Apple-2-SW
/
Applecorn
mirror of https://github.com/bobbimanners/Applecorn.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

More work on ADSR envelope.

This commit is contained in:
Bobbi Webber-Manners 2022-10-17 01:54:49 -04:00
parent 135bea7d2d
commit 5c67403cb4
2 changed files with 48 additions and 28 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

BIN
applecorn.po
View File

Binary file not shown.

76
mainmem.audio.s
View File

@ -403,8 +403,8 @@ ENSQISR INC COUNTER+0 ; Increment centisecond timer
STA CHANCTR,X ; Set envelope step counter to 1
STZ PITCHSECT,X ; Start on pitch section 0
STZ PITCHSTEP,X ; Start on step 0
STZ AMPSECT,X ; Start on amplitude section 0
LDA #$00 ; Initial amplitude is zero
LDA #$80 ; TEMPORARY HACK!!!
PHA ; Zero amplitude to stack
:S2 JSR REMAUDIO ; Remove byte from queue
@ -562,42 +562,62 @@ ADSRENV LDA CHANENV,X ; Set envelope number
BEQ :SUSTAIN ; Sustain, encoded as 2
* TODO: RELEASE logic here
RTS
:ATTACK LDY #ENVALA ; Parm: level at end of attack
:ATTACK LDY #ENVAA ; Parm: attack change/step
LDA (A1L),Y ; Get value of parm
CMP CURRAMP,X ; Compare with current level
BEQ :NEXTSECT ; If we are target, decay
LDY #ENVAA ; Parm: attack change/step
PHA
LDY #ENVALA ; Parm: level at end of attack
LDA (A1L),Y ; Get value of parm
CLC
ADC CURRAMP,X ; Add change to current amp
BCS :CLAMPALA ; If wrapped, clamp sum to max
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
PLY
JSR ADSRPHASE ; Generic ADSR phase handler
BCS :NEXTSECT ; Phase done -> decay
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
: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
:NEXTSECT INC AMPSECT,X ; Next section
RTS
* Update volume. Called by ADSRENV.
* On entry: A - Change of volume/step, X is audio channel #
* X is preserved
*UPDVOL STX OSCNUM
* CLC
* ADC CURRAMP,X ; Add change to current
* STA CURRAMP,X ; Update
* TAY
* JSR ENSQAMP ; Update Ensoniq regs
* RTS
* 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
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
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 ...