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251 lines (234 loc) · 7.44 KB
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/* infcodes.c -- process literals and length/distance pairs
* Copyright (C) 1995-2002 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
typedef enum { /* waiting for "i:"=input, "o:"=output, "x:"=nothing */
START, /* x: set up for LEN */
LEN, /* i: get length/literal/eob next */
LENEXT, /* i: getting length extra (have base) */
DIST, /* i: get distance next */
DISTEXT, /* i: getting distance extra */
COPY, /* o: copying bytes in window, waiting for space */
LIT, /* o: got literal, waiting for output space */
WASH, /* o: got eob, possibly still output waiting */
END, /* x: got eob and all data flushed */
BADCODE} /* x: got error */
inflate_codes_mode;
/* inflate codes private state */
struct inflate_codes_state {
/* mode */
inflate_codes_mode mode; /* current inflate_codes mode */
/* mode dependent information */
uInt len;
union {
struct {
inflate_huft *tree; /* pointer into tree */
uInt need; /* bits needed */
} code; /* if LEN or DIST, where in tree */
uInt lit; /* if LIT, literal */
struct {
uInt get; /* bits to get for extra */
uInt dist; /* distance back to copy from */
} copy; /* if EXT or COPY, where and how much */
} sub; /* submode */
/* mode independent information */
Byte lbits; /* ltree bits decoded per branch */
Byte dbits; /* dtree bits decoder per branch */
inflate_huft *ltree; /* literal/length/eob tree */
inflate_huft *dtree; /* distance tree */
};
inflate_codes_statef *inflate_codes_new(bl, bd, tl, td, z)
uInt bl, bd;
inflate_huft *tl;
inflate_huft *td; /* need separate declaration for Borland C++ */
z_streamp z;
{
inflate_codes_statef *c;
if ((c = (inflate_codes_statef *)
ZALLOC(z,1,sizeof(struct inflate_codes_state))) != Z_NULL)
{
c->mode = START;
c->lbits = (Byte)bl;
c->dbits = (Byte)bd;
c->ltree = tl;
c->dtree = td;
Tracev((stderr, "inflate: codes new\n"));
}
return c;
}
int inflate_codes(s, z, r)
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 */
Bytef *p; /* input data pointer */
uInt n; /* bytes available there */
Bytef *q; /* output window write pointer */
uInt m; /* bytes to end of window or read pointer */
Bytef *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 = 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 & inflate_mask[j]);
DUMPBITS(t->bits)
e = (uInt)(t->exop);
if (e == 0) /* literal */
{
c->sub.lit = t->base;
Tracevv((stderr, t->base >= 0x20 && t->base < 0x7f ?
"inflate: literal '%c'\n" :
"inflate: literal 0x%02x\n", 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 */
{
Tracevv((stderr, "inflate: end of block\n"));
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 & inflate_mask[j];
DUMPBITS(j)
c->sub.code.need = c->dbits;
c->sub.code.tree = c->dtree;
Tracevv((stderr, "inflate: length %u\n", c->len));
c->mode = DIST;
case DIST: /* i: get distance next */
j = c->sub.code.need;
NEEDBITS(j)
t = c->sub.code.tree + ((uInt)b & 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 & inflate_mask[j];
DUMPBITS(j)
Tracevv((stderr, "inflate: distance %u\n", c->sub.copy.dist));
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 */
{
Assert(k < 16, "inflate_codes grabbed too many bytes")
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 inflate_codes_free(c, z)
inflate_codes_statef *c;
z_streamp z;
{
ZFREE(z, c);
Tracev((stderr, "inflate: codes free\n"));
}