20 Nov
2005
20 Nov
'05
7:22 a.m.
Jussi Laako wrote:
On Sun, 2005-11-20 at 12:54 +1100, Dave Robillard
wrote:
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
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.