[SCV] Tone mode is broken

[freq-mod]

After the last commit, tone channels volume became extremely quiet, especially compared to noise channel. Then I made two instuments, one for beeper, other for upd noise... and tone channels just died. Completely.

.fur if you want to analyze - scvbug.fur.zip

p.S. Noise volume is also extremely weird, it changes the noise LFSR abit, but doesnt make the sound quieter or louder. Intended?

EDIT: bug is caused by setting volume macro to 0, then 1.

[freq-mod]

Ok, so I checked the SCV docs aaaand:

; |---------- PSG command ----------|

; initial byte: $01
; byte 1: Timbre          - %TTTPPPPP
; byte 2: Frequency       - %FFFFFFFF
; byte 3: Volume/Mode     - %---VVVVV
; byte 4: Square 1 Freq   - %FFFFFFFF
; byte 5: Square 2 Freq   - %FFFFFFFF
; byte 6: Square 3 Freq   - %FFFFFFFF
; byte 7: Square 1 Volume - %VVVVVVVV
; byte 8: Square 2 Volume - %VVVVVVVV
; byte 9: Square 3 Volume - %VVVVVVVV

; %---VVVVV - volume/mode will define which waveset to use, if it's 0, use the tone waveforms, if 1 to FF, use noise 'sawtooth' waveforms
; just like tone volume, this is loaded into Y register, causing the 3 top bits to be cropped out
; all Square volumes are uncapped because they're just load/not load conditions, no multiplication involved to crop the 3 MSBs

TL;DR: current furnace behaviour does not seem accurate.

[tildearrow]

Don't worry. I am still trying to improve the emilation core and left it in that state as I had to sleep.