[sdiy] In praise of the ATM STM32F303

[Olivier Gillet]

16384 16-bit words, Q4.12 (converted to/from float during processing -
ie the memory 16-bit word stores x * 4096.0f).

I don't remember if this is because I needed a bit of headroom, or if
I liked the "wash" of the truncation noise I got. Probably a
compromise between both.

Originally, I tried to use the same kind of 14-bit floating point
format used in the FV-1 (since I used the FV-1 to prototype the
effects in Clouds/Elements), but the decompression/compression was
extremely costly.