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reactos/dll/win32/itss/lzx.c
Amine Khaldi da0cd273de [ITSS] Sync with Wine Staging 4.18. CORE-16441
2019-11-02 18:37:34 +01:00

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/***************************************************************************
* lzx.c - LZX decompression routines *
* ------------------- *
* *
* maintainer: Jed Wing <jedwin@ugcs.caltech.edu> *
* source: modified lzx.c from cabextract v0.5 *
* notes: This file was taken from cabextract v0.5, which was, *
* itself, a modified version of the lzx decompression code *
* from unlzx. *
* *
* platforms: In its current incarnation, this file has been tested on *
* two different Linux platforms (one, redhat-based, with a *
* 2.1.2 glibc and gcc 2.95.x, and the other, Debian, with *
* 2.2.4 glibc and both gcc 2.95.4 and gcc 3.0.2). Both were *
* Intel x86 compatible machines. *
***************************************************************************/
/***************************************************************************
*
* Copyright(C) Stuart Caie
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
*
***************************************************************************/
#include "lzx.h"
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "windef.h"
#include "winbase.h"
/* sized types */
typedef unsigned char UBYTE; /* 8 bits exactly */
typedef unsigned short UWORD; /* 16 bits (or more) */
/* some constants defined by the LZX specification */
#define LZX_MIN_MATCH (2)
#define LZX_MAX_MATCH (257)
#define LZX_NUM_CHARS (256)
#define LZX_BLOCKTYPE_INVALID (0) /* also blocktypes 4-7 invalid */
#define LZX_BLOCKTYPE_VERBATIM (1)
#define LZX_BLOCKTYPE_ALIGNED (2)
#define LZX_BLOCKTYPE_UNCOMPRESSED (3)
#define LZX_PRETREE_NUM_ELEMENTS (20)
#define LZX_ALIGNED_NUM_ELEMENTS (8) /* aligned offset tree #elements */
#define LZX_NUM_PRIMARY_LENGTHS (7) /* this one missing from spec! */
#define LZX_NUM_SECONDARY_LENGTHS (249) /* length tree #elements */
/* LZX huffman defines: tweak tablebits as desired */
#define LZX_PRETREE_MAXSYMBOLS (LZX_PRETREE_NUM_ELEMENTS)
#define LZX_PRETREE_TABLEBITS (6)
#define LZX_MAINTREE_MAXSYMBOLS (LZX_NUM_CHARS + 50*8)
#define LZX_MAINTREE_TABLEBITS (12)
#define LZX_LENGTH_MAXSYMBOLS (LZX_NUM_SECONDARY_LENGTHS+1)
#define LZX_LENGTH_TABLEBITS (12)
#define LZX_ALIGNED_MAXSYMBOLS (LZX_ALIGNED_NUM_ELEMENTS)
#define LZX_ALIGNED_TABLEBITS (7)
#define LZX_LENTABLE_SAFETY (64) /* we allow length table decoding overruns */
#define LZX_DECLARE_TABLE(tbl) \
UWORD tbl##_table[(1<<LZX_##tbl##_TABLEBITS) + (LZX_##tbl##_MAXSYMBOLS<<1)];\
UBYTE tbl##_len [LZX_##tbl##_MAXSYMBOLS + LZX_LENTABLE_SAFETY]
struct LZXstate
{
UBYTE *window; /* the actual decoding window */
ULONG window_size; /* window size (32Kb through 2Mb) */
ULONG actual_size; /* window size when it was first allocated */
ULONG window_posn; /* current offset within the window */
ULONG R0, R1, R2; /* for the LRU offset system */
UWORD main_elements; /* number of main tree elements */
int header_read; /* have we started decoding at all yet? */
UWORD block_type; /* type of this block */
ULONG block_length; /* uncompressed length of this block */
ULONG block_remaining; /* uncompressed bytes still left to decode */
ULONG frames_read; /* the number of CFDATA blocks processed */
LONG intel_filesize; /* magic header value used for transform */
LONG intel_curpos; /* current offset in transform space */
int intel_started; /* have we seen any translatable data yet? */
LZX_DECLARE_TABLE(PRETREE);
LZX_DECLARE_TABLE(MAINTREE);
LZX_DECLARE_TABLE(LENGTH);
LZX_DECLARE_TABLE(ALIGNED);
};
/* LZX decruncher */
/* Microsoft's LZX document and their implementation of the
* com.ms.util.cab Java package do not concur.
*
* In the LZX document, there is a table showing the correlation between
* window size and the number of position slots. It states that the 1MB
* window = 40 slots and the 2MB window = 42 slots. In the implementation,
* 1MB = 42 slots, 2MB = 50 slots. The actual calculation is 'find the
* first slot whose position base is equal to or more than the required
* window size'. This would explain why other tables in the document refer
* to 50 slots rather than 42.
*
* The constant NUM_PRIMARY_LENGTHS used in the decompression pseudocode
* is not defined in the specification.
*
* The LZX document does not state the uncompressed block has an
* uncompressed length field. Where does this length field come from, so
* we can know how large the block is? The implementation has it as the 24
* bits following after the 3 blocktype bits, before the alignment
* padding.
*
* The LZX document states that aligned offset blocks have their aligned
* offset huffman tree AFTER the main and length trees. The implementation
* suggests that the aligned offset tree is BEFORE the main and length
* trees.
*
* The LZX document decoding algorithm states that, in an aligned offset
* block, if an extra_bits value is 1, 2 or 3, then that number of bits
* should be read and the result added to the match offset. This is
* correct for 1 and 2, but not 3, where just a huffman symbol (using the
* aligned tree) should be read.
*
* Regarding the E8 preprocessing, the LZX document states 'No translation
* may be performed on the last 6 bytes of the input block'. This is
* correct. However, the pseudocode provided checks for the *E8 leader*
* up to the last 6 bytes. If the leader appears between -10 and -7 bytes
* from the end, this would cause the next four bytes to be modified, at
* least one of which would be in the last 6 bytes, which is not allowed
* according to the spec.
*
* The specification states that the huffman trees must always contain at
* least one element. However, many CAB files contain blocks where the
* length tree is completely empty (because there are no matches), and
* this is expected to succeed.
*/
/* LZX uses what it calls 'position slots' to represent match offsets.
* What this means is that a small 'position slot' number and a small
* offset from that slot are encoded instead of one large offset for
* every match.
* - position_base is an index to the position slot bases
* - extra_bits states how many bits of offset-from-base data is needed.
*/
static const UBYTE extra_bits[51] = {
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, 14, 14,
15, 15, 16, 16, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17, 17,
17, 17, 17
};
static const ULONG position_base[51] = {
0, 1, 2, 3, 4, 6, 8, 12, 16, 24, 32, 48, 64, 96, 128, 192,
256, 384, 512, 768, 1024, 1536, 2048, 3072, 4096, 6144, 8192, 12288, 16384, 24576, 32768, 49152,
65536, 98304, 131072, 196608, 262144, 393216, 524288, 655360, 786432, 917504, 1048576, 1179648, 1310720, 1441792, 1572864, 1703936,
1835008, 1966080, 2097152
};
struct LZXstate *LZXinit(int wndsize)
{
struct LZXstate *pState=NULL;
int i, posn_slots;
/* allocate state and associated window */
pState = HeapAlloc(GetProcessHeap(), 0, sizeof(struct LZXstate));
if (!(pState->window = HeapAlloc(GetProcessHeap(), 0, wndsize)))
{
HeapFree(GetProcessHeap(), 0, pState);
return NULL;
}
pState->actual_size = wndsize;
pState->window_size = wndsize;
/* calculate required position slots */
posn_slots = i = 0;
while (i < wndsize) i += 1 << extra_bits[posn_slots++];
/* initialize other state */
pState->R0 = pState->R1 = pState->R2 = 1;
pState->main_elements = LZX_NUM_CHARS + (posn_slots << 3);
pState->header_read = 0;
pState->frames_read = 0;
pState->block_remaining = 0;
pState->block_type = LZX_BLOCKTYPE_INVALID;
pState->intel_curpos = 0;
pState->intel_started = 0;
pState->window_posn = 0;
/* initialise tables to 0 (because deltas will be applied to them) */
for (i = 0; i < LZX_MAINTREE_MAXSYMBOLS; i++) pState->MAINTREE_len[i] = 0;
for (i = 0; i < LZX_LENGTH_MAXSYMBOLS; i++) pState->LENGTH_len[i] = 0;
return pState;
}
void LZXteardown(struct LZXstate *pState)
{
if (pState)
{
HeapFree(GetProcessHeap(), 0, pState->window);
HeapFree(GetProcessHeap(), 0, pState);
}
}
int LZXreset(struct LZXstate *pState)
{
int i;
pState->R0 = pState->R1 = pState->R2 = 1;
pState->header_read = 0;
pState->frames_read = 0;
pState->block_remaining = 0;
pState->block_type = LZX_BLOCKTYPE_INVALID;
pState->intel_curpos = 0;
pState->intel_started = 0;
pState->window_posn = 0;
for (i = 0; i < LZX_MAINTREE_MAXSYMBOLS + LZX_LENTABLE_SAFETY; i++) pState->MAINTREE_len[i] = 0;
for (i = 0; i < LZX_LENGTH_MAXSYMBOLS + LZX_LENTABLE_SAFETY; i++) pState->LENGTH_len[i] = 0;
return DECR_OK;
}
/* Bitstream reading macros:
*
* INIT_BITSTREAM should be used first to set up the system
* READ_BITS(var,n) takes N bits from the buffer and puts them in var
*
* ENSURE_BITS(n) ensures there are at least N bits in the bit buffer
* PEEK_BITS(n) extracts (without removing) N bits from the bit buffer
* REMOVE_BITS(n) removes N bits from the bit buffer
*
* These bit access routines work by using the area beyond the MSB and the
* LSB as a free source of zeroes. This avoids having to mask any bits.
* So we have to know the bit width of the bitbuffer variable. This is
* sizeof(ULONG) * 8, also defined as ULONG_BITS
*/
/* number of bits in ULONG. Note: This must be at multiple of 16, and at
* least 32 for the bitbuffer code to work (ie, it must be able to ensure
* up to 17 bits - that's adding 16 bits when there's one bit left, or
* adding 32 bits when there are no bits left. The code should work fine
* for machines where ULONG >= 32 bits.
*/
#define ULONG_BITS (sizeof(ULONG)<<3)
#define INIT_BITSTREAM do { bitsleft = 0; bitbuf = 0; } while (0)
#define ENSURE_BITS(n) \
while (bitsleft < (n)) { \
bitbuf |= ((inpos[1]<<8)|inpos[0]) << (ULONG_BITS-16 - bitsleft); \
bitsleft += 16; inpos+=2; \
}
#define PEEK_BITS(n) (bitbuf >> (ULONG_BITS - (n)))
#define REMOVE_BITS(n) ((bitbuf <<= (n)), (bitsleft -= (n)))
#define READ_BITS(v,n) do { \
ENSURE_BITS(n); \
(v) = PEEK_BITS(n); \
REMOVE_BITS(n); \
} while (0)
/* Huffman macros */
#define TABLEBITS(tbl) (LZX_##tbl##_TABLEBITS)
#define MAXSYMBOLS(tbl) (LZX_##tbl##_MAXSYMBOLS)
#define SYMTABLE(tbl) (pState->tbl##_table)
#define LENTABLE(tbl) (pState->tbl##_len)
/* BUILD_TABLE(tablename) builds a huffman lookup table from code lengths.
* In reality, it just calls make_decode_table() with the appropriate
* values - they're all fixed by some #defines anyway, so there's no point
* writing each call out in full by hand.
*/
#define BUILD_TABLE(tbl) \
if (make_decode_table( \
MAXSYMBOLS(tbl), TABLEBITS(tbl), LENTABLE(tbl), SYMTABLE(tbl) \
)) { return DECR_ILLEGALDATA; }
/* READ_HUFFSYM(tablename, var) decodes one huffman symbol from the
* bitstream using the stated table and puts it in var.
*/
#define READ_HUFFSYM(tbl,var) do { \
ENSURE_BITS(16); \
hufftbl = SYMTABLE(tbl); \
if ((i = hufftbl[PEEK_BITS(TABLEBITS(tbl))]) >= MAXSYMBOLS(tbl)) { \
j = 1 << (ULONG_BITS - TABLEBITS(tbl)); \
do { \
j >>= 1; i <<= 1; i |= (bitbuf & j) ? 1 : 0; \
if (!j) { return DECR_ILLEGALDATA; } \
} while ((i = hufftbl[i]) >= MAXSYMBOLS(tbl)); \
} \
j = LENTABLE(tbl)[(var) = i]; \
REMOVE_BITS(j); \
} while (0)
/* READ_LENGTHS(tablename, first, last) reads in code lengths for symbols
* first to last in the given table. The code lengths are stored in their
* own special LZX way.
*/
#define READ_LENGTHS(tbl,first,last) do { \
lb.bb = bitbuf; lb.bl = bitsleft; lb.ip = inpos; \
if (lzx_read_lens(pState, LENTABLE(tbl),(first),(last),&lb)) { \
return DECR_ILLEGALDATA; \
} \
bitbuf = lb.bb; bitsleft = lb.bl; inpos = lb.ip; \
} while (0)
/* make_decode_table(nsyms, nbits, length[], table[])
*
* This function was coded by David Tritscher. It builds a fast huffman
* decoding table out of just a canonical huffman code lengths table.
*
* nsyms = total number of symbols in this huffman tree.
* nbits = any symbols with a code length of nbits or less can be decoded
* in one lookup of the table.
* length = A table to get code lengths from [0 to syms-1]
* table = The table to fill up with decoded symbols and pointers.
*
* Returns 0 for OK or 1 for error
*/
static int make_decode_table(ULONG nsyms, ULONG nbits, UBYTE *length, UWORD *table) {
register UWORD sym;
register ULONG leaf;
register UBYTE bit_num = 1;
ULONG fill;
ULONG pos = 0; /* the current position in the decode table */
ULONG table_mask = 1 << nbits;
ULONG bit_mask = table_mask >> 1; /* don't do 0 length codes */
ULONG next_symbol = bit_mask; /* base of allocation for long codes */
/* fill entries for codes short enough for a direct mapping */
while (bit_num <= nbits) {
for (sym = 0; sym < nsyms; sym++) {
if (length[sym] == bit_num) {
leaf = pos;
if((pos += bit_mask) > table_mask) return 1; /* table overrun */
/* fill all possible lookups of this symbol with the symbol itself */
fill = bit_mask;
while (fill-- > 0) table[leaf++] = sym;
}
}
bit_mask >>= 1;
bit_num++;
}
/* if there are any codes longer than nbits */
if (pos != table_mask) {
/* clear the remainder of the table */
for (sym = pos; sym < table_mask; sym++) table[sym] = 0;
/* give ourselves room for codes to grow by up to 16 more bits */
pos <<= 16;
table_mask <<= 16;
bit_mask = 1 << 15;
while (bit_num <= 16) {
for (sym = 0; sym < nsyms; sym++) {
if (length[sym] == bit_num) {
leaf = pos >> 16;
for (fill = 0; fill < bit_num - nbits; fill++) {
/* if this path hasn't been taken yet, 'allocate' two entries */
if (table[leaf] == 0) {
table[(next_symbol << 1)] = 0;
table[(next_symbol << 1) + 1] = 0;
table[leaf] = next_symbol++;
}
/* follow the path and select either left or right for next bit */
leaf = table[leaf] << 1;
if ((pos >> (15-fill)) & 1) leaf++;
}
table[leaf] = sym;
if ((pos += bit_mask) > table_mask) return 1; /* table overflow */
}
}
bit_mask >>= 1;
bit_num++;
}
}
/* full table? */
if (pos == table_mask) return 0;
/* either erroneous table, or all elements are 0 - let's find out. */
for (sym = 0; sym < nsyms; sym++) if (length[sym]) return 1;
return 0;
}
struct lzx_bits {
ULONG bb;
int bl;
UBYTE *ip;
};
static int lzx_read_lens(struct LZXstate *pState, UBYTE *lens, ULONG first, ULONG last, struct lzx_bits *lb) {
ULONG i,j, x,y;
int z;
register ULONG bitbuf = lb->bb;
register int bitsleft = lb->bl;
UBYTE *inpos = lb->ip;
UWORD *hufftbl;
for (x = 0; x < 20; x++) {
READ_BITS(y, 4);
LENTABLE(PRETREE)[x] = y;
}
BUILD_TABLE(PRETREE);
for (x = first; x < last; ) {
READ_HUFFSYM(PRETREE, z);
if (z == 17) {
READ_BITS(y, 4); y += 4;
while (y--) lens[x++] = 0;
}
else if (z == 18) {
READ_BITS(y, 5); y += 20;
while (y--) lens[x++] = 0;
}
else if (z == 19) {
READ_BITS(y, 1); y += 4;
READ_HUFFSYM(PRETREE, z);
z = lens[x] - z; if (z < 0) z += 17;
while (y--) lens[x++] = z;
}
else {
z = lens[x] - z; if (z < 0) z += 17;
lens[x++] = z;
}
}
lb->bb = bitbuf;
lb->bl = bitsleft;
lb->ip = inpos;
return 0;
}
int LZXdecompress(struct LZXstate *pState, unsigned char *inpos, unsigned char *outpos, int inlen, int outlen) {
UBYTE *endinp = inpos + inlen;
UBYTE *window = pState->window;
UBYTE *runsrc, *rundest;
UWORD *hufftbl; /* used in READ_HUFFSYM macro as chosen decoding table */
ULONG window_posn = pState->window_posn;
ULONG window_size = pState->window_size;
ULONG R0 = pState->R0;
ULONG R1 = pState->R1;
ULONG R2 = pState->R2;
register ULONG bitbuf;
register int bitsleft;
ULONG match_offset, i,j,k; /* ijk used in READ_HUFFSYM macro */
struct lzx_bits lb; /* used in READ_LENGTHS macro */
int togo = outlen, this_run, main_element, aligned_bits;
int match_length, length_footer, extra, verbatim_bits;
int copy_length;
INIT_BITSTREAM;
/* read header if necessary */
if (!pState->header_read) {
i = j = 0;
READ_BITS(k, 1); if (k) { READ_BITS(i,16); READ_BITS(j,16); }
pState->intel_filesize = (i << 16) | j; /* or 0 if not encoded */
pState->header_read = 1;
}
/* main decoding loop */
while (togo > 0) {
/* last block finished, new block expected */
if (pState->block_remaining == 0) {
if (pState->block_type == LZX_BLOCKTYPE_UNCOMPRESSED) {
if (pState->block_length & 1) inpos++; /* realign bitstream to word */
INIT_BITSTREAM;
}
READ_BITS(pState->block_type, 3);
READ_BITS(i, 16);
READ_BITS(j, 8);
pState->block_remaining = pState->block_length = (i << 8) | j;
switch (pState->block_type) {
case LZX_BLOCKTYPE_ALIGNED:
for (i = 0; i < 8; i++) { READ_BITS(j, 3); LENTABLE(ALIGNED)[i] = j; }
BUILD_TABLE(ALIGNED);
/* rest of aligned header is same as verbatim */
case LZX_BLOCKTYPE_VERBATIM:
READ_LENGTHS(MAINTREE, 0, 256);
READ_LENGTHS(MAINTREE, 256, pState->main_elements);
BUILD_TABLE(MAINTREE);
if (LENTABLE(MAINTREE)[0xE8] != 0) pState->intel_started = 1;
READ_LENGTHS(LENGTH, 0, LZX_NUM_SECONDARY_LENGTHS);
BUILD_TABLE(LENGTH);
break;
case LZX_BLOCKTYPE_UNCOMPRESSED:
pState->intel_started = 1; /* because we can't assume otherwise */
ENSURE_BITS(16); /* get up to 16 pad bits into the buffer */
if (bitsleft > 16) inpos -= 2; /* and align the bitstream! */
R0 = inpos[0]|(inpos[1]<<8)|(inpos[2]<<16)|(inpos[3]<<24);inpos+=4;
R1 = inpos[0]|(inpos[1]<<8)|(inpos[2]<<16)|(inpos[3]<<24);inpos+=4;
R2 = inpos[0]|(inpos[1]<<8)|(inpos[2]<<16)|(inpos[3]<<24);inpos+=4;
break;
default:
return DECR_ILLEGALDATA;
}
}
/* buffer exhaustion check */
if (inpos > endinp) {
/* it's possible to have a file where the next run is less than
* 16 bits in size. In this case, the READ_HUFFSYM() macro used
* in building the tables will exhaust the buffer, so we should
* allow for this, but not allow those accidentally read bits to
* be used (so we check that there are at least 16 bits
* remaining - in this boundary case they aren't really part of
* the compressed data)
*/
if (inpos > (endinp+2) || bitsleft < 16) return DECR_ILLEGALDATA;
}
while ((this_run = pState->block_remaining) > 0 && togo > 0) {
if (this_run > togo) this_run = togo;
togo -= this_run;
pState->block_remaining -= this_run;
/* apply 2^x-1 mask */
window_posn &= window_size - 1;
/* runs can't straddle the window wraparound */
if ((window_posn + this_run) > window_size)
return DECR_DATAFORMAT;
switch (pState->block_type) {
case LZX_BLOCKTYPE_VERBATIM:
while (this_run > 0) {
READ_HUFFSYM(MAINTREE, main_element);
if (main_element < LZX_NUM_CHARS) {
/* literal: 0 to LZX_NUM_CHARS-1 */
window[window_posn++] = main_element;
this_run--;
}
else {
/* match: LZX_NUM_CHARS + ((slot<<3) | length_header (3 bits)) */
main_element -= LZX_NUM_CHARS;
match_length = main_element & LZX_NUM_PRIMARY_LENGTHS;
if (match_length == LZX_NUM_PRIMARY_LENGTHS) {
READ_HUFFSYM(LENGTH, length_footer);
match_length += length_footer;
}
match_length += LZX_MIN_MATCH;
match_offset = main_element >> 3;
if (match_offset > 2) {
/* not repeated offset */
if (match_offset != 3) {
extra = extra_bits[match_offset];
READ_BITS(verbatim_bits, extra);
match_offset = position_base[match_offset] - 2 + verbatim_bits;
}
else {
match_offset = 1;
}
/* update repeated offset LRU queue */
R2 = R1; R1 = R0; R0 = match_offset;
}
else if (match_offset == 0) {
match_offset = R0;
}
else if (match_offset == 1) {
match_offset = R1;
R1 = R0; R0 = match_offset;
}
else /* match_offset == 2 */ {
match_offset = R2;
R2 = R0; R0 = match_offset;
}
rundest = window + window_posn;
this_run -= match_length;
/* copy any wrapped around source data */
if (window_posn >= match_offset) {
/* no wrap */
runsrc = rundest - match_offset;
} else {
runsrc = rundest + (window_size - match_offset);
copy_length = match_offset - window_posn;
if (copy_length < match_length) {
match_length -= copy_length;
window_posn += copy_length;
while (copy_length-- > 0) *rundest++ = *runsrc++;
runsrc = window;
}
}
window_posn += match_length;
/* copy match data - no worries about destination wraps */
while (match_length-- > 0) *rundest++ = *runsrc++;
}
}
break;
case LZX_BLOCKTYPE_ALIGNED:
while (this_run > 0) {
READ_HUFFSYM(MAINTREE, main_element);
if (main_element < LZX_NUM_CHARS) {
/* literal: 0 to LZX_NUM_CHARS-1 */
window[window_posn++] = main_element;
this_run--;
}
else {
/* match: LZX_NUM_CHARS + ((slot<<3) | length_header (3 bits)) */
main_element -= LZX_NUM_CHARS;
match_length = main_element & LZX_NUM_PRIMARY_LENGTHS;
if (match_length == LZX_NUM_PRIMARY_LENGTHS) {
READ_HUFFSYM(LENGTH, length_footer);
match_length += length_footer;
}
match_length += LZX_MIN_MATCH;
match_offset = main_element >> 3;
if (match_offset > 2) {
/* not repeated offset */
extra = extra_bits[match_offset];
match_offset = position_base[match_offset] - 2;
if (extra > 3) {
/* verbatim and aligned bits */
extra -= 3;
READ_BITS(verbatim_bits, extra);
match_offset += (verbatim_bits << 3);
READ_HUFFSYM(ALIGNED, aligned_bits);
match_offset += aligned_bits;
}
else if (extra == 3) {
/* aligned bits only */
READ_HUFFSYM(ALIGNED, aligned_bits);
match_offset += aligned_bits;
}
else if (extra > 0) { /* extra==1, extra==2 */
/* verbatim bits only */
READ_BITS(verbatim_bits, extra);
match_offset += verbatim_bits;
}
else /* extra == 0 */ {
/* ??? */
match_offset = 1;
}
/* update repeated offset LRU queue */
R2 = R1; R1 = R0; R0 = match_offset;
}
else if (match_offset == 0) {
match_offset = R0;
}
else if (match_offset == 1) {
match_offset = R1;
R1 = R0; R0 = match_offset;
}
else /* match_offset == 2 */ {
match_offset = R2;
R2 = R0; R0 = match_offset;
}
rundest = window + window_posn;
this_run -= match_length;
/* copy any wrapped around source data */
if (window_posn >= match_offset) {
/* no wrap */
runsrc = rundest - match_offset;
} else {
runsrc = rundest + (window_size - match_offset);
copy_length = match_offset - window_posn;
if (copy_length < match_length) {
match_length -= copy_length;
window_posn += copy_length;
while (copy_length-- > 0) *rundest++ = *runsrc++;
runsrc = window;
}
}
window_posn += match_length;
/* copy match data - no worries about destination wraps */
while (match_length-- > 0) *rundest++ = *runsrc++;
}
}
break;
case LZX_BLOCKTYPE_UNCOMPRESSED:
if ((inpos + this_run) > endinp) return DECR_ILLEGALDATA;
memcpy(window + window_posn, inpos, (size_t) this_run);
inpos += this_run; window_posn += this_run;
break;
default:
return DECR_ILLEGALDATA; /* might as well */
}
}
}
if (togo != 0) return DECR_ILLEGALDATA;
memcpy(outpos, window + ((!window_posn) ? window_size : window_posn) - outlen, (size_t) outlen);
pState->window_posn = window_posn;
pState->R0 = R0;
pState->R1 = R1;
pState->R2 = R2;
/* intel E8 decoding */
if ((pState->frames_read++ < 32768) && pState->intel_filesize != 0) {
if (outlen <= 6 || !pState->intel_started) {
pState->intel_curpos += outlen;
}
else {
UBYTE *data = outpos;
UBYTE *dataend = data + outlen - 10;
LONG curpos = pState->intel_curpos;
LONG filesize = pState->intel_filesize;
LONG abs_off, rel_off;
pState->intel_curpos = curpos + outlen;
while (data < dataend) {
if (*data++ != 0xE8) { curpos++; continue; }
abs_off = data[0] | (data[1]<<8) | (data[2]<<16) | (data[3]<<24);
if ((abs_off >= -curpos) && (abs_off < filesize)) {
rel_off = (abs_off >= 0) ? abs_off - curpos : abs_off + filesize;
data[0] = (UBYTE) rel_off;
data[1] = (UBYTE) (rel_off >> 8);
data[2] = (UBYTE) (rel_off >> 16);
data[3] = (UBYTE) (rel_off >> 24);
}
data += 4;
curpos += 5;
}
}
}
return DECR_OK;
}
#ifdef LZX_CHM_TESTDRIVER
int main(int c, char **v)
{
FILE *fin, *fout;
struct LZXstate state;
UBYTE ibuf[16384];
UBYTE obuf[32768];
int ilen, olen;
int status;
int i;
int count=0;
int w = atoi(v[1]);
LZXinit(&state, 1 << w);
fout = fopen(v[2], "wb");
for (i=3; i<c; i++)
{
fin = fopen(v[i], "rb");
ilen = fread(ibuf, 1, 16384, fin);
status = LZXdecompress(&state, ibuf, obuf, ilen, 32768);
switch (status)
{
case DECR_OK:
printf("ok\n");
fwrite(obuf, 1, 32768, fout);
break;
case DECR_DATAFORMAT:
printf("bad format\n");
break;
case DECR_ILLEGALDATA:
printf("illegal data\n");
break;
case DECR_NOMEMORY:
printf("no memory\n");
break;
default:
break;
}
fclose(fin);
if (++count == 2)
{
count = 0;
LZXreset(&state);
}
}
fclose(fout);
}
#endif
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