Probably you can make it even faster by avoiding the multiplication, like
unsigned int offset = 0;
for (i = 0; i < image.height; i++) {
dst[offset] = src[i];
offset += pitch;
}
More than two decades ago I learned to avoid mul and imul. Use shifts,
add and lea instead,
that was the credo those days. The name of the game was CP/M 80/86, a86,
d86 and ddt ;-)
But let´s get serious again.
Your proposed change of the patch results in a 21 ms performance
decrease on my system.
Yes, I do know that this is hard to believe. I tested a similar
variation before, and the results
were even worse.
Avoiding mul is a good idea in assembly language today, but often it is
better to write a
multiplication with the loop counter in C and not to introduce an extra
variable instead. The
compiler will optimize the code and it´s easier for gcc without that
extra variable.
More interesting would be the question what should be done for idx==2 or
idx==3. Probably
fb_pad_aligned_buffer() is also slower for those cases. But does anybody
use such fonts?
cu,
knut
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