"Nemosoft Unv." wrote:
>
> On 01-Jun-01 Ben Bridgwater wrote:
> > "Nemosoft Unv." wrote:
> >
> >> On 31-May-01 Ben Bridgwater wrote:
> > Not really - just add flags to indicate what processor attributes (MMX
> > etc) each converter needs, order the accelerated converters before the
> > others, then scan the list for the first matching one suported by the
> > actual processor attributes.
> >
> > I'm open to suggestion.
>
> I would simply replace the function pointer with the most optimized
> function during initialization; that way the logic in GetConvertor can be
> kept really simple (otherwise, you´d end up with a different GetConvertor on
> each platform!).
I don't see that. For example, If some converters are flagged as
requiring MMX, and a non-x86 CPU is detected by whatever means
(conditional compilation and/or /proc/cpuinfo), then the MMX processor
attribute would be set false and those converters would never match. Of
course we may or may not regardless have to do ./configure (not yet
supported!) based conditional compilation if gcc fails on assember that
doesn't match -mcpu/arch (I don't know what the behaviour is).
Let me see if I can get this out this weekend in it's current form, then
we'll have something more concrete to discuss.
> > For these formats "to" is useful for X display, and "from" is useful for
> > V4L and AVI. You're right that's the way it's implemented - as a bunch
> > of individual converters that cover the common XImage formats, but the
> > point is that the app can just do a dumb "descriptor.format = PackedRGB,
> > descriptor.r/g/b masks = XImage.r/g/b masks", then ask for a converter
> > to/from that format.
>
> So you have a ´general purpose´ convertor that can convert to almost
> anything (at the price of being slow, presumably)?
More importantly you have an application API that supports general
purpose image descriptors, and whether a particular conversion is
available is then just a library implementation issue. The application
isn't forced to consider individual formats unless it actually wants to.
Adding a fallback "general purpose" converter is simple - I'll add one
before I release it.
Ben
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