Problem when switching AR=0 tone

[okaxaki]

emu2413 v1.5.7 can not correctly perform ar0test.vgm.zip.

• emu2413: The tone is changed into pure sine from the 3rd note.
• real chip: The tone is changed into pure sine from the 4th note.

ar0test.vgm.zip is genarated from the following MGSDRV MML.

#opll_mode 1
#tempo 150

@v15 = { ;
;       TL FB
        63, 7,
; AR DR SL RR KL MT AM VB EG KR DT
  15, 0, 0,10, 0,15, 0, 0, 1, 0, 0,
  15, 0, 0,10, 0, 1, 0, 0, 1, 0, 0 }

@v16 = { ;
;       TL FB
        63, 7,
; AR DR SL RR KL MT AM VB EG KR DT
   0, 0, 0,10, 0,15, 0, 0, 1, 0, 0,
  15, 0, 0,10, 0, 1, 0, 0, 1, 0, 0 }

9 v15
9 @15 o4 c4 r4 c4 r4 @16 c4 r4 c4 r4

The intention of the MML above is to change the tone from the 3rd note.
The behavior of the real chip is counter-intuitive, but this should be emulated for accuracy.

[okaxaki]

Reopen: This is not fixed depends on register access timing.