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