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freebsd/gnu/usr.bin/gzip/unlzh.c

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9.0 KiB
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/* unlzh.c -- decompress files in SCO compress -H (LZH) format.
* The code in this file is directly derived from the public domain 'ar002'
* written by Haruhiko Okumura.
*/
#ifdef RCSID
static char rcsid[] = "$Id: unlzh.c,v 1.2 1993/06/24 10:59:01 jloup Exp $";
#endif
#include <stdio.h>
#include "tailor.h"
#include "gzip.h"
#include "lzw.h" /* just for consistency checking */
/* decode.c */
local unsigned decode OF((unsigned count, uch buffer[]));
local void decode_start OF((void));
/* huf.c */
local void huf_decode_start OF((void));
local unsigned decode_c OF((void));
local unsigned decode_p OF((void));
local void read_pt_len OF((int nn, int nbit, int i_special));
local void read_c_len OF((void));
/* io.c */
local void fillbuf OF((int n));
local unsigned getbits OF((int n));
local void init_getbits OF((void));
/* maketbl.c */
local void make_table OF((int nchar, uch bitlen[],
int tablebits, ush table[]));
#define DICBIT 13 /* 12(-lh4-) or 13(-lh5-) */
#define DICSIZ ((unsigned) 1 << DICBIT)
#ifndef CHAR_BIT
# define CHAR_BIT 8
#endif
#ifndef UCHAR_MAX
# define UCHAR_MAX 255
#endif
#define BITBUFSIZ (CHAR_BIT * 2 * sizeof(char))
/* Do not use CHAR_BIT * sizeof(bitbuf), does not work on machines
* for which short is not on 16 bits (Cray).
*/
/* encode.c and decode.c */
#define MAXMATCH 256 /* formerly F (not more than UCHAR_MAX + 1) */
#define THRESHOLD 3 /* choose optimal value */
/* huf.c */
#define NC (UCHAR_MAX + MAXMATCH + 2 - THRESHOLD)
/* alphabet = {0, 1, 2, ..., NC - 1} */
#define CBIT 9 /* $\lfloor \log_2 NC \rfloor + 1$ */
#define CODE_BIT 16 /* codeword length */
#define NP (DICBIT + 1)
#define NT (CODE_BIT + 3)
#define PBIT 4 /* smallest integer such that (1U << PBIT) > NP */
#define TBIT 5 /* smallest integer such that (1U << TBIT) > NT */
#if NT > NP
# define NPT NT
#else
# define NPT NP
#endif
/* local ush left[2 * NC - 1]; */
/* local ush right[2 * NC - 1]; */
#define left prev
#define right head
#if NC > (1<<(BITS-2))
error cannot overlay left+right and prev
#endif
/* local uch c_len[NC]; */
#define c_len outbuf
#if NC > OUTBUFSIZ
error cannot overlay c_len and outbuf
#endif
local uch pt_len[NPT];
local unsigned blocksize;
local ush pt_table[256];
/* local ush c_table[4096]; */
#define c_table d_buf
#if (DIST_BUFSIZE-1) < 4095
error cannot overlay c_table and d_buf
#endif
/***********************************************************
io.c -- input/output
***********************************************************/
local ush bitbuf;
local unsigned subbitbuf;
local int bitcount;
local void fillbuf(n) /* Shift bitbuf n bits left, read n bits */
int n;
{
bitbuf <<= n;
while (n > bitcount) {
bitbuf |= subbitbuf << (n -= bitcount);
subbitbuf = (unsigned)try_byte();
if ((int)subbitbuf == EOF) subbitbuf = 0;
bitcount = CHAR_BIT;
}
bitbuf |= subbitbuf >> (bitcount -= n);
}
local unsigned getbits(n)
int n;
{
unsigned x;
x = bitbuf >> (BITBUFSIZ - n); fillbuf(n);
return x;
}
local void init_getbits()
{
bitbuf = 0; subbitbuf = 0; bitcount = 0;
fillbuf(BITBUFSIZ);
}
/***********************************************************
maketbl.c -- make table for decoding
***********************************************************/
local void make_table(nchar, bitlen, tablebits, table)
int nchar;
uch bitlen[];
int tablebits;
ush table[];
{
ush count[17], weight[17], start[18], *p;
unsigned i, k, len, ch, jutbits, avail, nextcode, mask;
for (i = 1; i <= 16; i++) count[i] = 0;
for (i = 0; i < (unsigned)nchar; i++) count[bitlen[i]]++;
start[1] = 0;
for (i = 1; i <= 16; i++)
start[i + 1] = start[i] + (count[i] << (16 - i));
if ((start[17] & 0xffff) != 0)
error("Bad table\n");
jutbits = 16 - tablebits;
for (i = 1; i <= (unsigned)tablebits; i++) {
start[i] >>= jutbits;
weight[i] = (unsigned) 1 << (tablebits - i);
}
while (i <= 16) {
weight[i] = (unsigned) 1 << (16 - i);
i++;
}
i = start[tablebits + 1] >> jutbits;
if (i != 0) {
k = 1 << tablebits;
while (i != k) table[i++] = 0;
}
avail = nchar;
mask = (unsigned) 1 << (15 - tablebits);
for (ch = 0; ch < (unsigned)nchar; ch++) {
if ((len = bitlen[ch]) == 0) continue;
nextcode = start[len] + weight[len];
if (len <= (unsigned)tablebits) {
for (i = start[len]; i < nextcode; i++) table[i] = ch;
} else {
k = start[len];
p = &table[k >> jutbits];
i = len - tablebits;
while (i != 0) {
if (*p == 0) {
right[avail] = left[avail] = 0;
*p = avail++;
}
if (k & mask) p = &right[*p];
else p = &left[*p];
k <<= 1; i--;
}
*p = ch;
}
start[len] = nextcode;
}
}
/***********************************************************
huf.c -- static Huffman
***********************************************************/
local void read_pt_len(nn, nbit, i_special)
int nn;
int nbit;
int i_special;
{
int i, c, n;
unsigned mask;
n = getbits(nbit);
if (n == 0) {
c = getbits(nbit);
for (i = 0; i < nn; i++) pt_len[i] = 0;
for (i = 0; i < 256; i++) pt_table[i] = c;
} else {
i = 0;
while (i < n) {
c = bitbuf >> (BITBUFSIZ - 3);
if (c == 7) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 3);
while (mask & bitbuf) { mask >>= 1; c++; }
}
fillbuf((c < 7) ? 3 : c - 3);
pt_len[i++] = c;
if (i == i_special) {
c = getbits(2);
while (--c >= 0) pt_len[i++] = 0;
}
}
while (i < nn) pt_len[i++] = 0;
make_table(nn, pt_len, 8, pt_table);
}
}
local void read_c_len()
{
int i, c, n;
unsigned mask;
n = getbits(CBIT);
if (n == 0) {
c = getbits(CBIT);
for (i = 0; i < NC; i++) c_len[i] = 0;
for (i = 0; i < 4096; i++) c_table[i] = c;
} else {
i = 0;
while (i < n) {
c = pt_table[bitbuf >> (BITBUFSIZ - 8)];
if (c >= NT) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 8);
do {
if (bitbuf & mask) c = right[c];
else c = left [c];
mask >>= 1;
} while (c >= NT);
}
fillbuf((int) pt_len[c]);
if (c <= 2) {
if (c == 0) c = 1;
else if (c == 1) c = getbits(4) + 3;
else c = getbits(CBIT) + 20;
while (--c >= 0) c_len[i++] = 0;
} else c_len[i++] = c - 2;
}
while (i < NC) c_len[i++] = 0;
make_table(NC, c_len, 12, c_table);
}
}
local unsigned decode_c()
{
unsigned j, mask;
if (blocksize == 0) {
blocksize = getbits(16);
if (blocksize == 0) {
return NC; /* end of file */
}
read_pt_len(NT, TBIT, 3);
read_c_len();
read_pt_len(NP, PBIT, -1);
}
blocksize--;
j = c_table[bitbuf >> (BITBUFSIZ - 12)];
if (j >= NC) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 12);
do {
if (bitbuf & mask) j = right[j];
else j = left [j];
mask >>= 1;
} while (j >= NC);
}
fillbuf((int) c_len[j]);
return j;
}
local unsigned decode_p()
{
unsigned j, mask;
j = pt_table[bitbuf >> (BITBUFSIZ - 8)];
if (j >= NP) {
mask = (unsigned) 1 << (BITBUFSIZ - 1 - 8);
do {
if (bitbuf & mask) j = right[j];
else j = left [j];
mask >>= 1;
} while (j >= NP);
}
fillbuf((int) pt_len[j]);
if (j != 0) j = ((unsigned) 1 << (j - 1)) + getbits((int) (j - 1));
return j;
}
local void huf_decode_start()
{
init_getbits(); blocksize = 0;
}
/***********************************************************
decode.c
***********************************************************/
local int j; /* remaining bytes to copy */
local int done; /* set at end of input */
local void decode_start()
{
huf_decode_start();
j = 0;
done = 0;
}
/* Decode the input and return the number of decoded bytes put in buffer
*/
local unsigned decode(count, buffer)
unsigned count;
uch buffer[];
/* The calling function must keep the number of
bytes to be processed. This function decodes
either 'count' bytes or 'DICSIZ' bytes, whichever
is smaller, into the array 'buffer[]' of size
'DICSIZ' or more.
Call decode_start() once for each new file
before calling this function.
*/
{
local unsigned i;
unsigned r, c;
r = 0;
while (--j >= 0) {
buffer[r] = buffer[i];
i = (i + 1) & (DICSIZ - 1);
if (++r == count) return r;
}
for ( ; ; ) {
c = decode_c();
if (c == NC) {
done = 1;
return r;
}
if (c <= UCHAR_MAX) {
buffer[r] = c;
if (++r == count) return r;
} else {
j = c - (UCHAR_MAX + 1 - THRESHOLD);
i = (r - decode_p() - 1) & (DICSIZ - 1);
while (--j >= 0) {
buffer[r] = buffer[i];
i = (i + 1) & (DICSIZ - 1);
if (++r == count) return r;
}
}
}
}
/* ===========================================================================
* Unlzh in to out. Return OK or ERROR.
*/
int unlzh(in, out)
int in;
int out;
{
unsigned n;
ifd = in;
ofd = out;
decode_start();
while (!done) {
n = decode((unsigned) DICSIZ, window);
if (!test && n > 0) {
write_buf(out, (char*)window, n);
}
}
return OK;
}
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