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diff --git a/usr.bin/compress/doc/README b/usr.bin/compress/doc/README deleted file mode 100644 index 6803287..0000000 --- a/usr.bin/compress/doc/README +++ /dev/null @@ -1,283 +0,0 @@ - - @(#)README 8.1 (Berkeley) 6/9/93 - -Compress version 4.0 improvements over 3.0: - o compress() speedup (10-50%) by changing division hash to xor - o decompress() speedup (5-10%) - o Memory requirements reduced (3-30%) - o Stack requirements reduced to less than 4kb - o Removed 'Big+Fast' compress code (FBITS) because of compress speedup - o Portability mods for Z8000 and PC/XT (but not zeus 3.2) - o Default to 'quiet' mode - o Unification of 'force' flags - o Manual page overhaul - o Portability enhancement for M_XENIX - o Removed text on #else and #endif - o Added "-V" switch to print version and options - o Added #defines for SIGNED_COMPARE_SLOW - o Added Makefile and "usermem" program - o Removed all floating point computations - o New programs: [deleted] - -The "usermem" script attempts to determine the maximum process size. Some -editing of the script may be necessary (see the comments). [It should work -fine on 4.3 bsd.] If you can't get it to work at all, just create file -"USERMEM" containing the maximum process size in decimal. - -The following preprocessor symbols control the compilation of "compress.c": - - o USERMEM Maximum process memory on the system - o SACREDMEM Amount to reserve for other proceses - o SIGNED_COMPARE_SLOW Unsigned compare instructions are faster - o NO_UCHAR Don't use "unsigned char" types - o BITS Overrules default set by USERMEM-SACREDMEM - o vax Generate inline assembler - o interdata Defines SIGNED_COMPARE_SLOW - o M_XENIX Makes arrays < 65536 bytes each - o pdp11 BITS=12, NO_UCHAR - o z8000 BITS=12 - o pcxt BITS=12 - o BSD4_2 Allow long filenames ( > 14 characters) & - Call setlinebuf(stderr) - -The difference "usermem-sacredmem" determines the maximum BITS that can be -specified with the "-b" flag. - -memory: at least BITS ------- -- ----- ---- - 433,484 16 - 229,600 15 - 127,536 14 - 73,464 13 - 0 12 - -The default is BITS=16. - -The maximum bits can be overrulled by specifying "-DBITS=bits" at -compilation time. - -WARNING: files compressed on a large machine with more bits than allowed by -a version of compress on a smaller machine cannot be decompressed! Use the -"-b12" flag to generate a file on a large machine that can be uncompressed -on a 16-bit machine. - -The output of compress 4.0 is fully compatible with that of compress 3.0. -In other words, the output of compress 4.0 may be fed into uncompress 3.0 or -the output of compress 3.0 may be fed into uncompress 4.0. - -The output of compress 4.0 not compatible with that of -compress 2.0. However, compress 4.0 still accepts the output of -compress 2.0. To generate output that is compatible with compress -2.0, use the undocumented "-C" flag. - - -from mod.sources, submitted by vax135!petsd!joe (Joe Orost), 8/1/85 --------------------------------- - -Enclosed is compress version 3.0 with the following changes: - -1. "Block" compression is performed. After the BITS run out, the - compression ratio is checked every so often. If it is decreasing, - the table is cleared and a new set of substrings are generated. - - This makes the output of compress 3.0 not compatible with that of - compress 2.0. However, compress 3.0 still accepts the output of - compress 2.0. To generate output that is compatible with compress - 2.0, use the undocumented "-C" flag. - -2. A quiet "-q" flag has been added for use by the news system. - -3. The character chaining has been deleted and the program now uses - hashing. This improves the speed of the program, especially - during decompression. Other speed improvements have been made, - such as using putc() instead of fwrite(). - -4. A large table is used on large machines when a relatively small - number of bits is specified. This saves much time when compressing - for a 16-bit machine on a 32-bit virtual machine. Note that the - speed improvement only occurs when the input file is > 30000 - characters, and the -b BITS is less than or equal to the cutoff - described below. - -Most of these changes were made by James A. Woods (ames!jaw). Thank you -James! - -To compile compress: - - cc -O -DUSERMEM=usermem -o compress compress.c - -Where "usermem" is the amount of physical user memory available (in bytes). -If any physical memory is to be reserved for other processes, put in -"-DSACREDMEM sacredmem", where "sacredmem" is the amount to be reserved. - -The difference "usermem-sacredmem" determines the maximum BITS that can be -specified, and the cutoff bits where the large+fast table is used. - -memory: at least BITS cutoff ------- -- ----- ---- ------ - 4,718,592 16 13 - 2,621,440 16 12 - 1,572,864 16 11 - 1,048,576 16 10 - 631,808 16 -- - 329,728 15 -- - 178,176 14 -- - 99,328 13 -- - 0 12 -- - -The default memory size is 750,000 which gives a maximum BITS=16 and no -large+fast table. - -The maximum bits can be overruled by specifying "-DBITS=bits" at -compilation time. - -If your machine doesn't support unsigned characters, define "NO_UCHAR" -when compiling. - -If your machine has "int" as 16-bits, define "SHORT_INT" when compiling. - -After compilation, move "compress" to a standard executable location, such -as /usr/local. Then: - cd /usr/local - ln compress uncompress - ln compress zcat - -On machines that have a fixed stack size (such as Perkin-Elmer), set the -stack to at least 12kb. ("setstack compress 12" on Perkin-Elmer). - -Next, install the manual (compress.l). - cp compress.l /usr/man/manl - cd /usr/man/manl - ln compress.l uncompress.l - ln compress.l zcat.l - - - or - - - cp compress.l /usr/man/man1/compress.1 - cd /usr/man/man1 - ln compress.1 uncompress.1 - ln compress.1 zcat.1 - - regards, - petsd!joe - -Here is a note from the net: - ->From hplabs!pesnta!amd!turtlevax!ken Sat Jan 5 03:35:20 1985 -Path: ames!hplabs!pesnta!amd!turtlevax!ken -From: ken@turtlevax.UUCP (Ken Turkowski) -Newsgroups: net.sources -Subject: Re: Compress release 3.0 : sample Makefile -Organization: CADLINC, Inc. @ Menlo Park, CA - -In the compress 3.0 source recently posted to mod.sources, there is a -#define variable which can be set for optimum performance on a machine -with a large amount of memory. A program (usermem) to calculate the -useable amount of physical user memory is enclosed, as well as a sample -4.2bsd Vax Makefile for compress. - -Here is the README file from the previous version of compress (2.0): - ->Enclosed is compress.c version 2.0 with the following bugs fixed: -> ->1. The packed files produced by compress are different on different -> machines and dependent on the vax sysgen option. -> The bug was in the different byte/bit ordering on the -> various machines. This has been fixed. -> -> This version is NOT compatible with the original vax posting -> unless the '-DCOMPATIBLE' option is specified to the C -> compiler. The original posting has a bug which I fixed, -> causing incompatible files. I recommend you NOT to use this -> option unless you already have a lot of packed files from -> the original posting by thomas. ->2. The exit status is not well defined (on some machines) causing the -> scripts to fail. -> The exit status is now 0,1 or 2 and is documented in -> compress.l. ->3. The function getopt() is not available in all C libraries. -> The function getopt() is no longer referenced by the -> program. ->4. Error status is not being checked on the fwrite() and fflush() calls. -> Fixed. -> ->The following enhancements have been made: -> ->1. Added facilities of "compact" into the compress program. "Pack", -> "Unpack", and "Pcat" are no longer required (no longer supplied). ->2. Installed work around for C compiler bug with "-O". ->3. Added a magic number header (\037\235). Put the bits specified -> in the file. ->4. Added "-f" flag to force overwrite of output file. ->5. Added "-c" flag and "zcat" program. 'ln compress zcat' after you -> compile. ->6. The 'uncompress' script has been deleted; simply -> 'ln compress uncompress' after you compile and it will work. ->7. Removed extra bit masking for machines that support unsigned -> characters. If your machine doesn't support unsigned characters, -> define "NO_UCHAR" when compiling. -> ->Compile "compress.c" with "-O -o compress" flags. Move "compress" to a ->standard executable location, such as /usr/local. Then: -> cd /usr/local -> ln compress uncompress -> ln compress zcat -> ->On machines that have a fixed stack size (such as Perkin-Elmer), set the ->stack to at least 12kb. ("setstack compress 12" on Perkin-Elmer). -> ->Next, install the manual (compress.l). -> cp compress.l /usr/man/manl - or - -> cp compress.l /usr/man/man1/compress.1 -> ->Here is the README that I sent with my first posting: -> ->>Enclosed is a modified version of compress.c, along with scripts to make it ->>run identically to pack(1), unpack(1), an pcat(1). Here is what I ->>(petsd!joe) and a colleague (petsd!peora!srd) did: ->> ->>1. Removed VAX dependencies. ->>2. Changed the struct to separate arrays; saves mucho memory. ->>3. Did comparisons in unsigned, where possible. (Faster on Perkin-Elmer.) ->>4. Sorted the character next chain and changed the search to stop ->>prematurely. This saves a lot on the execution time when compressing. ->> ->>This version is totally compatible with the original version. Even though ->>lint(1) -p has no complaints about compress.c, it won't run on a 16-bit ->>machine, due to the size of the arrays. ->> ->>Here is the README file from the original author: ->> ->>>Well, with all this discussion about file compression (for news batching ->>>in particular) going around, I decided to implement the text compression ->>>algorithm described in the June Computer magazine. The author claimed ->>>blinding speed and good compression ratios. It's certainly faster than ->>>compact (but, then, what wouldn't be), but it's also the same speed as ->>>pack, and gets better compression than both of them. On 350K bytes of ->>>unix-wizards, compact took about 8 minutes of CPU, pack took about 80 ->>>seconds, and compress (herein) also took 80 seconds. But, compact and ->>>pack got about 30% compression, whereas compress got over 50%. So, I ->>>decided I had something, and that others might be interested, too. ->>> ->>>As is probably true of compact and pack (although I haven't checked), ->>>the byte order within a word is probably relevant here, but as long as ->>>you stay on a single machine type, you should be ok. (Can anybody ->>>elucidate on this?) There are a couple of asm's in the code (extv and ->>>insv instructions), so anyone porting it to another machine will have to ->>>deal with this anyway (and could probably make it compatible with Vax ->>>byte order at the same time). Anyway, I've linted the code (both with ->>>and without -p), so it should run elsewhere. Note the longs in the ->>>code, you can take these out if you reduce BITS to <= 15. ->>> ->>>Have fun, and as always, if you make good enhancements, or bug fixes, ->>>I'd like to see them. ->>> ->>>=Spencer (thomas@utah-20, {harpo,hplabs,arizona}!utah-cs!thomas) ->> ->> regards, ->> joe ->> ->>-- ->>Full-Name: Joseph M. Orost ->>UUCP: ..!{decvax,ucbvax,ihnp4}!vax135!petsd!joe ->>US Mail: MS 313; Perkin-Elmer; 106 Apple St; Tinton Falls, NJ 07724 ->>Phone: (201) 870-5844 |