Re: [f-cpu] Are 8 bits SIMD mode usefull ?

[Antoine <antoine@rezo.net>]

Hi,

Le ven 10/01/2003 à 21:37, nico a écrit :
> Just a stupid question : is 8 bits integer mode usefull ?

I think so ;)

> "Char" C type are going to be 16 bits (unicode)

The most widely used encoding of unicode, UTF-8, is based on regular
bytes (it's a variable length encoding backwards compatible with
Ascii). That means both legacy character strings and unicode strings 
will use byte operations. Protocol networks, compression formats will 
also remain byte-based. And so on ;)

> Gimp use 16 bit per channel

I think that's false, that's even why Film Gimp exists (movie guys
need more than 8 bits per channel and Gimp can't satisfy their needs).
However even if Gimp can do 16 bits per channel, most images will still
only require 8 bits per channel, leading to more compact representations
and faster calculations (and less memory transfers ;-)).

Also if you think SIMD in stuff like GIMP, operations with 8-bit
per channel will be twice faster than with 16-bit channel (because
your registers have a fixed size and you can stuff twice more bytes
than 16-bit integers into a register).

Hey, if you wanna write an x86 emulator for F-CPU, you'll also need 
bytes :-)))

Regards

Antoine.


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