ref: 540373b9f603825f27f853a441c6c046a04a0972
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(); Usage() { #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; main(argc, argv) 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. */ compress() { code_int ent, hsize_reg; code_int i = 0; 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}; output( code ) 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. */ decompress() { 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() { 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 printcodes() { /* * 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 */ writeerr() { perror(ofname); unlink(ofname); exit(1); } copystat(ifname, ofname) char *ifname, *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. */ foreground() { if(bgnd_flag) /* background? */ return 0; else /* foreground */ return isatty(2); /* and stderr is a tty */ } void onintr(int x) { unlink(ofname); exit(1); } void oops(int x) /* wild pointer -- assume bad input */ { if (do_decomp == 1) fprintf(stderr, "uncompress: corrupt input\n"); unlink(ofname); exit(1); } cl_block () /* 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 */ } } cl_hash(hsize) /* reset code table */ count_int hsize; { 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; } prratio(stream, num, den) FILE *stream; long num, 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); } version() { 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. */