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ADSR refactoring.

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Bobbi Webber-Manners 2022-10-18 00:15:39 -04:00
parent 5c67403cb4
commit 2eb2bb82f9
2 changed files with 18 additions and 11 deletions
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applecorn.po
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29
mainmem.audio.s
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@ -487,7 +487,7 @@ GETENVADDR LDA #<ENVBUF0 ; Copy ENVBUF0 to A1L,A1H
* Process pitch envelope
* On entry: X is audio channel #
* X is preserved
PITCHENV LDA CHANENV,X ; Set envelope number
PITCHENV LDA CHANENV,X ; Get envelope number
TAY
JSR GETENVADDR ; Addr of envelope -> A1L,A1H
LDA PITCHSECT,X ; See what section we are in
@ -551,7 +551,7 @@ UPDPITCH STX OSCNUM
* Process amplitude envelope
* On entry: X is audio channel #
* X is preserved
ADSRENV LDA CHANENV,X ; Set envelope number
ADSRENV LDA CHANENV,X ; Get envelope number
TAY
JSR GETENVADDR ; Addr of envelope -> A1L,A1H
LDA AMPSECT,X ; See what section we are in
@ -577,14 +577,14 @@ ADSRENV LDA CHANENV,X ; Set envelope number
LDY #ENVALD ; Parm: level at end of delay
LDA (A1L),Y ; Get value of parm
PLY
* JSR ADSRPHASE ; Generic ADSR phase handler
JSR ADSRPHASE ; Generic ADSR phase handler
BCS :NEXTSECT ; Phase done -> sustain
RTS
:SUSTAIN LDY #ENVAS ; Parm: delay change/step
LDA (A1L),Y ; Get value of parm
TAY
LDA #$00 ; Target level zero
* JSR ADSRPHASE ; Generic ADSR phase handler
JSR ADSRPHASE ; Generic ADSR phase handler
RTS
:NEXTSECT INC AMPSECT,X ; Next section
RTS
@ -593,21 +593,28 @@ ADSRENV LDA CHANENV,X ; Set envelope number
* Handle any individual phase of the ADSR envelope. Called by ADSRENV.
* On entry: A - level at end of phase, X - audio channel, Y - change/step
* On return: CS if end of phase, CC otherwise. X preserved.
ADSRPHASE CMP CURRAMP,X ; Compare tgt with current level
ADSRPHASE STX OSCNUM
STA :TARGET ; Stash target level for later
CPY #$00 ; Check sign of change/step
BMI :DESCEND ; Descending amplitude
:ASCEND CMP CURRAMP,X ; Compare tgt with current level
BNE :S1 ; Not equal to target, keep going
SEC ; CS to indicate phase is done
RTS
:S1 STA :TARGET ; Target level
TYA ; Change/step -> A
:S1 TYA ; Change/step -> A
CLC
ADC CURRAMP,X ; Add change to current amp
BCS :CLAMP ; If wrapped, clamp to target
CPY #$00 ; Check sign of change/step
BMI :DESCEND ; Descending amplitude
CMP :TARGET ; Compare with target
BCS :CLAMP ; If target < sum, clamp to target
BRA :UPDATE
:DESCEND CMP :TARGET ; Compare with target
:DESCEND CMP CURRAMP,X ; Compare tgt with current level
BNE :S2 ; Not equal to target, keep going
SEC ; CS to indicate phase is done
RTS
:S2 TYA ; Change/step -> A
CLC
ADC CURRAMP,X ; Add change to current amp
CMP :TARGET ; Compare with target
BCC :CLAMP ; If target >= sum, clamp to target
BRA :UPDATE
:CLAMP LDA :TARGET ; Recover target level