sceSasSetGrain took no validation at all, unlike sceSasInit's grain
size check - a bad value could both throw on SasInstance::SetGrainSize's
allocation and, for a moderately large but successfully-allocated
value beyond PSP_SAS_MAX_GRAIN, read out of bounds of the fixed-size
mixTemp_ buffer during mixing. Apply the same bounds sceSasInit uses.
SasReverb::SetPreset() only checked the upper bound of `preset` before
indexing presets[], not the lower bound (-1 means "off"). The only
live HLE entry point (sceSasRevType) already clamps to [-1, 8], but
DoState() passes a savestate-deserialized value straight through with
no revalidation, so a corrupted/malicious savestate could index
presets[] negatively.
Previously, it sounded horrible in Sol Trigger - can be observed in
tutorial boxes when going into battle, for example, and also several other
effects. Halving this value sounds a lot more correct.
It's not clear what value exactly is correct.
Added a bit of code that only enables it when a reverbed sound is active. This will need to be turned off later but useful right now for hearing when it's used..
Henrik Rydgård