kernel / pub / scm / linux / kernel / git / bwh / klibc / 3cba7636442f0ad076fb6c16230c6935353ce9c0 / . / usr / gzip / inflate.c

/* inflate.c -- Not copyrighted 1992 by Mark Adler | |

version c10p1, 10 January 1993 */ | |

/* You can do whatever you like with this source file, though I would | |

prefer that if you modify it and redistribute it that you include | |

comments to that effect with your name and the date. Thank you. | |

[The history has been moved to the file ChangeLog.] | |

*/ | |

/* | |

Inflate deflated (PKZIP's method 8 compressed) data. The compression | |

method searches for as much of the current string of bytes (up to a | |

length of 258) in the previous 32K bytes. If it doesn't find any | |

matches (of at least length 3), it codes the next byte. Otherwise, it | |

codes the length of the matched string and its distance backwards from | |

the current position. There is a single Huffman code that codes both | |

single bytes (called "literals") and match lengths. A second Huffman | |

code codes the distance information, which follows a length code. Each | |

length or distance code actually represents a base value and a number | |

of "extra" (sometimes zero) bits to get to add to the base value. At | |

the end of each deflated block is a special end-of-block (EOB) literal/ | |

length code. The decoding process is basically: get a literal/length | |

code; if EOB then done; if a literal, emit the decoded byte; if a | |

length then get the distance and emit the referred-to bytes from the | |

sliding window of previously emitted data. | |

There are (currently) three kinds of inflate blocks: stored, fixed, and | |

dynamic. The compressor deals with some chunk of data at a time, and | |

decides which method to use on a chunk-by-chunk basis. A chunk might | |

typically be 32K or 64K. If the chunk is uncompressible, then the | |

"stored" method is used. In this case, the bytes are simply stored as | |

is, eight bits per byte, with none of the above coding. The bytes are | |

preceded by a count, since there is no longer an EOB code. | |

If the data is compressible, then either the fixed or dynamic methods | |

are used. In the dynamic method, the compressed data is preceded by | |

an encoding of the literal/length and distance Huffman codes that are | |

to be used to decode this block. The representation is itself Huffman | |

coded, and so is preceded by a description of that code. These code | |

descriptions take up a little space, and so for small blocks, there is | |

a predefined set of codes, called the fixed codes. The fixed method is | |

used if the block codes up smaller that way (usually for quite small | |

chunks), otherwise the dynamic method is used. In the latter case, the | |

codes are customized to the probabilities in the current block, and so | |

can code it much better than the pre-determined fixed codes. | |

The Huffman codes themselves are decoded using a mutli-level table | |

lookup, in order to maximize the speed of decoding plus the speed of | |

building the decoding tables. See the comments below that precede the | |

lbits and dbits tuning parameters. | |

*/ | |

/* | |

Notes beyond the 1.93a appnote.txt: | |

1. Distance pointers never point before the beginning of the output | |

stream. | |

2. Distance pointers can point back across blocks, up to 32k away. | |

3. There is an implied maximum of 7 bits for the bit length table and | |

15 bits for the actual data. | |

4. If only one code exists, then it is encoded using one bit. (Zero | |

would be more efficient, but perhaps a little confusing.) If two | |

codes exist, they are coded using one bit each (0 and 1). | |

5. There is no way of sending zero distance codes--a dummy must be | |

sent if there are none. (History: a pre 2.0 version of PKZIP would | |

store blocks with no distance codes, but this was discovered to be | |

too harsh a criterion.) Valid only for 1.93a. 2.04c does allow | |

zero distance codes, which is sent as one code of zero bits in | |

length. | |

6. There are up to 286 literal/length codes. Code 256 represents the | |

end-of-block. Note however that the static length tree defines | |

288 codes just to fill out the Huffman codes. Codes 286 and 287 | |

cannot be used though, since there is no length base or extra bits | |

defined for them. Similarly, there are up to 30 distance codes. | |

However, static trees define 32 codes (all 5 bits) to fill out the | |

Huffman codes, but the last two had better not show up in the data. | |

7. Unzip can check dynamic Huffman blocks for complete code sets. | |

The exception is that a single code would not be complete (see #4). | |

8. The five bits following the block type is really the number of | |

literal codes sent minus 257. | |

9. Length codes 8,16,16 are interpreted as 13 length codes of 8 bits | |

(1+6+6). Therefore, to output three times the length, you output | |

three codes (1+1+1), whereas to output four times the same length, | |

you only need two codes (1+3). Hmm. | |

10. In the tree reconstruction algorithm, Code = Code + Increment | |

only if BitLength(i) is not zero. (Pretty obvious.) | |

11. Correction: 4 Bits: # of Bit Length codes - 4 (4 - 19) | |

12. Note: length code 284 can represent 227-258, but length code 285 | |

really is 258. The last length deserves its own, short code | |

since it gets used a lot in very redundant files. The length | |

258 is special since 258 - 3 (the min match length) is 255. | |

13. The literal/length and distance code bit lengths are read as a | |

single stream of lengths. It is possible (and advantageous) for | |

a repeat code (16, 17, or 18) to go across the boundary between | |

the two sets of lengths. | |

*/ | |

#ifdef RCSID | |

static char rcsid[] = "$Id: inflate.c,v 1.1 2002/08/18 00:59:21 hpa Exp $"; | |

#endif | |

#include <sys/types.h> | |

#include <stdlib.h> | |

#include "tailor.h" | |

#include "gzip.h" | |

#define slide window | |

/* Huffman code lookup table entry--this entry is four bytes for machines | |

that have 16-bit pointers (e.g. PC's in the small or medium model). | |

Valid extra bits are 0..13. e == 15 is EOB (end of block), e == 16 | |

means that v is a literal, 16 < e < 32 means that v is a pointer to | |

the next table, which codes e - 16 bits, and lastly e == 99 indicates | |

an unused code. If a code with e == 99 is looked up, this implies an | |

error in the data. */ | |

struct huft { | |

uch e; /* number of extra bits or operation */ | |

uch b; /* number of bits in this code or subcode */ | |

union { | |

ush n; /* literal, length base, or distance base */ | |

struct huft *t; /* pointer to next level of table */ | |

} v; | |

}; | |

/* Function prototypes */ | |

int huft_build OF((unsigned *, unsigned, unsigned, ush *, ush *, | |

struct huft **, int *)); | |

int huft_free OF((struct huft *)); | |

int inflate_codes OF((struct huft *, struct huft *, int, int)); | |

int inflate_stored OF((void)); | |

int inflate_fixed OF((void)); | |

int inflate_dynamic OF((void)); | |

int inflate_block OF((int *)); | |

int inflate OF((void)); | |

/* The inflate algorithm uses a sliding 32K byte window on the uncompressed | |

stream to find repeated byte strings. This is implemented here as a | |

circular buffer. The index is updated simply by incrementing and then | |

and'ing with 0x7fff (32K-1). */ | |

/* It is left to other modules to supply the 32K area. It is assumed | |

to be usable as if it were declared "uch slide[32768];" or as just | |

"uch *slide;" and then malloc'ed in the latter case. The definition | |

must be in unzip.h, included above. */ | |

/* unsigned wp; current position in slide */ | |

#define wp outcnt | |

#define flush_output(w) (wp=(w),flush_window()) | |

/* Tables for deflate from PKZIP's appnote.txt. */ | |

static unsigned border[] = { /* Order of the bit length code lengths */ | |

16, 17, 18, 0, 8, 7, 9, 6, 10, 5, 11, 4, 12, 3, 13, 2, 14, 1, 15}; | |

static ush cplens[] = { /* Copy lengths for literal codes 257..285 */ | |

3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31, | |

35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0}; | |

/* note: see note #13 above about the 258 in this list. */ | |

static ush cplext[] = { /* Extra bits for literal codes 257..285 */ | |

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, 99, 99}; /* 99==invalid */ | |

static ush cpdist[] = { /* Copy offsets for distance codes 0..29 */ | |

1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193, | |

257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145, | |

8193, 12289, 16385, 24577}; | |

static ush cpdext[] = { /* Extra bits for distance codes */ | |

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}; | |

/* Macros for inflate() bit peeking and grabbing. | |

The usage is: | |

NEEDBITS(j) | |

x = b & mask_bits[j]; | |

DUMPBITS(j) | |

where NEEDBITS makes sure that b has at least j bits in it, and | |

DUMPBITS removes the bits from b. The macros use the variable k | |

for the number of bits in b. Normally, b and k are register | |

variables for speed, and are initialized at the beginning of a | |

routine that uses these macros from a global bit buffer and count. | |

If we assume that EOB will be the longest code, then we will never | |

ask for bits with NEEDBITS that are beyond the end of the stream. | |

So, NEEDBITS should not read any more bytes than are needed to | |

meet the request. Then no bytes need to be "returned" to the buffer | |

at the end of the last block. | |

However, this assumption is not true for fixed blocks--the EOB code | |

is 7 bits, but the other literal/length codes can be 8 or 9 bits. | |

(The EOB code is shorter than other codes because fixed blocks are | |

generally short. So, while a block always has an EOB, many other | |

literal/length codes have a significantly lower probability of | |

showing up at all.) However, by making the first table have a | |

lookup of seven bits, the EOB code will be found in that first | |

lookup, and so will not require that too many bits be pulled from | |

the stream. | |

*/ | |

ulg bb; /* bit buffer */ | |

unsigned bk; /* bits in bit buffer */ | |

ush mask_bits[] = { | |

0x0000, | |

0x0001, 0x0003, 0x0007, 0x000f, 0x001f, 0x003f, 0x007f, 0x00ff, | |

0x01ff, 0x03ff, 0x07ff, 0x0fff, 0x1fff, 0x3fff, 0x7fff, 0xffff | |

}; | |

#ifdef CRYPT | |

uch cc; | |

# define NEXTBYTE() \ | |

(decrypt ? (cc = get_byte(), cc) : get_byte()) | |

#else | |

# define NEXTBYTE() (uch)get_byte() | |

#endif | |

#define NEEDBITS(n) {while(k<(n)){b|=((ulg)NEXTBYTE())<<k;k+=8;}} | |

#define DUMPBITS(n) {b>>=(n);k-=(n);} | |

/* | |

Huffman code decoding is performed using a multi-level table lookup. | |

The fastest way to decode is to simply build a lookup table whose | |

size is determined by the longest code. However, the time it takes | |

to build this table can also be a factor if the data being decoded | |

is not very long. The most common codes are necessarily the | |

shortest codes, so those codes dominate the decoding time, and hence | |

the speed. The idea is you can have a shorter table that decodes the | |

shorter, more probable codes, and then point to subsidiary tables for | |

the longer codes. The time it costs to decode the longer codes is | |

then traded against the time it takes to make longer tables. | |

This results of this trade are in the variables lbits and dbits | |

below. lbits is the number of bits the first level table for literal/ | |

length codes can decode in one step, and dbits is the same thing for | |

the distance codes. Subsequent tables are also less than or equal to | |

those sizes. These values may be adjusted either when all of the | |

codes are shorter than that, in which case the longest code length in | |

bits is used, or when the shortest code is *longer* than the requested | |

table size, in which case the length of the shortest code in bits is | |

used. | |

There are two different values for the two tables, since they code a | |

different number of possibilities each. The literal/length table | |

codes 286 possible values, or in a flat code, a little over eight | |

bits. The distance table codes 30 possible values, or a little less | |

than five bits, flat. The optimum values for speed end up being | |

about one bit more than those, so lbits is 8+1 and dbits is 5+1. | |

The optimum values may differ though from machine to machine, and | |

possibly even between compilers. Your mileage may vary. | |

*/ | |

int lbits = 9; /* bits in base literal/length lookup table */ | |

int dbits = 6; /* bits in base distance lookup table */ | |

/* If BMAX needs to be larger than 16, then h and x[] should be ulg. */ | |

#define BMAX 16 /* maximum bit length of any code (16 for explode) */ | |

#define N_MAX 288 /* maximum number of codes in any set */ | |

unsigned hufts; /* track memory usage */ | |

int huft_build(b, n, s, d, e, t, m) | |

unsigned *b; /* code lengths in bits (all assumed <= BMAX) */ | |

unsigned n; /* number of codes (assumed <= N_MAX) */ | |

unsigned s; /* number of simple-valued codes (0..s-1) */ | |

ush *d; /* list of base values for non-simple codes */ | |

ush *e; /* list of extra bits for non-simple codes */ | |

struct huft **t; /* result: starting table */ | |

int *m; /* maximum lookup bits, returns actual */ | |

/* Given a list of code lengths and a maximum table size, make a set of | |

tables to decode that set of codes. Return zero on success, one if | |

the given code set is incomplete (the tables are still built in this | |

case), two if the input is invalid (all zero length codes or an | |

oversubscribed set of lengths), and three if not enough memory. */ | |

{ | |

unsigned a; /* counter for codes of length k */ | |

unsigned c[BMAX+1]; /* bit length count table */ | |

unsigned f; /* i repeats in table every f entries */ | |

int g; /* maximum code length */ | |

int h; /* table level */ | |

register unsigned i; /* counter, current code */ | |

register unsigned j; /* counter */ | |

register int k; /* number of bits in current code */ | |

int l; /* bits per table (returned in m) */ | |

register unsigned *p; /* pointer into c[], b[], or v[] */ | |

register struct huft *q; /* points to current table */ | |

struct huft r; /* table entry for structure assignment */ | |

struct huft *u[BMAX]; /* table stack */ | |

unsigned v[N_MAX]; /* values in order of bit length */ | |

register int w; /* bits before this table == (l * h) */ | |

unsigned x[BMAX+1]; /* bit offsets, then code stack */ | |

unsigned *xp; /* pointer into x */ | |

int y; /* number of dummy codes added */ | |

unsigned z; /* number of entries in current table */ | |

/* Generate counts for each bit length */ | |

memzero(c, sizeof(c)); | |

p = b; i = n; | |

do { | |

Tracecv(*p, (stderr, (n-i >= ' ' && n-i <= '~' ? "%c %d\n" : "0x%x %d\n"), | |

n-i, *p)); | |

c[*p]++; /* assume all entries <= BMAX */ | |

p++; /* Can't combine with above line (Solaris bug) */ | |

} while (--i); | |

if (c[0] == n) /* null input--all zero length codes */ | |

{ | |

*t = (struct huft *)NULL; | |

*m = 0; | |

return 0; | |

} | |

/* Find minimum and maximum length, bound *m by those */ | |

l = *m; | |

for (j = 1; j <= BMAX; j++) | |

if (c[j]) | |

break; | |

k = j; /* minimum code length */ | |

if ((unsigned)l < j) | |

l = j; | |

for (i = BMAX; i; i--) | |

if (c[i]) | |

break; | |

g = i; /* maximum code length */ | |

if ((unsigned)l > i) | |

l = i; | |

*m = l; | |

/* Adjust last length count to fill out codes, if needed */ | |

for (y = 1 << j; j < i; j++, y <<= 1) | |

if ((y -= c[j]) < 0) | |

return 2; /* bad input: more codes than bits */ | |

if ((y -= c[i]) < 0) | |

return 2; | |

c[i] += y; | |

/* Generate starting offsets into the value table for each length */ | |

x[1] = j = 0; | |

p = c + 1; xp = x + 2; | |

while (--i) { /* note that i == g from above */ | |

*xp++ = (j += *p++); | |

} | |

/* Make a table of values in order of bit lengths */ | |

p = b; i = 0; | |

do { | |

if ((j = *p++) != 0) | |

v[x[j]++] = i; | |

} while (++i < n); | |

/* Generate the Huffman codes and for each, make the table entries */ | |

x[0] = i = 0; /* first Huffman code is zero */ | |

p = v; /* grab values in bit order */ | |

h = -1; /* no tables yet--level -1 */ | |

w = -l; /* bits decoded == (l * h) */ | |

u[0] = (struct huft *)NULL; /* just to keep compilers happy */ | |

q = (struct huft *)NULL; /* ditto */ | |

z = 0; /* ditto */ | |

/* go through the bit lengths (k already is bits in shortest code) */ | |

for (; k <= g; k++) | |

{ | |

a = c[k]; | |

while (a--) | |

{ | |

/* here i is the Huffman code of length k bits for value *p */ | |

/* make tables up to required level */ | |

while (k > w + l) | |

{ | |

h++; | |

w += l; /* previous table always l bits */ | |

/* compute minimum size table less than or equal to l bits */ | |

z = (z = g - w) > (unsigned)l ? (unsigned)l : z; /* upper limit on table size */ | |

if ((f = 1 << (j = k - w)) > a + 1) /* try a k-w bit table */ | |

{ /* too few codes for k-w bit table */ | |

f -= a + 1; /* deduct codes from patterns left */ | |

xp = c + k; | |

while (++j < z) /* try smaller tables up to z bits */ | |

{ | |

if ((f <<= 1) <= *++xp) | |

break; /* enough codes to use up j bits */ | |

f -= *xp; /* else deduct codes from patterns */ | |

} | |

} | |

z = 1 << j; /* table entries for j-bit table */ | |

/* allocate and link in new table */ | |

if ((q = (struct huft *)malloc((z + 1)*sizeof(struct huft))) == | |

(struct huft *)NULL) | |

{ | |

if (h) | |

huft_free(u[0]); | |

return 3; /* not enough memory */ | |

} | |

hufts += z + 1; /* track memory usage */ | |

*t = q + 1; /* link to list for huft_free() */ | |

*(t = &(q->v.t)) = (struct huft *)NULL; | |

u[h] = ++q; /* table starts after link */ | |

/* connect to last table, if there is one */ | |

if (h) | |

{ | |

x[h] = i; /* save pattern for backing up */ | |

r.b = (uch)l; /* bits to dump before this table */ | |

r.e = (uch)(16 + j); /* bits in this table */ | |

r.v.t = q; /* pointer to this table */ | |

j = i >> (w - l); /* (get around Turbo C bug) */ | |

u[h-1][j] = r; /* connect to last table */ | |

} | |

} | |

/* set up table entry in r */ | |

r.b = (uch)(k - w); | |

if (p >= v + n) | |

r.e = 99; /* out of values--invalid code */ | |

else if (*p < s) | |

{ | |

r.e = (uch)(*p < 256 ? 16 : 15); /* 256 is end-of-block code */ | |

r.v.n = (ush)(*p); /* simple code is just the value */ | |

p++; /* one compiler does not like *p++ */ | |

} | |

else | |

{ | |

r.e = (uch)e[*p - s]; /* non-simple--look up in lists */ | |

r.v.n = d[*p++ - s]; | |

} | |

/* fill code-like entries with r */ | |

f = 1 << (k - w); | |

for (j = i >> w; j < z; j += f) | |

q[j] = r; | |

/* backwards increment the k-bit code i */ | |

for (j = 1 << (k - 1); i & j; j >>= 1) | |

i ^= j; | |

i ^= j; | |

/* backup over finished tables */ | |

while ((i & ((1 << w) - 1)) != x[h]) | |

{ | |

h--; /* don't need to update q */ | |

w -= l; | |

} | |

} | |

} | |

/* Return true (1) if we were given an incomplete table */ | |

return y != 0 && g != 1; | |

} | |

int huft_free(t) | |

struct huft *t; /* table to free */ | |

/* Free the malloc'ed tables built by huft_build(), which makes a linked | |

list of the tables it made, with the links in a dummy first entry of | |

each table. */ | |

{ | |

register struct huft *p, *q; | |

/* Go through linked list, freeing from the malloced (t[-1]) address. */ | |

p = t; | |

while (p != (struct huft *)NULL) | |

{ | |

q = (--p)->v.t; | |

free((char*)p); | |

p = q; | |

} | |

return 0; | |

} | |

int inflate_codes(tl, td, bl, bd) | |

struct huft *tl, *td; /* literal/length and distance decoder tables */ | |

int bl, bd; /* number of bits decoded by tl[] and td[] */ | |

/* inflate (decompress) the codes in a deflated (compressed) block. | |

Return an error code or zero if it all goes ok. */ | |

{ | |

register unsigned e; /* table entry flag/number of extra bits */ | |

unsigned n, d; /* length and index for copy */ | |

unsigned w; /* current window position */ | |

struct huft *t; /* pointer to table entry */ | |

unsigned ml, md; /* masks for bl and bd bits */ | |

register ulg b; /* bit buffer */ | |

register unsigned k; /* number of bits in bit buffer */ | |

/* make local copies of globals */ | |

b = bb; /* initialize bit buffer */ | |

k = bk; | |

w = wp; /* initialize window position */ | |

/* inflate the coded data */ | |

ml = mask_bits[bl]; /* precompute masks for speed */ | |

md = mask_bits[bd]; | |

for (;;) /* do until end of block */ | |

{ | |

NEEDBITS((unsigned)bl) | |

if ((e = (t = tl + ((unsigned)b & ml))->e) > 16) | |

do { | |

if (e == 99) | |

return 1; | |

DUMPBITS(t->b) | |

e -= 16; | |

NEEDBITS(e) | |

} while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16); | |

DUMPBITS(t->b) | |

if (e == 16) /* then it's a literal */ | |

{ | |

slide[w++] = (uch)t->v.n; | |

Tracevv((stderr, "%c", slide[w-1])); | |

if (w == WSIZE) | |

{ | |

flush_output(w); | |

w = 0; | |

} | |

} | |

else /* it's an EOB or a length */ | |

{ | |

/* exit if end of block */ | |

if (e == 15) | |

break; | |

/* get length of block to copy */ | |

NEEDBITS(e) | |

n = t->v.n + ((unsigned)b & mask_bits[e]); | |

DUMPBITS(e); | |

/* decode distance of block to copy */ | |

NEEDBITS((unsigned)bd) | |

if ((e = (t = td + ((unsigned)b & md))->e) > 16) | |

do { | |

if (e == 99) | |

return 1; | |

DUMPBITS(t->b) | |

e -= 16; | |

NEEDBITS(e) | |

} while ((e = (t = t->v.t + ((unsigned)b & mask_bits[e]))->e) > 16); | |

DUMPBITS(t->b) | |

NEEDBITS(e) | |

d = w - t->v.n - ((unsigned)b & mask_bits[e]); | |

DUMPBITS(e) | |

Tracevv((stderr,"\\[%d,%d]", w-d, n)); | |

/* do the copy */ | |

do { | |

n -= (e = (e = WSIZE - ((d &= WSIZE-1) > w ? d : w)) > n ? n : e); | |

#if !defined(NOMEMCPY) && !defined(DEBUG) | |

if (w - d >= e) /* (this test assumes unsigned comparison) */ | |

{ | |

memcpy(slide + w, slide + d, e); | |

w += e; | |

d += e; | |

} | |

else /* do it slow to avoid memcpy() overlap */ | |

#endif /* !NOMEMCPY */ | |

do { | |

slide[w++] = slide[d++]; | |

Tracevv((stderr, "%c", slide[w-1])); | |

} while (--e); | |

if (w == WSIZE) | |

{ | |

flush_output(w); | |

w = 0; | |

} | |

} while (n); | |

} | |

} | |

/* restore the globals from the locals */ | |

wp = w; /* restore global window pointer */ | |

bb = b; /* restore global bit buffer */ | |

bk = k; | |

/* done */ | |

return 0; | |

} | |

int inflate_stored() | |

/* "decompress" an inflated type 0 (stored) block. */ | |

{ | |

unsigned n; /* number of bytes in block */ | |

unsigned w; /* current window position */ | |

register ulg b; /* bit buffer */ | |

register unsigned k; /* number of bits in bit buffer */ | |

/* make local copies of globals */ | |

b = bb; /* initialize bit buffer */ | |

k = bk; | |

w = wp; /* initialize window position */ | |

/* go to byte boundary */ | |

n = k & 7; | |

DUMPBITS(n); | |

/* get the length and its complement */ | |

NEEDBITS(16) | |

n = ((unsigned)b & 0xffff); | |

DUMPBITS(16) | |

NEEDBITS(16) | |

if (n != (unsigned)((~b) & 0xffff)) | |

return 1; /* error in compressed data */ | |

DUMPBITS(16) | |

/* read and output the compressed data */ | |

while (n--) | |

{ | |

NEEDBITS(8) | |

slide[w++] = (uch)b; | |

if (w == WSIZE) | |

{ | |

flush_output(w); | |

w = 0; | |

} | |

DUMPBITS(8) | |

} | |

/* restore the globals from the locals */ | |

wp = w; /* restore global window pointer */ | |

bb = b; /* restore global bit buffer */ | |

bk = k; | |

return 0; | |

} | |

int inflate_fixed() | |

/* decompress an inflated type 1 (fixed Huffman codes) block. We should | |

either replace this with a custom decoder, or at least precompute the | |

Huffman tables. */ | |

{ | |

int i; /* temporary variable */ | |

struct huft *tl; /* literal/length code table */ | |

struct huft *td; /* distance code table */ | |

int bl; /* lookup bits for tl */ | |

int bd; /* lookup bits for td */ | |

unsigned l[288]; /* length list for huft_build */ | |

/* set up literal table */ | |

for (i = 0; i < 144; i++) | |

l[i] = 8; | |

for (; i < 256; i++) | |

l[i] = 9; | |

for (; i < 280; i++) | |

l[i] = 7; | |

for (; i < 288; i++) /* make a complete, but wrong code set */ | |

l[i] = 8; | |

bl = 7; | |

if ((i = huft_build(l, 288, 257, cplens, cplext, &tl, &bl)) != 0) | |

return i; | |

/* set up distance table */ | |

for (i = 0; i < 30; i++) /* make an incomplete code set */ | |

l[i] = 5; | |

bd = 5; | |

if ((i = huft_build(l, 30, 0, cpdist, cpdext, &td, &bd)) > 1) | |

{ | |

huft_free(tl); | |

return i; | |

} | |

/* decompress until an end-of-block code */ | |

if (inflate_codes(tl, td, bl, bd)) | |

return 1; | |

/* free the decoding tables, return */ | |

huft_free(tl); | |

huft_free(td); | |

return 0; | |

} | |

int inflate_dynamic() | |

/* decompress an inflated type 2 (dynamic Huffman codes) block. */ | |

{ | |

int i; /* temporary variables */ | |

unsigned j; | |

unsigned l; /* last length */ | |

unsigned m; /* mask for bit lengths table */ | |

unsigned n; /* number of lengths to get */ | |

struct huft *tl; /* literal/length code table */ | |

struct huft *td; /* distance code table */ | |

int bl; /* lookup bits for tl */ | |

int bd; /* lookup bits for td */ | |

unsigned nb; /* number of bit length codes */ | |

unsigned nl; /* number of literal/length codes */ | |

unsigned nd; /* number of distance codes */ | |

#ifdef PKZIP_BUG_WORKAROUND | |

unsigned ll[288+32]; /* literal/length and distance code lengths */ | |

#else | |

unsigned ll[286+30]; /* literal/length and distance code lengths */ | |

#endif | |

register ulg b; /* bit buffer */ | |

register unsigned k; /* number of bits in bit buffer */ | |

/* make local bit buffer */ | |

b = bb; | |

k = bk; | |

/* read in table lengths */ | |

NEEDBITS(5) | |

nl = 257 + ((unsigned)b & 0x1f); /* number of literal/length codes */ | |

DUMPBITS(5) | |

NEEDBITS(5) | |

nd = 1 + ((unsigned)b & 0x1f); /* number of distance codes */ | |

DUMPBITS(5) | |

NEEDBITS(4) | |

nb = 4 + ((unsigned)b & 0xf); /* number of bit length codes */ | |

DUMPBITS(4) | |

#ifdef PKZIP_BUG_WORKAROUND | |

if (nl > 288 || nd > 32) | |

#else | |

if (nl > 286 || nd > 30) | |

#endif | |

return 1; /* bad lengths */ | |

/* read in bit-length-code lengths */ | |

for (j = 0; j < nb; j++) | |

{ | |

NEEDBITS(3) | |

ll[border[j]] = (unsigned)b & 7; | |

DUMPBITS(3) | |

} | |

for (; j < 19; j++) | |

ll[border[j]] = 0; | |

/* build decoding table for trees--single level, 7 bit lookup */ | |

bl = 7; | |

if ((i = huft_build(ll, 19, 19, NULL, NULL, &tl, &bl)) != 0) | |

{ | |

if (i == 1) | |

huft_free(tl); | |

return i; /* incomplete code set */ | |

} | |

/* read in literal and distance code lengths */ | |

n = nl + nd; | |

m = mask_bits[bl]; | |

i = l = 0; | |

while ((unsigned)i < n) | |

{ | |

NEEDBITS((unsigned)bl) | |

j = (td = tl + ((unsigned)b & m))->b; | |

DUMPBITS(j) | |

j = td->v.n; | |

if (j < 16) /* length of code in bits (0..15) */ | |

ll[i++] = l = j; /* save last length in l */ | |

else if (j == 16) /* repeat last length 3 to 6 times */ | |

{ | |

NEEDBITS(2) | |

j = 3 + ((unsigned)b & 3); | |

DUMPBITS(2) | |

if ((unsigned)i + j > n) | |

return 1; | |

while (j--) | |

ll[i++] = l; | |

} | |

else if (j == 17) /* 3 to 10 zero length codes */ | |

{ | |

NEEDBITS(3) | |

j = 3 + ((unsigned)b & 7); | |

DUMPBITS(3) | |

if ((unsigned)i + j > n) | |

return 1; | |

while (j--) | |

ll[i++] = 0; | |

l = 0; | |

} | |

else /* j == 18: 11 to 138 zero length codes */ | |

{ | |

NEEDBITS(7) | |

j = 11 + ((unsigned)b & 0x7f); | |

DUMPBITS(7) | |

if ((unsigned)i + j > n) | |

return 1; | |

while (j--) | |

ll[i++] = 0; | |

l = 0; | |

} | |

} | |

/* free decoding table for trees */ | |

huft_free(tl); | |

/* restore the global bit buffer */ | |

bb = b; | |

bk = k; | |

/* build the decoding tables for literal/length and distance codes */ | |

bl = lbits; | |

if ((i = huft_build(ll, nl, 257, cplens, cplext, &tl, &bl)) != 0) | |

{ | |

if (i == 1) { | |

fprintf(stderr, " incomplete literal tree\n"); | |

huft_free(tl); | |

} | |

return i; /* incomplete code set */ | |

} | |

bd = dbits; | |

if ((i = huft_build(ll + nl, nd, 0, cpdist, cpdext, &td, &bd)) != 0) | |

{ | |

if (i == 1) { | |

fprintf(stderr, " incomplete distance tree\n"); | |

#ifdef PKZIP_BUG_WORKAROUND | |

i = 0; | |

} | |

#else | |

huft_free(td); | |

} | |

huft_free(tl); | |

return i; /* incomplete code set */ | |

#endif | |

} | |

/* decompress until an end-of-block code */ | |

if (inflate_codes(tl, td, bl, bd)) | |

return 1; | |

/* free the decoding tables, return */ | |

huft_free(tl); | |

huft_free(td); | |

return 0; | |

} | |

int inflate_block(e) | |

int *e; /* last block flag */ | |

/* decompress an inflated block */ | |

{ | |

unsigned t; /* block type */ | |

register ulg b; /* bit buffer */ | |

register unsigned k; /* number of bits in bit buffer */ | |

/* make local bit buffer */ | |

b = bb; | |

k = bk; | |

/* read in last block bit */ | |

NEEDBITS(1) | |

*e = (int)b & 1; | |

DUMPBITS(1) | |

/* read in block type */ | |

NEEDBITS(2) | |

t = (unsigned)b & 3; | |

DUMPBITS(2) | |

/* restore the global bit buffer */ | |

bb = b; | |

bk = k; | |

/* inflate that block type */ | |

if (t == 2) | |

return inflate_dynamic(); | |

if (t == 0) | |

return inflate_stored(); | |

if (t == 1) | |

return inflate_fixed(); | |

/* bad block type */ | |

return 2; | |

} | |

int inflate() | |

/* decompress an inflated entry */ | |

{ | |

int e; /* last block flag */ | |

int r; /* result code */ | |

unsigned h; /* maximum struct huft's malloc'ed */ | |

/* initialize window, bit buffer */ | |

wp = 0; | |

bk = 0; | |

bb = 0; | |

/* decompress until the last block */ | |

h = 0; | |

do { | |

hufts = 0; | |

if ((r = inflate_block(&e)) != 0) | |

return r; | |

if (hufts > h) | |

h = hufts; | |

} while (!e); | |

/* Undo too much lookahead. The next read will be byte aligned so we | |

* can discard unused bits in the last meaningful byte. | |

*/ | |

while (bk >= 8) { | |

bk -= 8; | |

inptr--; | |

} | |

/* flush out slide */ | |

flush_output(wp); | |

/* return success */ | |

#ifdef DEBUG | |

fprintf(stderr, "<%u> ", h); | |

#endif /* DEBUG */ | |

return 0; | |

} |