->extra_bits;
int base = desc->extra_base;
int max_code = desc->max_code;
int max_length = desc->max_length;
ct_data *stree = desc->static_tree;
int h; /* heap index */
int n, m; /* iterate over the tree elements */
int bits; /* bit length */
int xbits; /* extra bits */
ush f; /* frequency */
int overflow = 0; /* number of elements with bit length too large */
for (bits = 0; bits <= MAX_BITS; bits++)
G2.bl_count[bits] = 0;
/* In a first pass, compute the optimal bit lengths (which may
* overflow in the case of the bit length tree).
*/
tree[G2.heap[G2.heap_max]].Len = 0; /* root of the heap */
for (h = G2.heap_max + 1; h < HEAP_SIZE; h++) {
n = G2.heap[h];
bits = tree[tree[n].Dad].Len + 1;
if (bits > max_length) {
bits = max_length;
overflow++;
}
tree[n].Len = (ush) bits;
/* We overwrite tree[n].Dad which is no longer needed */
if (n > max_code)
continue; /* not a leaf node */
G2.bl_count[bits]++;
xbits = 0;
if (n >= base)
xbits = extra[n - base];
f = tree[n].Freq;
G2.opt_len += (ulg) f *(bits + xbits);
if (stree)
G2.static_len += (ulg) f * (stree[n].Len + xbits);
}
if (overflow == 0)
return;
Trace((stderr, "\nbit length overflow\n"));
/* This happens for example on obj2 and pic of the Calgary corpus */
/* Find the first bit length which could increase: */
do {
bits = max_length - 1;
while (G2.bl_count[bits] == 0)
bits--;
G2.bl_count[bits]--; /* move one leaf down the tree */
G2.bl_count[bits + 1] += 2; /* move one overflow item as its brother */
G2.bl_count[max_length]--;
/* The brother of the overflow item also moves one step up,
* but this does not affect bl_count[max_length]
*/
overflow -= 2;
} while (overflow > 0);
/* Now recompute all bit lengths, scanning in increasing frequency.
* h is still equal to HEAP_SIZE. (It is simpler to reconstruct all
* lengths instead of fixing only the wrong ones. This idea is taken
* from 'ar' written by Haruhiko Okumura.)
*/
for (bits = max_length; bits != 0; bits--) {
n = G2.bl_count[bits];
while (n != 0) {
m = G2.heap[--h];
if (m > max_code)
continue;
if (tree[m].Len != (unsigned) bits) {
Trace((stderr, "code %d bits %d->%d\n", m, tree[m].Len, bits));
G2.opt_len += ((int32_t) bits - tree[m].Len) * tree[m].Freq;
tree[m].Len = bits;
}
n--;
}
}
}
/* ===========================================================================
* Generate the codes for a given tree and bit counts (which need not be
* optimal).
* IN assertion: the array bl_count contains the bit length statistics for
* the given tree and the field len is set for all tree elements.
* OUT assertion: the field code is set for all tree elements of non
* zero code length.
*/
static void gen_codes(ct_data * tree, int max_code)
{
ush next_code[MAX_BITS + 1]; /* next code value for each bit length */
ush code = 0; /* running code value */
int bits; /* bit index */
int n; /* code index */
/* The distribution counts are first used to generate the code values
* without bit reversal.
*/
for (bits = 1; bits <= MAX_BITS; bits++) {
next_code[bits] = code = (code + G2.bl_count[bits - 1]) << 1;
}
/* Check that the bit counts in bl_count are consistent. The last code
* must be all ones.
*/
Assert(code + G2.bl_count[MAX_BITS] - 1 == (1 << MAX_BITS) - 1,
"inconsistent bit counts");
Tracev((stderr, "\ngen_codes: max_code %d ", max_code));
for (n = 0; n <= max_code; n++) {
int len = tree[n].Len;
if (len == 0)
continue;
/* Now reverse the bits */
tree[n].Code = bi_reverse(next_code[len]++, len);
Tracec(tree != G2.static_ltree,
(stderr, "\nn %3d %c l %2d c %4x (%x) ", n,
(isgraph(n) ? n : ' '), len, tree[n].Code,
next_code[len] - 1));
}
}
/* ===========================================================================
* Construct one Huffman tree and assigns the code bit strings and lengths.
* Update the total bit length for the current block.
* IN assertion: the field freq is set for all tree elements.
* OUT assertions: the fields len and code are set to the optimal bit length
* and corresponding code. The length opt_len is updated; static_len is
* also updated if stree is not null. The field max_code is set.
*/
/* Remove the smallest element from the heap and recreate the heap with
* one less element. Updates heap and heap_len. */
#define SMALLEST 1
/* Index within the heap array of least frequent node in the Huffman tree */
#define PQREMOVE(tree, top) \
do { \
top = G2.heap[SMALLEST]; \
G2.heap[SMALLEST] = G2.heap[G2.heap_len--]; \
pqdownheap(tree, SMALLEST); \
} while (0)
static void build_tree(tree_desc * desc)
{
ct_data *tree = desc->dyn_tree;
ct_data *stree = desc->static_tree;
int elems = desc->elems;
int n, m; /* iterate over heap elements */
int max_code = -1; /* largest code with non zero frequency */
int node = elems; /* next internal node of the tree */
/* Construct the initial heap, with least frequent element in
* heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n+1].
* heap[0] is not used.
*/
G2.heap_len = 0;
G2.heap_max = HEAP_SIZE;
for (n = 0; n < elems; n++) {
if (tree[n].Freq != 0) {
G2.heap[++G2.heap_len] = max_code = n;
G2.depth[n] = 0;
} else {
tree[n].Len = 0;
}
}
/* The pkzip format requires that at least one distance code exists,
* and that at least one bit should be sent even if there is only one
* possible code. So to avoid special checks later on we force at least
* two codes of non zero frequency.
*/
while (G2.heap_len < 2) {
int new = G2.heap[++G2.heap_len] = (max_code < 2 ? ++max_code : 0);
tree[new].Freq = 1;
G2.depth[new] = 0;
G2.opt_len--;
if (stree)
G2.static_len -= stree[new].Len;
/* new is 0 or 1 so it does not have extra bits */
}
desc->max_code = max_code;
/* The elements heap[heap_len/2+1 .. heap_len] are leaves of the tree,
* establish sub-heaps of increasing lengths:
*/
for (n = G2.heap_len / 2; n >= 1; n--)
pqdownheap(tree, n);
/* Construct the Huffman tree by repeatedly combining the least two
* frequent nodes.
*/
do {
PQREMOVE(tree, n); /* n = node of least frequency */
m = G2.heap[SMALLEST]; /* m = node of next least frequency */
G2.heap[--G2.heap_max] = n; /* keep the nodes sorted by frequency */
G2.heap[--G2.heap_max] = m;
/* Create a new node father of n and m */
tree[node].Freq = tree[n].Freq + tree[m].Freq;
G2.depth[node] = MAX(G2.depth[n], G2.depth[m]) + 1;
tree[n].Dad = tree[m].Dad = (ush) node;
#ifdef DUMP_BL_TREE
if (tree == G2.bl_tree) {
bb_error_msg("\nnode %d(%d), sons %d(%d) %d(%d)",
node, tree[node].Freq, n, tree[n].Freq, m, tree[m].Freq);
}
#endif
/* and insert the new node in the heap */
G2.heap[SMALLEST] = node++;
pqdownheap(tree, SMALLEST);
} while (G2.heap_len >= 2);
G2.heap[--G2.heap_max] = G2.heap[SMALLEST];
/* At this point, the fields freq and dad are set. We can now
* generate the bit lengths.
*/
gen_bitlen((tree_desc *) desc);
/* The field len is now set, we can generate the bit codes */
gen_codes((ct_data *) tree, max_code);
}
/* ===========================================================================
* Scan a literal or distance tree to determine the frequencies of the codes
* in the bit length tree. Updates opt_len to take into account the repeat
* counts. (The contribution of the bit length codes will be added later
* during the construction of bl_tree.)
*/
static void scan_tree(ct_data * tree, int max_code)
{
int n; /* iterates over all tree elements */
int prevlen = -1; /* last emitted length */
int curlen; /* length of current code */
int nextlen = tree[0].Len; /* length of next code */
int count = 0; /* repeat count of the current code */
int max_count = 7; /* max repeat count */
int min_count = 4; /* min repeat count */
if (nextlen == 0) {
max_count = 138;
min_count = 3;
}
tree[max_code + 1].Len = 0xffff; /* guard */
for (n = 0; n <= max_code; n++) {
curlen = nextlen;
nextlen = tree[n + 1].Len;
if (++count < max_count && curlen == nextlen)
continue;
if (count < min_count) {
G2.bl_tree[curlen].Freq += count;
} else if (curlen != 0) {
if (curlen != prevlen)
G2.bl_tree[curlen].Freq++;
G2.bl_tree[REP_3_6].Freq++;
} else if (count <= 10) {
G2.bl_tree[REPZ_3_10].Freq++;
} else {
G2.bl_tree[REPZ_11_138].Freq++;
}
count = 0;
prevlen = curlen;
max_count = 7;
min_count = 4;
if (nextlen == 0) {
max_count = 138;
min_count = 3;
} else if (curlen == nextlen) {
max_count = 6;
min_count = 3;
}
}
}
/* ===========================================================================
* Send a literal or distance tree in compressed form, using the codes in
* bl_tree.
*/
static void send_tree(ct_data * tree, int max_code)
{
int n; /* iterates over all tree elements */
int prevlen = -1; /* last emitted length */
int curlen; /* length of current code */
int nextlen = tree[0].Len; /* length of next code */
int count = 0; /* repeat count of the current code */
int max_count = 7; /* max repeat count */
int min_count = 4; /* min repeat count */
/* tree[max_code+1].Len = -1; *//* guard already set */
if (nextlen == 0)
max_count = 138, min_count = 3;
for (n = 0; n <= max_code; n++) {
curlen = nextlen;
nextlen = tree[n + 1].Len;
if (++count < max_count && curlen == nextlen) {
continue;
} else if (count < min_count) {
do {
SEND_CODE(curlen, G2.bl_tree);
} while (--count);
} else if (curlen != 0) {
if (curlen != prevlen) {
SEND_CODE(curlen, G2.bl_tree);
count--;
}
Assert(count >= 3 && count <= 6, " 3_6?");
SEND_CODE(REP_3_6, G2.bl_tree);
send_bits(count - 3, 2);
} else if (count <= 10) {
SEND_CODE(REPZ_3_10, G2.bl_tree);
send_bits(count - 3, 3);
} else {
SEND_CODE(REPZ_11_138, G2.bl_tree);
send_bits(count - 11, 7);
}
count = 0;
prevlen = curlen;
if (nextlen == 0) {
max_count = 138;
min_count = 3;
} else if (curlen == nextlen) {
max_count = 6;
min_count = 3;
} else {
max_count = 7;
min_count = 4;
}
}
}
/* ===========================================================================
* Construct the Huffman tree for the bit lengths and return the index in
* bl_order of the last bit length code to send.
*/
static int build_bl_tree(void)
{
int max_blindex; /* index of last bit length code of non zero freq */
/* Determine the bit length frequencies for literal and distance trees */
scan_tree(G2.dyn_ltree, G2.l_desc.max_code);
scan_tree(G2.dyn_dtree, G2.d_desc.max_code);
/* Build the bit length tree: */
build_tree(&G2.bl_desc);
/* opt_len now includes the length of the tree representations, except
* the lengths of the bit lengths codes and the 5+5+4 bits for the counts.
*/
/* Determine the number of bit length codes to send. The pkzip format
* requires that at least 4 bit length codes be sent. (appnote.txt says
* 3 but the actual value used is 4.)
*/
for (max_blindex = BL_CODES - 1; max_blindex >= 3; max_blindex--) {
if (G2.bl_tree[bl_order[max_blindex]].Len != 0)
break;
}
/* Update opt_len to include the bit length tree and counts */
G2.opt_len += 3 * (max_blindex + 1) + 5 + 5 + 4;
Tracev((stderr, "\ndyn trees: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
return max_blindex;
}
/* ===========================================================================
* Send the header for a block using dynamic Huffman trees: the counts, the
* lengths of the bit length codes, the literal tree and the distance tree.
* IN assertion: lcodes >= 257, dcodes >= 1, blcodes >= 4.
*/
static void send_all_trees(int lcodes, int dcodes, int blcodes)
{
int rank; /* index in bl_order */
Assert(lcodes >= 257 && dcodes >= 1 && blcodes >= 4, "not enough codes");
Assert(lcodes <= L_CODES && dcodes <= D_CODES
&& blcodes <= BL_CODES, "too many codes");
Tracev((stderr, "\nbl counts: "));
send_bits(lcodes - 257, 5); /* not +255 as stated in appnote.txt */
send_bits(dcodes - 1, 5);
send_bits(blcodes - 4, 4); /* not -3 as stated in appnote.txt */
for (rank = 0; rank < blcodes; rank++) {
Tracev((stderr, "\nbl code %2d ", bl_order[rank]));
send_bits(G2.bl_tree[bl_order[rank]].Len, 3);
}
Tracev((stderr, "\nbl tree: sent %ld", G1.bits_sent));
send_tree((ct_data *) G2.dyn_ltree, lcodes - 1); /* send the literal tree */
Tracev((stderr, "\nlit tree: sent %ld", G1.bits_sent));
send_tree((ct_data *) G2.dyn_dtree, dcodes - 1); /* send the distance tree */
Tracev((stderr, "\ndist tree: sent %ld", G1.bits_sent));
}
/* ===========================================================================
* Save the match info and tally the frequency counts. Return true if
* the current block must be flushed.
*/
static int ct_tally(int dist, int lc)
{
G1.l_buf[G2.last_lit++] = lc;
if (dist == 0) {
/* lc is the unmatched char */
G2.dyn_ltree[lc].Freq++;
} else {
/* Here, lc is the match length - MIN_MATCH */
dist--; /* dist = match distance - 1 */
Assert((ush) dist < (ush) MAX_DIST
&& (ush) lc <= (ush) (MAX_MATCH - MIN_MATCH)
&& (ush) D_CODE(dist) < (ush) D_CODES, "ct_tally: bad match"
);
G2.dyn_ltree[G2.length_code[lc] + LITERALS + 1].Freq++;
G2.dyn_dtree[D_CODE(dist)].Freq++;
G1.d_buf[G2.last_dist++] = dist;
G2.flags |= G2.flag_bit;
}
G2.flag_bit <<= 1;
/* Output the flags if they fill a byte: */
if ((G2.last_lit & 7) == 0) {
G2.flag_buf[G2.last_flags++] = G2.flags;
G2.flags = 0;
G2.flag_bit = 1;
}
/* Try to guess if it is profitable to stop the current block here */
if ((G2.last_lit & 0xfff) == 0) {
/* Compute an upper bound for the compressed length */
ulg out_length = G2.last_lit * 8L;
ulg in_length = (ulg) G1.strstart - G1.block_start;
int dcode;
for (dcode = 0; dcode < D_CODES; dcode++) {
out_length += G2.dyn_dtree[dcode].Freq * (5L + extra_dbits[dcode]);
}
out_length >>= 3;
Trace((stderr,
"\nlast_lit %u, last_dist %u, in %ld, out ~%ld(%ld%%) ",
G2.last_lit, G2.last_dist, in_length, out_length,
100L - out_length * 100L / in_length));
if (G2.last_dist < G2.last_lit / 2 && out_length < in_length / 2)
return 1;
}
return (G2.last_lit == LIT_BUFSIZE - 1 || G2.last_dist == DIST_BUFSIZE);
/* We avoid equality with LIT_BUFSIZE because of wraparound at 64K
* on 16 bit machines and because stored blocks are restricted to
* 64K-1 bytes.
*/
}
/* ===========================================================================
* Send the block data compressed using the given Huffman trees
*/
static void compress_block(ct_data * ltree, ct_data * dtree)
{
unsigned dist; /* distance of matched string */
int lc; /* match length or unmatched char (if dist == 0) */
unsigned lx = 0; /* running index in l_buf */
unsigned dx = 0; /* running index in d_buf */
unsigned fx = 0; /* running index in flag_buf */
uch flag = 0; /* current flags */
unsigned code; /* the code to send */
int extra; /* number of extra bits to send */
if (G2.last_lit != 0) do {
if ((lx & 7) == 0)
flag = G2.flag_buf[fx++];
lc = G1.l_buf[lx++];
if ((flag & 1) == 0) {
SEND_CODE(lc, ltree); /* send a literal byte */
Tracecv(isgraph(lc), (stderr, " '%c' ", lc));
} else {
/* Here, lc is the match length - MIN_MATCH */
code = G2.length_code[lc];
SEND_CODE(code + LITERALS + 1, ltree); /* send the length code */
extra = extra_lbits[code];
if (extra != 0) {
lc -= G2.base_length[code];
send_bits(lc, extra); /* send the extra length bits */
}
dist = G1.d_buf[dx++];
/* Here, dist is the match distance - 1 */
code = D_CODE(dist);
Assert(code < D_CODES, "bad d_code");
SEND_CODE(code, dtree); /* send the distance code */
extra = extra_dbits[code];
if (extra != 0) {
dist -= G2.base_dist[code];
send_bits(dist, extra); /* send the extra distance bits */
}
} /* literal or match pair ? */
flag >>= 1;
} while (lx < G2.last_lit);
SEND_CODE(END_BLOCK, ltree);
}
/* ===========================================================================
* Determine the best encoding for the current block: dynamic trees, static
* trees or store, and output the encoded block to the zip file. This function
* returns the total compressed length for the file so far.
*/
static ulg flush_block(char *buf, ulg stored_len, int eof)
{
ulg opt_lenb, static_lenb; /* opt_len and static_len in bytes */
int max_blindex; /* index of last bit length code of non zero freq */
G2.flag_buf[G2.last_flags] = G2.flags; /* Save the flags for the last 8 items */
/* Construct the literal and distance trees */
build_tree(&G2.l_desc);
Tracev((stderr, "\nlit data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
build_tree(&G2.d_desc);
Tracev((stderr, "\ndist data: dyn %ld, stat %ld", G2.opt_len, G2.static_len));
/* At this point, opt_len and static_len are the total bit lengths of
* the compressed block data, excluding the tree representations.
*/
/* Build the bit length tree for the above two trees, and get the index
* in bl_order of the last bit length code to send.
*/
max_blindex = build_bl_tree();
/* Determine the best encoding. Compute first the block length in bytes */
opt_lenb = (G2.opt_len + 3 + 7) >> 3;
static_lenb = (G2.static_len + 3 + 7) >> 3;
Trace((stderr,
"\nopt %lu(%lu) stat %lu(%lu) stored %lu lit %u dist %u ",
opt_lenb, G2.opt_len, static_lenb, G2.static_len, stored_len,
G2.last_lit, G2.last_dist));
if (static_lenb <= opt_lenb)
opt_lenb = static_lenb;
/* If compression failed and this is the first and last block,
* and if the zip file can be seeked (to rewrite the local header),
* the whole file is transformed into a stored file:
*/
if (stored_len <= opt_lenb && eof && G2.compressed_len == 0L && seekable()) {
/* Since LIT_BUFSIZE <= 2*WSIZE, the input data must be there: */
if (buf == NULL)
bb_error_msg("block vanished");
copy_block(buf, (unsigned) stored_len, 0); /* without header */
G2.compressed_len = stored_len << 3;
} else if (stored_len + 4 <= opt_lenb && buf != NULL) {
/* 4: two words for the lengths */
/* The test buf != NULL is only necessary if LIT_BUFSIZE > WSIZE.
* Otherwise we can't have processed more than WSIZE input bytes since
* the last block flush, because compression would have been
* successful. If LIT_BUFSIZE <= WSIZE, it is never too late to
* transform a block into a stored block.
*/
send_bits((STORED_BLOCK << 1) + eof, 3); /* send block type */
G2.compressed_len = (G2.compressed_len + 3 + 7) & ~7L;
G2.compressed_len += (stored_len + 4) << 3;
copy_block(buf, (unsigned) stored_len, 1); /* with header */
} else if (static_lenb == opt_lenb) {
send_bits((STATIC_TREES << 1) + eof, 3);
compress_block((ct_data *) G2.static_ltree, (ct_data *) G2.static_dtree);
G2.compressed_len += 3 + G2.static_len;
} else {
send_bits((DYN_TREES << 1) + eof, 3);
send_all_trees(G2.l_desc.max_code + 1, G2.d_desc.max_code + 1,
max_blindex + 1);
compress_block((ct_data *) G2.dyn_ltree, (ct_data *) G2.dyn_dtree);
G2.compressed_len += 3 + G2.opt_len;
}
Assert(G2.compressed_len == G1.bits_sent, "bad compressed size");
init_block();
if (eof) {
bi_windup();
G2.compressed_len += 7; /* align on byte boundary */
}
Tracev((stderr, "\ncomprlen %lu(%lu) ", G2.compressed_len >> 3,
G2.compressed_len - 7 * eof));
return G2.compressed_len >> 3;
}
/* ===========================================================================
* Update a hash value with the given input byte
* IN assertion: all calls to to UPDATE_HASH are made with consecutive
* input characters, so that a running hash key can be computed from the
* previous key instead of complete recalculation each time.
*/
#define UPDATE_HASH(h, c) (h = (((h)<<H_SHIFT) ^ (c)) & HASH_MASK)
/* ===========================================================================
* Same as above, but achieves better compression. We use a lazy
* evaluation for matches: a match is finally adopted only if there is
* no better match at the next window position.
*
* Processes a new input file and return its compressed length. Sets
* the compressed length, crc, deflate flags and internal file
* attributes.
*/
/* Flush the current block, with given end-of-file flag.
* IN assertion: strstart is set to the end of the current match. */
#define FLUSH_BLOCK(eof) \
flush_block( \
G1.block_start >= 0L \
? (char*)&G1.window[(unsigned)G1.block_start] \
: (char*)NULL, \
(ulg)G1.strstart - G1.block_start, \
(eof) \
)
/* Insert string s in the dictionary and set match_head to the previous head
* of the hash chain (the most recent string with same hash key). Return
* the previous length of the hash chain.
* IN assertion: all calls to to INSERT_STRING are made with consecutive
* input characters and the first MIN_MATCH bytes of s are valid
* (except for the last MIN_MATCH-1 bytes of the input file). */
#define INSERT_STRING(s, match_head) \
do { \
UPDATE_HASH(G1.ins_h, G1.window[(s) + MIN_MATCH-1]); \
G1.prev[(s) & WMASK] = match_head = head[G1.ins_h]; \
head[G1.ins_h] = (s); \
} while (0)
static ulg deflate(void)
{
IPos hash_head; /* head of hash chain */
IPos prev_match; /* previous match */
int flush; /* set if current block must be flushed */
int match_available = 0; /* set if previous match exists */
unsigned match_length = MIN_MATCH - 1; /* length of best match */
/* Process the input block. */
while (G1.lookahead != 0) {
/* Insert the string window[strstart .. strstart+2] in the
* dictionary, and set hash_head to the head of the hash chain:
*/
INSERT_STRING(G1.strstart, hash_head);
/* Find the longest match, discarding those <= prev_length.
*/
G1.prev_length = match_length;
prev_match = G1.match_start;
match_length = MIN_MATCH - 1;
if (hash_head != 0 && G1.prev_length < max_lazy_match
&& G1.strstart - hash_head <= MAX_DIST
) {
/* To simplify the code, we prevent matches with the string
* of window index 0 (in particular we have to avoid a match
* of the string with itself at the start of the input file).
*/
match_length = longest_match(hash_head);
/* longest_match() sets match_start */
if (match_length > G1.lookahead)
match_length = G1.lookahead;
/* Ignore a length 3 match if it is too distant: */
if (match_length == MIN_MATCH && G1.strstart - G1.match_start > TOO_FAR) {
/* If prev_match is also MIN_MATCH, G1.match_start is garbage
* but we will ignore the current match anyway.
*/
match_length--;
}
}
/* If there was a match at the previous step and the current
* match is not better, output the previous match:
*/
if (G1.prev_length >= MIN_MATCH && match_length <= G1.prev_length) {
check_match(G1.strstart - 1, prev_match, G1.prev_length);
flush = ct_tally(G1.strstart - 1 - prev_match, G1.prev_length - MIN_MATCH);
/* Insert in hash table all strings up to the end of the match.
* strstart-1 and strstart are already inserted.
*/
G1.lookahead -= G1.prev_length - 1;
G1.prev_length -= 2;
do {
G1.strstart++;
INSERT_STRING(G1.strstart, hash_head);
/* strstart never exceeds WSIZE-MAX_MATCH, so there are
* always MIN_MATCH bytes ahead. If lookahead < MIN_MATCH
* these bytes are garbage, but it does not matter since the
* next lookahead bytes will always be emitted as literals.
*/
} while (--G1.prev_length != 0);
match_available = 0;
match_length = MIN_MATCH - 1;
G1.strstart++;
if (flush) {
FLUSH_BLOCK(0);
G1.block_start = G1.strstart;
}
} else if (match_available) {
/* If there was no match at the previous position, output a
* single literal. If there was a match but the current match
* is longer, truncate the previous match to a single literal.
*/
Tracevv((stderr, "%c", G1.window[G1.strstart - 1]));
if (ct_tally(0, G1.window[G1.strstart - 1])) {
FLUSH_BLOCK(0);
G1.block_start = G1.strstart;
}
G1.strstart++;
G1.lookahead--;
} else {
/* There is no previous match to compare with, wait for
* the next step to decide.
*/
match_available = 1;
G1.strstart++;
G1.lookahead--;
}
Assert(G1.strstart <= G1.isize && lookahead <= G1.isize, "a bit too far");
/* Make sure that we always have enough lookahead, except
* at the end of the input file. We need MAX_MATCH bytes
* for the next match, plus MIN_MATCH bytes to insert the
* string following the next match.
*/
while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
fill_window();
}
if (match_available)
ct_tally(0, G1.window[G1.strstart - 1]);
return FLUSH_BLOCK(1); /* eof */
}
/* ===========================================================================
* Initialize the bit string routines.
*/
static void bi_init(void)
{
G1.bi_buf = 0;
G1.bi_valid = 0;
#ifdef DEBUG
G1.bits_sent = 0L;
#endif
}
/* ===========================================================================
* Initialize the "longest match" routines for a new file
*/
static void lm_init(ush * flagsp)
{
unsigned j;
/* Initialize the hash table. */
memset(head, 0, HASH_SIZE * sizeof(*head));
/* prev will be initialized on the fly */
/* speed options for the general purpose bit flag */
*flagsp |= 2; /* FAST 4, SLOW 2 */
/* ??? reduce max_chain_length for binary files */
G1.strstart = 0;
G1.block_start = 0L;
G1.lookahead = file_read(G1.window,
sizeof(int) <= 2 ? (unsigned) WSIZE : 2 * WSIZE);
if (G1.lookahead == 0 || G1.lookahead == (unsigned) -1) {
G1.eofile = 1;
G1.lookahead = 0;
return;
}
G1.eofile = 0;
/* Make sure that we always have enough lookahead. This is important
* if input comes from a device such as a tty.
*/
while (G1.lookahead < MIN_LOOKAHEAD && !G1.eofile)
fill_window();
G1.ins_h = 0;
for (j = 0; j < MIN_MATCH - 1; j++)
UPDATE_HASH(G1.ins_h, G1.window[j]);
/* If lookahead < MIN_MATCH, ins_h is garbage, but this is
* not important since only literal bytes will be emitted.
*/
}
/* ===========================================================================
* Allocate the match buffer, initialize the various tables and save the
* location of the internal file attribute (ascii/binary) and method
* (DEFLATE/STORE).
* One callsite in zip()
*/
static void ct_init(void)
{
int n; /* iterates over tree elements */
int length; /* length value */
int code; /* code value */
int dist; /* distance index */
G2.compressed_len = 0L;
#ifdef NOT_NEEDED
if (G2.static_dtree[0].Len != 0)
return; /* ct_init already called */
#endif
/* Initialize the mapping length (0..255) -> length code (0..28) */
length = 0;
for (code = 0; code < LENGTH_CODES - 1; code++) {
G2.base_length[code] = length;
for (n = 0; n < (1 << extra_lbits[code]); n++) {
G2.length_code[length++] = code;
}
}
Assert(length == 256, "ct_init: length != 256");
/* Note that the length 255 (match length 258) can be represented
* in two different ways: code 284 + 5 bits or code 285, so we
* overwrite length_code[255] to use the best encoding:
*/
G2.length_code[length - 1] = code;
/* Initialize the mapping dist (0..32K) -> dist code (0..29) */
dist = 0;
for (code = 0; code < 16; code++) {
G2.base_dist[code] = dist;
for (n = 0; n < (1 << extra_dbits[code]); n++) {
G2.dist_code[dist++] = code;
}
}
Assert(dist == 256, "ct_init: dist != 256");
dist >>= 7; /* from now on, all distances are divided by 128 */
for (; code < D_CODES; code++) {
G2.base_dist[code] = dist << 7;
for (n = 0; n < (1 << (extra_dbits[code] - 7)); n++) {
G2.dist_code[256 + dist++] = code;
}
}
Assert(dist == 256, "ct_init: 256+dist != 512");
/* Construct the codes of the static literal tree */
/* already zeroed - it's in bss
for (n = 0; n <= MAX_BITS; n++)
G2.bl_count[n] = 0; */
n = 0;
while (n <= 143) {
G2.static_ltree[n++].Len = 8;
G2.bl_count[8]++;
}
while (n <= 255) {
G2.static_ltree[n++].Len = 9;
G2.bl_count[9]++;
}
while (n <= 279) {
G2.static_ltree[n++].Len = 7;
G2.bl_count[7]++;
}
while (n <= 287) {
G2.static_ltree[n++].Len = 8;
G2.bl_count[8]++;
}
/* Codes 286 and 287 do not exist, but we must include them in the
* tree construction to get a canonical Huffman tree (longest code
* all ones)
*/
gen_codes((ct_data *) G2.static_ltree, L_CODES + 1);
/* The static distance tree is trivial: */
for (n = 0; n < D_CODES; n++) {
G2.static_dtree[n].Len = 5;
G2.static_dtree[n].Code = bi_reverse(n, 5);
}
/* Initialize the first block of the first file: */
init_block();
}
/* ===========================================================================
* Deflate in to out.
* IN assertions: the input and output buffers are cleared.
*/
static void zip(ulg time_stamp)
{
ush deflate_flags = 0; /* pkzip -es, -en or -ex equivalent */
G1.outcnt = 0;
/* Write the header to the gzip file. See algorithm.doc for the format */
/* magic header for gzip files: 1F 8B */
/* compression method: 8 (DEFLATED) */
/* general flags: 0 */
put_32bit(0x00088b1f);
put_32bit(time_stamp);
/* Write deflated file to zip file */
G1.crc = ~0;
bi_init();
ct_init();
lm_init(&deflate_flags);
put_8bit(deflate_flags); /* extra flags */
put_8bit(3); /* OS identifier = 3 (Unix) */
deflate();
/* Write the crc and uncompressed size */
put_32bit(~G1.crc);
put_32bit(G1.isize);
flush_outbuf();
}
/* ======================================================================== */
static
char* make_new_name_gzip(char *filename)
{
return xasprintf("%s.gz", filename);
}
static
USE_DESKTOP(long long) int pack_gzip(void)
{
struct stat s;
clear_bufs();
s.st_ctime = 0;
fstat(STDIN_FILENO, &s);
zip(s.st_ctime);
return 0;
}
int gzip_main(int argc, char **argv);
int gzip_main(int argc, char **argv)
{
unsigned opt;
/* Must match bbunzip's constants OPT_STDOUT, OPT_FORCE! */
opt = getopt32(argv, "cfv" USE_GUNZIP("d") "q123456789" );
option_mask32 &= 0x7; /* Clear -d, ignore -q, -0..9 */
//if (opt & 0x1) // -c
//if (opt & 0x2) // -f
//if (opt & 0x4) // -v
#if ENABLE_GUNZIP /* gunzip_main may not be visible... */
if (opt & 0x8) { // -d
return gunzip_main(argc, argv);
}
#endif
argv += optind;
PTR_TO_GLOBALS = xzalloc(sizeof(struct globals) + sizeof(struct globals2))
+ sizeof(struct globals);
G2.l_desc.dyn_tree = G2.dyn_ltree;
G2.l_desc.static_tree = G2.static_ltree;
G2.l_desc.extra_bits = extra_lbits;
G2.l_desc.extra_base = LITERALS + 1;
G2.l_desc.elems = L_CODES;
G2.l_desc.max_length = MAX_BITS;
//G2.l_desc.max_code = 0;
G2.d_desc.dyn_tree = G2.dyn_dtree;
G2.d_desc.static_tree = G2.static_dtree;
G2.d_desc.extra_bits = extra_dbits;
//G2.d_desc.extra_base = 0;
G2.d_desc.elems = D_CODES;
G2.d_desc.max_length = MAX_BITS;
//G2.d_desc.max_code = 0;
G2.bl_desc.dyn_tree = G2.bl_tree;
//G2.bl_desc.static_tree = NULL;
G2.bl_desc.extra_bits = extra_blbits,
//G2.bl_desc.extra_base = 0;
G2.bl_desc.elems = BL_CODES;
G2.bl_desc.max_length = MAX_BL_BITS;
//G2.bl_desc.max_code = 0;
/* Allocate all global buffers (for DYN_ALLOC option) */
ALLOC(uch, G1.l_buf, INBUFSIZ);
ALLOC(uch, G1.outbuf, OUTBUFSIZ);
ALLOC(ush, G1.d_buf, DIST_BUFSIZE);
ALLOC(uch, G1.window, 2L * WSIZE);
ALLOC(ush, G1.prev, 1L << BITS);
/* Initialise the CRC32 table */
G1.crc_32_tab = crc32_filltable(NULL, 0);
return bbunpack(argv, make_new_name_gzip, pack_gzip);
}
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