so... it appears that pitch slides in Genesis system aren't truly linear
instead, they are "kind of linear". the frequency isn't linear, and when
it overflows the range of an octave, the high bit changes and the
frequency is shifted right
- round to nearest instead of round to zero in SMS period calc
- implement arpeggio
- implement arp macro (kinda)
- polish the SMS platform
- correct the DIV_CMD_PITCH range to 1 semitone
- fix PSG volume in Genesis
- use a better register write strat in Genesis
- fix a bug caused by legacy code
- implement ECxx command
- implement EDxx command
- implement SN noise mode command
- vibrato table is now 64 positions long (instead of 60)
tildearrow