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tdevelop/parts/documentation/protocols/chm/decompress.cpp

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/* Most of this file is taken from:
cabextract 0.5 - a program to extract Microsoft Cabinet files
(C) 2000-2001 Stuart Caie <kyzer@4u.net>
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "decompress.h"
int make_decode_table(ULONG nsyms, ULONG nbits, UBYTE *length, UWORD *table);
int lzx_read_lens(UBYTE *lens, ULONG first, ULONG last, lzx_bits *lb);
/*--------------------------------------------------------------------------*/
/* our archiver information / state */
/* LZX stuff */
/* 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);
};
/* generic stuff */
#define CAB(x) (decomp_state.x)
#define LZX(x) (decomp_state.lzx.x)
#define DECR_OK (0)
#define DECR_DATAFORMAT (1)
#define DECR_ILLEGALDATA (2)
#define DECR_NOMEMORY (3)
#define DECR_CHECKSUM (4)
#define DECR_INPUT (5)
#define DECR_OUTPUT (6)
struct
{
struct LZXstate lzx;
} decomp_state;
/* 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 ULONG position_base[51];
static UBYTE extra_bits[51];
int LZXinit(int window) {
ULONG wndsize = 1 << window;
int i, j, posn_slots;
/* LZX supports window sizes of 2^15 (32Kb) through 2^21 (2Mb) */
/* if a previously allocated window is big enough, keep it */
if (window < 15 || window > 21) return DECR_DATAFORMAT;
if (LZX(actual_size) < wndsize)
{
if (LZX(window)) free(LZX(window));
LZX(window) = NULL;
}
if (!LZX(window))
{
if (!(LZX(window) = (UBYTE*)malloc(wndsize))) return DECR_NOMEMORY;
LZX(actual_size) = wndsize;
}
LZX(window_size) = wndsize;
/* initialise static tables */
for (i=0, j=0; i <= 49; i += 2)
{
extra_bits[i] = extra_bits[i+1] = j; /* 0,0,0,0,1,1,2,2,3,3... */
if ((i != 0) && (j < 17)) j++; /* 0,0,1,2,3,4...15,16,17,17,17,17... */
}
for (i=0, j=0; i <= 50; i++)
{
position_base[i] = j; /* 0,1,2,3,4,6,8,12,16,24,32,... */
j += 1 << extra_bits[i]; /* 1,1,1,1,2,2,4,4,8,8,16,16,32,32,... */
}
/* calculate required position slots */
if (window == 20) posn_slots = 42;
else if (window == 21) posn_slots = 50;
else posn_slots = window << 1;
/*posn_slots=i=0; while (i < wndsize) i += 1 << extra_bits[posn_slots++]; */
LZX(R0) = LZX(R1) = LZX(R2) = 1;
LZX(main_elements) = LZX_NUM_CHARS + (posn_slots << 3);
LZX(header_read) = 0;
LZX(frames_read) = 0;
LZX(block_remaining) = 0;
LZX(block_type) = LZX_BLOCKTYPE_INVALID;
LZX(intel_curpos) = 0;
LZX(intel_started) = 0;
LZX(window_posn) = 0;
/* initialise tables to 0 (because deltas will be applied to them) */
for (i = 0; i < LZX_MAINTREE_MAXSYMBOLS; i++) LZX(MAINTREE_len)[i] = 0;
for (i = 0; i < LZX_LENGTH_MAXSYMBOLS; i++) LZX(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) (LZX(tbl##_table))
#define LENTABLE(tbl) (LZX(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(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
*/
int make_decode_table(ULONG nsyms, ULONG nbits, UBYTE *length, UWORD *table) {
UWORD sym;
ULONG leaf;
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;
}
int lzx_read_lens(UBYTE *lens, ULONG first, ULONG last, lzx_bits *lb) {
ULONG i,j, x,y;
int z;
ULONG bitbuf = lb->bb;
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(UBYTE* inpos, int inlen, UBYTE* outpos, int outlen) {
UBYTE *endinp = inpos + inlen;
UBYTE *window = LZX(window);
UBYTE *runsrc, *rundest;
UWORD *hufftbl; /* used in READ_HUFFSYM macro as chosen decoding table */
ULONG window_posn = LZX(window_posn);
ULONG window_size = LZX(window_size);
ULONG R0 = LZX(R0);
ULONG R1 = LZX(R1);
ULONG R2 = LZX(R2);
ULONG bitbuf;
int bitsleft;
ULONG match_offset, i,j,k; /* ijk used in READ_HUFFSYM macro */
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;
INIT_BITSTREAM;
/* read header if necessary */
if (!LZX(header_read))
{
i = j = 0;
READ_BITS(k, 1); if (k)
{
READ_BITS(i,16); READ_BITS(j,16);
}
LZX(intel_filesize) = (i << 16) | j; /* or 0 if not encoded */
LZX(header_read) = 1;
}
/* main decoding loop */
while (togo > 0)
{
/* last block finished, new block expected */
if (LZX(block_remaining) == 0)
{
if (LZX(block_type) == LZX_BLOCKTYPE_UNCOMPRESSED)
{
if (LZX(block_length) & 1) inpos++; /* realign bitstream to word */
INIT_BITSTREAM;
}
READ_BITS(LZX(block_type), 3);
READ_BITS(i, 16);
READ_BITS(j, 8);
LZX(block_remaining) = LZX(block_length) = (i << 8) | j;
switch (LZX(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, LZX(main_elements));
BUILD_TABLE(MAINTREE);
if (LENTABLE(MAINTREE)[0xE8] != 0) LZX(intel_started) = 1;
READ_LENGTHS(LENGTH, 0, LZX_NUM_SECONDARY_LENGTHS);
BUILD_TABLE(LENGTH);
break;
case LZX_BLOCKTYPE_UNCOMPRESSED:
LZX(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 = LZX(block_remaining)) > 0 && togo > 0)
{
if (this_run > togo) this_run = togo;
togo -= this_run;
LZX(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 (LZX(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;
runsrc = rundest - match_offset;
window_posn += match_length;
this_run -= match_length;
/* copy any wrapped around source data */
while ((runsrc < window) && (match_length-- > 0))
{
*rundest++ = *(runsrc + window_size); runsrc++;
}
/* 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;
runsrc = rundest - match_offset;
window_posn += match_length;
this_run -= match_length;
/* copy any wrapped around source data */
while ((runsrc < window) && (match_length-- > 0))
{
*rundest++ = *(runsrc + window_size); runsrc++;
}
/* 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);
LZX(window_posn) = window_posn;
LZX(R0) = R0;
LZX(R1) = R1;
LZX(R2) = R2;
/* intel E8 decoding */
if ((LZX(frames_read)++ < 32768) && LZX(intel_filesize) != 0)
{
if (outlen <= 6 || !LZX(intel_started))
{
LZX(intel_curpos) += outlen;
}
else
{
UBYTE *data = outpos;
UBYTE *dataend = data + outlen - 10;
LONG curpos = LZX(intel_curpos);
LONG filesize = LZX(intel_filesize);
LONG abs_off, rel_off;
LZX(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;
}
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