diff options
Diffstat (limited to 'parts/documentation/protocols/chm/decompress.cpp')
| -rw-r--r-- | parts/documentation/protocols/chm/decompress.cpp | 796 |
1 files changed, 796 insertions, 0 deletions
diff --git a/parts/documentation/protocols/chm/decompress.cpp b/parts/documentation/protocols/chm/decompress.cpp new file mode 100644 index 00000000..0356d86e --- /dev/null +++ b/parts/documentation/protocols/chm/decompress.cpp @@ -0,0 +1,796 @@ +/* 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., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, 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) { + 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; +} + +int lzx_read_lens(UBYTE *lens, ULONG first, ULONG last, 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(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); + + register ULONG bitbuf; + register 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; +} + |