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[unix-history] / gnu / usr.bin / gzip / unlzw.c
/* unlzw.c -- decompress files in LZW format.
* The code in this file is directly derived from the public domain 'compress'
* written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
* Ken Turkowski, Dave Mack and Peter Jannesen.
*
* This is a temporary version which will be rewritten in some future version
* to accommodate in-memory decompression.
*/
#ifndef lint
static char rcsid[] = "$Id: unlzw.c,v 0.15 1993/06/10 13:28:35 jloup Exp $";
#endif
#include <sys/types.h>
#include "tailor.h"
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#ifndef NO_FCNTL_H
# include <fcntl.h>
#endif
#include "gzip.h"
#include "lzw.h"
typedef unsigned char char_type;
typedef long code_int;
typedef unsigned long count_int;
typedef unsigned short count_short;
typedef unsigned long cmp_code_int;
#define MAXCODE(n) (1L << (n))
#ifndef REGISTERS
# define REGISTERS 2
#endif
#define REG1
#define REG2
#define REG3
#define REG4
#define REG5
#define REG6
#define REG7
#define REG8
#define REG9
#define REG10
#define REG11
#define REG12
#define REG13
#define REG14
#define REG15
#define REG16
#if REGISTERS >= 1
# undef REG1
# define REG1 register
#endif
#if REGISTERS >= 2
# undef REG2
# define REG2 register
#endif
#if REGISTERS >= 3
# undef REG3
# define REG3 register
#endif
#if REGISTERS >= 4
# undef REG4
# define REG4 register
#endif
#if REGISTERS >= 5
# undef REG5
# define REG5 register
#endif
#if REGISTERS >= 6
# undef REG6
# define REG6 register
#endif
#if REGISTERS >= 7
# undef REG7
# define REG7 register
#endif
#if REGISTERS >= 8
# undef REG8
# define REG8 register
#endif
#if REGISTERS >= 9
# undef REG9
# define REG9 register
#endif
#if REGISTERS >= 10
# undef REG10
# define REG10 register
#endif
#if REGISTERS >= 11
# undef REG11
# define REG11 register
#endif
#if REGISTERS >= 12
# undef REG12
# define REG12 register
#endif
#if REGISTERS >= 13
# undef REG13
# define REG13 register
#endif
#if REGISTERS >= 14
# undef REG14
# define REG14 register
#endif
#if REGISTERS >= 15
# undef REG15
# define REG15 register
#endif
#if REGISTERS >= 16
# undef REG16
# define REG16 register
#endif
#ifndef BYTEORDER
# define BYTEORDER 0000
#endif
#ifndef NOALLIGN
# define NOALLIGN 0
#endif
union bytes {
long word;
struct {
#if BYTEORDER == 4321
char_type b1;
char_type b2;
char_type b3;
char_type b4;
#else
#if BYTEORDER == 1234
char_type b4;
char_type b3;
char_type b2;
char_type b1;
#else
# undef BYTEORDER
int dummy;
#endif
#endif
} bytes;
};
#if BYTEORDER == 4321 && NOALLIGN == 1
# define input(b,o,c,n,m){ \
(c) = (*(long *)(&(b)[(o)>>3])>>((o)&0x7))&(m); \
(o) += (n); \
}
#else
# define input(b,o,c,n,m){ \
REG1 char_type *p = &(b)[(o)>>3]; \
(c) = ((((long)(p[0]))|((long)(p[1])<<8)| \
((long)(p[2])<<16))>>((o)&0x7))&(m); \
(o) += (n); \
}
#endif
#ifndef MAXSEG_64K
/* DECLARE(ush, tab_prefix, (1<<BITS)); -- prefix code */
# define tab_prefixof(i) tab_prefix[i]
# define clear_tab_prefixof() memzero(tab_prefix, 256);
#else
/* DECLARE(ush, tab_prefix0, (1<<(BITS-1)); -- prefix for even codes */
/* DECLARE(ush, tab_prefix1, (1<<(BITS-1)); -- prefix for odd codes */
ush *tab_prefix[2];
# define tab_prefixof(i) tab_prefix[(i)&1][(i)>>1]
# define clear_tab_prefixof() \
memzero(tab_prefix0, 128), \
memzero(tab_prefix1, 128);
#endif
#define de_stack ((char_type *)(&d_buf[DIST_BUFSIZE-1]))
#define tab_suffixof(i) tab_suffix[i]
int block_mode = BLOCK_MODE; /* block compress mode -C compatible with 2.0 */
/* ============================================================================
* Decompress in to out. This routine adapts to the codes in the
* file building the "string" table on-the-fly; requiring no table to
* be stored in the compressed file.
* IN assertions: the buffer inbuf contains already the beginning of
* the compressed data, from offsets iptr to insize-1 included.
* The magic header has already been checked and skipped.
* bytes_in and bytes_out have been initialized.
*/
int unlzw(in, out)
int in, out; /* input and output file descriptors */
{
REG2 char_type *stackp;
REG3 code_int code;
REG4 int finchar;
REG5 code_int oldcode;
REG6 code_int incode;
REG7 long inbits;
REG8 long posbits;
REG9 int outpos;
/* REG10 int insize; (global) */
REG11 unsigned bitmask;
REG12 code_int free_ent;
REG13 code_int maxcode;
REG14 code_int maxmaxcode;
REG15 int n_bits;
REG16 int rsize;
#ifdef MAXSEG_64K
tab_prefix[0] = tab_prefix0;
tab_prefix[1] = tab_prefix1;
#endif
maxbits = get_byte();
block_mode = maxbits & BLOCK_MODE;
if ((maxbits & LZW_RESERVED) != 0) {
WARN((stderr, "\n%s: %s: warning, unknown flags 0x%x\n",
progname, ifname, maxbits & LZW_RESERVED));
}
maxbits &= BIT_MASK;
maxmaxcode = MAXCODE(maxbits);
if (maxbits > BITS) {
fprintf(stderr,
"\n%s: %s: compressed with %d bits, can only handle %d bits\n",
progname, ifname, maxbits, BITS);
exit_code = ERROR;
return ERROR;
}
rsize = insize;
maxcode = MAXCODE(n_bits = INIT_BITS)-1;
bitmask = (1<<n_bits)-1;
oldcode = -1;
finchar = 0;
outpos = 0;
posbits = inptr<<3;
free_ent = ((block_mode) ? FIRST : 256);
clear_tab_prefixof(); /* Initialize the first 256 entries in the table. */
for (code = 255 ; code >= 0 ; --code) {
tab_suffixof(code) = (char_type)code;
}
do {
REG1 int i;
int e;
int o;
resetbuf:
e = insize-(o = (posbits>>3));
for (i = 0 ; i < e ; ++i) {
inbuf[i] = inbuf[i+o];
}
insize = e;
posbits = 0;
if (insize < INBUF_EXTRA) {
if ((rsize = read(in, (char*)inbuf+insize, INBUFSIZ)) == EOF) {
read_error();
}
insize += rsize;
bytes_in += (ulg)rsize;
}
inbits = ((rsize != 0) ? ((long)insize - insize%n_bits)<<3 :
((long)insize<<3)-(n_bits-1));
while (inbits > posbits) {
if (free_ent > maxcode) {
posbits = ((posbits-1) +
((n_bits<<3)-(posbits-1+(n_bits<<3))%(n_bits<<3)));
++n_bits;
if (n_bits == maxbits) {
maxcode = maxmaxcode;
} else {
maxcode = MAXCODE(n_bits)-1;
}
bitmask = (1<<n_bits)-1;
goto resetbuf;
}
input(inbuf,posbits,code,n_bits,bitmask);
if (oldcode == -1) {
outbuf[outpos++] = (char_type)(finchar = (int)(oldcode=code));
continue;
}
if (code == CLEAR && block_mode) {
clear_tab_prefixof();
free_ent = FIRST - 1;
posbits = ((posbits-1) +
((n_bits<<3)-(posbits-1+(n_bits<<3))%(n_bits<<3)));
maxcode = MAXCODE(n_bits = INIT_BITS)-1;
bitmask = (1<<n_bits)-1;
goto resetbuf;
}
incode = code;
stackp = de_stack;
if (code >= free_ent) { /* Special case for KwKwK string. */
if (code > free_ent) {
#ifdef DEBUG
char_type *p;
posbits -= n_bits;
p = &inbuf[posbits>>3];
fprintf(stderr,
"code:%ld free_ent:%ld n_bits:%d insize:%u\n",
code, free_ent, n_bits, insize);
fprintf(stderr,
"posbits:%ld inbuf:%02X %02X %02X %02X %02X\n",
posbits, p[-1],p[0],p[1],p[2],p[3]);
#endif
if (!test && outpos > 0) {
write_buf(out, (char*)outbuf, outpos);
bytes_out += (ulg)outpos;
}
error("corrupt input. Use zcat to recover some data.");
}
*--stackp = (char_type)finchar;
code = oldcode;
}
while ((cmp_code_int)code >= (cmp_code_int)256) {
/* Generate output characters in reverse order */
*--stackp = tab_suffixof(code);
code = tab_prefixof(code);
}
*--stackp = (char_type)(finchar = tab_suffixof(code));
/* And put them out in forward order */
{
REG1 int i;
if (outpos+(i = (de_stack-stackp)) >= OUTBUFSIZ) {
do {
if (i > OUTBUFSIZ-outpos) i = OUTBUFSIZ-outpos;
if (i > 0) {
memcpy(outbuf+outpos, stackp, i);
outpos += i;
}
if (outpos >= OUTBUFSIZ) {
if (!test) {
write_buf(out, (char*)outbuf, outpos);
bytes_out += (ulg)outpos;
}
outpos = 0;
}
stackp+= i;
} while ((i = (de_stack-stackp)) > 0);
} else {
memcpy(outbuf+outpos, stackp, i);
outpos += i;
}
}
if ((code = free_ent) < maxmaxcode) { /* Generate the new entry. */
tab_prefixof(code) = (unsigned short)oldcode;
tab_suffixof(code) = (char_type)finchar;
free_ent = code+1;
}
oldcode = incode; /* Remember previous code. */
}
} while (rsize != 0);
if (!test && outpos > 0) {
write_buf(out, (char*)outbuf, outpos);
bytes_out += (ulg)outpos;
}
return OK;
}
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.