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More work on ADSR envelope.

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Bobbi Webber-Manners 2022-10-17 01:54:49 -04:00
parent 135bea7d2d
commit 5c67403cb4
2 changed files with 48 additions and 28 deletions
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applecorn.po
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76
mainmem.audio.s
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@ -403,8 +403,8 @@ ENSQISR INC COUNTER+0 ; Increment centisecond timer
STA CHANCTR,X ; Set envelope step counter to 1 STA CHANCTR,X ; Set envelope step counter to 1
STZ PITCHSECT,X ; Start on pitch section 0 STZ PITCHSECT,X ; Start on pitch section 0
STZ PITCHSTEP,X ; Start on step 0 STZ PITCHSTEP,X ; Start on step 0
STZ AMPSECT,X ; Start on amplitude section 0
LDA #$00 ; Initial amplitude is zero LDA #$00 ; Initial amplitude is zero
LDA #$80 ; TEMPORARY HACK!!!
PHA ; Zero amplitude to stack PHA ; Zero amplitude to stack
:S2 JSR REMAUDIO ; Remove byte from queue :S2 JSR REMAUDIO ; Remove byte from queue
@ -562,42 +562,62 @@ ADSRENV LDA CHANENV,X ; Set envelope number
BEQ :SUSTAIN ; Sustain, encoded as 2 BEQ :SUSTAIN ; Sustain, encoded as 2
* TODO: RELEASE logic here * TODO: RELEASE logic here
RTS RTS
:ATTACK LDY #ENVALA ; Parm: level at end of attack :ATTACK LDY #ENVAA ; Parm: attack change/step
LDA (A1L),Y ; Get value of parm LDA (A1L),Y ; Get value of parm
CMP CURRAMP,X ; Compare with current level PHA
BEQ :NEXTSECT ; If we are target, decay LDY #ENVALA ; Parm: level at end of attack
LDY #ENVAA ; Parm: attack change/step
LDA (A1L),Y ; Get value of parm LDA (A1L),Y ; Get value of parm
CLC PLY
ADC CURRAMP,X ; Add change to current amp JSR ADSRPHASE ; Generic ADSR phase handler
BCS :CLAMPALA ; If wrapped, clamp sum to max BCS :NEXTSECT ; Phase done -> decay
LDY #ENVALA ; Parm: level of end of attack
CMP (A1L),Y ; Compare sum with parm
BCS :CLAMPALA ; If parm < sum, clamp sum to max
BRA :UPDATT
:CLAMPALA LDA (A1L),Y ; Clamp sum to max
:UPDATT STA CURRAMP,X ; Store updated amplitude
TAY ; Tell the Ensoniq
JSR ENSQAMP
RTS RTS
:DECAY :DECAY LDY #ENVAD ; Parm: delay change/step
LDA (A1L),Y ; Get value of parm
PHA
LDY #ENVALD ; Parm: level at end of delay
LDA (A1L),Y ; Get value of parm
PLY
* JSR ADSRPHASE ; Generic ADSR phase handler
BCS :NEXTSECT ; Phase done -> sustain
RTS RTS
:SUSTAIN :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
RTS RTS
:NEXTSECT INC AMPSECT,X ; Next section :NEXTSECT INC AMPSECT,X ; Next section
RTS RTS
* Update volume. Called by ADSRENV. * Handle any individual phase of the ADSR envelope. Called by ADSRENV.
* On entry: A - Change of volume/step, X is audio channel # * On entry: A - level at end of phase, X - audio channel, Y - change/step
* X is preserved * On return: CS if end of phase, CC otherwise. X preserved.
*UPDVOL STX OSCNUM ADSRPHASE CMP CURRAMP,X ; Compare tgt with current level
* CLC BNE :S1 ; Not equal to target, keep going
* ADC CURRAMP,X ; Add change to current SEC ; CS to indicate phase is done
* STA CURRAMP,X ; Update RTS
* TAY :S1 STA :TARGET ; Target level
* JSR ENSQAMP ; Update Ensoniq regs TYA ; Change/step -> A
* RTS 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
BCC :CLAMP ; If target >= sum, clamp to target
BRA :UPDATE
:CLAMP LDA :TARGET ; Recover target level
:UPDATE STA CURRAMP,X ; Store updated amplitude
TAY ; Tell the Ensoniq
JSR ENSQAMP
CLC ; CC to indicate phase continues
RTS
:TARGET DB $00
***************************************************************************** *****************************************************************************
* Ensoniq DOC Driver for Apple IIGS Follows ... * Ensoniq DOC Driver for Apple IIGS Follows ...