[linux-audio-dev] Channels and best practice

[James Courtier-Dutton]

Jussi Laako wrote:
> On Sun, 2005-11-20 at 12:54 +1100, Dave Robillard wrote:
> 
>>Out of curiosity, how expensive is this runtime architechture check?
> 
> 
> It's done only once at initialization time and even there it's matter of
> < 100 machine instructions.
> 
> At runtime the cost is doing integer comparison.
> 
> 
For multimedia applications, one crafts a different entire function per 
CPU type. One then simply uses function pointers to select the best 
function at init stage. This therefore results in a jump without a 
comparison.
For example, A resampling routine. There is a CPU specific function to 
handle a block of samples, so the extra "jump" cost is only used per 
sample block, and not per SIMD instruction.

James