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Diffstat (limited to 'lib/chmlib/lzx.c')
| -rw-r--r-- | lib/chmlib/lzx.c | 812 |
1 files changed, 812 insertions, 0 deletions
diff --git a/lib/chmlib/lzx.c b/lib/chmlib/lzx.c new file mode 100644 index 0000000..7a5545b --- /dev/null +++ b/lib/chmlib/lzx.c @@ -0,0 +1,812 @@ +/* $Id: lzx.c 148 2007-03-07 09:22:36Z gyunaev $ */ +/*************************************************************************** + * 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. * + ***************************************************************************/ + +/*************************************************************************** + * * + * This program is free software; you can redistribute it and/or modify * + * it under the terms of the GNU General Public License as published by * + * the Free Software Foundation; either version 2 of the License, or * + * (at your option) any later version. Note that an exemption to this * + * license has been granted by Stuart Caie for the purposes of * + * distribution with chmlib. This does not, to the best of my * + * knowledge, constitute a change in the license of this (the LZX) code * + * in general. * + * * + ***************************************************************************/ + +#include "lzx.h" +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#ifdef __GNUC__ +#define memcpy __builtin_memcpy +#endif + +/* sized types */ +typedef unsigned char UBYTE; /* 8 bits exactly */ +typedef unsigned short UWORD; /* 16 bits (or more) */ +typedef unsigned int ULONG; /* 32 bits (or more) */ +typedef signed int LONG; /* 32 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 window) +{ + struct LZXstate *pState=NULL; + ULONG wndsize = 1 << window; + int i, 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 NULL; + + /* allocate state and associated window */ + pState = (struct LZXstate *)malloc(sizeof(struct LZXstate)); + if (!(pState->window = (UBYTE *)malloc(wndsize))) + { + free(pState); + return NULL; + } + pState->actual_size = wndsize; + pState->window_size = wndsize; + + /* calculate required position slots */ + if (window == 20) posn_slots = 42; + else if (window == 21) posn_slots = 50; + else posn_slots = window << 1; + + /** alternatively **/ + /* 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) + { + if (pState->window) + free(pState->window); + free(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; + + 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; + runsrc = rundest - match_offset; + window_posn += match_length; + if (window_posn > window_size) return DECR_ILLEGALDATA; + 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; + if (window_posn > window_size) return DECR_ILLEGALDATA; + 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); + + 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, 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 |