Optimisation of the midi player, reducing the number of multiplications and memory accesses inside a very frequently executed loop, also does shifting of the whole sample when synthing is done which improves accurracy slightly, ~10% fewer buffer misses

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@14983 a1c6a512-1295-4272-9138-f99709370657
5 files changed