ROMManager: optimise ROMIcon function

Precompute all 16 5-bit RGB palette colours into 8-bit RGBA to avoid
repeated and superfluous calculation within the nested loop at the
point of index lookup.

A speedup was observed, from ~7ms, to a consistent 1ms
(i.e. now practically instantaneous) through timing with
std::chrono::high_resolution_clock.

Also improve comprehensibility, by using meaningful names, where
appropriate, for loop counter variables.

0 files changed, 0 insertions, 0 deletions