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yabba

Section: User Commands (1)
Index

NAME

yabba - compress data with Y coding

whap - compress data with AP coding

SYNTAX

yabba[-mmem] [-znum] [-Zfuzz] [-qQv^rR] [-ACHUVW]

whap[-mmem] [-znum] [-Zfuzz] [-qQv^rR] [-ACHUVW]

DESCRIPTION

yabbacompresses its standard inputand writes the result to its standard output.yabbadfiles can be restoredwithunyabba.

whapis likeyabba,but uses AP coding.Warning: If you usewhapexcept for experimental use,you may be infringing upon a patent.

OptionsACHUVWprint the authorship notice,copyright notice,help notice,short usage summary,version number,and warranty information respectively.

yabbahas several flags:

: Produce output for memory sizemem.unyabbamust be given the same value ofmem.memcannot be larger than a value specified at compile-time;if you compress with amemlarger than the maximum value for thetargetunyabba,you will not be able to decompress the file.Typical values ofmemare 12000, 20000, 40000, 65533, 200000, 500000, and 1000000.
: Produce ``randomized'' output suitable for encryption.yabbawill introducepseudo-random bits of informationinto the output, and will leave off its usual output header.Normally, for efficiency and so thatyabbacan produce output before seeing the end of the input,compressed texts must have some slight output redundancy.Undermost of this redundancy disappearsand almost allY'dtexts are possible.Caveat: the beginningof the output depends onlyon the beginningof the input,so you should make suretoprecede the uncompressed inputby unpredictable databefore feeding it toyabba.
: Do not randomize output, and include the usual header.This is the default.
: yabbamaintains a``dictionary''of stringsadapted to the data seen so far.Whenyabbaruns out of memory (as specified byit will periodically test whether the compression ratio isgood enough.If not, it will adapt to the next ``block''of the fileby throwing out the dictionary and starting over.fuzzhas some vaguely defined effecton what ``good enough'' means;the higherfuzzis, the longeryabbawill hold out before clearing the dictionary.fuzzis 30 by default.
: numsets how oftenyabbawill check for clearing the dictionary.The default is every 8192 characters.
: yabbawill be ``verbose'' and report compression statisticsto standard error.
: Same asbut reports the percent saved rather than the percent left.
: Quiet.yabbawill not usestandard error in any way.
: Normal level of verbosity.

andchange the structure of the compressed file.Be careful to select the same flags forunyabba.

DIAGNOSTICS

In: xxx chars Out: xxx chars Y'd to: xx%: The utilizer of the computational machineryhas specified the ``verbose'' optiontoyabbavia theestablishment of the character vwithin an argumentpreceded by a hyphen.
fatal: output error: Self-explanatory.

EXIT CODE

0 normally, 1 for syntax errors or usage notices,2 for output errors.

FILES

None.

BUGS

None known.

VERSION

yabba 1.00, March 19, 1991.

AUTHOR

Placed into the public domain by Daniel J. Bernstein.

REFERENCES

D. J. Bernstein, ``Y coding.''Preprints available soon.

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