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Further work on ENVELOPE data structures.

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Bobbi Webber-Manners 2022-10-15 02:35:21 -04:00
parent 7ef3eaf70f
commit 30119703d3
2 changed files with 24 additions and 3 deletions
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applecorn.po
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27
mainmem.audio.s
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@ -393,7 +393,7 @@ ENSQISR INC COUNTER+0 ; Increment centisecond timer
* Handle envelope tick counter
* On entry: X is audio channel #
* On exit: CS if this cycle is a tick, CC otherwise.
* On return: CS if this cycle is a tick, CC otherwise.
ENVTICKS DEC CHANCTR,X ; Decrement counter
BEQ :ZERO ; Expired
CLC ; Not expired
@ -406,13 +406,34 @@ ENVTICKS DEC CHANCTR,X ; Decrement counter
* Reset envelope tick counter
* On entry: X is audio channel #
RSTTICKS LDA CHANENV,X ; Get envelope number
* TODO: Just assume ENV0 for now ... need some indexing
LDA ENVBUF0+ENVT ; Length of each step
TAY
JSR GETENVADDR ; Envelope address in A1L,A1H
LDY ENVT ; Parm for length of each step
LDA (A1L),Y ; Get value of parm
AND #$7F ; Mask out MSB
STA CHANCTR,X ; Reset counter
RTS
* On entry: Y is envelope number
* On return: A1L,A1H point to start of buffer for this envelope
GETENVADDR LDA #<ENVBUF0 ; Copy ENVBUF0 to A1L,A1H
STA A1L
LDA #>ENVBUF0
STA A1H
:L1 CPY #$00 ; See if Y is zero
BEQ :DONE ; If so, we are done
LDA A1L ; Add 13 to A1L,A1H
CLC
ADC #13
STA A1L
LDA A1H
ADC #00
STA A1H
DEY ; Decr envelopes remaining
BRA :L1 ; Go again
:DONE RTS
* Process pitch envelope
PITCHENV
RTS