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progc
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progc
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/*
* Compress - data compression program
*/
#define min(a,b) ((a>b) ? b : a)
/*
* machine variants which require cc -Dmachine: pdp11, z8000, pcxt
*/
/*
* Set USERMEM to the maximum amount of physical user memory available
* in bytes. USERMEM is used to determine the maximum BITS that can be used
* for compression.
*
* SACREDMEM is the amount of physical memory saved for others; compress
* will hog the rest.
*/
#ifndef SACREDMEM
#define SACREDMEM 0
#endif
#ifndef USERMEM
# define USERMEM 450000 /* default user memory */
#endif
#ifdef interdata /* (Perkin-Elmer) */
#define SIGNED_COMPARE_SLOW /* signed compare is slower than unsigned */
#endif
#ifdef pdp11
# define BITS 12 /* max bits/code for 16-bit machine */
# define NO_UCHAR /* also if "unsigned char" functions as signed char */
# undef USERMEM
#endif /* pdp11 */ /* don't forget to compile with -i */
#ifdef z8000
# define BITS 12
# undef vax /* weird preprocessor */
# undef USERMEM
#endif /* z8000 */
#ifdef pcxt
# define BITS 12
# undef USERMEM
#endif /* pcxt */
#ifdef USERMEM
# if USERMEM >= (433484+SACREDMEM)
# define PBITS 16
# else
# if USERMEM >= (229600+SACREDMEM)
# define PBITS 15
# else
# if USERMEM >= (127536+SACREDMEM)
# define PBITS 14
# else
# if USERMEM >= (73464+SACREDMEM)
# define PBITS 13
# else
# define PBITS 12
# endif
# endif
# endif
# endif
# undef USERMEM
#endif /* USERMEM */
#ifdef PBITS /* Preferred BITS for this memory size */
# ifndef BITS
# define BITS PBITS
# endif BITS
#endif /* PBITS */
#if BITS == 16
# define HSIZE 69001 /* 95% occupancy */
#endif
#if BITS == 15
# define HSIZE 35023 /* 94% occupancy */
#endif
#if BITS == 14
# define HSIZE 18013 /* 91% occupancy */
#endif
#if BITS == 13
# define HSIZE 9001 /* 91% occupancy */
#endif
#if BITS <= 12
# define HSIZE 5003 /* 80% occupancy */
#endif
#ifdef M_XENIX /* Stupid compiler can't handle arrays with */
# if BITS == 16 /* more than 65535 bytes - so we fake it */
# define XENIX_16
# else
# if BITS > 13 /* Code only handles BITS = 12, 13, or 16 */
# define BITS 13
# endif
# endif
#endif
/*
* a code_int must be able to hold 2**BITS values of type int, and also -1
*/
#if BITS > 15
typedef long int code_int;
#else
typedef int code_int;
#endif
#ifdef SIGNED_COMPARE_SLOW
typedef unsigned long int count_int;
typedef unsigned short int count_short;
#else
typedef long int count_int;
#endif
#ifdef NO_UCHAR
typedef char char_type;
#else
typedef unsigned char char_type;
#endif /* UCHAR */
char_type magic_header[] = { "\037\235" }; /* 1F 9D */
/* Defines for third byte of header */
#define BIT_MASK 0x1f
#define BLOCK_MASK 0x80
/* Masks 0x40 and 0x20 are free. I think 0x20 should mean that there is
a fourth header byte (for expansion).
*/
#define INIT_BITS 9 /* initial number of bits/code */
/*
* compress.c - File compression ala IEEE Computer, June 1984.
*
* Authors: Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas)
* Jim McKie (decvax!mcvax!jim)
* Steve Davies (decvax!vax135!petsd!peora!srd)
* Ken Turkowski (decvax!decwrl!turtlevax!ken)
* James A. Woods (decvax!ihnp4!ames!jaw)
* Joe Orost (decvax!vax135!petsd!joe)
*
* $Header: compress.c,v 4.0 85/07/30 12:50:00 joe Release $
* $Log: compress.c,v $
* Revision 4.0 85/07/30 12:50:00 joe
* Removed ferror() calls in output routine on every output except first.
* Prepared for release to the world.
*
* Revision 3.6 85/07/04 01:22:21 joe
* Remove much wasted storage by overlaying hash table with the tables
* used by decompress: tab_suffix[1<<BITS], stack[8000]. Updated USERMEM
* computations. Fixed dump_tab() DEBUG routine.
*
* Revision 3.5 85/06/30 20:47:21 jaw
* Change hash function to use exclusive-or. Rip out hash cache. These
* speedups render the megamemory version defunct, for now. Make decoder
* stack global. Parts of the RCS trunks 2.7, 2.6, and 2.1 no longer apply.
*
* Revision 3.4 85/06/27 12:00:00 ken
* Get rid of all floating-point calculations by doing all compression ratio
* calculations in fixed point.
*
* Revision 3.3 85/06/24 21:53:24 joe
* Incorporate portability suggestion for M_XENIX. Got rid of text on #else
* and #endif lines. Cleaned up #ifdefs for vax and interdata.
*
* Revision 3.2 85/06/06 21:53:24 jaw
* Incorporate portability suggestions for Z8000, IBM PC/XT from mailing list.
* Default to "quiet" output (no compression statistics).
*
* Revision 3.1 85/05/12 18:56:13 jaw
* Integrate decompress() stack speedups (from early pointer mods by McKie).
* Repair multi-file USERMEM gaffe. Unify 'force' flags to mimic semantics
* of SVR2 'pack'. Streamline block-compress table clear logic. Increase
* output byte count by magic number size.
*
* Revision 3.0 84/11/27 11:50:00 petsd!joe
* Set HSIZE depending on BITS. Set BITS depending on USERMEM. Unrolled
* loops in clear routines. Added "-C" flag for 2.0 compatibility. Used
* unsigned compares on Perkin-Elmer. Fixed foreground check.
*
* Revision 2.7 84/11/16 19:35:39 ames!jaw
* Cache common hash codes based on input statistics; this improves
* performance for low-density raster images. Pass on #ifdef bundle
* from Turkowski.
*
* Revision 2.6 84/11/05 19:18:21 ames!jaw
* Vary size of hash tables to reduce time for small files.
* Tune PDP-11 hash function.
*
* Revision 2.5 84/10/30 20:15:14 ames!jaw
* Junk chaining; replace with the simpler (and, on the VAX, faster)
* double hashing, discussed within. Make block compression standard.
*
* Revision 2.4 84/10/16 11:11:11 ames!jaw
* Introduce adaptive reset for block compression, to boost the rate
* another several percent. (See mailing list notes.)
*
* Revision 2.3 84/09/22 22:00:00 petsd!joe
* Implemented "-B" block compress. Implemented REVERSE sorting of tab_next.
* Bug fix for last bits. Changed fwrite to putchar loop everywhere.
*
* Revision 2.2 84/09/18 14:12:21 ames!jaw
* Fold in news changes, small machine typedef from thomas,
* #ifdef interdata from joe.
*
* Revision 2.1 84/09/10 12:34:56 ames!jaw
* Configured fast table lookup for 32-bit machines.
* This cuts user time in half for b <= FBITS, and is useful for news batching
* from VAX to PDP sites. Also sped up decompress() [fwrite->putc] and
* added signal catcher [plus beef in writeerr()] to delete effluvia.
*
* Revision 2.0 84/08/28 22:00:00 petsd!joe
* Add check for foreground before prompting user. Insert maxbits into
* compressed file. Force file being uncompressed to end with ".Z".
* Added "-c" flag and "zcat". Prepared for release.
*
* Revision 1.10 84/08/24 18:28:00 turtlevax!ken
* Will only compress regular files (no directories), added a magic number
* header (plus an undocumented -n flag to handle old files without headers),
* added -f flag to force overwriting of possibly existing destination file,
* otherwise the user is prompted for a response. Will tack on a .Z to a
* filename if it doesn't have one when decompressing. Will only replace
* file if it was compressed.
*
* Revision 1.9 84/08/16 17:28:00 turtlevax!ken
* Removed scanargs(), getopt(), added .Z extension and unlimited number of
* filenames to compress. Flags may be clustered (-Ddvb12) or separated
* (-D -d -v -b 12), or combination thereof. Modes and other status is
* copied with copystat(). -O bug for 4.2 seems to have disappeared with
* 1.8.
*
* Revision 1.8 84/08/09 23:15:00 joe
* Made it compatible with vax version, installed jim's fixes/enhancements
*
* Revision 1.6 84/08/01 22:08:00 joe
* Sped up algorithm significantly by sorting the compress chain.
*
* Revision 1.5 84/07/13 13:11:00 srd
* Added C version of vax asm routines. Changed structure to arrays to
* save much memory. Do unsigned compares where possible (faster on
* Perkin-Elmer)
*
* Revision 1.4 84/07/05 03:11:11 thomas
* Clean up the code a little and lint it. (Lint complains about all
* the regs used in the asm, but I'm not going to "fix" this.)
*
* Revision 1.3 84/07/05 02:06:54 thomas
* Minor fixes.
*
* Revision 1.2 84/07/05 00:27:27 thomas
* Add variable bit length output.
*
*/
static char rcs_ident[] =
"$Header: compress.c,v 4.0 85/07/30 12:50:00 joe Release $";
#include <stdio.h>
#include <ctype.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#define ARGVAL() (*++(*argv) || (--argc && *++argv))
int n_bits; /* number of bits/code */
int maxbits = BITS; /* user settable max # bits/code */
code_int maxcode; /* maximum code, given n_bits */
code_int maxmaxcode = 1 << BITS; /* should NEVER generate this code */
#ifdef COMPATIBLE /* But wrong! */
# define MAXCODE(n_bits) (1 << (n_bits) - 1)
#else
# define MAXCODE(n_bits) ((1 << (n_bits)) - 1)
#endif /* COMPATIBLE */
#ifdef XENIX_16
count_int htab0[8192];
count_int htab1[8192];
count_int htab2[8192];
count_int htab3[8192];
count_int htab4[8192];
count_int htab5[8192];
count_int htab6[8192];
count_int htab7[8192];
count_int htab8[HSIZE-65536];
count_int * htab[9] = {
htab0, htab1, htab2, htab3, htab4, htab5, htab6, htab7, htab8 };
#define htabof(i) (htab[(i) >> 13][(i) & 0x1fff])
unsigned short code0tab[16384];
unsigned short code1tab[16384];
unsigned short code2tab[16384];
unsigned short code3tab[16384];
unsigned short code4tab[16384];
unsigned short * codetab[5] = {
code0tab, code1tab, code2tab, code3tab, code4tab };
#define codetabof(i) (codetab[(i) >> 14][(i) & 0x3fff])
#else /* Normal machine */
count_int htab [HSIZE];
unsigned short codetab [HSIZE];
#define htabof(i) htab[i]
#define codetabof(i) codetab[i]
#endif /* XENIX_16 */
code_int hsize = HSIZE; /* for dynamic table sizing */
count_int fsize;
/*
* To save much memory, we overlay the table used by compress() with those
* used by decompress(). The tab_prefix table is the same size and type
* as the codetab. The tab_suffix table needs 2**BITS characters. We
* get this from the beginning of htab. The output stack uses the rest
* of htab, and contains characters. There is plenty of room for any
* possible stack (stack used to be 8000 characters).
*/
#define tab_prefixof(i) codetabof(i)
#ifdef XENIX_16
# define tab_suffixof(i) ((char_type *)htab[(i)>>15])[(i) & 0x7fff]
# define de_stack ((char_type *)(htab2))
#else /* Normal machine */
# define tab_suffixof(i) ((char_type *)(htab))[i]
# define de_stack ((char_type *)&tab_suffixof(1<<BITS))
#endif /* XENIX_16 */
code_int free_ent = 0; /* first unused entry */
int exit_stat = 0;
code_int getcode();
Usage() {
#ifdef DEBUG
fprintf(stderr,"Usage: compress [-dDVfc] [-b maxbits] [file ...]\n");
}
int debug = 0;
#else
fprintf(stderr,"Usage: compress [-dfvcV] [-b maxbits] [file ...]\n");
}
#endif /* DEBUG */
int nomagic = 0; /* Use a 3-byte magic number header, unless old file */
int zcat_flg = 0; /* Write output on stdout, suppress messages */
int quiet = 1; /* don't tell me about compression */
/*
* block compression parameters -- after all codes are used up,
* and compression rate changes, start over.
*/
int block_compress = BLOCK_MASK;
int clear_flg = 0;
long int ratio = 0;
#define CHECK_GAP 10000 /* ratio check interval */
count_int checkpoint = CHECK_GAP;
/*
* the next two codes should not be changed lightly, as they must not
* lie within the contiguous general code space.
*/
#define FIRST 257 /* first free entry */
#define CLEAR 256 /* table clear output code */
int force = 0;
char ofname [100];
#ifdef DEBUG
int verbose = 0;
#endif /* DEBUG */
int (*bgnd_flag)();
int do_decomp = 0;
/*****************************************************************
* TAG( main )
*
* Algorithm from "A Technique for High Performance Data Compression",
* Terry A. Welch, IEEE Computer Vol 17, No 6 (June 1984), pp 8-19.
*
* Usage: compress [-dfvc] [-b bits] [file ...]
* Inputs:
* -d: If given, decompression is done instead.
*
* -c: Write output on stdout, don't remove original.
*
* -b: Parameter limits the max number of bits/code.
*
* -f: Forces output file to be generated, even if one already
* exists, and even if no space is saved by compressing.
* If -f is not used, the user will be prompted if stdin is
* a tty, otherwise, the output file will not be overwritten.
*
* -v: Write compression statistics
*
* file ...: Files to be compressed. If none specified, stdin
* is used.
* Outputs:
* file.Z: Compressed form of file with same mode, owner, and utimes
* or stdout (if stdin used as input)
*
* Assumptions:
* When filenames are given, replaces with the compressed version
* (.Z suffix) only if the file decreases in size.
* Algorithm:
* Modified Lempel-Ziv method (LZW). Basically finds common
* substrings and replaces them with a variable size code. This is
* deterministic, and can be done on the fly. Thus, the decompression
* procedure needs no input table, but tracks the way the table was built.
*/
main( argc, argv )
register int argc; char **argv;
{
int overwrite = 0; /* Do not overwrite unless given -f flag */
char tempname[100];
char **filelist, **fileptr;
char *cp, *rindex(), *malloc();
struct stat statbuf;
extern onintr(), oops();
if ( (bgnd_flag = signal ( SIGINT, SIG_IGN )) != SIG_IGN ) {
signal ( SIGINT, onintr );
signal ( SIGSEGV, oops );
}
#ifdef COMPATIBLE
nomagic = 1; /* Original didn't have a magic number */
#endif /* COMPATIBLE */
filelist = fileptr = (char **)(malloc(argc * sizeof(*argv)));
*filelist = NULL;
if((cp = rindex(argv[0], '/')) != 0) {
cp++;
} else {
cp = argv[0];
}
if(strcmp(cp, "uncompress") == 0) {
do_decomp = 1;
} else if(strcmp(cp, "zcat") == 0) {
do_decomp = 1;
zcat_flg = 1;
}
#ifdef BSD4_2
/* 4.2BSD dependent - take it out if not */
setlinebuf( stderr );
#endif /* BSD4_2 */
/* Argument Processing
* All flags are optional.
* -D => debug
* -V => print Version; debug verbose
* -d => do_decomp
* -v => unquiet
* -f => force overwrite of output file
* -n => no header: useful to uncompress old files
* -b maxbits => maxbits. If -b is specified, then maxbits MUST be
* given also.
* -c => cat all output to stdout
* -C => generate output compatible with compress 2.0.
* if a string is left, must be an input filename.
*/
for (argc--, argv++; argc > 0; argc--, argv++) {
if (**argv == '-') { /* A flag argument */
while (*++(*argv)) { /* Process all flags in this arg */
switch (**argv) {
#ifdef DEBUG
case 'D':
debug = 1;
break;
case 'V':
verbose = 1;
version();
break;
#else
case 'V':
version();
break;
#endif /* DEBUG */
case 'v':
quiet = 0;
break;
case 'd':
do_decomp = 1;
break;
case 'f':
case 'F':
overwrite = 1;
force = 1;
break;
case 'n':
nomagic = 1;
break;
case 'C':
block_compress = 0;
break;
case 'b':
if (!ARGVAL()) {
fprintf(stderr, "Missing maxbits\n");
Usage();
exit(1);
}
maxbits = atoi(*argv);
goto nextarg;
case 'c':
zcat_flg = 1;
break;
case 'q':
quiet = 1;
break;
default:
fprintf(stderr, "Unknown flag: '%c'; ", **argv);
Usage();
exit(1);
}
}
}
else { /* Input file name */
*fileptr++ = *argv; /* Build input file list */
*fileptr = NULL;
/* process nextarg; */
}
nextarg: continue;
}
if(maxbits < INIT_BITS) maxbits = INIT_BITS;
if (maxbits > BITS) maxbits = BITS;
maxmaxcode = 1 << maxbits;
if (*filelist != NULL) {
for (fileptr = filelist; *fileptr; fileptr++) {
exit_stat = 0;
if (do_decomp != 0) { /* DECOMPRESSION */
/* Check for .Z suffix */
if (strcmp(*fileptr + strlen(*fileptr) - 2, ".Z") != 0) {
/* No .Z: tack one on */
strcpy(tempname, *fileptr);
strcat(tempname, ".Z");
*fileptr = tempname;
}
/* Open input file */
if ((freopen(*fileptr, "r", stdin)) == NULL) {
perror(*fileptr); continue;
}
/* Check the magic number */
if (nomagic == 0) {
if ((getchar() != (magic_header[0] & 0xFF))
|| (getchar() != (magic_header[1] & 0xFF))) {
fprintf(stderr, "%s: not in compressed format\n",
*fileptr);
continue;
}
maxbits = getchar(); /* set -b from file */
block_compress = maxbits & BLOCK_MASK;
maxbits &= BIT_MASK;
maxmaxcode = 1 << maxbits;
if(maxbits > BITS) {
fprintf(stderr,
"%s: compressed with %d bits, can only handle %d bits\n",
*fileptr, maxbits, BITS);
continue;
}
}
/* Generate output filename */
strcpy(ofname, *fileptr);
ofname[strlen(*fileptr) - 2] = '\0'; /* Strip off .Z */
} else { /* COMPRESSION */
if (strcmp(*fileptr + strlen(*fileptr) - 2, ".Z") == 0) {
fprintf(stderr, "%s: already has .Z suffix -- no change\n",
*fileptr);
continue;
}
/* Open input file */
if ((freopen(*fileptr, "r", stdin)) == NULL) {
perror(*fileptr); continue;
}
stat ( *fileptr, &statbuf );
fsize = (long) statbuf.st_size;
/*
* tune hash table size for small files -- ad hoc,
* but the sizes match earlier #defines, which
* serve as upper bounds on the number of output codes.
*/
hsize = HSIZE;
if ( fsize < (1 << 12) )
hsize = min ( 5003, HSIZE );
else if ( fsize < (1 << 13) )
hsize = min ( 9001, HSIZE );
else if ( fsize < (1 << 14) )
hsize = min ( 18013, HSIZE );
else if ( fsize < (1 << 15) )
hsize = min ( 35023, HSIZE );
else if ( fsize < 47000 )
hsize = min ( 50021, HSIZE );
/* Generate output filename */
strcpy(ofname, *fileptr);
#ifndef BSD4_2 /* Short filenames */
if ((cp=rindex(ofname,'/')) != NULL) cp++;
else cp = ofname;
if (strlen(cp) > 12) {
fprintf(stderr,"%s: filename too long to tack on .Z\n",cp);
continue;
}
#endif /* BSD4_2 Long filenames allowed */
strcat(ofname, ".Z");
}
/* Check for overwrite of existing file */
if (overwrite == 0 && zcat_flg == 0) {
if (stat(ofname, &statbuf) == 0) {
char response[2];
response[0] = 'n';
fprintf(stderr, "%s already exists;", ofname);
if (foreground()) {
fprintf(stderr, " do you wish to overwrite %s (y or n)? ",
ofname);
fflush(stderr);
read(2, response, 2);
while (response[1] != '\n') {
if (read(2, response+1, 1) < 0) { /* Ack! */
perror("stderr"); break;
}
}
}
if (response[0] != 'y') {
fprintf(stderr, "\tnot overwritten\n");
continue;
}
}
}
if(zcat_flg == 0) { /* Open output file */
if (freopen(ofname, "w", stdout) == NULL) {
perror(ofname);
continue;
}
if(!quiet)
fprintf(stderr, "%s: ", *fileptr);
}
/* Actually do the compression/decompression */
if (do_decomp == 0) compress();
#ifndef DEBUG
else decompress();
#else
else if (debug == 0) decompress();
else printcodes();
if (verbose) dump_tab();
#endif /* DEBUG */
if(zcat_flg == 0) {
copystat(*fileptr, ofname); /* Copy stats */
if((exit_stat == 1) || (!quiet))
putc('\n', stderr);
}
}
} else { /* Standard input */
if (do_decomp == 0) {
compress();
#ifdef DEBUG
if(verbose) dump_tab();
#endif /* DEBUG */
if(!quiet)
putc('\n', stderr);
} else {
/* Check the magic number */
if (nomagic == 0) {
if ((getchar()!=(magic_header[0] & 0xFF))
|| (getchar()!=(magic_header[1] & 0xFF))) {
fprintf(stderr, "stdin: not in compressed format\n");
exit(1);
}
maxbits = getchar(); /* set -b from file */
block_compress = maxbits & BLOCK_MASK;
maxbits &= BIT_MASK;
maxmaxcode = 1 << maxbits;
fsize = 100000; /* assume stdin large for USERMEM */
if(maxbits > BITS) {
fprintf(stderr,
"stdin: compressed with %d bits, can only handle %d bits\n",
maxbits, BITS);
exit(1);
}
}
#ifndef DEBUG
decompress();
#else
if (debug == 0) decompress();
else printcodes();
if (verbose) dump_tab();
#endif /* DEBUG */
}
}
exit(exit_stat);
}
static int offset;
long int in_count = 1; /* length of input */
long int bytes_out; /* length of compressed output */
long int out_count = 0; /* # of codes output (for debugging) */
/*
* compress stdin to stdout
*
* Algorithm: use open addressing double hashing (no chaining) on the
* prefix code / next character combination. We do a variant of Knuth's
* algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime
* secondary probe. Here, the modular division first probe is gives way
* to a faster exclusive-or manipulation. Also do block compression with
* an adaptive reset, whereby the code table is cleared when the compression
* ratio decreases, but after the table fills. The variable-length output
* codes are re-sized at this point, and a special CLEAR code is generated
* for the decompressor. Late addition: construct the table according to
* file size for noticeable speed improvement on small files. Please direct
* questions about this implementation to ames!jaw.
*/
compress() {
register long fcode;
register code_int i = 0;
register int c;
register code_int ent;
#ifdef XENIX_16
register code_int disp;
#else /* Normal machine */
register int disp;
#endif
register code_int hsize_reg;
register int hshift;
#ifndef COMPATIBLE
if (nomagic == 0) {
putchar(magic_header[0]); putchar(magic_header[1]);
putchar((char)(maxbits | block_compress));
if(ferror(stdout))
writeerr();
}
#endif /* COMPATIBLE */
offset = 0;
bytes_out = 3; /* includes 3-byte header mojo */
out_count = 0;
clear_flg = 0;
ratio = 0;
in_count = 1;
checkpoint = CHECK_GAP;
maxcode = MAXCODE(n_bits = INIT_BITS);
free_ent = ((block_compress) ? FIRST : 256 );
ent = getchar ();
hshift = 0;
for ( fcode = (long) hsize; fcode < 65536L; fcode *= 2L )
hshift++;
hshift = 8 - hshift; /* set hash code range bound */
hsize_reg = hsize;
cl_hash( (count_int) hsize_reg); /* clear hash table */
#ifdef SIGNED_COMPARE_SLOW
while ( (c = getchar()) != (unsigned) EOF ) {
#else
while ( (c = getchar()) != EOF ) {
#endif
in_count++;
fcode = (long) (((long) c << maxbits) + ent);
i = ((c << hshift) ^ ent); /* xor hashing */
if ( htabof (i) == fcode ) {
ent = codetabof (i);
continue;
} else if ( (long)htabof (i) < 0 ) /* empty slot */
goto nomatch;
disp = hsize_reg - i; /* secondary hash (after G. Knott) */
if ( i == 0 )
disp = 1;
probe:
if ( (i -= disp) < 0 )
i += hsize_reg;
if ( htabof (i) == fcode ) {
ent = codetabof (i);
continue;
}
if ( (long)htabof (i) > 0 )
goto probe;
nomatch:
output ( (code_int) ent );
out_count++;
ent = c;
#ifdef SIGNED_COMPARE_SLOW
if ( (unsigned) free_ent < (unsigned) maxmaxcode) {
#else
if ( free_ent < maxmaxcode ) {
#endif
codetabof (i) = free_ent++; /* code -> hashtable */
htabof (i) = fcode;
}
else if ( (count_int)in_count >= checkpoint && block_compress )
cl_block ();
}
/*
* Put out the final code.
*/
output( (code_int)ent );
out_count++;
output( (code_int)-1 );
/*
* Print out stats on stderr
*/
if(zcat_flg == 0 && !quiet) {
#ifdef DEBUG
fprintf( stderr,
"%ld chars in, %ld codes (%ld bytes) out, compression factor: ",
in_count, out_count, bytes_out );
prratio( stderr, in_count, bytes_out );
fprintf( stderr, "\n");
fprintf( stderr, "\tCompression as in compact: " );
prratio( stderr, in_count-bytes_out, in_count );
fprintf( stderr, "\n");
fprintf( stderr, "\tLargest code (of last block) was %d (%d bits)\n",
free_ent - 1, n_bits );
#else /* !DEBUG */
fprintf( stderr, "Compression: " );
prratio( stderr, in_count-bytes_out, in_count );
#endif /* DEBUG */
}
if(bytes_out > in_count) /* exit(2) if no savings */
exit_stat = 2;
return;
}
/*****************************************************************
* TAG( output )
*
* Output the given code.
* Inputs:
* code: A n_bits-bit integer. If == -1, then EOF. This assumes
* that n_bits =< (long)wordsize - 1.
* Outputs:
* Outputs code to the file.
* Assumptions:
* Chars are 8 bits long.
* Algorithm:
* Maintain a BITS character long buffer (so that 8 codes will
* fit in it exactly). Use the VAX insv instruction to insert each
* code in turn. When the buffer fills up empty it and start over.
*/
static char buf[BITS];
#ifndef vax
char_type lmask[9] = {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00};
char_type rmask[9] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
#endif /* vax */
output( code )
code_int code;
{
#ifdef DEBUG
static int col = 0;
#endif /* DEBUG */
/*
* On the VAX, it is important to have the register declarations
* in exactly the order given, or the asm will break.
*/
register int r_off = offset, bits= n_bits;
register char * bp = buf;
#ifdef DEBUG
if ( verbose )
fprintf( stderr, "%5d%c", code,
(col+=6) >= 74 ? (col = 0, '\n') : ' ' );
#endif /* DEBUG */
if ( code >= 0 ) {
#ifdef vax
/* VAX DEPENDENT!! Implementation on other machines is below.
*
* Translation: Insert BITS bits from the argument starting at
* offset bits from the beginning of buf.
*/
0; /* Work around for pcc -O bug with asm and if stmt */
asm( "insv 4(ap),r11,r10,(r9)" );
#else /* not a vax */
/*
* byte/bit numbering on the VAX is simulated by the following code
*/
/*
* Get to the first byte.
*/
bp += (r_off >> 3);
r_off &= 7;
/*
* Since code is always >= 8 bits, only need to mask the first
* hunk on the left.
*/
*bp = (*bp & rmask[r_off]) | (code << r_off) & lmask[r_off];
bp++;
bits -= (8 - r_off);
code >>= 8 - r_off;
/* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */
if ( bits >= 8 ) {
*bp++ = code;
code >>= 8;
bits -= 8;
}
/* Last bits. */
if(bits)
*bp = code;
#endif /* vax */
offset += n_bits;
if ( offset == (n_bits << 3) ) {
bp = buf;
bits = n_bits;
bytes_out += bits;
do
putchar(*bp++);
while(--bits);
offset = 0;
}
/*
* If the next entry is going to be too big for the code size,
* then increase it, if possible.
*/
if ( free_ent > maxcode || (clear_flg > 0))
{
/*
* Write the whole buffer, because the input side won't
* discover the size increase until after it has read it.
*/
if ( offset > 0 ) {
if( fwrite( buf, 1, n_bits, stdout ) != n_bits)
writeerr();
bytes_out += n_bits;
}
offset = 0;
if ( clear_flg ) {
maxcode = MAXCODE (n_bits = INIT_BITS);
clear_flg = 0;
}
else {
n_bits++;
if ( n_bits == maxbits )
maxcode = maxmaxcode;
else
maxcode = MAXCODE(n_bits);
}
#ifdef DEBUG
if ( debug ) {
fprintf( stderr, "\nChange to %d bits\n", n_bits );
col = 0;
}
#endif /* DEBUG */
}
} else {
/*
* At EOF, write the rest of the buffer.
*/
if ( offset > 0 )
fwrite( buf, 1, (offset + 7) / 8, stdout );
bytes_out += (offset + 7) / 8;
offset = 0;
fflush( stdout );
#ifdef DEBUG
if ( verbose )
fprintf( stderr, "\n" );
#endif /* DEBUG */
if( ferror( stdout ) )
writeerr();
}
}
/*
* Decompress stdin to stdout. 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. The tables used herein are shared
* with those of the compress() routine. See the definitions above.
*/
decompress() {
register char_type *stackp;
register int finchar;
register code_int code, oldcode, incode;
/*
* As above, initialize the first 256 entries in the table.
*/
maxcode = MAXCODE(n_bits = INIT_BITS);
for ( code = 255; code >= 0; code-- ) {
tab_prefixof(code) = 0;
tab_suffixof(code) = (char_type)code;
}
free_ent = ((block_compress) ? FIRST : 256 );
finchar = oldcode = getcode();
if(oldcode == -1) /* EOF already? */
return; /* Get out of here */
putchar( (char)finchar ); /* first code must be 8 bits = char */
if(ferror(stdout)) /* Crash if can't write */
writeerr();
stackp = de_stack;