1 /*
2 * compress - File compression ala IEEE Computer, June 1984.
3 *
4 * Algorithm from "A Technique for High Performance Data Compression",
5 * Terry A. Welch, IEEE Computer Vol 17, No 6 (June 1984), pp 8-19.
6 *
7 * Usage: compress [-dfvc] [-b bits] [file ...]
8 * Inputs:
9 * -b: limit the max number of bits/code.
10 * -c: write output on stdout, don't remove original.
11 * -d: decompress instead.
12 * -f: Forces output file to be generated, even if one already
13 * exists, and even if no space is saved by compressing.
14 * If -f is not used, the user will be prompted if stdin is
15 * a tty, otherwise, the output file will not be overwritten.
16 * -v: Write compression statistics
17 *
18 * file ...: Files to be compressed. If none specified, stdin is used.
19 * Outputs:
20 * file.Z: Compressed form of file with same mode, owner, and utimes
21 * or stdout (if stdin used as input)
22 *
23 * Assumptions:
24 * When filenames are given, replaces with the compressed version
25 * (.Z suffix) only if the file decreases in size.
26 * Algorithm:
27 * Modified Lempel-Ziv method (LZW). Basically finds common
28 * substrings and replaces them with a variable size code. This is
29 * deterministic, and can be done on the fly. Thus, the decompression
30 * procedure needs no input table, but tracks the way the table was built.
31
32 * Authors: Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
33 * Jim McKie (decvax!mcvax!jim)
34 * Steve Davies (decvax!vax135!petsd!peora!srd)
35 * Ken Turkowski (decvax!decwrl!turtlevax!ken)
36 * James A. Woods (decvax!ihnp4!ames!jaw)
37 * Joe Orost (decvax!vax135!petsd!joe)
38 */
39 #define _PLAN9_SOURCE
40 #define _BSD_EXTENSION
41 #define _POSIX_SOURCE
42
43 #include <u.h>
44 #include <stdio.h>
45 #include <ctype.h>
46 #include <stdlib.h>
47 #include <unistd.h>
48 #include <string.h>
49 #include <signal.h>
50 #include <utime.h>
51 #include <sys/types.h>
52 #include <sys/stat.h>
53
54 #define min(a,b) ((a>b) ? b : a)
55
56 #define BITS 16
57 #define HSIZE 69001 /* 95% occupancy */
58
59 /*
60 * a code_int must be able to hold 2**BITS values of type int, and also -1
61 */
62 typedef long code_int;
63 typedef long count_int;
64
65 static char rcs_ident[] = "$Header: compress.c,v 4.0 85/07/30 12:50:00 joe Release $";
66
67 uchar magic_header[] = { 0x1F, 0x9D }; /* 1F 9D */
68
69 /* Defines for third byte of header */
70 #define BIT_MASK 0x1f
71 #define BLOCK_MASK 0x80
72 /* Masks 0x40 and 0x20 are free. I think 0x20 should mean that there is
73 a fourth header byte (for expansion).
74 */
75 #define INIT_BITS 9 /* initial number of bits/code */
76
77 #define ARGVAL() (*++(*argv) || (--argc && *++argv))
78
79 int n_bits; /* number of bits/code */
80 int maxbits = BITS; /* user settable max # bits/code */
81 code_int maxcode; /* maximum code, given n_bits */
82 code_int maxmaxcode = 1 << BITS; /* should NEVER generate this code */
83
84 #define MAXCODE(n_bits) ((1 << (n_bits)) - 1)
85
86 count_int htab[HSIZE];
87 ushort codetab[HSIZE];
88
89 #define htabof(i) htab[i]
90 #define codetabof(i) codetab[i]
91
92 code_int hsize = HSIZE; /* for dynamic table sizing */
93 count_int fsize;
94
95 /*
96 * To save much memory, we overlay the table used by compress() with those
97 * used by decompress(). The tab_prefix table is the same size and type
98 * as the codetab. The tab_suffix table needs 2**BITS characters. We
99 * get this from the beginning of htab. The output stack uses the rest
100 * of htab, and contains characters. There is plenty of room for any
101 * possible stack (stack used to be 8000 characters).
102 */
103
104 #define tab_prefixof(i) codetabof(i)
105 #define tab_suffixof(i) ((uchar *)(htab))[i]
106 #define de_stack ((uchar *)&tab_suffixof(1<<BITS))
107
108 code_int free_ent = 0; /* first unused entry */
109 int exit_stat = 0;
110
111 void cl_block(void);
112 void cl_hash(count_int);
113 void compress(void);
114 void copystat(char *, char *);
115 void decompress(void);
116 int foreground(void);
117 code_int getcode(void);
118 void onintr(int);
119 void oops(int);
120 void output(code_int);
121 void prratio(FILE *, long, long);
122 void version(void);
123 void writeerr(void);
124
125 void
Usage(void)126 Usage(void)
127 {
128 #ifdef DEBUG
129 fprintf(stderr,"Usage: compress [-cdfDV] [-b maxbits] [file ...]\n");
130 #else
131 fprintf(stderr,"Usage: compress [-cdfvV] [-b maxbits] [file ...]\n");
132 #endif /* DEBUG */
133 }
134
135 int debug = 0;
136 int nomagic = 0; /* Use a 3-byte magic number header, unless old file */
137 int zcat_flg = 0; /* Write output on stdout, suppress messages */
138 int quiet = 1; /* don't tell me about compression */
139
140 /*
141 * block compression parameters -- after all codes are used up,
142 * and compression rate changes, start over.
143 */
144 int block_compress = BLOCK_MASK;
145 int clear_flg = 0;
146 long ratio = 0;
147 #define CHECK_GAP 10000 /* ratio check interval */
148 count_int checkpoint = CHECK_GAP;
149 /*
150 * the next two codes should not be changed lightly, as they must not
151 * lie within the contiguous general code space.
152 */
153 #define FIRST 257 /* first free entry */
154 #define CLEAR 256 /* table clear output code */
155
156 int force = 0;
157 char ofname [100];
158 #ifdef DEBUG
159 int verbose = 0;
160 #endif /* DEBUG */
161 void (*bgnd_flag)(int);
162
163 int do_decomp = 0;
164
main(argc,argv)165 main(argc, argv)
166 int argc;
167 char **argv;
168 {
169 int overwrite = 0; /* Do not overwrite unless given -f flag */
170 char tempname[512];
171 char **filelist, **fileptr;
172 char *cp;
173 struct stat statbuf;
174
175 if ( (bgnd_flag = signal ( SIGINT, SIG_IGN )) != SIG_IGN ) {
176 signal(SIGINT, onintr);
177 signal(SIGSEGV, oops);
178 }
179
180 filelist = fileptr = (char **)(malloc(argc * sizeof(*argv)));
181 *filelist = NULL;
182
183 if((cp = strrchr(argv[0], '/')) != 0)
184 cp++;
185 else
186 cp = argv[0];
187 if(strcmp(cp, "uncompress") == 0)
188 do_decomp = 1;
189 else if(strcmp(cp, "zcat") == 0) {
190 do_decomp = 1;
191 zcat_flg = 1;
192 }
193
194 /*
195 * Argument Processing
196 * All flags are optional.
197 * -C generate output compatible with compress 2.0.
198 * -D debug
199 * -V print Version; debug verbose
200 * -b maxbits maxbits. If -b is specified, then maxbits MUST be
201 * given also.
202 * -c cat all output to stdout
203 * -d do_decomp
204 * -f force overwrite of output file
205 * -n no header: useful to uncompress old files
206 * -v unquiet
207 * if a string is left, must be an input filename.
208 */
209 for (argc--, argv++; argc > 0; argc--, argv++) {
210 if (**argv == '-') { /* A flag argument */
211 while (*++(*argv)) { /* Process all flags in this arg */
212 switch (**argv) {
213 case 'C':
214 block_compress = 0;
215 break;
216 #ifdef DEBUG
217 case 'D':
218 debug = 1;
219 break;
220 case 'V':
221 verbose = 1;
222 version();
223 break;
224 #else
225 case 'V':
226 version();
227 break;
228 #endif
229 case 'b':
230 if (!ARGVAL()) {
231 fprintf(stderr, "Missing maxbits\n");
232 Usage();
233 exit(1);
234 }
235 maxbits = atoi(*argv);
236 goto nextarg;
237 case 'c':
238 zcat_flg = 1;
239 break;
240 case 'd':
241 do_decomp = 1;
242 break;
243 case 'f':
244 case 'F':
245 overwrite = 1;
246 force = 1;
247 break;
248 case 'n':
249 nomagic = 1;
250 break;
251 case 'q':
252 quiet = 1;
253 break;
254 case 'v':
255 quiet = 0;
256 break;
257 default:
258 fprintf(stderr, "Unknown flag: '%c'; ", **argv);
259 Usage();
260 exit(1);
261 }
262 }
263 } else { /* Input file name */
264 *fileptr++ = *argv; /* Build input file list */
265 *fileptr = NULL;
266 /* process nextarg; */
267 }
268 nextarg:
269 continue;
270 }
271
272 if(maxbits < INIT_BITS) maxbits = INIT_BITS;
273 if (maxbits > BITS) maxbits = BITS;
274 maxmaxcode = 1 << maxbits;
275
276 if (*filelist != NULL) {
277 for (fileptr = filelist; *fileptr; fileptr++) {
278 exit_stat = 0;
279 if (do_decomp != 0) { /* DECOMPRESSION */
280 /* Check for .Z suffix */
281 if (strcmp(*fileptr + strlen(*fileptr) - 2, ".Z") != 0) {
282 /* No .Z: tack one on */
283 strcpy(tempname, *fileptr);
284 strcat(tempname, ".Z");
285 *fileptr = tempname;
286 }
287 /* Open input file */
288 if ((freopen(*fileptr, "r", stdin)) == NULL) {
289 perror(*fileptr);
290 continue;
291 }
292 /* Check the magic number */
293 if (nomagic == 0) {
294 if ((getchar() != (magic_header[0] & 0xFF))
295 || (getchar() != (magic_header[1] & 0xFF))) {
296 fprintf(stderr, "%s: not in compressed format\n",
297 *fileptr);
298 continue;
299 }
300 maxbits = getchar(); /* set -b from file */
301 block_compress = maxbits & BLOCK_MASK;
302 maxbits &= BIT_MASK;
303 maxmaxcode = 1 << maxbits;
304 if(maxbits > BITS) {
305 fprintf(stderr,
306 "%s: compressed with %d bits, can only handle %d bits\n",
307 *fileptr, maxbits, BITS);
308 continue;
309 }
310 }
311 /* Generate output filename */
312 strcpy(ofname, *fileptr);
313 ofname[strlen(*fileptr) - 2] = '\0'; /* Strip off .Z */
314 } else { /* COMPRESSION */
315 if (strcmp(*fileptr + strlen(*fileptr) - 2, ".Z") == 0) {
316 fprintf(stderr,
317 "%s: already has .Z suffix -- no change\n",
318 *fileptr);
319 continue;
320 }
321 /* Open input file */
322 if ((freopen(*fileptr, "r", stdin)) == NULL) {
323 perror(*fileptr);
324 continue;
325 }
326 (void) stat(*fileptr, &statbuf);
327 fsize = (long) statbuf.st_size;
328 /*
329 * tune hash table size for small files -- ad hoc,
330 * but the sizes match earlier #defines, which
331 * serve as upper bounds on the number of output codes.
332 */
333 hsize = HSIZE;
334 if (fsize < (1 << 12))
335 hsize = min(5003, HSIZE);
336 else if (fsize < (1 << 13))
337 hsize = min(9001, HSIZE);
338 else if (fsize < (1 << 14))
339 hsize = min (18013, HSIZE);
340 else if (fsize < (1 << 15))
341 hsize = min (35023, HSIZE);
342 else if (fsize < 47000)
343 hsize = min (50021, HSIZE);
344
345 /* Generate output filename */
346 strcpy(ofname, *fileptr);
347 #ifndef BSD4_2
348 if ((cp=strrchr(ofname,'/')) != NULL)
349 cp++;
350 else
351 cp = ofname;
352 /*
353 *** changed 12 to 25; should be NAMELEN-3, but I don't want
354 * to fight the headers. ehg 5 Nov 92 **
355 */
356 if (strlen(cp) > 25) {
357 fprintf(stderr, "%s: filename too long to tack on .Z\n",
358 cp);
359 continue;
360 }
361 #endif
362 strcat(ofname, ".Z");
363 }
364 /* Check for overwrite of existing file */
365 if (overwrite == 0 && zcat_flg == 0 &&
366 stat(ofname, &statbuf) == 0) {
367 char response[2];
368
369 response[0] = 'n';
370 fprintf(stderr, "%s already exists;", ofname);
371 if (foreground()) {
372 fprintf(stderr,
373 " do you wish to overwrite %s (y or n)? ",
374 ofname);
375 fflush(stderr);
376 (void) read(2, response, 2);
377 while (response[1] != '\n')
378 if (read(2, response+1, 1) < 0) {
379 /* Ack! */
380 perror("stderr");
381 break;
382 }
383 }
384 if (response[0] != 'y') {
385 fprintf(stderr, "\tnot overwritten\n");
386 continue;
387 }
388 }
389 if(zcat_flg == 0) { /* Open output file */
390 if (freopen(ofname, "w", stdout) == NULL) {
391 perror(ofname);
392 continue;
393 }
394 if(!quiet)
395 fprintf(stderr, "%s: ", *fileptr);
396 }
397
398 /* Actually do the compression/decompression */
399 if (do_decomp == 0)
400 compress();
401 #ifndef DEBUG
402 else
403 decompress();
404 #else
405 else if (debug == 0)
406 decompress();
407 else
408 printcodes();
409 if (verbose)
410 dump_tab();
411 #endif /* DEBUG */
412 if(zcat_flg == 0) {
413 copystat(*fileptr, ofname); /* Copy stats */
414 if (exit_stat == 1 || !quiet)
415 putc('\n', stderr);
416 }
417 }
418 } else { /* Standard input */
419 if (do_decomp == 0) {
420 compress();
421 #ifdef DEBUG
422 if(verbose)
423 dump_tab();
424 #endif
425 if(!quiet)
426 putc('\n', stderr);
427 } else {
428 /* Check the magic number */
429 if (nomagic == 0) {
430 if ((getchar()!=(magic_header[0] & 0xFF))
431 || (getchar()!=(magic_header[1] & 0xFF))) {
432 fprintf(stderr, "stdin: not in compressed format\n");
433 exit(1);
434 }
435 maxbits = getchar(); /* set -b from file */
436 block_compress = maxbits & BLOCK_MASK;
437 maxbits &= BIT_MASK;
438 maxmaxcode = 1 << maxbits;
439 fsize = 100000; /* assume stdin large for USERMEM */
440 if(maxbits > BITS) {
441 fprintf(stderr,
442 "stdin: compressed with %d bits, can only handle %d bits\n",
443 maxbits, BITS);
444 exit(1);
445 }
446 }
447 #ifndef DEBUG
448 decompress();
449 #else
450 if (debug == 0)
451 decompress();
452 else
453 printcodes();
454 if (verbose)
455 dump_tab();
456 #endif /* DEBUG */
457 }
458 }
459 exit(exit_stat);
460 return 0;
461 }
462
463 static int offset;
464 long in_count = 1; /* length of input */
465 long bytes_out; /* length of compressed output */
466 long out_count = 0; /* # of codes output (for debugging) */
467
468 /*
469 * compress stdin to stdout
470 *
471 * Algorithm: use open addressing double hashing (no chaining) on the
472 * prefix code / next character combination. We do a variant of Knuth's
473 * algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
474 * secondary probe. Here, the modular division first probe is gives way
475 * to a faster exclusive-or manipulation. Also do block compression with
476 * an adaptive reset, whereby the code table is cleared when the compression
477 * ratio decreases, but after the table fills. The variable-length output
478 * codes are re-sized at this point, and a special CLEAR code is generated
479 * for the decompressor. Late addition: construct the table according to
480 * file size for noticeable speed improvement on small files. Please direct
481 * questions about this implementation to ames!jaw.
482 */
483 void
compress(void)484 compress(void)
485 {
486 code_int ent, hsize_reg;
487 code_int i;
488 int c, disp, hshift;
489 long fcode;
490
491 if (nomagic == 0) {
492 putchar(magic_header[0]);
493 putchar(magic_header[1]);
494 putchar((char)(maxbits | block_compress));
495 if(ferror(stdout))
496 writeerr();
497 }
498 offset = 0;
499 bytes_out = 3; /* includes 3-byte header mojo */
500 out_count = 0;
501 clear_flg = 0;
502 ratio = 0;
503 in_count = 1;
504 checkpoint = CHECK_GAP;
505 maxcode = MAXCODE(n_bits = INIT_BITS);
506 free_ent = (block_compress? FIRST: 256);
507
508 ent = getchar ();
509
510 hshift = 0;
511 for (fcode = (long)hsize; fcode < 65536L; fcode *= 2)
512 hshift++;
513 hshift = 8 - hshift; /* set hash code range bound */
514
515 hsize_reg = hsize;
516 cl_hash( (count_int) hsize_reg); /* clear hash table */
517
518 while ((c = getchar()) != EOF) {
519 in_count++;
520 fcode = (long) (((long) c << maxbits) + ent);
521 i = ((c << hshift) ^ ent); /* xor hashing */
522
523 if (htabof (i) == fcode) {
524 ent = codetabof(i);
525 continue;
526 } else if ((long)htabof(i) < 0 ) /* empty slot */
527 goto nomatch;
528 disp = hsize_reg - i; /* secondary hash (after G. Knott) */
529 if (i == 0)
530 disp = 1;
531 probe:
532 if ((i -= disp) < 0)
533 i += hsize_reg;
534
535 if (htabof (i) == fcode) {
536 ent = codetabof(i);
537 continue;
538 }
539 if ((long)htabof(i) > 0)
540 goto probe;
541 nomatch:
542 output((code_int)ent);
543 out_count++;
544 ent = c;
545 if (free_ent < maxmaxcode) {
546 codetabof(i) = free_ent++; /* code -> hashtable */
547 htabof(i) = fcode;
548 } else if ((count_int)in_count >= checkpoint && block_compress)
549 cl_block ();
550 }
551 /*
552 * Put out the final code.
553 */
554 output( (code_int)ent );
555 out_count++;
556 output( (code_int)-1 );
557
558 /*
559 * Print out stats on stderr
560 */
561 if(zcat_flg == 0 && !quiet) {
562 #ifdef DEBUG
563 fprintf( stderr,
564 "%ld chars in, %ld codes (%ld bytes) out, compression factor: ",
565 in_count, out_count, bytes_out );
566 prratio( stderr, in_count, bytes_out );
567 fprintf( stderr, "\n");
568 fprintf( stderr, "\tCompression as in compact: " );
569 prratio( stderr, in_count-bytes_out, in_count );
570 fprintf( stderr, "\n");
571 fprintf( stderr, "\tLargest code (of last block) was %d (%d bits)\n",
572 free_ent - 1, n_bits );
573 #else /* !DEBUG */
574 fprintf( stderr, "Compression: " );
575 prratio( stderr, in_count-bytes_out, in_count );
576 #endif /* DEBUG */
577 }
578 if(bytes_out > in_count) /* exit(2) if no savings */
579 exit_stat = 2;
580 }
581
582 /*
583 * TAG( output )
584 *
585 * Output the given code.
586 * Inputs:
587 * code: A n_bits-bit integer. If == -1, then EOF. This assumes
588 * that n_bits =< (long)wordsize - 1.
589 * Outputs:
590 * Outputs code to the file.
591 * Assumptions:
592 * Chars are 8 bits long.
593 * Algorithm:
594 * Maintain a BITS character long buffer (so that 8 codes will
595 * fit in it exactly). When the buffer fills up empty it and start over.
596 */
597
598 static char buf[BITS];
599
600 uchar lmask[9] = {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00};
601 uchar rmask[9] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
602
603 void
output(code)604 output( code )
605 code_int code;
606 {
607 #ifdef DEBUG
608 static int col = 0;
609 #endif
610 int r_off = offset, bits= n_bits;
611 char *bp = buf;
612
613 #ifdef DEBUG
614 if (verbose)
615 fprintf(stderr, "%5d%c", code,
616 (col+=6) >= 74? (col = 0, '\n'): ' ');
617 #endif
618 if (code >= 0) {
619 /*
620 * byte/bit numbering on the VAX is simulated by the
621 * following code
622 */
623 /*
624 * Get to the first byte.
625 */
626 bp += (r_off >> 3);
627 r_off &= 7;
628 /*
629 * Since code is always >= 8 bits, only need to mask the first
630 * hunk on the left.
631 */
632 *bp = (*bp & rmask[r_off]) | (code << r_off) & lmask[r_off];
633 bp++;
634 bits -= 8 - r_off;
635 code >>= 8 - r_off;
636 /* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */
637 if ( bits >= 8 ) {
638 *bp++ = code;
639 code >>= 8;
640 bits -= 8;
641 }
642 /* Last bits. */
643 if(bits)
644 *bp = code;
645
646 offset += n_bits;
647 if ( offset == (n_bits << 3) ) {
648 bp = buf;
649 bits = n_bits;
650 bytes_out += bits;
651 do {
652 putchar(*bp++);
653 } while(--bits);
654 offset = 0;
655 }
656
657 /*
658 * If the next entry is going to be too big for the code size,
659 * then increase it, if possible.
660 */
661 if ( free_ent > maxcode || (clear_flg > 0)) {
662 /*
663 * Write the whole buffer, because the input side won't
664 * discover the size increase until after it has read it.
665 */
666 if ( offset > 0 ) {
667 if( fwrite( buf, 1, n_bits, stdout ) != n_bits)
668 writeerr();
669 bytes_out += n_bits;
670 }
671 offset = 0;
672
673 if ( clear_flg ) {
674 maxcode = MAXCODE (n_bits = INIT_BITS);
675 clear_flg = 0;
676 } else {
677 n_bits++;
678 if ( n_bits == maxbits )
679 maxcode = maxmaxcode;
680 else
681 maxcode = MAXCODE(n_bits);
682 }
683 #ifdef DEBUG
684 if ( debug ) {
685 fprintf(stderr,
686 "\nChange to %d bits\n", n_bits);
687 col = 0;
688 }
689 #endif
690 }
691 } else {
692 /*
693 * At EOF, write the rest of the buffer.
694 */
695 if ( offset > 0 )
696 fwrite( buf, 1, (offset + 7) / 8, stdout );
697 bytes_out += (offset + 7) / 8;
698 offset = 0;
699 fflush( stdout );
700 #ifdef DEBUG
701 if ( verbose )
702 fprintf( stderr, "\n" );
703 #endif
704 if( ferror( stdout ) )
705 writeerr();
706 }
707 }
708
709 /*
710 * Decompress stdin to stdout. This routine adapts to the codes in the
711 * file building the "string" table on-the-fly; requiring no table to
712 * be stored in the compressed file. The tables used herein are shared
713 * with those of the compress() routine. See the definitions above.
714 */
715 void
decompress(void)716 decompress(void)
717 {
718 int finchar;
719 code_int code, oldcode, incode;
720 uchar *stackp;
721
722 /*
723 * As above, initialize the first 256 entries in the table.
724 */
725 maxcode = MAXCODE(n_bits = INIT_BITS);
726 for (code = 255; code >= 0; code--) {
727 tab_prefixof(code) = 0;
728 tab_suffixof(code) = (uchar)code;
729 }
730 free_ent = (block_compress? FIRST: 256);
731
732 finchar = oldcode = getcode();
733 if(oldcode == -1) /* EOF already? */
734 return; /* Get out of here */
735 putchar((char)finchar); /* first code must be 8 bits = char */
736 if(ferror(stdout)) /* Crash if can't write */
737 writeerr();
738 stackp = de_stack;
739
740 while ((code = getcode()) > -1) {
741 if ((code == CLEAR) && block_compress) {
742 for (code = 255; code >= 0; code--)
743 tab_prefixof(code) = 0;
744 clear_flg = 1;
745 free_ent = FIRST - 1;
746 if ((code = getcode()) == -1) /* O, untimely death! */
747 break;
748 }
749 incode = code;
750 /*
751 * Special case for KwKwK string.
752 */
753 if (code >= free_ent) {
754 *stackp++ = finchar;
755 code = oldcode;
756 }
757
758 /*
759 * Generate output characters in reverse order
760 */
761 while (code >= 256) {
762 *stackp++ = tab_suffixof(code);
763 code = tab_prefixof(code);
764 }
765 *stackp++ = finchar = tab_suffixof(code);
766
767 /*
768 * And put them out in forward order
769 */
770 do {
771 putchar(*--stackp);
772 } while (stackp > de_stack);
773
774 /*
775 * Generate the new entry.
776 */
777 if ( (code=free_ent) < maxmaxcode ) {
778 tab_prefixof(code) = (ushort)oldcode;
779 tab_suffixof(code) = finchar;
780 free_ent = code+1;
781 }
782 /*
783 * Remember previous code.
784 */
785 oldcode = incode;
786 }
787 fflush(stdout);
788 if(ferror(stdout))
789 writeerr();
790 }
791
792 /*
793 * TAG( getcode )
794 *
795 * Read one code from the standard input. If EOF, return -1.
796 * Inputs:
797 * stdin
798 * Outputs:
799 * code or -1 is returned.
800 */
801 code_int
getcode()802 getcode()
803 {
804 int r_off, bits;
805 code_int code;
806 static int offset = 0, size = 0;
807 static uchar buf[BITS];
808 uchar *bp = buf;
809
810 if ( clear_flg > 0 || offset >= size || free_ent > maxcode ) {
811 /*
812 * If the next entry will be too big for the current code
813 * size, then we must increase the size. This implies reading
814 * a new buffer full, too.
815 */
816 if ( free_ent > maxcode ) {
817 n_bits++;
818 if ( n_bits == maxbits )
819 maxcode = maxmaxcode; /* won't get any bigger now */
820 else
821 maxcode = MAXCODE(n_bits);
822 }
823 if ( clear_flg > 0) {
824 maxcode = MAXCODE(n_bits = INIT_BITS);
825 clear_flg = 0;
826 }
827 size = fread(buf, 1, n_bits, stdin);
828 if (size <= 0)
829 return -1; /* end of file */
830 offset = 0;
831 /* Round size down to integral number of codes */
832 size = (size << 3) - (n_bits - 1);
833 }
834 r_off = offset;
835 bits = n_bits;
836 /*
837 * Get to the first byte.
838 */
839 bp += (r_off >> 3);
840 r_off &= 7;
841 /* Get first part (low order bits) */
842 code = (*bp++ >> r_off);
843 bits -= (8 - r_off);
844 r_off = 8 - r_off; /* now, offset into code word */
845 /* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */
846 if (bits >= 8) {
847 code |= *bp++ << r_off;
848 r_off += 8;
849 bits -= 8;
850 }
851 /* high order bits. */
852 code |= (*bp & rmask[bits]) << r_off;
853 offset += n_bits;
854 return code;
855 }
856
857 #ifdef DEBUG
printcodes()858 printcodes()
859 {
860 /*
861 * Just print out codes from input file. For debugging.
862 */
863 code_int code;
864 int col = 0, bits;
865
866 bits = n_bits = INIT_BITS;
867 maxcode = MAXCODE(n_bits);
868 free_ent = ((block_compress) ? FIRST : 256 );
869 while ( ( code = getcode() ) >= 0 ) {
870 if ( (code == CLEAR) && block_compress ) {
871 free_ent = FIRST - 1;
872 clear_flg = 1;
873 }
874 else if ( free_ent < maxmaxcode )
875 free_ent++;
876 if ( bits != n_bits ) {
877 fprintf(stderr, "\nChange to %d bits\n", n_bits );
878 bits = n_bits;
879 col = 0;
880 }
881 fprintf(stderr, "%5d%c", code, (col+=6) >= 74 ? (col = 0, '\n') : ' ' );
882 }
883 putc( '\n', stderr );
884 exit( 0 );
885 }
886
887 code_int sorttab[1<<BITS]; /* sorted pointers into htab */
888
889 #define STACK_SIZE 15000
890
dump_tab()891 dump_tab() /* dump string table */
892 {
893 int i, first, c, ent;
894 int stack_top = STACK_SIZE;
895
896 if(do_decomp == 0) { /* compressing */
897 int flag = 1;
898
899 for(i=0; i<hsize; i++) { /* build sort pointers */
900 if((long)htabof(i) >= 0) {
901 sorttab[codetabof(i)] = i;
902 }
903 }
904 first = block_compress ? FIRST : 256;
905 for(i = first; i < free_ent; i++) {
906 fprintf(stderr, "%5d: \"", i);
907 de_stack[--stack_top] = '\n';
908 de_stack[--stack_top] = '"';
909 stack_top = in_stack((htabof(sorttab[i])>>maxbits)&0xff,
910 stack_top);
911 for(ent=htabof(sorttab[i]) & ((1<<maxbits)-1);
912 ent > 256;
913 ent=htabof(sorttab[ent]) & ((1<<maxbits)-1)) {
914 stack_top = in_stack(htabof(sorttab[ent]) >> maxbits,
915 stack_top);
916 }
917 stack_top = in_stack(ent, stack_top);
918 fwrite( &de_stack[stack_top], 1, STACK_SIZE-stack_top, stderr);
919 stack_top = STACK_SIZE;
920 }
921 } else if(!debug) { /* decompressing */
922
923 for ( i = 0; i < free_ent; i++ ) {
924 ent = i;
925 c = tab_suffixof(ent);
926 if ( isascii(c) && isprint(c) )
927 fprintf( stderr, "%5d: %5d/'%c' \"",
928 ent, tab_prefixof(ent), c );
929 else
930 fprintf( stderr, "%5d: %5d/\\%03o \"",
931 ent, tab_prefixof(ent), c );
932 de_stack[--stack_top] = '\n';
933 de_stack[--stack_top] = '"';
934 for ( ; ent != NULL;
935 ent = (ent >= FIRST ? tab_prefixof(ent) : NULL) ) {
936 stack_top = in_stack(tab_suffixof(ent), stack_top);
937 }
938 fwrite( &de_stack[stack_top], 1, STACK_SIZE - stack_top, stderr );
939 stack_top = STACK_SIZE;
940 }
941 }
942 }
943
944 int
in_stack(int c,int stack_top)945 in_stack(int c, int stack_top)
946 {
947 if ( (isascii(c) && isprint(c) && c != '\\') || c == ' ' ) {
948 de_stack[--stack_top] = c;
949 } else {
950 switch( c ) {
951 case '\n': de_stack[--stack_top] = 'n'; break;
952 case '\t': de_stack[--stack_top] = 't'; break;
953 case '\b': de_stack[--stack_top] = 'b'; break;
954 case '\f': de_stack[--stack_top] = 'f'; break;
955 case '\r': de_stack[--stack_top] = 'r'; break;
956 case '\\': de_stack[--stack_top] = '\\'; break;
957 default:
958 de_stack[--stack_top] = '0' + c % 8;
959 de_stack[--stack_top] = '0' + (c / 8) % 8;
960 de_stack[--stack_top] = '0' + c / 64;
961 break;
962 }
963 de_stack[--stack_top] = '\\';
964 }
965 return stack_top;
966 }
967 #endif /* DEBUG */
968
969 void
writeerr(void)970 writeerr(void)
971 {
972 perror(ofname);
973 unlink(ofname);
974 exit(1);
975 }
976
977 void
copystat(ifname,ofname)978 copystat(ifname, ofname)
979 char *ifname, *ofname;
980 {
981 int mode;
982 time_t timep[2]; /* should be struct utimbuf */
983 struct stat statbuf;
984
985 fclose(stdout);
986 if (stat(ifname, &statbuf)) { /* Get stat on input file */
987 perror(ifname);
988 return;
989 }
990 if (!S_ISREG(statbuf.st_mode)) {
991 if (quiet)
992 fprintf(stderr, "%s: ", ifname);
993 fprintf(stderr, " -- not a regular file: unchanged");
994 exit_stat = 1;
995 } else if (exit_stat == 2 && !force) {
996 /* No compression: remove file.Z */
997 if (!quiet)
998 fprintf(stderr, " -- file unchanged");
999 } else { /* Successful Compression */
1000 exit_stat = 0;
1001 mode = statbuf.st_mode & 0777;
1002 if (chmod(ofname, mode)) /* Copy modes */
1003 perror(ofname);
1004 /* Copy ownership */
1005 chown(ofname, statbuf.st_uid, statbuf.st_gid);
1006 timep[0] = statbuf.st_atime;
1007 timep[1] = statbuf.st_mtime;
1008 /* Update last accessed and modified times */
1009 utime(ofname, (struct utimbuf *)timep);
1010 // if (unlink(ifname)) /* Remove input file */
1011 // perror(ifname);
1012 return; /* success */
1013 }
1014
1015 /* Unsuccessful return -- one of the tests failed */
1016 if (unlink(ofname))
1017 perror(ofname);
1018 }
1019
1020 /*
1021 * This routine returns 1 if we are running in the foreground and stderr
1022 * is a tty.
1023 */
1024 int
foreground(void)1025 foreground(void)
1026 {
1027 if(bgnd_flag) /* background? */
1028 return 0;
1029 else /* foreground */
1030 return isatty(2); /* and stderr is a tty */
1031 }
1032
1033 void
onintr(int x)1034 onintr(int x)
1035 {
1036 USED(x);
1037 unlink(ofname);
1038 exit(1);
1039 }
1040
1041 void
oops(int x)1042 oops(int x) /* wild pointer -- assume bad input */
1043 {
1044 USED(x);
1045 if (do_decomp == 1)
1046 fprintf(stderr, "uncompress: corrupt input\n");
1047 unlink(ofname);
1048 exit(1);
1049 }
1050
1051 void
cl_block(void)1052 cl_block(void) /* table clear for block compress */
1053 {
1054 long rat;
1055
1056 checkpoint = in_count + CHECK_GAP;
1057 #ifdef DEBUG
1058 if ( debug ) {
1059 fprintf ( stderr, "count: %ld, ratio: ", in_count );
1060 prratio ( stderr, in_count, bytes_out );
1061 fprintf ( stderr, "\n");
1062 }
1063 #endif /* DEBUG */
1064
1065 if (in_count > 0x007fffff) { /* shift will overflow */
1066 rat = bytes_out >> 8;
1067 if (rat == 0) /* Don't divide by zero */
1068 rat = 0x7fffffff;
1069 else
1070 rat = in_count / rat;
1071 } else
1072 rat = (in_count << 8) / bytes_out; /* 8 fractional bits */
1073 if (rat > ratio)
1074 ratio = rat;
1075 else {
1076 ratio = 0;
1077 #ifdef DEBUG
1078 if (verbose)
1079 dump_tab(); /* dump string table */
1080 #endif
1081 cl_hash((count_int)hsize);
1082 free_ent = FIRST;
1083 clear_flg = 1;
1084 output((code_int)CLEAR);
1085 #ifdef DEBUG
1086 if (debug)
1087 fprintf(stderr, "clear\n");
1088 #endif /* DEBUG */
1089 }
1090 }
1091
1092 void
cl_hash(count_int hsize)1093 cl_hash(count_int hsize) /* reset code table */
1094 {
1095 count_int *htab_p = htab+hsize;
1096 long i;
1097 long m1 = -1;
1098
1099 i = hsize - 16;
1100 do { /* might use Sys V memset(3) here */
1101 *(htab_p-16) = m1;
1102 *(htab_p-15) = m1;
1103 *(htab_p-14) = m1;
1104 *(htab_p-13) = m1;
1105 *(htab_p-12) = m1;
1106 *(htab_p-11) = m1;
1107 *(htab_p-10) = m1;
1108 *(htab_p-9) = m1;
1109 *(htab_p-8) = m1;
1110 *(htab_p-7) = m1;
1111 *(htab_p-6) = m1;
1112 *(htab_p-5) = m1;
1113 *(htab_p-4) = m1;
1114 *(htab_p-3) = m1;
1115 *(htab_p-2) = m1;
1116 *(htab_p-1) = m1;
1117 htab_p -= 16;
1118 } while ((i -= 16) >= 0);
1119 for ( i += 16; i > 0; i-- )
1120 *--htab_p = m1;
1121 }
1122
1123 void
prratio(stream,num,den)1124 prratio(stream, num, den)
1125 FILE *stream;
1126 long num, den;
1127 {
1128 int q; /* Doesn't need to be long */
1129
1130 if(num > 214748L) /* 2147483647/10000 */
1131 q = num / (den / 10000L);
1132 else
1133 q = 10000L * num / den; /* Long calculations, though */
1134 if (q < 0) {
1135 putc('-', stream);
1136 q = -q;
1137 }
1138 fprintf(stream, "%d.%02d%%", q / 100, q % 100);
1139 }
1140
1141 void
version(void)1142 version(void)
1143 {
1144 fprintf(stderr, "%s\n", rcs_ident);
1145 fprintf(stderr, "Options: ");
1146 #ifdef DEBUG
1147 fprintf(stderr, "DEBUG, ");
1148 #endif
1149 #ifdef BSD4_2
1150 fprintf(stderr, "BSD4_2, ");
1151 #endif
1152 fprintf(stderr, "BITS = %d\n", BITS);
1153 }
1154
1155 /*
1156 * The revision-history novel:
1157 *
1158 * $Header: compress.c,v 4.0 85/07/30 12:50:00 joe Release $
1159 * $Log: compress.c,v $
1160 * Revision 4.0 85/07/30 12:50:00 joe
1161 * Removed ferror() calls in output routine on every output except first.
1162 * Prepared for release to the world.
1163 *
1164 * Revision 3.6 85/07/04 01:22:21 joe
1165 * Remove much wasted storage by overlaying hash table with the tables
1166 * used by decompress: tab_suffix[1<<BITS], stack[8000]. Updated USERMEM
1167 * computations. Fixed dump_tab() DEBUG routine.
1168 *
1169 * Revision 3.5 85/06/30 20:47:21 jaw
1170 * Change hash function to use exclusive-or. Rip out hash cache. These
1171 * speedups render the megamemory version defunct, for now. Make decoder
1172 * stack global. Parts of the RCS trunks 2.7, 2.6, and 2.1 no longer apply.
1173 *
1174 * Revision 3.4 85/06/27 12:00:00 ken
1175 * Get rid of all floating-point calculations by doing all compression ratio
1176 * calculations in fixed point.
1177 *
1178 * Revision 3.3 85/06/24 21:53:24 joe
1179 * Incorporate portability suggestion for M_XENIX. Got rid of text on #else
1180 * and #endif lines. Cleaned up #ifdefs for vax and interdata.
1181 *
1182 * Revision 3.2 85/06/06 21:53:24 jaw
1183 * Incorporate portability suggestions for Z8000, IBM PC/XT from mailing list.
1184 * Default to "quiet" output (no compression statistics).
1185 *
1186 * Revision 3.1 85/05/12 18:56:13 jaw
1187 * Integrate decompress() stack speedups (from early pointer mods by McKie).
1188 * Repair multi-file USERMEM gaffe. Unify 'force' flags to mimic semantics
1189 * of SVR2 'pack'. Streamline block-compress table clear logic. Increase
1190 * output byte count by magic number size.
1191 *
1192 * Revision 3.0 84/11/27 11:50:00 petsd!joe
1193 * Set HSIZE depending on BITS. Set BITS depending on USERMEM. Unrolled
1194 * loops in clear routines. Added "-C" flag for 2.0 compatibility. Used
1195 * unsigned compares on Perkin-Elmer. Fixed foreground check.
1196 *
1197 * Revision 2.7 84/11/16 19:35:39 ames!jaw
1198 * Cache common hash codes based on input statistics; this improves
1199 * performance for low-density raster images. Pass on #ifdef bundle
1200 * from Turkowski.
1201 *
1202 * Revision 2.6 84/11/05 19:18:21 ames!jaw
1203 * Vary size of hash tables to reduce time for small files.
1204 * Tune PDP-11 hash function.
1205 *
1206 * Revision 2.5 84/10/30 20:15:14 ames!jaw
1207 * Junk chaining; replace with the simpler (and, on the VAX, faster)
1208 * double hashing, discussed within. Make block compression standard.
1209 *
1210 * Revision 2.4 84/10/16 11:11:11 ames!jaw
1211 * Introduce adaptive reset for block compression, to boost the rate
1212 * another several percent. (See mailing list notes.)
1213 *
1214 * Revision 2.3 84/09/22 22:00:00 petsd!joe
1215 * Implemented "-B" block compress. Implemented REVERSE sorting of tab_next.
1216 * Bug fix for last bits. Changed fwrite to putchar loop everywhere.
1217 *
1218 * Revision 2.2 84/09/18 14:12:21 ames!jaw
1219 * Fold in news changes, small machine typedef from thomas,
1220 * #ifdef interdata from joe.
1221 *
1222 * Revision 2.1 84/09/10 12:34:56 ames!jaw
1223 * Configured fast table lookup for 32-bit machines.
1224 * This cuts user time in half for b <= FBITS, and is useful for news batching
1225 * from VAX to PDP sites. Also sped up decompress() [fwrite->putc] and
1226 * added signal catcher [plus beef in writeerr()] to delete effluvia.
1227 *
1228 * Revision 2.0 84/08/28 22:00:00 petsd!joe
1229 * Add check for foreground before prompting user. Insert maxbits into
1230 * compressed file. Force file being uncompressed to end with ".Z".
1231 * Added "-c" flag and "zcat". Prepared for release.
1232 *
1233 * Revision 1.10 84/08/24 18:28:00 turtlevax!ken
1234 * Will only compress regular files (no directories), added a magic number
1235 * header (plus an undocumented -n flag to handle old files without headers),
1236 * added -f flag to force overwriting of possibly existing destination file,
1237 * otherwise the user is prompted for a response. Will tack on a .Z to a
1238 * filename if it doesn't have one when decompressing. Will only replace
1239 * file if it was compressed.
1240 *
1241 * Revision 1.9 84/08/16 17:28:00 turtlevax!ken
1242 * Removed scanargs(), getopt(), added .Z extension and unlimited number of
1243 * filenames to compress. Flags may be clustered (-Ddvb12) or separated
1244 * (-D -d -v -b 12), or combination thereof. Modes and other status is
1245 * copied with copystat(). -O bug for 4.2 seems to have disappeared with
1246 * 1.8.
1247 *
1248 * Revision 1.8 84/08/09 23:15:00 joe
1249 * Made it compatible with vax version, installed jim's fixes/enhancements
1250 *
1251 * Revision 1.6 84/08/01 22:08:00 joe
1252 * Sped up algorithm significantly by sorting the compress chain.
1253 *
1254 * Revision 1.5 84/07/13 13:11:00 srd
1255 * Added C version of vax asm routines. Changed structure to arrays to
1256 * save much memory. Do unsigned compares where possible (faster on
1257 * Perkin-Elmer)
1258 *
1259 * Revision 1.4 84/07/05 03:11:11 thomas
1260 * Clean up the code a little and lint it. (Lint complains about all
1261 * the regs used in the asm, but I'm not going to "fix" this.)
1262 *
1263 * Revision 1.3 84/07/05 02:06:54 thomas
1264 * Minor fixes.
1265 *
1266 * Revision 1.2 84/07/05 00:27:27 thomas
1267 * Add variable bit length output.
1268 */
1269