tcompress: import Plan9 compress - plan9port - [fork] Plan 9 from user space
(HTM) git clone git://src.adamsgaard.dk/plan9port
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---
(DIR) commit cb58f3291cd93a50489d646a198f5437fdffc3ef
(DIR) parent 6510a2d3530132753a6a1dfb2589e9ad82bc271c
(HTM) Author: sean <phonologus@gmail.com>
Date: Wed, 15 Jan 2020 11:54:20 +0000
compress: import Plan9 compress
Add #define USED(x)... boilerplate
compress: import Plan9 manpage.
Diffstat:
A man/man1/compress.1 | 237 +++++++++++++++++++++++++++++++
A src/cmd/compress/compress.c | 1274 +++++++++++++++++++++++++++++++
A src/cmd/compress/mkfile | 15 +++++++++++++++
3 files changed, 1526 insertions(+), 0 deletions(-)
---
(DIR) diff --git a/man/man1/compress.1 b/man/man1/compress.1
t@@ -0,0 +1,237 @@
+.TH COMPRESS 1
+.SH NAME
+compress, uncompress, zcat \- compress and expand data
+.SH SYNOPSIS
+.B compress
+[
+.B \-f
+] [
+.B \-v
+] [
+.B \-c
+] [
+.B \-V
+] [
+.B \-b
+.I bits
+] [
+.I "name \&..."
+]
+.PP
+.B uncompress
+[
+.B \-f
+] [
+.B \-v
+] [
+.B \-c
+] [
+.B \-V
+] [
+.I "name \&..."
+]
+.PP
+.B zcat
+[
+.B \-V
+] [
+.I "name \&..."
+]
+.SH DESCRIPTION
+.I Compress
+reduces the size of the named files using adaptive Lempel-Ziv coding.
+Whenever possible,
+each file is replaced by one with the extension
+.B "\&.Z,"
+while keeping the same ownership modes, access and modification times.
+If no files are specified, the standard input is compressed to the
+standard output.
+Compressed files can be restored to their original form using
+.I uncompress
+or
+.I zcat.
+.PP
+The
+.B \-f
+option will force compression of
+.I name.
+This is useful for compressing an entire directory,
+even if some of the files do not actually shrink.
+If
+.B \-f
+is not given and
+.I compress
+is run in the foreground,
+the user is prompted as to whether an existing file should be overwritten.
+.PP
+The
+.B \-c
+option makes
+.I compress/uncompress
+write to the standard output; no files are changed.
+The nondestructive behavior of
+.I zcat
+is identical to that of
+.I uncompress
+.B \-c.
+.PP
+.I Compress
+uses the modified Lempel-Ziv algorithm popularized in
+"A Technique for High Performance Data Compression",
+Terry A. Welch,
+.I "IEEE Computer,"
+vol. 17, no. 6 (June 1984), pp. 8-19.
+Common substrings in the file are first replaced by 9-bit codes 257 and up.
+When code 512 is reached, the algorithm switches to 10-bit codes and
+continues to use more bits until the
+limit specified by the
+.B \-b
+flag is reached (default 16).
+.I Bits
+must be between 9 and 16. The default can be changed in the source to allow
+.I compress
+to be run on a smaller machine.
+.PP
+After the
+.I bits
+limit is attained,
+.I compress
+periodically checks the compression ratio. If it is increasing,
+.I compress
+continues to use the existing code dictionary. However,
+if the compression ratio decreases,
+.I compress
+discards the table of substrings and rebuilds it from scratch. This allows
+the algorithm to adapt to the next "block" of the file.
+.PP
+Note that the
+.B \-b
+flag is omitted for
+.I uncompress,
+since the
+.I bits
+parameter specified during compression
+is encoded within the output, along with
+a magic number to ensure that neither decompression of random data nor
+recompression of compressed data is attempted.
+.PP
+.ne 8
+The amount of compression obtained depends on the size of the
+input, the number of
+.I bits
+per code, and the distribution of common substrings.
+Typically, text such as source code or English
+is reduced by 50\-60%.
+Compression is generally much better than that achieved by
+Huffman coding (as used in
+.IR pack ),
+or adaptive Huffman coding
+.RI ( compact ),
+and takes less time to compute.
+.PP
+Under the
+.B \-v
+option,
+a message is printed yielding the percentage of
+reduction for each file compressed.
+.PP
+If the
+.B \-V
+option is specified, the current version and compile options are printed on
+stderr.
+.PP
+Exit status is normally 0;
+if the last file is larger after (attempted) compression, the status is 2;
+if an error occurs, exit status is 1.
+.SH "SEE ALSO"
+pack(1), compact(1)
+.SH "DIAGNOSTICS"
+Usage: compress [\-dfvcV] [\-b maxbits] [file ...]
+.in +8
+Invalid options were specified on the command line.
+.in -8
+Missing maxbits
+.in +8
+Maxbits must follow
+.BR \-b \.
+.in -8
+.IR file :
+not in compressed format
+.in +8
+The file specified to
+.I uncompress
+has not been compressed.
+.in -8
+.IR file :
+compressed with
+.I xx
+bits, can only handle
+.I yy
+bits
+.in +8
+.I File
+was compressed by a program that could deal with
+more
+.I bits
+than the compress code on this machine.
+Recompress the file with smaller
+.IR bits \.
+.in -8
+.IR file :
+already has .Z suffix -- no change
+.in +8
+The file is assumed to be already compressed.
+Rename the file and try again.
+.in -8
+.IR file :
+filename too long to tack on .Z
+.in +8
+The file cannot be compressed because its name is longer than
+12 characters.
+Rename and try again.
+This message does not occur on BSD systems.
+.in -8
+.I file
+already exists; do you wish to overwrite (y or n)?
+.in +8
+Respond "y" if you want the output file to be replaced; "n" if not.
+.in -8
+uncompress: corrupt input
+.in +8
+A SIGSEGV violation was detected which usually means that the input file has
+been corrupted.
+.in -8
+Compression:
+.I "xx.xx%"
+.in +8
+Percentage of the input saved by compression.
+(Relevant only for
+.BR \-v \.)
+.in -8
+-- not a regular file: unchanged
+.in +8
+When the input file is not a regular file,
+(e.g. a directory), it is
+left unaltered.
+.in -8
+-- has
+.I xx
+other links: unchanged
+.in +8
+The input file has links; it is left unchanged. See
+.IR ln "(1)"
+for more information.
+.in -8
+-- file unchanged
+.in +8
+No savings is achieved by
+compression. The input remains virgin.
+.in -8
+.SH SOURCE
+.B \*9/src/cmd/compress/compress.c
+.SH "BUGS"
+Although compressed files are compatible between machines with large memory,
+.BR \-b \12
+should be used for file transfer to architectures with
+a small process data space (64KB or less, as exhibited by the DEC PDP
+series, the Intel 80286, etc.)
(DIR) diff --git a/src/cmd/compress/compress.c b/src/cmd/compress/compress.c
t@@ -0,0 +1,1274 @@
+/*
+ * 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)
+ */
+
+#ifndef USED
+# define USED(x) if(x);else
+#endif
+
+#define _PLAN9_SOURCE
+#define _BSD_EXTENSION
+#define _POSIX_SOURCE
+
+#include <u.h>
+#include <stdio.h>
+#include <ctype.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <string.h>
+#include <signal.h>
+#include <utime.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 */
+
+#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;
+
+void cl_block(void);
+void cl_hash(count_int);
+void compress(void);
+void copystat(char *, char *);
+void decompress(void);
+int foreground(void);
+code_int getcode(void);
+void onintr(int);
+void oops(int);
+void output(code_int);
+void prratio(FILE *, long, long);
+void version(void);
+void writeerr(void);
+
+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;
+
+int
+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);
+ return 0;
+}
+
+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 )
+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()
+{
+ 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 */
+
+void
+writeerr(void)
+{
+ perror(ofname);
+ unlink(ofname);
+ exit(1);
+}
+
+void
+copystat(ifname, ofname)
+char *ifname, *ofname;
+{
+ int mode;
+ time_t timep[2]; /* should be struct utimbuf */
+ 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, (struct utimbuf *)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 x)
+{
+ USED(x);
+ unlink(ofname);
+ exit(1);
+}
+
+void
+oops(int x) /* wild pointer -- assume bad input */
+{
+ USED(x);
+ 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(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);
+}
+
+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.
+ */
(DIR) diff --git a/src/cmd/compress/mkfile b/src/cmd/compress/mkfile
t@@ -0,0 +1,15 @@
+<$PLAN9/src/mkhdr
+
+TARG=\
+ compress \
+ zcat \
+ uncompress
+
+$O.uncompress:Q: $O.compress
+ cp $prereq $target
+
+$O.zcat:Q: $O.compress
+ cp $prereq $target
+
+<$PLAN9/src/mkmany
+