1 /* unlzw.c -- decompress files in LZW format.
2 * The code in this file is directly derived from the public domain 'compress'
3 * written by Spencer Thomas, Joe Orost, James Woods, Jim McKie, Steve Davies,
4 * Ken Turkowski, Dave Mack and Peter Jannesen.
6 * This is a temporary version which will be rewritten in some future version
7 * to accommodate in-memory decompression.
11 static char rcsid[] = "$FreeBSD: src/gnu/usr.bin/gzip/unlzw.c,v 1.7 1999/08/27 23:35:53 peter Exp $";
14 #include <sys/types.h>
28 typedef unsigned char char_type;
29 typedef long code_int;
30 typedef unsigned long count_int;
31 typedef unsigned short count_short;
32 typedef unsigned long cmp_code_int;
34 #define MAXCODE(n) (1L << (n))
57 # define REG1 register
61 # define REG2 register
65 # define REG3 register
69 # define REG4 register
73 # define REG5 register
77 # define REG6 register
81 # define REG7 register
85 # define REG8 register
89 # define REG9 register
93 # define REG10 register
97 # define REG11 register
101 # define REG12 register
105 # define REG13 register
109 # define REG14 register
113 # define REG15 register
117 # define REG16 register
121 # define BYTEORDER 0000
132 #if BYTEORDER == 4321
138 #if BYTEORDER == 1234
151 #if BYTEORDER == 4321 && NOALLIGN == 1
152 # define input(b,o,c,n,m){ \
153 (c) = (*(long *)(&(b)[(o)>>3])>>((o)&0x7))&(m); \
157 # define input(b,o,c,n,m){ \
158 REG1 char_type *p = &(b)[(o)>>3]; \
159 (c) = ((((long)(p[0]))|((long)(p[1])<<8)| \
160 ((long)(p[2])<<16))>>((o)&0x7))&(m); \
166 /* DECLARE(ush, tab_prefix, (1<<BITS)); -- prefix code */
167 # define tab_prefixof(i) tab_prefix[i]
168 # define clear_tab_prefixof() memzero(tab_prefix, 256);
170 /* DECLARE(ush, tab_prefix0, (1<<(BITS-1)); -- prefix for even codes */
171 /* DECLARE(ush, tab_prefix1, (1<<(BITS-1)); -- prefix for odd codes */
173 # define tab_prefixof(i) tab_prefix[(i)&1][(i)>>1]
174 # define clear_tab_prefixof() \
175 memzero(tab_prefix0, 128), \
176 memzero(tab_prefix1, 128);
178 #define de_stack ((char_type *)(&d_buf[DIST_BUFSIZE-1]))
179 #define tab_suffixof(i) tab_suffix[i]
181 int block_mode = BLOCK_MODE; /* block compress mode -C compatible with 2.0 */
183 /* ============================================================================
184 * Decompress in to out. This routine adapts to the codes in the
185 * file building the "string" table on-the-fly; requiring no table to
186 * be stored in the compressed file.
187 * IN assertions: the buffer inbuf contains already the beginning of
188 * the compressed data, from offsets iptr to insize-1 included.
189 * The magic header has already been checked and skipped.
190 * bytes_in and bytes_out have been initialized.
193 int in, out; /* input and output file descriptors */
195 REG2 char_type *stackp;
198 REG5 code_int oldcode;
199 REG6 code_int incode;
203 /* REG10 int insize; (global) */
204 REG11 unsigned bitmask;
205 REG12 code_int free_ent;
206 REG13 code_int maxcode;
207 REG14 code_int maxmaxcode;
212 tab_prefix[0] = tab_prefix0;
213 tab_prefix[1] = tab_prefix1;
215 maxbits = get_byte();
216 block_mode = maxbits & BLOCK_MODE;
217 if ((maxbits & LZW_RESERVED) != 0) {
218 WARN((stderr, "\n%s: %s: warning, unknown flags 0x%x\n",
219 progname, ifname, maxbits & LZW_RESERVED));
222 maxmaxcode = MAXCODE(maxbits);
224 if (maxbits > BITS) {
226 "\n%s: %s: compressed with %d bits, can only handle %d bits\n",
227 progname, ifname, maxbits, BITS);
232 maxcode = MAXCODE(n_bits = INIT_BITS)-1;
233 bitmask = (1<<n_bits)-1;
239 free_ent = ((block_mode) ? FIRST : 256);
241 clear_tab_prefixof(); /* Initialize the first 256 entries in the table. */
243 for (code = 255 ; code >= 0 ; --code) {
244 tab_suffixof(code) = (char_type)code;
252 e = insize-(o = (posbits>>3));
254 for (i = 0 ; i < e ; ++i) {
255 inbuf[i] = inbuf[i+o];
260 if (insize < INBUF_EXTRA) {
261 if ((rsize = read(in, (char*)inbuf+insize, INBUFSIZ)) == EOF) {
265 bytes_in += (ulg)rsize;
267 inbits = ((rsize != 0) ? ((long)insize - insize%n_bits)<<3 :
268 ((long)insize<<3)-(n_bits-1));
270 while (inbits > posbits) {
271 if (free_ent > maxcode) {
272 posbits = ((posbits-1) +
273 ((n_bits<<3)-(posbits-1+(n_bits<<3))%(n_bits<<3)));
275 if (n_bits == maxbits) {
276 maxcode = maxmaxcode;
278 maxcode = MAXCODE(n_bits)-1;
280 bitmask = (1<<n_bits)-1;
283 input(inbuf,posbits,code,n_bits,bitmask);
284 Tracev((stderr, "%d ", code));
287 if (code >= 256) error("corrupt input.");
288 outbuf[outpos++] = (char_type)(finchar = (int)(oldcode=code));
291 if (code == CLEAR && block_mode) {
292 clear_tab_prefixof();
293 free_ent = FIRST - 1;
294 posbits = ((posbits-1) +
295 ((n_bits<<3)-(posbits-1+(n_bits<<3))%(n_bits<<3)));
296 maxcode = MAXCODE(n_bits = INIT_BITS)-1;
297 bitmask = (1<<n_bits)-1;
303 if (code >= free_ent) { /* Special case for KwKwK string. */
304 if (code > free_ent) {
309 p = &inbuf[posbits>>3];
311 "code:%ld free_ent:%ld n_bits:%d insize:%u\n",
312 code, free_ent, n_bits, insize);
314 "posbits:%ld inbuf:%02X %02X %02X %02X %02X\n",
315 posbits, p[-1],p[0],p[1],p[2],p[3]);
317 if (!test && outpos > 0) {
318 write_buf(out, (char*)outbuf, outpos);
319 bytes_out += (ulg)outpos;
321 error(to_stdout ? "corrupt input." :
322 "corrupt input. Use zcat to recover some data.");
324 *--stackp = (char_type)finchar;
328 while ((cmp_code_int)code >= (cmp_code_int)256) {
329 /* Generate output characters in reverse order */
330 *--stackp = tab_suffixof(code);
331 code = tab_prefixof(code);
333 *--stackp = (char_type)(finchar = tab_suffixof(code));
335 /* And put them out in forward order */
339 if (outpos+(i = (de_stack-stackp)) >= OUTBUFSIZ) {
341 if (i > OUTBUFSIZ-outpos) i = OUTBUFSIZ-outpos;
344 memcpy(outbuf+outpos, stackp, i);
347 if (outpos >= OUTBUFSIZ) {
349 write_buf(out, (char*)outbuf, outpos);
350 bytes_out += (ulg)outpos;
355 } while ((i = (de_stack-stackp)) > 0);
357 memcpy(outbuf+outpos, stackp, i);
362 if ((code = free_ent) < maxmaxcode) { /* Generate the new entry. */
364 tab_prefixof(code) = (unsigned short)oldcode;
365 tab_suffixof(code) = (char_type)finchar;
368 oldcode = incode; /* Remember previous code. */
370 } while (rsize != 0);
372 if (!test && outpos > 0) {
373 write_buf(out, (char*)outbuf, outpos);
374 bytes_out += (ulg)outpos;