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/* infcodes.c -- process literals and length/distance pairs
* Copyright (C) 1995-1998 Mark Adler
* For conditions of distribution and use, see copyright notice in zlib.h
*/
#include "zutil.h"
#include "inftrees.h"
#include "infblock.h"
#include "infcodes.h"
#include "infutil.h"
#include "inffast.h"
/* simplify the use of the inflate_huft type with some defines */
#define exop word.what.Exop
#define bits word.what.Bits
inflate_codes_statef *zlib_inflate_codes_new(
uInt bl,
uInt bd,
inflate_huft *tl,
inflate_huft *td, /* need separate declaration for Borland C++ */
z_streamp z
)
{
inflate_codes_statef *c;
c = &WS(z)->working_state;
{
c->mode = START;
c->lbits = (Byte)bl;
c->dbits = (Byte)bd;
c->ltree = tl;
c->dtree = td;
}
return c;
}
int zlib_inflate_codes(
inflate_blocks_statef *s,
z_streamp z,
int r
)
{
uInt j; /* temporary storage */
inflate_huft *t; /* temporary pointer */
uInt e; /* extra bits or operation */
uLong b; /* bit buffer */
uInt k; /* bits in bit buffer */
Byte *p; /* input data pointer */
uInt n; /* bytes available there */
Byte *q; /* output window write pointer */
uInt m; /* bytes to end of window or read pointer */
Byte *f; /* pointer to copy strings from */
inflate_codes_statef *c = s->sub.decode.codes; /* codes state */
/* copy input/output information to locals (UPDATE macro restores) */
LOAD
/* process input and output based on current state */
while (1) switch (c->mode)
{ /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
case START: /* x: set up for LEN */
#ifndef SLOW
if (m >= 258 && n >= 10)
{
UPDATE
r = zlib_inflate_fast(c->lbits, c->dbits, c->ltree, c->dtree, s, z);
LOAD
if (r != Z_OK)
{
c->mode = r == Z_STREAM_END ? WASH : BADCODE;
break;
}
}
#endif /* !SLOW */
c->sub.code.need = c->lbits;
c->sub.code.tree = c->ltree;
c->mode = LEN;
case LEN: /* i: get length/literal/eob next */
j = c->sub.code.need;
NEEDBITS(j)
t = c->sub.code.tree + ((uInt)b & zlib_inflate_mask[j]);
DUMPBITS(t->bits)
e = (uInt)(t->exop);
if (e == 0) /* literal */
{
c->sub.lit = t->base;
c->mode = LIT;
break;
}
if (e & 16) /* length */
{
c->sub.copy.get = e & 15;
c->len = t->base;
c->mode = LENEXT;
break;
}
if ((e & 64) == 0) /* next table */
{
c->sub.code.need = e;
c->sub.code.tree = t + t->base;
break;
}
if (e & 32) /* end of block */
{
c->mode = WASH;
break;
}
c->mode = BADCODE; /* invalid code */
z->msg = (char*)"invalid literal/length code";
r = Z_DATA_ERROR;
LEAVE
case LENEXT: /* i: getting length extra (have base) */
j = c->sub.copy.get;
NEEDBITS(j)
c->len += (uInt)b & zlib_inflate_mask[j];
DUMPBITS(j)
c->sub.code.need = c->dbits;
c->sub.code.tree = c->dtree;
c->mode = DIST;
case DIST: /* i: get distance next */
j = c->sub.code.need;
NEEDBITS(j)
t = c->sub.code.tree + ((uInt)b & zlib_inflate_mask[j]);
DUMPBITS(t->bits)
e = (uInt)(t->exop);
if (e & 16) /* distance */
{
c->sub.copy.get = e & 15;
c->sub.copy.dist = t->base;
c->mode = DISTEXT;
break;
}
if ((e & 64) == 0) /* next table */
{
c->sub.code.need = e;
c->sub.code.tree = t + t->base;
break;
}
c->mode = BADCODE; /* invalid code */
z->msg = (char*)"invalid distance code";
r = Z_DATA_ERROR;
LEAVE
case DISTEXT: /* i: getting distance extra */
j = c->sub.copy.get;
NEEDBITS(j)
c->sub.copy.dist += (uInt)b & zlib_inflate_mask[j];
DUMPBITS(j)
c->mode = COPY;
case COPY: /* o: copying bytes in window, waiting for space */
f = q - c->sub.copy.dist;
while (f < s->window) /* modulo window size-"while" instead */
f += s->end - s->window; /* of "if" handles invalid distances */
while (c->len)
{
NEEDOUT
OUTBYTE(*f++)
if (f == s->end)
f = s->window;
c->len--;
}
c->mode = START;
break;
case LIT: /* o: got literal, waiting for output space */
NEEDOUT
OUTBYTE(c->sub.lit)
c->mode = START;
break;
case WASH: /* o: got eob, possibly more output */
if (k > 7) /* return unused byte, if any */
{
k -= 8;
n++;
p--; /* can always return one */
}
FLUSH
if (s->read != s->write)
LEAVE
c->mode = END;
case END:
r = Z_STREAM_END;
LEAVE
case BADCODE: /* x: got error */
r = Z_DATA_ERROR;
LEAVE
default:
r = Z_STREAM_ERROR;
LEAVE
}
#ifdef NEED_DUMMY_RETURN
return Z_STREAM_ERROR; /* Some dumb compilers complain without this */
#endif
}
void zlib_inflate_codes_free(
inflate_codes_statef *c,
z_streamp z
)
{
}
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