Rex (Side A): Routine at D6DB

D6DB: Configure note for current channel

Used by the routine at D68C.

Input
IX	address pointer to channel data buffer

D6DB

LD A,(IX+$00)

Return if channel is not active

D6DE

CP $FF

D6E0

RET Z

D6E1

CALL $D744

Send channel volume command

D6E4

CALL $D759

Send channel volume command

D6E7

LD L,(IX+$02)

Set IY to the address pointer for the sound data

D6EA

LD H,(IX+$03)

D6ED

PUSH HL

D6EE

POP IY

D6F0

DEC (IX+$01)

Decrement variation counter

D6F3

JP Z,$D715

If counter is 0 jump to configure next note

D6F6

LD E,(IY+$01)

Set BC value of pitch and coarse delta

D6F9

LD C,E

D6FA

RL E

D6FC

SBC A,A

D6FD

LD B,A

D6FE

LD L,(IX+$04)

Increment pitch and coarse data for tone/noise

D701

LD H,(IX+$05)

D704

ADD HL,BC

D705

LD (IX+$04),L

D708

LD (IX+$05),H

D70B

LD A,(IX+$07)

Increment/decrement volume

D70E

ADD A,(IY+$02)

D711

LD (IX+$07),A

D714

RET

check if there are more tones

D715

DEC (IX+$00)

Decrement tones number?

D718

JP Z,$D733

if zero jump to disable channel

D71B

INC IY

Point IY to the next tone data

D71D

INC IY

D71F

INC IY

D721

PUSH IY

Update address pointer to tone data

D723

POP HL

D724

LD (IX+$02),L

D727

LD (IX+$03),H

D72A

LD A,(IY+$00)

Set new variation counter

D72D

LD (IX+$01),A

D730

JP $D6DB

Configure next tone

disable channel

D733

LD A,($D857)

Set volume to zero for current channel

D736

ADD A,$07

D738

LD D,A

D739

LD E,$00

D73B

CALL $D759

Send volume command

D73E

LD A,$FF

Disable current channel

D740

LD (IX+$00),A

D743

RET