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Diffstat (limited to 'lib/zlib_inflate/inftrees.c')
| -rw-r--r-- | lib/zlib_inflate/inftrees.c | 683 |
1 files changed, 300 insertions, 383 deletions
diff --git a/lib/zlib_inflate/inftrees.c b/lib/zlib_inflate/inftrees.c index 874950ec485..62343c53bf7 100644 --- a/lib/zlib_inflate/inftrees.c +++ b/lib/zlib_inflate/inftrees.c @@ -1,412 +1,329 @@ /* inftrees.c -- generate Huffman trees for efficient decoding - * Copyright (C) 1995-1998 Mark Adler - * For conditions of distribution and use, see copyright notice in zlib.h + * Copyright (C) 1995-2005 Mark Adler + * For conditions of distribution and use, see copyright notice in zlib.h */ #include <linux/zutil.h> #include "inftrees.h" -#include "infutil.h" -static const char inflate_copyright[] __attribute_used__ = - " inflate 1.1.3 Copyright 1995-1998 Mark Adler "; +#define MAXBITS 15 + +const char inflate_copyright[] = + " inflate 1.2.3 Copyright 1995-2005 Mark Adler "; /* If you use the zlib library in a product, an acknowledgment is welcome in the documentation of your product. If for some reason you cannot include such an acknowledgment, I would appreciate that you keep this copyright string in the executable of your product. */ -struct internal_state; - -/* simplify the use of the inflate_huft type with some defines */ -#define exop word.what.Exop -#define bits word.what.Bits - - -static int huft_build ( - uInt *, /* code lengths in bits */ - uInt, /* number of codes */ - uInt, /* number of "simple" codes */ - const uInt *, /* list of base values for non-simple codes */ - const uInt *, /* list of extra bits for non-simple codes */ - inflate_huft **, /* result: starting table */ - uInt *, /* maximum lookup bits (returns actual) */ - inflate_huft *, /* space for trees */ - uInt *, /* hufts used in space */ - uInt * ); /* space for values */ - -/* Tables for deflate from PKZIP's appnote.txt. */ -static const uInt cplens[31] = { /* 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}; - /* see note #13 above about 258 */ -static const uInt cplext[31] = { /* 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, 112, 112}; /* 112==invalid */ -static const uInt cpdist[30] = { /* 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 const uInt cpdext[30] = { /* 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}; /* - 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. + Build a set of tables to decode the provided canonical Huffman code. + The code lengths are lens[0..codes-1]. The result starts at *table, + whose indices are 0..2^bits-1. work is a writable array of at least + lens shorts, which is used as a work area. type is the type of code + to be generated, CODES, LENS, or DISTS. On return, zero is success, + -1 is an invalid code, and +1 means that ENOUGH isn't enough. table + on return points to the next available entry's address. bits is the + requested root table index bits, and on return it is the actual root + table index bits. It will differ if the request is greater than the + longest code or if it is less than the shortest code. */ - - -/* If BMAX needs to be larger than 16, then h and x[] should be uLong. */ -#define BMAX 15 /* maximum bit length of any code */ - -static int huft_build( - uInt *b, /* code lengths in bits (all assumed <= BMAX) */ - uInt n, /* number of codes (assumed <= 288) */ - uInt s, /* number of simple-valued codes (0..s-1) */ - const uInt *d, /* list of base values for non-simple codes */ - const uInt *e, /* list of extra bits for non-simple codes */ - inflate_huft **t, /* result: starting table */ - uInt *m, /* maximum lookup bits, returns actual */ - inflate_huft *hp, /* space for trees */ - uInt *hn, /* hufts used in space */ - uInt *v /* working area: values in order of bit length */ -) -/* Given a list of code lengths and a maximum table size, make a set of - tables to decode that set of codes. Return Z_OK on success, Z_BUF_ERROR - if the given code set is incomplete (the tables are still built in this - case), Z_DATA_ERROR if the input is invalid (an over-subscribed set of - lengths), or Z_MEM_ERROR if not enough memory. */ +int zlib_inflate_table(type, lens, codes, table, bits, work) +codetype type; +unsigned short *lens; +unsigned codes; +code **table; +unsigned *bits; +unsigned short *work; { + unsigned len; /* a code's length in bits */ + unsigned sym; /* index of code symbols */ + unsigned min, max; /* minimum and maximum code lengths */ + unsigned root; /* number of index bits for root table */ + unsigned curr; /* number of index bits for current table */ + unsigned drop; /* code bits to drop for sub-table */ + int left; /* number of prefix codes available */ + unsigned used; /* code entries in table used */ + unsigned huff; /* Huffman code */ + unsigned incr; /* for incrementing code, index */ + unsigned fill; /* index for replicating entries */ + unsigned low; /* low bits for current root entry */ + unsigned mask; /* mask for low root bits */ + code this; /* table entry for duplication */ + code *next; /* next available space in table */ + const unsigned short *base; /* base value table to use */ + const unsigned short *extra; /* extra bits table to use */ + int end; /* use base and extra for symbol > end */ + unsigned short count[MAXBITS+1]; /* number of codes of each length */ + unsigned short offs[MAXBITS+1]; /* offsets in table for each length */ + static const unsigned short lbase[31] = { /* Length codes 257..285 base */ + 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}; + static const unsigned short lext[31] = { /* Length codes 257..285 extra */ + 16, 16, 16, 16, 16, 16, 16, 16, 17, 17, 17, 17, 18, 18, 18, 18, + 19, 19, 19, 19, 20, 20, 20, 20, 21, 21, 21, 21, 16, 201, 196}; + static const unsigned short dbase[32] = { /* Distance codes 0..29 base */ + 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, 0, 0}; + static const unsigned short dext[32] = { /* Distance codes 0..29 extra */ + 16, 16, 16, 16, 17, 17, 18, 18, 19, 19, 20, 20, 21, 21, 22, 22, + 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, + 28, 28, 29, 29, 64, 64}; + + /* + Process a set of code lengths to create a canonical Huffman code. The + code lengths are lens[0..codes-1]. Each length corresponds to the + symbols 0..codes-1. The Huffman code is generated by first sorting the + symbols by length from short to long, and retaining the symbol order + for codes with equal lengths. Then the code starts with all zero bits + for the first code of the shortest length, and the codes are integer + increments for the same length, and zeros are appended as the length + increases. For the deflate format, these bits are stored backwards + from their more natural integer increment ordering, and so when the + decoding tables are built in the large loop below, the integer codes + are incremented backwards. + + This routine assumes, but does not check, that all of the entries in + lens[] are in the range 0..MAXBITS. The caller must assure this. + 1..MAXBITS is interpreted as that code length. zero means that that + symbol does not occur in this code. + + The codes are sorted by computing a count of codes for each length, + creating from that a table of starting indices for each length in the + sorted table, and then entering the symbols in order in the sorted + table. The sorted table is work[], with that space being provided by + the caller. + + The length counts are used for other purposes as well, i.e. finding + the minimum and maximum length codes, determining if there are any + codes at all, checking for a valid set of lengths, and looking ahead + at length counts to determine sub-table sizes when building the + decoding tables. + */ + + /* accumulate lengths for codes (assumes lens[] all in 0..MAXBITS) */ + for (len = 0; len <= MAXBITS; len++) + count[len] = 0; + for (sym = 0; sym < codes; sym++) + count[lens[sym]]++; + + /* bound code lengths, force root to be within code lengths */ + root = *bits; + for (max = MAXBITS; max >= 1; max--) + if (count[max] != 0) break; + if (root > max) root = max; + if (max == 0) { /* no symbols to code at all */ + this.op = (unsigned char)64; /* invalid code marker */ + this.bits = (unsigned char)1; + this.val = (unsigned short)0; + *(*table)++ = this; /* make a table to force an error */ + *(*table)++ = this; + *bits = 1; + return 0; /* no symbols, but wait for decoding to report error */ + } + for (min = 1; min <= MAXBITS; min++) + if (count[min] != 0) break; + if (root < min) root = min; + + /* check for an over-subscribed or incomplete set of lengths */ + left = 1; + for (len = 1; len <= MAXBITS; len++) { + left <<= 1; + left -= count[len]; + if (left < 0) return -1; /* over-subscribed */ + } + if (left > 0 && (type == CODES || max != 1)) + return -1; /* incomplete set */ + + /* generate offsets into symbol table for each length for sorting */ + offs[1] = 0; + for (len = 1; len < MAXBITS; len++) + offs[len + 1] = offs[len] + count[len]; + + /* sort symbols by length, by symbol order within each length */ + for (sym = 0; sym < codes; sym++) + if (lens[sym] != 0) work[offs[lens[sym]]++] = (unsigned short)sym; + + /* + Create and fill in decoding tables. In this loop, the table being + filled is at next and has curr index bits. The code being used is huff + with length len. That code is converted to an index by dropping drop + bits off of the bottom. For codes where len is less than drop + curr, + those top drop + curr - len bits are incremented through all values to + fill the table with replicated entries. + + root is the number of index bits for the root table. When len exceeds + root, sub-tables are created pointed to by the root entry with an index + of the low root bits of huff. This is saved in low to check for when a + new sub-table should be started. drop is zero when the root table is + being filled, and drop is root when sub-tables are being filled. + + When a new sub-table is needed, it is necessary to look ahead in the + code lengths to determine what size sub-table is needed. The length + counts are used for this, and so count[] is decremented as codes are + entered in the tables. + + used keeps track of how many table entries have been allocated from the + provided *table space. It is checked when a LENS table is being made + against the space in *table, ENOUGH, minus the maximum space needed by + the worst case distance code, MAXD. This should never happen, but the + sufficiency of ENOUGH has not been proven exhaustively, hence the check. + This assumes that when type == LENS, bits == 9. + + sym increments through all symbols, and the loop terminates when + all codes of length max, i.e. all codes, have been processed. This + routine permits incomplete codes, so another loop after this one fills + in the rest of the decoding tables with invalid code markers. + */ + + /* set up for code type */ + switch (type) { + case CODES: + base = extra = work; /* dummy value--not used */ + end = 19; + break; + case LENS: + base = lbase; + base -= 257; + extra = lext; + extra -= 257; + end = 256; + break; + default: /* DISTS */ + base = dbase; + extra = dext; + end = -1; + } - uInt a; /* counter for codes of length k */ - uInt c[BMAX+1]; /* bit length count table */ - uInt f; /* i repeats in table every f entries */ - int g; /* maximum code length */ - int h; /* table level */ - register uInt i; /* counter, current code */ - register uInt j; /* counter */ - register int k; /* number of bits in current code */ - int l; /* bits per table (returned in m) */ - uInt mask; /* (1 << w) - 1, to avoid cc -O bug on HP */ - register uInt *p; /* pointer into c[], b[], or v[] */ - inflate_huft *q; /* points to current table */ - struct inflate_huft_s r; /* table entry for structure assignment */ - inflate_huft *u[BMAX]; /* table stack */ - register int w; /* bits before this table == (l * h) */ - uInt x[BMAX+1]; /* bit offsets, then code stack */ - uInt *xp; /* pointer into x */ - int y; /* number of dummy codes added */ - uInt z; /* number of entries in current table */ - - - /* Generate counts for each bit length */ - p = c; -#define C0 *p++ = 0; -#define C2 C0 C0 C0 C0 -#define C4 C2 C2 C2 C2 - C4 /* clear c[]--assume BMAX+1 is 16 */ - p = b; i = n; - do { - c[*p++]++; /* assume all entries <= BMAX */ - } while (--i); - if (c[0] == n) /* null input--all zero length codes */ - { - *t = NULL; - *m = 0; - return Z_OK; - } - - - /* 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 ((uInt)l < j) - l = j; - for (i = BMAX; i; i--) - if (c[i]) - break; - g = i; /* maximum code length */ - if ((uInt)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 Z_DATA_ERROR; - if ((y -= c[i]) < 0) - return Z_DATA_ERROR; - 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); - n = x[g]; /* set n to length of v */ - - - /* 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] = NULL; /* just to keep compilers happy */ - q = 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 = g - w; - z = z > (uInt)l ? l : z; /* table size upper limit */ - 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; - if (j < z) - 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 */ - } + /* initialize state for loop */ + huff = 0; /* starting code */ + sym = 0; /* starting code symbol */ + len = min; /* starting code length */ + next = *table; /* current table to fill in */ + curr = root; /* current table index bits */ + drop = 0; /* current bits to drop from code for index */ + low = (unsigned)(-1); /* trigger new sub-table when len > root */ + used = 1U << root; /* use root table entries */ + mask = used - 1; /* mask for comparing low */ + + /* check available table space */ + if (type == LENS && used >= ENOUGH - MAXD) + return 1; + + /* process all codes and make table entries */ + for (;;) { + /* create table entry */ + this.bits = (unsigned char)(len - drop); + if ((int)(work[sym]) < end) { + this.op = (unsigned char)0; + this.val = work[sym]; } - z = 1 << j; /* table entries for j-bit table */ - - /* allocate new table */ - if (*hn + z > MANY) /* (note: doesn't matter for fixed) */ - return Z_DATA_ERROR; /* overflow of MANY */ - u[h] = q = hp + *hn; - *hn += z; - - /* connect to last table, if there is one */ - if (h) - { - x[h] = i; /* save pattern for backing up */ - r.bits = (Byte)l; /* bits to dump before this table */ - r.exop = (Byte)j; /* bits in this table */ - j = i >> (w - l); - r.base = (uInt)(q - u[h-1] - j); /* offset to this table */ - u[h-1][j] = r; /* connect to last table */ + else if ((int)(work[sym]) > end) { + this.op = (unsigned char)(extra[work[sym]]); + this.val = base[work[sym]]; + } + else { + this.op = (unsigned char)(32 + 64); /* end of block */ + this.val = 0; } - else - *t = q; /* first table is returned result */ - } - - /* set up table entry in r */ - r.bits = (Byte)(k - w); - if (p >= v + n) - r.exop = 128 + 64; /* out of values--invalid code */ - else if (*p < s) - { - r.exop = (Byte)(*p < 256 ? 0 : 32 + 64); /* 256 is end-of-block */ - r.base = *p++; /* simple code is just the value */ - } - else - { - r.exop = (Byte)(e[*p - s] + 16 + 64);/* non-simple--look up in lists */ - r.base = 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 */ - mask = (1 << w) - 1; /* needed on HP, cc -O bug */ - while ((i & mask) != x[h]) - { - h--; /* don't need to update q */ - w -= l; - mask = (1 << w) - 1; - } - } - } + /* replicate for those indices with low len bits equal to huff */ + incr = 1U << (len - drop); + fill = 1U << curr; + min = fill; /* save offset to next table */ + do { + fill -= incr; + next[(huff >> drop) + fill] = this; + } while (fill != 0); + + /* backwards increment the len-bit code huff */ + incr = 1U << (len - 1); + while (huff & incr) + incr >>= 1; + if (incr != 0) { + huff &= incr - 1; + huff += incr; + } + else + huff = 0; - /* Return Z_BUF_ERROR if we were given an incomplete table */ - return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK; -} + /* go to next symbol, update count, len */ + sym++; + if (--(count[len]) == 0) { + if (len == max) break; + len = lens[work[sym]]; + } + /* create new sub-table if needed */ + if (len > root && (huff & mask) != low) { + /* if first time, transition to sub-tables */ + if (drop == 0) + drop = root; + + /* increment past last table */ + next += min; /* here min is 1 << curr */ + + /* determine length of next table */ + curr = len - drop; + left = (int)(1 << curr); + while (curr + drop < max) { + left -= count[curr + drop]; + if (left <= 0) break; + curr++; + left <<= 1; + } -int zlib_inflate_trees_bits( - uInt *c, /* 19 code lengths */ - uInt *bb, /* bits tree desired/actual depth */ - inflate_huft **tb, /* bits tree result */ - inflate_huft *hp, /* space for trees */ - z_streamp z /* for messages */ -) -{ - int r; - uInt hn = 0; /* hufts used in space */ - uInt *v; /* work area for huft_build */ - - v = WS(z)->tree_work_area_1; - r = huft_build(c, 19, 19, NULL, NULL, tb, bb, hp, &hn, v); - if (r == Z_DATA_ERROR) - z->msg = (char*)"oversubscribed dynamic bit lengths tree"; - else if (r == Z_BUF_ERROR || *bb == 0) - { - z->msg = (char*)"incomplete dynamic bit lengths tree"; - r = Z_DATA_ERROR; - } - return r; -} + /* check for enough space */ + used += 1U << curr; + if (type == LENS && used >= ENOUGH - MAXD) + return 1; -int zlib_inflate_trees_dynamic( - uInt nl, /* number of literal/length codes */ - uInt nd, /* number of distance codes */ - uInt *c, /* that many (total) code lengths */ - uInt *bl, /* literal desired/actual bit depth */ - uInt *bd, /* distance desired/actual bit depth */ - inflate_huft **tl, /* literal/length tree result */ - inflate_huft **td, /* distance tree result */ - inflate_huft *hp, /* space for trees */ - z_streamp z /* for messages */ -) -{ - int r; - uInt hn = 0; /* hufts used in space */ - uInt *v; /* work area for huft_build */ - - /* allocate work area */ - v = WS(z)->tree_work_area_2; - - /* build literal/length tree */ - r = huft_build(c, nl, 257, cplens, cplext, tl, bl, hp, &hn, v); - if (r != Z_OK || *bl == 0) - { - if (r == Z_DATA_ERROR) - z->msg = (char*)"oversubscribed literal/length tree"; - else if (r != Z_MEM_ERROR) - { - z->msg = (char*)"incomplete literal/length tree"; - r = Z_DATA_ERROR; - } - return r; - } - - /* build distance tree */ - r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, hp, &hn, v); - if (r != Z_OK || (*bd == 0 && nl > 257)) - { - if (r == Z_DATA_ERROR) - z->msg = (char*)"oversubscribed distance tree"; - else if (r == Z_BUF_ERROR) { -#ifdef PKZIP_BUG_WORKAROUND - r = Z_OK; - } -#else - z->msg = (char*)"incomplete distance tree"; - r = Z_DATA_ERROR; - } - else if (r != Z_MEM_ERROR) - { - z->msg = (char*)"empty distance tree with lengths"; - r = Z_DATA_ERROR; + /* point entry in root table to sub-table */ + low = huff & mask; + (*table)[low].op = (unsigned char)curr; + (*table)[low].bits = (unsigned char)root; + (*table)[low].val = (unsigned short)(next - *table); + } } - return r; -#endif - } - /* done */ - return Z_OK; -} + /* + Fill in rest of table for incomplete codes. This loop is similar to the + loop above in incrementing huff for table indices. It is assumed that + len is equal to curr + drop, so there is no loop needed to increment + through high index bits. When the current sub-table is filled, the loop + drops back to the root table to fill in any remaining entries there. + */ + this.op = (unsigned char)64; /* invalid code marker */ + this.bits = (unsigned char)(len - drop); + this.val = (unsigned short)0; + while (huff != 0) { + /* when done with sub-table, drop back to root table */ + if (drop != 0 && (huff & mask) != low) { + drop = 0; + len = root; + next = *table; + this.bits = (unsigned char)len; + } + /* put invalid code marker in table */ + next[huff >> drop] = this; -int zlib_inflate_trees_fixed( - uInt *bl, /* literal desired/actual bit depth */ - uInt *bd, /* distance desired/actual bit depth */ - inflate_huft **tl, /* literal/length tree result */ - inflate_huft **td, /* distance tree result */ - inflate_huft *hp, /* space for trees */ - z_streamp z /* for memory allocation */ -) -{ - int i; /* temporary variable */ - unsigned l[288]; /* length list for huft_build */ - uInt *v; /* work area 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 = 9; - v = WS(z)->tree_work_area_1; - if ((i = huft_build(l, 288, 257, cplens, cplext, tl, bl, hp, &i, v)) != 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, hp, &i, v)) > 1) - return i; - - return Z_OK; + /* backwards increment the len-bit code huff */ + incr = 1U << (len - 1); + while (huff & incr) + incr >>= 1; + if (incr != 0) { + huff &= incr - 1; + huff += incr; + } + else + huff = 0; + } + + /* set return parameters */ + *table += used; + *bits = root; + return 0; } |