Re: [pclasses-devel] IOFilters / ZLibIOFilter

[Christian P. <cp...@se...>]

Am Freitag 07 Januar 2005 18:05 schrieb stephan beal:
> Don't forget to update the manual ;).
> (Just kidding - i'll do that if you don't want to.)

if you would be so kind ;-)
my documentation english sucks.

> AFAIK zlib has gzip_xxx() functions, but i *think* it only has file
> variants, not in-memory variants.

i've used zlib "low-level" API. gz_xxx are all operating on an file 
descriptor.

> That's exactly what i'm thinking. i have LGPL code for std::i/ostreams
> which use gzip and bzip2 (i didn't write the gzip support, and bzip2
> was simply a copy/paste plus a one-line change). These should be fairly
> trivial to port to FileStream subclasses. In fact, since they're
> already std::i/ostream[buffers], they may be usable as-is in P, after
> renaming them for P convensions.

BZip2IOFilter is already in CVS.

Problem with i/ostream[buffers] is .. that they only will be usable when using 
P::IO::IOStream. When using IOFilter's it will be transparent to IODevice and 
IOStream !

ZlibIOFilter gets a bit complicated... theire 3 different zlib format's out 
there:

1. zlib "raw" deflate format
2. zlib "deflate" format (header + zlib raw + trailer)  -> RFC 1950
3. gzip format (gzip header + zlib raw + trailer) -> RFC 1952

Based on the raw ZlibIOFilter i will implement zlib deflate and gzip formats.


Greetings,
Christian