ref: 37a8fc6168b3bf82df198fb20be5a8a53996187c
dir: /sys/src/cmd/compress/compress.c/
/*
* compress - File compression ala IEEE Computer, June 1984.
*
* 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:
* -b: limit the max number of bits/code.
* -c: write output on stdout, don't remove original.
* -d: decompress instead.
* -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.
* 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)
*/
#define _PLAN9_SOURCE
#include <u.h>
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#define min(a,b) ((a>b) ? b : a)
#define BITS 16
#define HSIZE 69001 /* 95% occupancy */
/*
* a code_int must be able to hold 2**BITS values of type int, and also -1
*/
typedef long code_int;
typedef long count_int;
static char rcs_ident[] = "$Header: compress.c,v 4.0 85/07/30 12:50:00 joe Release $";
uchar magic_header[] = { 0x1F, 0x9D }; /* 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 */
void onintr(int);
void oops(int);
#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 */
#define MAXCODE(n_bits) ((1 << (n_bits)) - 1)
count_int htab[HSIZE];
ushort codetab[HSIZE];
#define htabof(i) htab[i]
#define codetabof(i) codetab[i]
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)
#define tab_suffixof(i) ((uchar *)(htab))[i]
#define de_stack ((uchar *)&tab_suffixof(1<<BITS))
code_int free_ent = 0; /* first unused entry */
int exit_stat = 0;
code_int getcode();
void
Usage(void)
{
#ifdef DEBUG
fprintf(stderr,"usage: compress [-cdfDV] [-b maxbits] [file ...]\n");
#else
fprintf(stderr,"usage: compress [-cdfvV] [-b maxbits] [file ...]\n");
#endif /* DEBUG */
}
int debug = 0;
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 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 */
void (*bgnd_flag)(int);
int do_decomp = 0;
void decompress(void);
void compress(void);
void output(code_int);
void writeerr(void);
void copystat(char*, char*);
void cl_block(void);
void cl_hash(long);
void prratio(FILE*, long, long);
void version(void);
void
main(int argc, char **argv)
{
int overwrite = 0; /* Do not overwrite unless given -f flag */
char tempname[512];
char **filelist, **fileptr;
char *cp;
struct stat statbuf;
if ( (bgnd_flag = signal ( SIGINT, SIG_IGN )) != SIG_IGN ) {
signal(SIGINT, onintr);
signal(SIGSEGV, oops);
}
filelist = fileptr = (char **)(malloc(argc * sizeof(*argv)));
*filelist = NULL;
if((cp = strrchr(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;
}
/*
* Argument Processing
* All flags are optional.
* -C generate output compatible with compress 2.0.
* -D debug
* -V print Version; debug verbose
* -b maxbits maxbits. If -b is specified, then maxbits MUST be
* given also.
* -c cat all output to stdout
* -d do_decomp
* -f force overwrite of output file
* -n no header: useful to uncompress old files
* -v unquiet
* 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) {
case 'C':
block_compress = 0;
break;
#ifdef DEBUG
case 'D':
debug = 1;
break;
case 'V':
verbose = 1;
version();
break;
#else
case 'V':
version();
break;
#endif
case 'b':
if (!ARGVAL()) {
fprintf(stderr, "Missing maxbits\n");
Usage();
exit(1);
}
maxbits = atoi(*argv);
goto nextarg;
case 'c':
zcat_flg = 1;
break;
case 'd':
do_decomp = 1;
break;
case 'f':
case 'F':
overwrite = 1;
force = 1;
break;
case 'n':
nomagic = 1;
break;
case 'q':
quiet = 1;
break;
case 'v':
quiet = 0;
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;
}
(void) 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
if ((cp=strrchr(ofname,'/')) != NULL)
cp++;
else
cp = ofname;
/*
*** changed 12 to 25; should be NAMELEN-3, but I don't want
* to fight the headers. ehg 5 Nov 92 **
*/
if (strlen(cp) > 25) {
fprintf(stderr, "%s: filename too long to tack on .Z\n",
cp);
continue;
}
#endif
strcat(ofname, ".Z");
}
/* Check for overwrite of existing file */
if (overwrite == 0 && zcat_flg == 0 &&
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);
(void) 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
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 in_count = 1; /* length of input */
long bytes_out; /* length of compressed output */
long 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.
*/
void
compress(void)
{
code_int ent, hsize_reg;
code_int i;
int c, disp, hshift;
long fcode;
if (nomagic == 0) {
putchar(magic_header[0]);
putchar(magic_header[1]);
putchar((char)(maxbits | block_compress));
if(ferror(stdout))
writeerr();
}
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 *= 2)
hshift++;
hshift = 8 - hshift; /* set hash code range bound */
hsize_reg = hsize;
cl_hash( (count_int) hsize_reg); /* clear hash table */
while ((c = getchar()) != EOF) {
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;
if (free_ent < maxmaxcode) {
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;
}
/*
* 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). When the buffer fills up empty it and start over.
*/
static char buf[BITS];
uchar lmask[9] = {0xff, 0xfe, 0xfc, 0xf8, 0xf0, 0xe0, 0xc0, 0x80, 0x00};
uchar rmask[9] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
void
output(code_int code)
{
#ifdef DEBUG
static int col = 0;
#endif
int r_off = offset, bits= n_bits;
char *bp = buf;
#ifdef DEBUG
if (verbose)
fprintf(stderr, "%5d%c", code,
(col+=6) >= 74? (col = 0, '\n'): ' ');
#endif
if (code >= 0) {
/*
* 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;
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
}
} 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
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.
*/
void
decompress(void)
{
int finchar;
code_int code, oldcode, incode;
uchar *stackp;
/*
* 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) = (uchar)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;
while ((code = getcode()) > -1) {
if ((code == CLEAR) && block_compress) {
for (code = 255; code >= 0; code--)
tab_prefixof(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) {
*stackp++ = finchar;
code = oldcode;
}
/*
* Generate output characters in reverse order
*/
while (code >= 256) {
*stackp++ = tab_suffixof(code);
code = tab_prefixof(code);
}
*stackp++ = finchar = tab_suffixof(code);
/*
* And put them out in forward order
*/
do {
putchar(*--stackp);
} while (stackp > de_stack);
/*
* Generate the new entry.
*/
if ( (code=free_ent) < maxmaxcode ) {
tab_prefixof(code) = (ushort)oldcode;
tab_suffixof(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(void)
{
int r_off, bits;
code_int code;
static int offset = 0, size = 0;
static uchar buf[BITS];
uchar *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;
/*
* Get to the first byte.
*/
bp += (r_off >> 3);
r_off &= 7;
/* Get first part (low order bits) */
code = (*bp++ >> r_off);
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) {
code |= *bp++ << r_off;
r_off += 8;
bits -= 8;
}
/* high order bits. */
code |= (*bp & rmask[bits]) << r_off;
offset += n_bits;
return code;
}
#ifdef DEBUG
void
printcodes(void)
{
/*
* Just print out codes from input file. 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 );
}
code_int sorttab[1<<BITS]; /* sorted pointers into htab */
#define STACK_SIZE 15000
dump_tab() /* dump string table */
{
int i, first, c, ent;
int stack_top = STACK_SIZE;
if(do_decomp == 0) { /* compressing */
int flag = 1;
for(i=0; i<hsize; i++) { /* build sort pointers */
if((long)htabof(i) >= 0) {
sorttab[codetabof(i)] = i;
}
}
first = block_compress ? FIRST : 256;
for(i = first; i < free_ent; i++) {
fprintf(stderr, "%5d: \"", i);
de_stack[--stack_top] = '\n';
de_stack[--stack_top] = '"';
stack_top = in_stack((htabof(sorttab[i])>>maxbits)&0xff,
stack_top);
for(ent=htabof(sorttab[i]) & ((1<<maxbits)-1);
ent > 256;
ent=htabof(sorttab[ent]) & ((1<<maxbits)-1)) {
stack_top = in_stack(htabof(sorttab[ent]) >> maxbits,
stack_top);
}
stack_top = in_stack(ent, stack_top);
fwrite( &de_stack[stack_top], 1, STACK_SIZE-stack_top, stderr);
stack_top = STACK_SIZE;
}
} else if(!debug) { /* decompressing */
for ( i = 0; i < free_ent; i++ ) {
ent = i;
c = tab_suffixof(ent);
if ( isascii(c) && isprint(c) )
fprintf( stderr, "%5d: %5d/'%c' \"",
ent, tab_prefixof(ent), c );
else
fprintf( stderr, "%5d: %5d/\\%03o \"",
ent, tab_prefixof(ent), c );
de_stack[--stack_top] = '\n';
de_stack[--stack_top] = '"';
for ( ; ent != NULL;
ent = (ent >= FIRST ? tab_prefixof(ent) : NULL) ) {
stack_top = in_stack(tab_suffixof(ent), stack_top);
}
fwrite( &de_stack[stack_top], 1, STACK_SIZE - stack_top, stderr );
stack_top = STACK_SIZE;
}
}
}
int
in_stack(int c, int stack_top)
{
if ( (isascii(c) && isprint(c) && c != '\\') || c == ' ' ) {
de_stack[--stack_top] = c;
} else {
switch( c ) {
case '\n': de_stack[--stack_top] = 'n'; break;
case '\t': de_stack[--stack_top] = 't'; break;
case '\b': de_stack[--stack_top] = 'b'; break;
case '\f': de_stack[--stack_top] = 'f'; break;
case '\r': de_stack[--stack_top] = 'r'; break;
case '\\': de_stack[--stack_top] = '\\'; break;
default:
de_stack[--stack_top] = '0' + c % 8;
de_stack[--stack_top] = '0' + (c / 8) % 8;
de_stack[--stack_top] = '0' + c / 64;
break;
}
de_stack[--stack_top] = '\\';
}
return stack_top;
}
#endif /* DEBUG */
void
writeerr(void)
{
perror(ofname);
unlink(ofname);
exit(1);
}
void
copystat(char *ifname, char *ofname)
{
int mode;
time_t timep[2];
struct stat statbuf;
fclose(stdout);
if (stat(ifname, &statbuf)) { /* Get stat on input file */
perror(ifname);
return;
}
if (!S_ISREG(statbuf.st_mode)) {
if (quiet)
fprintf(stderr, "%s: ", ifname);
fprintf(stderr, " -- not a regular file: unchanged");
exit_stat = 1;
} else if (exit_stat == 2 && !force) {
/* No compression: remove file.Z */
if (!quiet)
fprintf(stderr, " -- file unchanged");
} else { /* Successful Compression */
exit_stat = 0;
mode = statbuf.st_mode & 0777;
if (chmod(ofname, mode)) /* Copy modes */
perror(ofname);
/* Copy ownership */
chown(ofname, statbuf.st_uid, statbuf.st_gid);
timep[0] = statbuf.st_atime;
timep[1] = statbuf.st_mtime;
/* Update last accessed and modified times */
utime(ofname, timep);
// if (unlink(ifname)) /* Remove input file */
// perror(ifname);
return; /* success */
}
/* 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.
*/
int
foreground(void)
{
if(bgnd_flag) /* background? */
return 0;
else /* foreground */
return isatty(2); /* and stderr is a tty */
}
void
onintr(int)
{
unlink(ofname);
exit(1);
}
void
oops(int) /* wild pointer -- assume bad input */
{
if (do_decomp == 1)
fprintf(stderr, "uncompress: corrupt input\n");
unlink(ofname);
exit(1);
}
void
cl_block (void) /* table clear for block compress */
{
long rat;
checkpoint = in_count + CHECK_GAP;
#ifdef DEBUG
if ( debug ) {
fprintf ( stderr, "count: %ld, ratio: ", in_count );
prratio ( stderr, in_count, bytes_out );
fprintf ( stderr, "\n");
}
#endif /* DEBUG */
if (in_count > 0x007fffff) { /* shift will overflow */
rat = bytes_out >> 8;
if (rat == 0) /* Don't divide by zero */
rat = 0x7fffffff;
else
rat = in_count / rat;
} else
rat = (in_count << 8) / bytes_out; /* 8 fractional bits */
if (rat > ratio)
ratio = rat;
else {
ratio = 0;
#ifdef DEBUG
if (verbose)
dump_tab(); /* dump string table */
#endif
cl_hash((count_int)hsize);
free_ent = FIRST;
clear_flg = 1;
output((code_int)CLEAR);
#ifdef DEBUG
if (debug)
fprintf(stderr, "clear\n");
#endif /* DEBUG */
}
}
void
cl_hash(count_int hsize) /* reset code table */
{
count_int *htab_p = htab+hsize;
long i;
long m1 = -1;
i = hsize - 16;
do { /* might use Sys V memset(3) here */
*(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;
}
void
prratio(FILE *stream, long num, long den)
{
int q; /* Doesn't need to be long */
if(num > 214748L) /* 2147483647/10000 */
q = num / (den / 10000L);
else
q = 10000L * num / den; /* Long calculations, though */
if (q < 0) {
putc('-', stream);
q = -q;
}
fprintf(stream, "%d.%02d%%", q / 100, q % 100);
}
void
version(void)
{
fprintf(stderr, "%s\n", rcs_ident);
fprintf(stderr, "Options: ");
#ifdef DEBUG
fprintf(stderr, "DEBUG, ");
#endif
#ifdef BSD4_2
fprintf(stderr, "BSD4_2, ");
#endif
fprintf(stderr, "BITS = %d\n", BITS);
}
/*
* The revision-history novel:
*
* $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.
*/