todo.txt

Issues: 
- Testbench UART reader does not handle error replies well.
- software reset does not work well.
- Reading back pitch does not work correctly.

Features:
- envelope looping
- legato/slew limiter
- better filter
- LFO: delayed start
- ring modulator 
- LFO: single cycle mode (only in trigger mode)
- more waveforms 
- high frequency LFO mode
- Step like frame interpolation
- filter: allow filter to open further
- better noise source
- envelope parameters as mod destinations
- double click to disable mod in mod matrix
- spectrum analyzer
- add volume control (not voice mixer base value)
- mutiplicative mod mappings? Can cause problems with sign

Optimizations:
- LFO: use smaller phase accumulator to allow natural overflow.
- Replace output buffers by using accumulators e.g. directly.
- Table address generator can be unified (really?).
- Mod matrix could reuse mod value register array and multiplex multipliers.
- Use less bits for phase registers in envelope (32) and lfo (48).
- serializing table_address_generator output could reduce the 10k flipflops with a factor 64.

Open Problems:
- integrating midi velocity in the voice mixer (mapping to sustain works).
- Hardwire envelope 0 to volume? Would enable better voice muting based on envelope active.
  -> replace volume base value with envelope 0 in mod matrix.