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First hack at attack envelope. Seems to work.

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Bobbi Webber-Manners 2022-10-16 18:10:25 -04:00
parent ba828c5ad4
commit 135bea7d2d
2 changed files with 69 additions and 4 deletions
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BIN
applecorn.po
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73
mainmem.audio.s
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@ -92,8 +92,21 @@ CURRPITCH DB $00
DB $00
DB $00
* Amplitude envelope section (0..4)
AMPSECT DB $00
DB $00
DB $00
DB $00
* Current amplitude
CURRAMP DB $00
DB $00
DB $00
DB $00
* Get address of sound buffer
* On entry: X is buffer number
* On entry: X is buffer number (4..7)
* On exit: A1L,A1H points to start of buffer
* Called with interrupts disabled
GETBUFADDR LDA :BUFADDRL,X
@ -401,6 +414,7 @@ ENSQISR INC COUNTER+0 ; Increment centisecond timer
STA CHANTIMES,X
PLA ; Recover frequency
STA CURRPITCH,X ; Store for pitch envelope
STZ CURRAMP,X ; Amp envelope starts at zero
PLY ; Recover amplitude
JSR ENSQNOTE ; Start note playing
:NEXT DEX
@ -537,15 +551,53 @@ UPDPITCH STX OSCNUM
* Process amplitude envelope
* On entry: X is audio channel #
* X is preserved
ADSRENV
ADSRENV LDA CHANENV,X ; Set envelope number
TAY
JSR GETENVADDR ; Addr of envelope -> A1L,A1H
LDA AMPSECT,X ; See what section we are in
BEQ :ATTACK ; Attack, encoded as 0
CMP #$01
BEQ :DECAY ; Decay, encoded as 1
CMP #$02
BEQ :SUSTAIN ; Sustain, encoded as 2
* TODO: RELEASE logic here
RTS
:ATTACK LDY #ENVALA ; Parm: level at end of attack
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
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
RTS
:DECAY
RTS
:SUSTAIN
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
RTS
*UPDVOL STX OSCNUM
* CLC
* ADC CURRAMP,X ; Add change to current
* STA CURRAMP,X ; Update
* TAY
* JSR ENSQAMP ; Update Ensoniq regs
* RTS
*****************************************************************************
* Ensoniq DOC Driver for Apple IIGS Follows ...
@ -689,6 +741,19 @@ ENSQFREQ PHX
RTS
* Adjust amplitude of note already playing
* On entry: Y - amplitude to set
* Preserves X & Y
ENSQAMP PHX
PHY ; Gonna need it again
LDA #$40 ; DOC register base $00 (Freq Lo)
JSR ADDOSC ; Actual register in X
JSR ENSQWRTDOC
PLY
PHY
RTS
* Add oscillator number to value in A, return sum in X
* Used by ENSQNOTE & ENSQFREQ
ADDOSC CLC