378 lines
8.6 KiB
C
378 lines
8.6 KiB
C
/* unlzw.c -- decompress files in LZW format.
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* The code in this file is directly derived from the public domain 'compress'
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* written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
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* Ken Turkowski, Dave Mack and Peter Jannesen.
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*
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* This is a temporary version which will be rewritten in some future version
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* to accommodate in-memory decompression.
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*/
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#ifdef RCSID
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static char rcsid[] = "$Id: unlzw.c,v 1.3 1993/10/14 00:33:17 nate Exp $";
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#endif
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#include <sys/types.h>
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#include "tailor.h"
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#ifdef HAVE_UNISTD_H
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# include <unistd.h>
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#endif
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#ifndef NO_FCNTL_H
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# include <fcntl.h>
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#endif
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#include "gzip.h"
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#include "lzw.h"
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typedef unsigned char char_type;
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typedef long code_int;
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typedef unsigned long count_int;
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typedef unsigned short count_short;
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typedef unsigned long cmp_code_int;
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#define MAXCODE(n) (1L << (n))
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#ifndef REGISTERS
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# define REGISTERS 2
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#endif
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#define REG1
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#define REG2
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#define REG3
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#define REG4
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#define REG5
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#define REG6
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#define REG7
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#define REG8
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#define REG9
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#define REG10
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#define REG11
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#define REG12
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#define REG13
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#define REG14
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#define REG15
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#define REG16
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#if REGISTERS >= 1
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# undef REG1
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# define REG1 register
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#endif
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#if REGISTERS >= 2
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# undef REG2
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# define REG2 register
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#endif
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#if REGISTERS >= 3
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# undef REG3
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# define REG3 register
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#endif
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#if REGISTERS >= 4
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# undef REG4
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# define REG4 register
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#endif
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#if REGISTERS >= 5
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# undef REG5
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# define REG5 register
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#endif
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#if REGISTERS >= 6
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# undef REG6
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# define REG6 register
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#endif
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#if REGISTERS >= 7
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# undef REG7
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# define REG7 register
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#endif
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#if REGISTERS >= 8
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# undef REG8
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# define REG8 register
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#endif
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#if REGISTERS >= 9
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# undef REG9
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# define REG9 register
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#endif
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#if REGISTERS >= 10
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# undef REG10
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# define REG10 register
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#endif
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#if REGISTERS >= 11
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# undef REG11
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# define REG11 register
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#endif
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#if REGISTERS >= 12
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# undef REG12
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# define REG12 register
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#endif
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#if REGISTERS >= 13
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# undef REG13
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# define REG13 register
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#endif
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#if REGISTERS >= 14
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# undef REG14
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# define REG14 register
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#endif
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#if REGISTERS >= 15
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# undef REG15
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# define REG15 register
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#endif
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#if REGISTERS >= 16
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# undef REG16
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# define REG16 register
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#endif
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#ifndef BYTEORDER
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# define BYTEORDER 0000
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#endif
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#ifndef NOALLIGN
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# define NOALLIGN 0
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#endif
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union bytes {
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long word;
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struct {
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#if BYTEORDER == 4321
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char_type b1;
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char_type b2;
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char_type b3;
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char_type b4;
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#else
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#if BYTEORDER == 1234
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char_type b4;
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char_type b3;
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char_type b2;
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char_type b1;
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#else
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# undef BYTEORDER
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int dummy;
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#endif
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#endif
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} bytes;
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};
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#if BYTEORDER == 4321 && NOALLIGN == 1
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# define input(b,o,c,n,m){ \
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(c) = (*(long *)(&(b)[(o)>>3])>>((o)&0x7))&(m); \
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(o) += (n); \
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}
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#else
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# define input(b,o,c,n,m){ \
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REG1 char_type *p = &(b)[(o)>>3]; \
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(c) = ((((long)(p[0]))|((long)(p[1])<<8)| \
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((long)(p[2])<<16))>>((o)&0x7))&(m); \
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(o) += (n); \
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}
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#endif
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#ifndef MAXSEG_64K
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/* DECLARE(ush, tab_prefix, (1<<BITS)); -- prefix code */
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# define tab_prefixof(i) tab_prefix[i]
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# define clear_tab_prefixof() memzero(tab_prefix, 256);
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#else
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/* DECLARE(ush, tab_prefix0, (1<<(BITS-1)); -- prefix for even codes */
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/* DECLARE(ush, tab_prefix1, (1<<(BITS-1)); -- prefix for odd codes */
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ush *tab_prefix[2];
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# define tab_prefixof(i) tab_prefix[(i)&1][(i)>>1]
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# define clear_tab_prefixof() \
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memzero(tab_prefix0, 128), \
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memzero(tab_prefix1, 128);
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#endif
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#define de_stack ((char_type *)(&d_buf[DIST_BUFSIZE-1]))
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#define tab_suffixof(i) tab_suffix[i]
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int block_mode = BLOCK_MODE; /* block compress mode -C compatible with 2.0 */
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/* ============================================================================
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* Decompress in to out. This routine adapts to the codes in the
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* file building the "string" table on-the-fly; requiring no table to
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* be stored in the compressed file.
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* IN assertions: the buffer inbuf contains already the beginning of
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* the compressed data, from offsets iptr to insize-1 included.
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* The magic header has already been checked and skipped.
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* bytes_in and bytes_out have been initialized.
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*/
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int unlzw(in, out)
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int in, out; /* input and output file descriptors */
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{
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REG2 char_type *stackp;
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REG3 code_int code;
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REG4 int finchar;
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REG5 code_int oldcode;
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REG6 code_int incode;
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REG7 long inbits;
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REG8 long posbits;
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REG9 int outpos;
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/* REG10 int insize; (global) */
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REG11 unsigned bitmask;
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REG12 code_int free_ent;
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REG13 code_int maxcode;
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REG14 code_int maxmaxcode;
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REG15 int n_bits;
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REG16 int rsize;
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#ifdef MAXSEG_64K
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tab_prefix[0] = tab_prefix0;
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tab_prefix[1] = tab_prefix1;
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#endif
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maxbits = get_byte();
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block_mode = maxbits & BLOCK_MODE;
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if ((maxbits & LZW_RESERVED) != 0) {
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WARN((stderr, "\n%s: %s: warning, unknown flags 0x%x\n",
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progname, ifname, maxbits & LZW_RESERVED));
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}
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maxbits &= BIT_MASK;
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maxmaxcode = MAXCODE(maxbits);
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if (maxbits > BITS) {
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fprintf(stderr,
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"\n%s: %s: compressed with %d bits, can only handle %d bits\n",
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progname, ifname, maxbits, BITS);
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exit_code = ERROR;
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return ERROR;
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}
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rsize = insize;
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maxcode = MAXCODE(n_bits = INIT_BITS)-1;
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bitmask = (1<<n_bits)-1;
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oldcode = -1;
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finchar = 0;
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outpos = 0;
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posbits = inptr<<3;
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free_ent = ((block_mode) ? FIRST : 256);
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clear_tab_prefixof(); /* Initialize the first 256 entries in the table. */
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for (code = 255 ; code >= 0 ; --code) {
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tab_suffixof(code) = (char_type)code;
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}
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do {
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REG1 int i;
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int e;
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int o;
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resetbuf:
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e = insize-(o = (posbits>>3));
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for (i = 0 ; i < e ; ++i) {
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inbuf[i] = inbuf[i+o];
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}
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insize = e;
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posbits = 0;
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if (insize < INBUF_EXTRA) {
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if ((rsize = read(in, (char*)inbuf+insize, INBUFSIZ)) == EOF) {
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read_error();
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}
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insize += rsize;
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bytes_in += (ulg)rsize;
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}
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inbits = ((rsize != 0) ? ((long)insize - insize%n_bits)<<3 :
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((long)insize<<3)-(n_bits-1));
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while (inbits > posbits) {
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if (free_ent > maxcode) {
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posbits = ((posbits-1) +
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((n_bits<<3)-(posbits-1+(n_bits<<3))%(n_bits<<3)));
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++n_bits;
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if (n_bits == maxbits) {
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maxcode = maxmaxcode;
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} else {
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maxcode = MAXCODE(n_bits)-1;
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}
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bitmask = (1<<n_bits)-1;
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goto resetbuf;
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}
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input(inbuf,posbits,code,n_bits,bitmask);
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Tracev((stderr, "%d ", code));
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if (oldcode == -1) {
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if (code >= 256) error("corrupt input.");
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outbuf[outpos++] = (char_type)(finchar = (int)(oldcode=code));
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continue;
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}
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if (code == CLEAR && block_mode) {
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clear_tab_prefixof();
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free_ent = FIRST - 1;
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posbits = ((posbits-1) +
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((n_bits<<3)-(posbits-1+(n_bits<<3))%(n_bits<<3)));
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maxcode = MAXCODE(n_bits = INIT_BITS)-1;
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bitmask = (1<<n_bits)-1;
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goto resetbuf;
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}
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incode = code;
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stackp = de_stack;
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if (code >= free_ent) { /* Special case for KwKwK string. */
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if (code > free_ent) {
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#ifdef DEBUG
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char_type *p;
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posbits -= n_bits;
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p = &inbuf[posbits>>3];
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fprintf(stderr,
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"code:%ld free_ent:%ld n_bits:%d insize:%u\n",
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code, free_ent, n_bits, insize);
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fprintf(stderr,
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"posbits:%ld inbuf:%02X %02X %02X %02X %02X\n",
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posbits, p[-1],p[0],p[1],p[2],p[3]);
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#endif
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if (!test && outpos > 0) {
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write_buf(out, (char*)outbuf, outpos);
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bytes_out += (ulg)outpos;
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}
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error(to_stdout ? "corrupt input." :
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"corrupt input. Use zcat to recover some data.");
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}
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*--stackp = (char_type)finchar;
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code = oldcode;
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}
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while ((cmp_code_int)code >= (cmp_code_int)256) {
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/* Generate output characters in reverse order */
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*--stackp = tab_suffixof(code);
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code = tab_prefixof(code);
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}
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*--stackp = (char_type)(finchar = tab_suffixof(code));
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/* And put them out in forward order */
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{
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REG1 int i;
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if (outpos+(i = (de_stack-stackp)) >= OUTBUFSIZ) {
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do {
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if (i > OUTBUFSIZ-outpos) i = OUTBUFSIZ-outpos;
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if (i > 0) {
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memcpy(outbuf+outpos, stackp, i);
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outpos += i;
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}
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if (outpos >= OUTBUFSIZ) {
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if (!test) {
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write_buf(out, (char*)outbuf, outpos);
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bytes_out += (ulg)outpos;
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}
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outpos = 0;
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}
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stackp+= i;
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} while ((i = (de_stack-stackp)) > 0);
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} else {
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memcpy(outbuf+outpos, stackp, i);
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outpos += i;
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}
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}
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if ((code = free_ent) < maxmaxcode) { /* Generate the new entry. */
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tab_prefixof(code) = (unsigned short)oldcode;
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tab_suffixof(code) = (char_type)finchar;
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free_ent = code+1;
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}
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oldcode = incode; /* Remember previous code. */
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}
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} while (rsize != 0);
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if (!test && outpos > 0) {
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write_buf(out, (char*)outbuf, outpos);
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bytes_out += (ulg)outpos;
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}
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return OK;
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}
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