1da177e4c3
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
413 lines
15 KiB
C
413 lines
15 KiB
C
/* inftrees.c -- generate Huffman trees for efficient decoding
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* Copyright (C) 1995-1998 Mark Adler
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* For conditions of distribution and use, see copyright notice in zlib.h
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*/
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#include <linux/zutil.h>
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#include "inftrees.h"
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#include "infutil.h"
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static const char inflate_copyright[] __attribute_used__ =
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" inflate 1.1.3 Copyright 1995-1998 Mark Adler ";
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/*
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If you use the zlib library in a product, an acknowledgment is welcome
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in the documentation of your product. If for some reason you cannot
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include such an acknowledgment, I would appreciate that you keep this
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copyright string in the executable of your product.
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*/
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struct internal_state;
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/* simplify the use of the inflate_huft type with some defines */
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#define exop word.what.Exop
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#define bits word.what.Bits
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static int huft_build (
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uInt *, /* code lengths in bits */
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uInt, /* number of codes */
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uInt, /* number of "simple" codes */
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const uInt *, /* list of base values for non-simple codes */
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const uInt *, /* list of extra bits for non-simple codes */
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inflate_huft **, /* result: starting table */
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uInt *, /* maximum lookup bits (returns actual) */
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inflate_huft *, /* space for trees */
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uInt *, /* hufts used in space */
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uInt * ); /* space for values */
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/* Tables for deflate from PKZIP's appnote.txt. */
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static const uInt cplens[31] = { /* Copy lengths for literal codes 257..285 */
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3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 15, 17, 19, 23, 27, 31,
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35, 43, 51, 59, 67, 83, 99, 115, 131, 163, 195, 227, 258, 0, 0};
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/* see note #13 above about 258 */
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static const uInt cplext[31] = { /* Extra bits for literal codes 257..285 */
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0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2,
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3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 0, 112, 112}; /* 112==invalid */
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static const uInt cpdist[30] = { /* Copy offsets for distance codes 0..29 */
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1, 2, 3, 4, 5, 7, 9, 13, 17, 25, 33, 49, 65, 97, 129, 193,
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257, 385, 513, 769, 1025, 1537, 2049, 3073, 4097, 6145,
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8193, 12289, 16385, 24577};
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static const uInt cpdext[30] = { /* Extra bits for distance codes */
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0, 0, 0, 0, 1, 1, 2, 2, 3, 3, 4, 4, 5, 5, 6, 6,
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7, 7, 8, 8, 9, 9, 10, 10, 11, 11,
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12, 12, 13, 13};
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/*
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Huffman code decoding is performed using a multi-level table lookup.
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The fastest way to decode is to simply build a lookup table whose
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size is determined by the longest code. However, the time it takes
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to build this table can also be a factor if the data being decoded
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is not very long. The most common codes are necessarily the
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shortest codes, so those codes dominate the decoding time, and hence
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the speed. The idea is you can have a shorter table that decodes the
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shorter, more probable codes, and then point to subsidiary tables for
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the longer codes. The time it costs to decode the longer codes is
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then traded against the time it takes to make longer tables.
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This results of this trade are in the variables lbits and dbits
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below. lbits is the number of bits the first level table for literal/
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length codes can decode in one step, and dbits is the same thing for
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the distance codes. Subsequent tables are also less than or equal to
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those sizes. These values may be adjusted either when all of the
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codes are shorter than that, in which case the longest code length in
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bits is used, or when the shortest code is *longer* than the requested
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table size, in which case the length of the shortest code in bits is
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used.
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There are two different values for the two tables, since they code a
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different number of possibilities each. The literal/length table
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codes 286 possible values, or in a flat code, a little over eight
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bits. The distance table codes 30 possible values, or a little less
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than five bits, flat. The optimum values for speed end up being
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about one bit more than those, so lbits is 8+1 and dbits is 5+1.
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The optimum values may differ though from machine to machine, and
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possibly even between compilers. Your mileage may vary.
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*/
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/* If BMAX needs to be larger than 16, then h and x[] should be uLong. */
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#define BMAX 15 /* maximum bit length of any code */
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static int huft_build(
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uInt *b, /* code lengths in bits (all assumed <= BMAX) */
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uInt n, /* number of codes (assumed <= 288) */
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uInt s, /* number of simple-valued codes (0..s-1) */
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const uInt *d, /* list of base values for non-simple codes */
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const uInt *e, /* list of extra bits for non-simple codes */
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inflate_huft **t, /* result: starting table */
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uInt *m, /* maximum lookup bits, returns actual */
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inflate_huft *hp, /* space for trees */
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uInt *hn, /* hufts used in space */
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uInt *v /* working area: values in order of bit length */
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)
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/* Given a list of code lengths and a maximum table size, make a set of
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tables to decode that set of codes. Return Z_OK on success, Z_BUF_ERROR
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if the given code set is incomplete (the tables are still built in this
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case), Z_DATA_ERROR if the input is invalid (an over-subscribed set of
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lengths), or Z_MEM_ERROR if not enough memory. */
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{
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uInt a; /* counter for codes of length k */
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uInt c[BMAX+1]; /* bit length count table */
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uInt f; /* i repeats in table every f entries */
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int g; /* maximum code length */
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int h; /* table level */
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register uInt i; /* counter, current code */
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register uInt j; /* counter */
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register int k; /* number of bits in current code */
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int l; /* bits per table (returned in m) */
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uInt mask; /* (1 << w) - 1, to avoid cc -O bug on HP */
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register uInt *p; /* pointer into c[], b[], or v[] */
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inflate_huft *q; /* points to current table */
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struct inflate_huft_s r; /* table entry for structure assignment */
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inflate_huft *u[BMAX]; /* table stack */
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register int w; /* bits before this table == (l * h) */
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uInt x[BMAX+1]; /* bit offsets, then code stack */
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uInt *xp; /* pointer into x */
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int y; /* number of dummy codes added */
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uInt z; /* number of entries in current table */
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/* Generate counts for each bit length */
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p = c;
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#define C0 *p++ = 0;
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#define C2 C0 C0 C0 C0
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#define C4 C2 C2 C2 C2
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C4 /* clear c[]--assume BMAX+1 is 16 */
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p = b; i = n;
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do {
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c[*p++]++; /* assume all entries <= BMAX */
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} while (--i);
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if (c[0] == n) /* null input--all zero length codes */
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{
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*t = NULL;
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*m = 0;
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return Z_OK;
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}
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/* Find minimum and maximum length, bound *m by those */
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l = *m;
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for (j = 1; j <= BMAX; j++)
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if (c[j])
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break;
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k = j; /* minimum code length */
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if ((uInt)l < j)
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l = j;
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for (i = BMAX; i; i--)
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if (c[i])
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break;
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g = i; /* maximum code length */
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if ((uInt)l > i)
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l = i;
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*m = l;
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/* Adjust last length count to fill out codes, if needed */
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for (y = 1 << j; j < i; j++, y <<= 1)
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if ((y -= c[j]) < 0)
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return Z_DATA_ERROR;
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if ((y -= c[i]) < 0)
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return Z_DATA_ERROR;
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c[i] += y;
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/* Generate starting offsets into the value table for each length */
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x[1] = j = 0;
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p = c + 1; xp = x + 2;
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while (--i) { /* note that i == g from above */
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*xp++ = (j += *p++);
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}
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/* Make a table of values in order of bit lengths */
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p = b; i = 0;
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do {
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if ((j = *p++) != 0)
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v[x[j]++] = i;
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} while (++i < n);
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n = x[g]; /* set n to length of v */
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/* Generate the Huffman codes and for each, make the table entries */
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x[0] = i = 0; /* first Huffman code is zero */
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p = v; /* grab values in bit order */
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h = -1; /* no tables yet--level -1 */
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w = -l; /* bits decoded == (l * h) */
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u[0] = NULL; /* just to keep compilers happy */
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q = NULL; /* ditto */
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z = 0; /* ditto */
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/* go through the bit lengths (k already is bits in shortest code) */
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for (; k <= g; k++)
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{
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a = c[k];
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while (a--)
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{
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/* here i is the Huffman code of length k bits for value *p */
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/* make tables up to required level */
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while (k > w + l)
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{
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h++;
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w += l; /* previous table always l bits */
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/* compute minimum size table less than or equal to l bits */
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z = g - w;
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z = z > (uInt)l ? l : z; /* table size upper limit */
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if ((f = 1 << (j = k - w)) > a + 1) /* try a k-w bit table */
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{ /* too few codes for k-w bit table */
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f -= a + 1; /* deduct codes from patterns left */
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xp = c + k;
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if (j < z)
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while (++j < z) /* try smaller tables up to z bits */
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{
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if ((f <<= 1) <= *++xp)
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break; /* enough codes to use up j bits */
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f -= *xp; /* else deduct codes from patterns */
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}
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}
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z = 1 << j; /* table entries for j-bit table */
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/* allocate new table */
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if (*hn + z > MANY) /* (note: doesn't matter for fixed) */
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return Z_DATA_ERROR; /* overflow of MANY */
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u[h] = q = hp + *hn;
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*hn += z;
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/* connect to last table, if there is one */
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if (h)
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{
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x[h] = i; /* save pattern for backing up */
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r.bits = (Byte)l; /* bits to dump before this table */
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r.exop = (Byte)j; /* bits in this table */
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j = i >> (w - l);
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r.base = (uInt)(q - u[h-1] - j); /* offset to this table */
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u[h-1][j] = r; /* connect to last table */
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}
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else
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*t = q; /* first table is returned result */
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}
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/* set up table entry in r */
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r.bits = (Byte)(k - w);
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if (p >= v + n)
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r.exop = 128 + 64; /* out of values--invalid code */
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else if (*p < s)
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{
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r.exop = (Byte)(*p < 256 ? 0 : 32 + 64); /* 256 is end-of-block */
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r.base = *p++; /* simple code is just the value */
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}
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else
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{
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r.exop = (Byte)(e[*p - s] + 16 + 64);/* non-simple--look up in lists */
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r.base = d[*p++ - s];
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}
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/* fill code-like entries with r */
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f = 1 << (k - w);
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for (j = i >> w; j < z; j += f)
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q[j] = r;
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/* backwards increment the k-bit code i */
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for (j = 1 << (k - 1); i & j; j >>= 1)
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i ^= j;
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i ^= j;
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/* backup over finished tables */
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mask = (1 << w) - 1; /* needed on HP, cc -O bug */
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while ((i & mask) != x[h])
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{
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h--; /* don't need to update q */
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w -= l;
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mask = (1 << w) - 1;
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}
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}
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}
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/* Return Z_BUF_ERROR if we were given an incomplete table */
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return y != 0 && g != 1 ? Z_BUF_ERROR : Z_OK;
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}
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int zlib_inflate_trees_bits(
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uInt *c, /* 19 code lengths */
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uInt *bb, /* bits tree desired/actual depth */
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inflate_huft **tb, /* bits tree result */
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inflate_huft *hp, /* space for trees */
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z_streamp z /* for messages */
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)
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{
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int r;
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uInt hn = 0; /* hufts used in space */
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uInt *v; /* work area for huft_build */
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v = WS(z)->tree_work_area_1;
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r = huft_build(c, 19, 19, NULL, NULL, tb, bb, hp, &hn, v);
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if (r == Z_DATA_ERROR)
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z->msg = (char*)"oversubscribed dynamic bit lengths tree";
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else if (r == Z_BUF_ERROR || *bb == 0)
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{
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z->msg = (char*)"incomplete dynamic bit lengths tree";
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r = Z_DATA_ERROR;
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}
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return r;
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}
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int zlib_inflate_trees_dynamic(
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uInt nl, /* number of literal/length codes */
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uInt nd, /* number of distance codes */
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uInt *c, /* that many (total) code lengths */
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uInt *bl, /* literal desired/actual bit depth */
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uInt *bd, /* distance desired/actual bit depth */
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inflate_huft **tl, /* literal/length tree result */
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inflate_huft **td, /* distance tree result */
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inflate_huft *hp, /* space for trees */
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z_streamp z /* for messages */
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)
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{
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int r;
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uInt hn = 0; /* hufts used in space */
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uInt *v; /* work area for huft_build */
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/* allocate work area */
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v = WS(z)->tree_work_area_2;
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/* build literal/length tree */
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r = huft_build(c, nl, 257, cplens, cplext, tl, bl, hp, &hn, v);
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if (r != Z_OK || *bl == 0)
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{
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if (r == Z_DATA_ERROR)
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z->msg = (char*)"oversubscribed literal/length tree";
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else if (r != Z_MEM_ERROR)
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{
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z->msg = (char*)"incomplete literal/length tree";
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r = Z_DATA_ERROR;
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}
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return r;
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}
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/* build distance tree */
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r = huft_build(c + nl, nd, 0, cpdist, cpdext, td, bd, hp, &hn, v);
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if (r != Z_OK || (*bd == 0 && nl > 257))
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{
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if (r == Z_DATA_ERROR)
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z->msg = (char*)"oversubscribed distance tree";
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else if (r == Z_BUF_ERROR) {
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#ifdef PKZIP_BUG_WORKAROUND
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r = Z_OK;
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}
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#else
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z->msg = (char*)"incomplete distance tree";
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r = Z_DATA_ERROR;
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}
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else if (r != Z_MEM_ERROR)
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{
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z->msg = (char*)"empty distance tree with lengths";
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r = Z_DATA_ERROR;
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}
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return r;
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#endif
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}
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/* done */
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return Z_OK;
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}
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int zlib_inflate_trees_fixed(
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uInt *bl, /* literal desired/actual bit depth */
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uInt *bd, /* distance desired/actual bit depth */
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inflate_huft **tl, /* literal/length tree result */
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inflate_huft **td, /* distance tree result */
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inflate_huft *hp, /* space for trees */
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z_streamp z /* for memory allocation */
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)
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{
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int i; /* temporary variable */
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unsigned l[288]; /* length list for huft_build */
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uInt *v; /* work area for huft_build */
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/* set up literal table */
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for (i = 0; i < 144; i++)
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l[i] = 8;
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for (; i < 256; i++)
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l[i] = 9;
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for (; i < 280; i++)
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l[i] = 7;
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for (; i < 288; i++) /* make a complete, but wrong code set */
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l[i] = 8;
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*bl = 9;
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v = WS(z)->tree_work_area_1;
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if ((i = huft_build(l, 288, 257, cplens, cplext, tl, bl, hp, &i, v)) != 0)
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return i;
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/* set up distance table */
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for (i = 0; i < 30; i++) /* make an incomplete code set */
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l[i] = 5;
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*bd = 5;
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if ((i = huft_build(l, 30, 0, cpdist, cpdext, td, bd, hp, &i, v)) > 1)
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return i;
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return Z_OK;
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}
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