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The C Users' Group Library 1994 August
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1985-03-10
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2KB
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51 lines
The file LZWCOM.DOC is from Computer Language
Magazine's BBS system. A commentary on this
file compression technique appears in the March 1985
edition of that fine magazine.
This tech. is better than the Huffman codeing used
by the SQ-USQ utilities for Text and program source
for files smaller than about 40K. For instance the
file LZWCOM.DOC, that contains the .DOC and .C for
this system is 2K smaller when compressed with
LZWCOM.COM .
While I do not see the LZW system (in it's present
form) replaceing the SQ-USQ system, it shows promise
as a system embedded in other programs that store
and retrieve presentation text (message systems,
help texts, or any other indexable text), where the
8K or so of overhead code can be balenced against
saved secondary storage.
The modules in this Library were compiled with
Aztec C in 8080 mode (as opposed to the CZ compiler
option suggested in the .DOC file). I did this
because the Z80 option [in Axtec] only allows the
Z80s index regs (IX and IY) to be used as onboard
storage for register variables. And I didn't feel
that this small speed increase was worth excluding
folks with 8080s and 8085s from useing and testing
this new compression technique.
These modules just show the power of the LZW
technique. They leave implementation to the C
programmer. For instance making TypeLZW (an analog
to TYPESQ), by redirecting the output file to the
screen. And the Compressed files can be called
whatever you fancy they should be called. May I
offer a suggestion that they be given an extension
.cZc . as an analog to SQs .cQc .
Enjoy
David Giunti, March 10, 1985
One great thing about the Micro Revolution is that
things are always getting better! Today I found that
the author of this system has found a few possible
errors and so reloaded the LZW system to the CL BBS.
Not only the new code, but MS-DOS implementations as
well (sorry no 68K yet). Anyway, the new .C files,
the new .DOC file, AND the .EXEs are now in this
file squeezed with SQ.
Updating-ly your
Dave, March 21, 1985
the new .DOC file, AND the .EXEs are now in this
file squeezed w