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top - downloadIndex: ┃ T c ┃
Length: 38348 (0x95cc)
Types: TextFile
Names: »compress.c«
└─⟦a0efdde77⟧ Bits:30001252 EUUGD11 Tape, 1987 Spring Conference Helsinki
└─ ⟦this⟧ »EUUGD11/gnu-31mar87/compress/compress.c«
/* 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. If USERMEM is big enough, use fast compression algorithm.
*
* SACREDMEM is the amount of physical memory saved for others; compress
* will hog the rest.
*/
#ifndef SACREDMEM
#define SACREDMEM 0
#endif
#ifdef pdp11
# define BITS 12 /* max bits/code for 16-bit machine */
# define NO_UCHAR /* also if "unsigned char" functions as signed char */
# define SHORT_INT /* ints are short */
# undef USERMEM
#else !pdp11
# ifndef USERMEM
# define USERMEM 750000 /* default user memory */
# endif
#endif !pdp11
/*
* Define FBITS for machines with several MB of physical memory, to use
* table lookup for (b <= FBITS). If FBITS is made too large, performance
* will decrease due to increased swapping/paging. Since the program minus
* the fast lookup table is about a half Meg, we can allocate the rest of
* available physical memory to the fast lookup table.
*
* If FBITS is set to 12, a 2 MB array is allocated, but only 1 MB is
* addressed for parity-free input (i.e. text).
*
* FBITS=10 yields 1/2 meg lookup table + 4K code memory
* FBITS=11 yields 1 meg lookup table + 8K code memory
* FBITS=12 yields 2 meg lookup table + 16K code memory
* FBITS=13 yields 4 meg lookup table + 32K code memory
*
*/
#ifdef USERMEM
# if USERMEM >= (2621440+SACREDMEM)
# if USERMEM >= (4718592+SACREDMEM)
# define FBITS 13
# define PBITS 16
# else 2.5M <= USERMEM < 4.5M
# define FBITS 12
# define PBITS 16
# endif USERMEM <=> 4.5M
# else USERMEM < 2.5M
# if USERMEM >= (1572864+SACREDMEM)
# define FBITS 11
# define PBITS 16
# else USERMEM < 1.5M
# if USERMEM >= (1048576+SACREDMEM)
# define FBITS 10
# define PBITS 16
# else USERMEM < 1M
# if USERMEM >= (631808+SACREDMEM)
# define PBITS 16
# else
# if USERMEM >= (329728+SACREDMEM)
# define PBITS 15
# else
# if USERMEM >= (178176+SACREDMEM)
# define PBITS 14
# else
# if USERMEM >= (99328+SACREDMEM)
# define PBITS 13
# else
# define PBITS 12
# endif
# endif
# endif
# endif
# undef USERMEM
# endif USERMEM <=> 1M
# endif USERMEM <=> 1.5M
# endif USERMEM <=> 2.5M
#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
#if BITS == 11
# define HSIZE 2591 /* 79% occupancy */
#endif
#if BITS == 10
# define HSIZE 1291 /* 79% occupancy */
#endif
#if BITS == 9
# define HSIZE 691 /* 74% occupancy */
#endif
/* BITS < 9 will cause an error */
/*
* 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 interdata
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 UCHAR
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 3.0 84/11/27 11:50:00 joe Exp $
* $Log: compress.c,v $
* 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 compatability. 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.
*
*/
#ifndef lint
static char rcs_ident[] = "$Header: compress.c,v 3.0 84/11/27 11:50:00 joe Exp $";
#endif !lint
#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 COMPATIBLE
# define MAXCODE(n_bits) ((1 << (n_bits)) - 1)
#endif COMPATIBLE
/*
* One code could conceivably represent (1<<BITS) characters, but
* to get a code of length N requires an input string of at least
* N*(N-1)/2 characters. With 5000 chars in the stack, an input
* file would have to contain a 25Mb string of a single character.
* This seems unlikely.
*/
#ifdef SHORT_INT
# define MAXSTACK 5000 /* size of output stack */
#else !SHORT_INT
# define MAXSTACK 8000 /* size of output stack */
#endif !SHORT_INT
count_int htab [HSIZE];
unsigned short codetab [HSIZE];
code_int hsize = HSIZE; /* for dynamic table sizing */
count_int fsize;
#define tab_prefix codetab /* prefix code for this entry */
char_type tab_suffix[1<<BITS]; /* last char in this entry */
#ifdef USERMEM
short ftable [(1 << FBITS) * 256];
count_int fcodemem [1 << FBITS];
#endif USERMEM
code_int free_ent = 0; /* first unused entry */
int exit_stat = 0;
code_int getcode();
Usage() {
#ifdef DEBUG
fprintf(stderr,"Usage: compress [-dDvqfFc] [-b maxbits] [file ...]\n");
}
int debug = 0;
#else DEBUG
fprintf(stderr,"Usage: compress [-dfFqc] [-b maxbits] [file ...]\n");
}
#endif DEBUG
int nomagic = 0; /* Use a 2 byte magic number header, unless old file */
int zcat_flg = 0; /* Write output on stdout, suppress messages */
int quiet = 0; /* 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;
double ratio = 0.0; /* compression ratio for last block */
#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)();
/*****************************************************************
* 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 [-dfFqc] [-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; if -f is not used, the user will be prompted if
* the stdin is a tty, otherwise, the output file will not
* be overwritten.
*
* -F: Forces output file to be generated, even if no space is
* saved by compressing.
*
* -q: No output, unless error
*
* 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 decreased 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 do_decomp = 0;
int overwrite = 0; /* Do not overwrite unless given -f flag */
char tempname[100];
char **filelist, **fileptr;
char *cp, *rindex();
struct stat statbuf;
extern onintr();
if ( (bgnd_flag = signal ( SIGINT, SIG_IGN )) != SIG_IGN )
signal ( SIGINT, onintr );
#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
* -d => do_decomp
* -v => verbose
* -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 compatable 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;
break;
#endif DEBUG
case 'd':
do_decomp = 1;
break;
case 'f':
overwrite = 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;
case 'F':
force = 1;
break;
default:
fprintf(stderr, "Unknown flag: '%c'; ", **argv);
Usage();
exit(1);
}
}
}
else { /* Input file name */
*fileptr++ = *argv; /* Build input file list */
*fileptr = NULL;
/* goto 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
*/
#if HSIZE > 5003
if ( fsize < (1 << 12) )
hsize = 5003;
#if HSIZE > 9001
else if ( fsize < (1 << 13) )
hsize = 9001;
#if HSIZE > 18013
else if ( fsize < (1 << 14) )
hsize = 18013;
#if HSIZE > 35023
else if ( fsize < (1 << 15) )
hsize = 35023;
else if ( fsize < 47000 )
hsize = 50021;
#endif HSIZE > 35023
#endif HSIZE > 18013
#endif HSIZE > 9001
else
#endif HSIZE > 5003
hsize = 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 (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 DEBUG
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 || (!quiet))
putc('\n', stderr);
}
}
} else { /* Standard input */
if (do_decomp == 0) {
compress();
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 DEBUG
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) */
#define HOG_CHECK ((count_int) 2000) /* Number of chars to read b4 check */
#define MAX_CACHE ((count_int) 1<<BITS) /* Next line is this constant too */
unsigned short hashcache [1<<BITS]; /* common hash short circuit cache */
count_int cfreq [256]; /* character counts */
#ifndef vax
char chog; /* most common character from input */
# define CHOG ' ' /* Assume space is most frequent */
#else
int chog; /* char arith slow on VAX */
# define CHOG (int) ' ' /* Assume space is most frequent */
#endif
int cstat_flg = 0; /* on after determining char hog */
/*
* compress stdin to stdout
*
* Algorithm: on large machines, for maxbits <= FBITS, use fast direct table
* lookup on the prefix code / next character combination. For smaller code
* size, use open addressing modular division double hashing (no chaining), ala
* Knuth vol. 3, sec. 6.4 Algorithm D, along with G. Knott's relatively-prime
* secondary probe. 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. For the
* megamemory version, the sparse array is cleared indirectly through a
* "shadow" output code history. Late additions: for the hashing code,
* construct the table according to file size for noticeable speed improvement
* on small files. Also detect and cache codes associated with the most
* common character to bypass hash calculation on these codes (a characteristic
* of highly-compressable raster images). 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;
register int disp;
register code_int hsize_reg;
#ifndef COMPATIBLE
if (nomagic == 0) {
putchar(magic_header[0]); putchar(magic_header[1]);
putchar((char)(maxbits | block_compress));
}
#endif COMPATIBLE
offset = 0;
bytes_out = 0;
out_count = 0;
clear_flg = 0;
ratio = 0.0;
in_count = 1;
checkpoint = CHECK_GAP;
maxcode = MAXCODE(n_bits = INIT_BITS);
free_ent = ((block_compress) ? FIRST : 256 );
ent = getchar ();
#ifdef USERMEM
if ( maxbits <= FBITS && (fsize >= 30000) ) { /* use hashing on small files */
while ( (c = getchar()) != EOF ) {
in_count++;
fcode = (long) (((long) c << maxbits) + ent);
if ( ftable [fcode] != 0 ) /* test for code in "string" table */
ent = ftable [fcode];
else {
output ( (code_int) ent );
out_count++;
ent = c;
if ( free_ent >= maxmaxcode ) {
if ( (count_int)in_count < checkpoint || (!block_compress) )
continue;
else {
clear ();
i = 0;
}
} else { /* put code in table */
ftable [fcode] = (short) free_ent++;
fcodemem [i++] = fcode; /* memorize for block compression */
}
}
}
goto fin;
}
#endif USERMEM
chog = CHOG; /* assumed character for the hog */
cstat_flg = 0;
hsize_reg = hsize;
cl_hash(hsize_reg); /* clear hash tables */
while ( (c = getchar()) != EOF ) {
in_count++;
if ( cstat_flg == 0 ) {
cfreq [c]++; /* gather frequencies at start of input */
if ( (count_int)in_count > HOG_CHECK ) {
cstat_flg = 1;
chog = hogtally(); /* compute char hog */
if(chog != CHOG) /* fixup for wrong assumption */
creset( (count_int) free_ent );
}
}
if ( c == chog )
if ( (i = hashcache [ent]) ) { /* cache -> code */
ent = i;
continue;
}
fcode = (long) (((long) c << maxbits) + ent);
#ifdef SHORT_INT
i = (((c + 12347) * ent) & 077777) % HSIZE; /* avoid 'lrem' call */
#else !SHORT_INT
i = fcode % hsize_reg; /* division hashing */
#endif SHORT_INT
if ( htab [i] == fcode ) {
ent = codetab [i];
continue;
} else if ( (long)htab [i] < 0 ) /* empty slot */
goto nomatch;
disp = hsize_reg - i; /* secondary hash (G. Knott) */
if ( i == 0 )
disp = 1;
probe:
if ( (i -= disp) < 0 )
i += hsize_reg;
if ( htab [i] == fcode ) {
ent = codetab [i];
continue;
}
if ( (long)htab [i] > 0 )
goto probe;
nomatch:
output ( (code_int) ent );
out_count++;
#ifdef interdata
if ( (unsigned) free_ent < (unsigned) maxmaxcode) {
#else
if ( free_ent < maxmaxcode ) {
#endif
if ( c == chog ) /* code -> cache */
hashcache [ent] = free_ent;
/* code -> hashtable */
codetab [i] = free_ent++;
htab [i] = fcode;
}
else if ( (count_int)in_count >= checkpoint && block_compress )
clear ();
ent = c;
}
fin:
/*
* 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 %g\n",
in_count, out_count, bytes_out,
(double)in_count / (double)bytes_out );
fprintf( stderr, "\tCompression as in compact: %5.2f%%\n",
100.0 * ( in_count - bytes_out ) / (double) in_count );
fprintf( stderr, "\tLargest code was %d (%d bits)\n", free_ent - 1, n_bits );
#else DEBUG
fprintf( stderr, "Compression: %5.2f%%",
100.0 * ( in_count - bytes_out ) / (double) 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;
if ( code >= 0 ) {
#ifdef DEBUG
if ( verbose )
fprintf( stderr, "%5d%c", code,
(col+=6) >= 74 ? (col = 0, '\n') : ' ' );
#endif DEBUG
#ifdef vax
/* VAX DEPENDENT!! Implementation on other machines may be
* difficult.
*
* Translation: Insert BITS bits from the argument starting at
* offset bits from the beginning of buf.
*/
0; /* C compiler bug ?? */
asm( "insv 4(ap),r11,r10,(r9)" );
#else not a vax
/* WARNING: 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);
if (ferror(stdout))
writeerr();
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() {
register int stack_top = MAXSTACK;
register code_int code, oldcode, incode;
register int finchar;
char stack[MAXSTACK];
/*
* As above, initialize the first 256 entries in the table.
*/
maxcode = MAXCODE(n_bits = INIT_BITS);
for ( code = 255; code >= 0; code-- ) {
tab_prefix[code] = 0;
tab_suffix[code] = (char_type)code;
}
free_ent = ((block_compress) ? FIRST : 256 );
finchar = oldcode = getcode();
putchar( (char)finchar ); /* first code must be 8 bits = char */
while ( (code = getcode()) != -1 ) {
if ( (code == CLEAR) && block_compress ) {
for ( code = 255; code > 0; code -= 4 ) {
tab_prefix [code-3] = 0;
tab_prefix [code-2] = 0;
tab_prefix [code-1] = 0;
tab_prefix [code] = 0;
}
clear_flg = 1;
free_ent = FIRST - 1;
if ( (code = getcode ()) == -1 ) /* O, untimely death! */
break;
}
incode = code;
/*
* Special case for KwKwK string.
*/
if ( code >= free_ent ) {
stack[--stack_top] = finchar;
code = oldcode;
}
/*
* Generate output characters in reverse order
*/
#ifdef interdata
while ( ((unsigned long)code) >= ((unsigned long)256) ) {
#else !interdata
while ( code >= 256 ) {
#endif interdata
stack[--stack_top] = tab_suffix[code];
code = tab_prefix[code];
}
stack[--stack_top] = finchar = tab_suffix[code];
/*
* And put them out in forward order
*/
for ( ; stack_top < MAXSTACK; stack_top++ )
putchar(stack[stack_top]);
if (ferror(stdout))
writeerr ( );
stack_top = MAXSTACK;
/*
* Generate the new entry.
*/
if ( (code=free_ent) < maxmaxcode ) {
tab_prefix[code] = (unsigned short)oldcode;
tab_suffix[code] = finchar;
free_ent = code+1;
}
/*
* Remember previous code.
*/
oldcode = incode;
}
fflush( stdout );
if(ferror(stdout))
writeerr();
}
/*****************************************************************
* TAG( getcode )
*
* Read one code from the standard input. If EOF, return -1.
* Inputs:
* stdin
* Outputs:
* code or -1 is returned.
*/
code_int
getcode() {
/*
* On the VAX, it is important to have the register declarations
* in exactly the order given, or the asm will break.
*/
register code_int code;
static int offset = 0, size = 0;
static char_type buf[BITS];
register int r_off, bits;
register char_type *bp = buf;
if ( clear_flg > 0 || offset >= size || free_ent > maxcode ) {
/*
* If the next entry will be too big for the current code
* size, then we must increase the size. This implies reading
* a new buffer full, too.
*/
if ( free_ent > maxcode ) {
n_bits++;
if ( n_bits == maxbits )
maxcode = maxmaxcode; /* won't get any bigger now */
else
maxcode = MAXCODE(n_bits);
}
if ( clear_flg > 0) {
maxcode = MAXCODE (n_bits = INIT_BITS);
clear_flg = 0;
}
size = fread( buf, 1, n_bits, stdin );
if ( size <= 0 )
return -1; /* end of file */
offset = 0;
/* Round size down to integral number of codes */
size = (size << 3) - (n_bits - 1);
}
r_off = offset;
bits = n_bits;
#ifdef vax
asm( "extzv r10,r9,(r8),r11" );
#else not a vax
/*
* Get to the first byte.
*/
bp += (r_off >> 3);
r_off &= 7;
/* Get first part (low order bits) */
#ifdef NO_UCHAR
code = ((*bp++ >> r_off) & rmask[8 - r_off]) & 0xff;
#else NO_UCHAR
code = (*bp++ >> r_off);
#endif NO_UCHAR
bits -= (8 - r_off);
r_off = 8 - r_off; /* now, offset into code word */
/* Get any 8 bit parts in the middle (<=1 for up to 16 bits). */
if ( bits >= 8 ) {
#ifdef NO_UCHAR
code |= (*bp++ & 0xff) << r_off;
#else NO_UCHAR
code |= *bp++ << r_off;
#endif NO_UCHAR
r_off += 8;
bits -= 8;
}
/* high order bits. */
code |= (*bp & rmask[bits]) << r_off;
#endif vax
offset += n_bits;
return code;
}
char *
rindex(s, c) /* For those who don't have it in libc.a */
register char *s, c;
{
char *p;
for (p = NULL; *s; s++)
if (*s == c)
p = s;
return(p);
}
#ifdef DEBUG
printcodes()
{
/*
* Just print out codes from input file. Mostly for debugging.
*/
code_int code;
int col = 0, bits;
bits = n_bits = INIT_BITS;
maxcode = MAXCODE(n_bits);
free_ent = ((block_compress) ? FIRST : 256 );
while ( ( code = getcode() ) >= 0 ) {
if ( (code == CLEAR) && block_compress ) {
free_ent = FIRST - 1;
clear_flg = 1;
}
else if ( free_ent < maxmaxcode )
free_ent++;
if ( bits != n_bits ) {
fprintf(stderr, "\nChange to %d bits\n", n_bits );
bits = n_bits;
col = 0;
}
fprintf(stderr, "%5d%c", code, (col+=6) >= 74 ? (col = 0, '\n') : ' ' );
}
putc( '\n', stderr );
exit( 0 );
}
dump_tab() /* dump string table */
{
register int i;
register ent;
char stack[4 * MAXSTACK]; /* \nnn makes it 4 times bigger */
int stack_top = 4 * MAXSTACK;
for ( i = 0; i < free_ent; i++ ) {
ent = i;
if ( isascii(tab_suffix[ent]) && isprint(tab_suffix[ent]) )
fprintf( stderr, "%5d: %5d/'%c' \"",
ent, tab_prefix[ent], tab_suffix[ent] );
else
fprintf( stderr, "%5d: %5d/\\%03o \"",
ent, tab_prefix[ent], tab_suffix[ent] );
stack[--stack_top] = '\n';
stack[--stack_top] = '"';
for ( ; ent != NULL;
ent = (ent >= FIRST ? tab_prefix[ent] : NULL) ) {
if ( isascii(tab_suffix[ent]) && isprint(tab_suffix[ent]) )
stack[--stack_top] = tab_suffix[ent];
else {
switch( tab_suffix[ent] ) {
case '\n': stack[--stack_top] = 'n'; break;
case '\t': stack[--stack_top] = 't'; break;
case '\b': stack[--stack_top] = 'b'; break;
case '\f': stack[--stack_top] = 'f'; break;
case '\r': stack[--stack_top] = 'r'; break;
default:
stack[--stack_top] = '0' + tab_suffix[ent] % 8;
stack[--stack_top] = '0' + (tab_suffix[ent] / 8) % 8;
stack[--stack_top] = '0' + tab_suffix[ent] / 64;
break;
}
stack[--stack_top] = '\\';
}
}
fwrite( &stack[stack_top], 1, 4 * MAXSTACK - stack_top, stderr );
stack_top = 4 * MAXSTACK;
}
}
#endif DEBUG
/*****************************************************************
* TAG( writeerr )
*
* Exits with a message. We only check for write errors often enough
* to avoid a lot of "file system full" messages, not on every write.
* ferror() check after fflush will catch any others (I trust).
*
*/
writeerr()
{
perror ( ofname );
unlink ( ofname );
exit ( 1 );
}
copystat(ifname, ofname)
char *ifname, *ofname;
{
struct stat statbuf;
int mode;
time_t timep[2];
fclose(stdout);
if (stat(ifname, &statbuf)) { /* Get stat on input file */
perror(ifname);
return;
}
if ((statbuf.st_mode & S_IFMT/*0170000*/) != S_IFREG/*0100000*/) {
if(quiet)
fprintf(stderr, "%s: ", ifname);
fprintf(stderr, " -- not a regular file: unchanged");
exit_stat = 1;
} else if (statbuf.st_nlink > 1) {
if(quiet)
fprintf(stderr, "%s: ", ifname);
fprintf(stderr, " -- has %d other links: unchanged",
statbuf.st_nlink - 1);
exit_stat = 1;
} else if (exit_stat == 2 && (!force)) { /* No compression: remove file.Z */
fprintf(stderr, " -- file unchanged");
} else { /* ***** Successful Compression ***** */
exit_stat = 0;
mode = statbuf.st_mode & 07777;
if (chmod(ofname, mode)) /* Copy modes */
perror(ofname);
chown(ofname, statbuf.st_uid, statbuf.st_gid); /* Copy ownership */
timep[0] = statbuf.st_atime;
timep[1] = statbuf.st_mtime;
utime(ofname, timep); /* Update last accessed and modified times */
if (unlink(ifname)) /* Remove input file */
perror(ifname);
if(!quiet)
fprintf(stderr, " -- replaced with %s", ofname);
return; /* Successful return */
}
/* Unsuccessful return -- one of the tests failed */
if (unlink(ofname))
perror(ofname);
}
/*
* This routine returns 1 if we are running in the foreground and stderr
* is a tty.
*/
foreground()
{
if(bgnd_flag) { /* background? */
return(0);
} else { /* foreground */
if(isatty(2)) { /* and stderr is a tty */
return(1);
} else {
return(0);
}
}
}
onintr ( )
{
unlink ( ofname );
exit ( 1 );
}
clear () /* table clear for block compress */
{
register code_int i;
register count_int *p, *endp;
register unsigned short *q;
#ifdef DEBUG
if(debug)
fprintf ( stderr, "count: %ld ratio: %f\n", in_count,
(double) in_count / (double) bytes_out );
#endif DEBUG
checkpoint = in_count + CHECK_GAP;
if ( (double) in_count / (double) bytes_out > ratio )
ratio = (double) in_count / (double) bytes_out;
else {
ratio = 0.0;
#ifdef USERMEM
if ( maxbits <= FBITS ) /* sparse array clear */
for ( i = (1 << maxbits) - 1; i >= 0; i-- )
ftable [fcodemem [i]] = 0; /* indirect thru "shadow" */
else
#endif USERMEM /* hash table clear */
{
endp = &htab [hsize];
for ( p = &htab [0], q = &codetab [0]; p < endp; ) {
*p++ = -1;
*q++ = 0;
}
creset ( MAX_CACHE );
}
free_ent = FIRST;
clear_flg = 1;
output ( (code_int) CLEAR );
#ifdef DEBUG
if(debug)
fprintf ( stderr, "clear\n" );
#endif DEBUG
}
}
creset ( n ) /* clear hash cache */
register count_int n; /* clear at least this many entries */
{
register count_int i;
register unsigned short *hash_p;
register unsigned short zero = 0;
static int nfiles = 0;
if ( nfiles++ == 0 ) /* No clear needed if first time */
return;
n = (n+15) & (-16);
hash_p = hashcache + n;
for ( i = n; i > 0; i -=16 ) {
*(hash_p-16) = zero;
*(hash_p-15) = zero;
*(hash_p-14) = zero;
*(hash_p-13) = zero;
*(hash_p-12) = zero;
*(hash_p-11) = zero;
*(hash_p-10) = zero;
*(hash_p-9) = zero;
*(hash_p-8) = zero;
*(hash_p-7) = zero;
*(hash_p-6) = zero;
*(hash_p-5) = zero;
*(hash_p-4) = zero;
*(hash_p-3) = zero;
*(hash_p-2) = zero;
*(hash_p-1) = zero;
hash_p -= 16;
}
}
hogtally () /* compute character code hog */
{
register int i, most;
for ( i = most = 0; i < 256; i++ )
if ( cfreq [i] >= cfreq [most] )
most = i;
return ( most );
}
cl_hash(hsize)
register int hsize;
{
register count_int *htab_p = htab+hsize;
register int i;
register long m1 = -1;
/* clear hashcache */
#define min(a,b) ((a>b) ? b : a)
creset( min((count_int)hsize, MAX_CACHE) );
i = hsize - 16;
do {
*(htab_p-16) = m1;
*(htab_p-15) = m1;
*(htab_p-14) = m1;
*(htab_p-13) = m1;
*(htab_p-12) = m1;
*(htab_p-11) = m1;
*(htab_p-10) = m1;
*(htab_p-9) = m1;
*(htab_p-8) = m1;
*(htab_p-7) = m1;
*(htab_p-6) = m1;
*(htab_p-5) = m1;
*(htab_p-4) = m1;
*(htab_p-3) = m1;
*(htab_p-2) = m1;
*(htab_p-1) = m1;
htab_p -= 16;
} while ((i -= 16) >= 0);
for ( i += 16; i > 0; i-- )
*--htab_p = m1;
}