[Spice-devel] [spice-common] Some steps toward quic_tmpl.c and quic_rgb_tmpl.c 'unification'

[Christophe Fergeau]

Any more thoughts/reviews on this series?

Christophe

On Wed, Jul 05, 2017 at 10:27:18AM -0400, Frediano Ziglio wrote:
> > 
> > Hey,
> > 
> > This is a v2 of the initial 2 patches, but looking a bit closer at the quic
> > code led me down a rabbit hole ;) We currently have 2 different quic
> > implementations using the preprocessor as a template engine. These 2
> > implementations are quic_tmpl.c which handles 1 byte and 4 bytes images,
> > and the quic_rgb_tmpl.c which handles 24bpp/32bpp/16bpp images.
> > 
> 
> Looks like this more than a series is a set of chained series dealing with
> 1- compiler problems
> 2- typos
> 3- removal obsolete stuff
> 4- code reuse/unification
> 
> I think 1) and 2) could be integrated straight forward. 3) requires
> mostly a team agreement that I don't think is hard to have, Quic is used
> only by Spice, already superseded by other encoding so I don't see any
> point keeping old dead code branches dealing with different settings.
> 
> > The main difference is that the former implementation handles a single
> > channel,
> > while the rgb implementation handles each color component separately. Besides
> > that,
> > the implementation is the same, but this is not obvious at all by just
> > comparing the
> > 2 files. This patch series makes the 2 files closer, but not easily mergeable
> > yet ;)
> > 
> > The biggest pending difference is that quic_tmpl.c carries around a 'channel'
> > with the data it needs, while quic_rgb_tmpl.c iterates over Encoder::channels
> > when needed.
> > 
> > This imo does not justify duplicating that much code, but I don't want to
> > spend
> > too much time on quic either, so I'll stop there for now :)
> > 
> > I've only tested the RGB32 case, as I'm not sure how to trigger the 1 byte or
> > 4
> > byte code paths (I've tried win7 and fedora 25 guests so far).
> > 
> > Christophe
> 
> The problem of point 4) is that is worth but if we are not sure we are
> not breaking stuff is not that great. We should have a test that test only
> image compression/decompression. I was trying to write a similar test
> for Windows agent for png using a mix of shell/ImageMagick/C code. Lost
> the commands I was using :-( but mainly in imagemagick there are some test
> images, I was taking these images with different formats (grey/palette/rgb/
> rgba and so on) and trying to compress -> uncompress checking that input
> and output was the same (as PNG is lossless).
> 
> Frediano
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