258 lines
7.6 KiB
C
258 lines
7.6 KiB
C
/* infcodes.c -- process literals and length/distance pairs
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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 "zutil.h"
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#include "inftrees.h"
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#include "infblock.h"
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#include "infcodes.h"
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#include "infutil.h"
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#include "inffast.h"
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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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typedef enum { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
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START, /* x: set up for LEN */
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LEN, /* i: get length/literal/eob next */
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LENEXT, /* i: getting length extra (have base) */
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DIST, /* i: get distance next */
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DISTEXT, /* i: getting distance extra */
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COPY, /* o: copying bytes in window, waiting for space */
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LIT, /* o: got literal, waiting for output space */
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WASH, /* o: got eob, possibly still output waiting */
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END, /* x: got eob and all data flushed */
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BADCODE} /* x: got error */
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inflate_codes_mode;
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/* inflate codes private state */
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struct inflate_codes_state {
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/* mode */
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inflate_codes_mode mode; /* current inflate_codes mode */
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/* mode dependent information */
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uInt len;
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union {
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struct {
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inflate_huft *tree; /* pointer into tree */
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uInt need; /* bits needed */
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} code; /* if LEN or DIST, where in tree */
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uInt lit; /* if LIT, literal */
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struct {
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uInt get; /* bits to get for extra */
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uInt dist; /* distance back to copy from */
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} copy; /* if EXT or COPY, where and how much */
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} sub; /* submode */
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/* mode independent information */
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Byte lbits; /* ltree bits decoded per branch */
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Byte dbits; /* dtree bits decoder per branch */
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inflate_huft *ltree; /* literal/length/eob tree */
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inflate_huft *dtree; /* distance tree */
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};
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inflate_codes_statef *inflate_codes_new(bl, bd, tl, td, z)
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uInt bl, bd;
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inflate_huft *tl;
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inflate_huft *td; /* need separate declaration for Borland C++ */
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z_streamp z;
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{
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inflate_codes_statef *c;
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if ((c = (inflate_codes_statef *)
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ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
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{
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c->mode = START;
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c->lbits = (Byte)bl;
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c->dbits = (Byte)bd;
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c->ltree = tl;
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c->dtree = td;
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Tracev((stderr, "inflate: codes new\n"));
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}
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return c;
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}
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int inflate_codes(s, z, r)
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inflate_blocks_statef *s;
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z_streamp z;
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int r;
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{
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uInt j; /* temporary storage */
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inflate_huft *t; /* temporary pointer */
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uInt e; /* extra bits or operation */
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uLong b; /* bit buffer */
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uInt k; /* bits in bit buffer */
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Bytef *p; /* input data pointer */
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uInt n; /* bytes available there */
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Bytef *q; /* output window write pointer */
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uInt m; /* bytes to end of window or read pointer */
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Bytef *f; /* pointer to copy strings from */
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inflate_codes_statef *c = s->sub.decode.codes; /* codes state */
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/* copy input/output information to locals (UPDATE macro restores) */
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LOAD
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/* process input and output based on current state */
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while (1) switch (c->mode)
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{ /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
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case START: /* x: set up for LEN */
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#ifndef SLOW
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if (m >= 258 && n >= 10)
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{
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UPDATE
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r = inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
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LOAD
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if (r != Z_OK)
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{
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c->mode = r == Z_STREAM_END ? WASH : BADCODE;
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break;
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}
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}
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#endif /* !SLOW */
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c->sub.code.need = c->lbits;
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c->sub.code.tree = c->ltree;
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c->mode = LEN;
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case LEN: /* i: get length/literal/eob next */
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j = c->sub.code.need;
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NEEDBITS(j)
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t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
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DUMPBITS(t->bits)
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e = (uInt)(t->exop);
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if (e == 0) /* literal */
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{
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c->sub.lit = t->base;
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Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
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"inflate: literal '%c'\n" :
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"inflate: literal 0x%02x\n", t->base));
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c->mode = LIT;
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break;
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}
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if (e & 16) /* length */
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{
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c->sub.copy.get = e & 15;
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c->len = t->base;
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c->mode = LENEXT;
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break;
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}
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if ((e & 64) == 0) /* next table */
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{
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c->sub.code.need = e;
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c->sub.code.tree = t + t->base;
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break;
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}
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if (e & 32) /* end of block */
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{
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Tracevv((stderr, "inflate: end of block\n"));
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c->mode = WASH;
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break;
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}
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c->mode = BADCODE; /* invalid code */
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z->msg = (char*)"invalid literal/length code";
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r = Z_DATA_ERROR;
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LEAVE
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case LENEXT: /* i: getting length extra (have base) */
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j = c->sub.copy.get;
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NEEDBITS(j)
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c->len += (uInt)b & inflate_mask[j];
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DUMPBITS(j)
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c->sub.code.need = c->dbits;
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c->sub.code.tree = c->dtree;
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Tracevv((stderr, "inflate: length %u\n", c->len));
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c->mode = DIST;
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case DIST: /* i: get distance next */
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j = c->sub.code.need;
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NEEDBITS(j)
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t = c->sub.code.tree + ((uInt)b & inflate_mask[j]);
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DUMPBITS(t->bits)
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e = (uInt)(t->exop);
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if (e & 16) /* distance */
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{
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c->sub.copy.get = e & 15;
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c->sub.copy.dist = t->base;
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c->mode = DISTEXT;
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break;
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}
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if ((e & 64) == 0) /* next table */
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{
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c->sub.code.need = e;
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c->sub.code.tree = t + t->base;
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break;
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}
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c->mode = BADCODE; /* invalid code */
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z->msg = (char*)"invalid distance code";
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r = Z_DATA_ERROR;
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LEAVE
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case DISTEXT: /* i: getting distance extra */
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j = c->sub.copy.get;
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NEEDBITS(j)
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c->sub.copy.dist += (uInt)b & inflate_mask[j];
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DUMPBITS(j)
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Tracevv((stderr, "inflate: distance %u\n", c->sub.copy.dist));
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c->mode = COPY;
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case COPY: /* o: copying bytes in window, waiting for space */
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#ifndef __TURBOC__ /* Turbo C bug for following expression */
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f = (uInt)(q - s->window) < c->sub.copy.dist ?
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s->end - (c->sub.copy.dist - (q - s->window)) :
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q - c->sub.copy.dist;
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#else
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f = q - c->sub.copy.dist;
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if ((uInt)(q - s->window) < c->sub.copy.dist)
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f = s->end - (c->sub.copy.dist - (uInt)(q - s->window));
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#endif
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while (c->len)
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{
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NEEDOUT
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OUTBYTE(*f++)
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if (f == s->end)
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f = s->window;
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c->len--;
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}
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c->mode = START;
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break;
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case LIT: /* o: got literal, waiting for output space */
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NEEDOUT
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OUTBYTE(c->sub.lit)
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c->mode = START;
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break;
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case WASH: /* o: got eob, possibly more output */
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if (k > 7) /* return unused byte, if any */
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{
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Assert(k < 16, "inflate_codes grabbed too many bytes")
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k -= 8;
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n++;
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p--; /* can always return one */
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}
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FLUSH
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if (s->read != s->write)
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LEAVE
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c->mode = END;
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case END:
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r = Z_STREAM_END;
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LEAVE
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case BADCODE: /* x: got error */
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r = Z_DATA_ERROR;
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LEAVE
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default:
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r = Z_STREAM_ERROR;
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LEAVE
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}
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#ifdef NEED_DUMMY_RETURN
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return Z_STREAM_ERROR; /* Some dumb compilers complain without this */
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#endif
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}
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void inflate_codes_free(c, z)
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inflate_codes_statef *c;
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z_streamp z;
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{
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ZFREE(z, c);
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Tracev((stderr, "inflate: codes free\n"));
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}
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