More groundwork for ENVELOPE. Volume is now 0 to -15, like Beeb.
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Bobbi Webber-Manners
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applecorn.po
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applecorn.po
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104
mainmem.audio.s
104
mainmem.audio.s
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@ -50,7 +50,19 @@ ENVALA EQU 11 ; Target at end of attack
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ENVALD EQU 12 ; Target at end of decay
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* Time remaining for current note, in 1/20th of second
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OSCTIMES DB $00
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CHANTIMES DB $00
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DB $00
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DB $00
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DB $00
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* Envelope number for current note. $FF if no envelope.
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CHANENV DB $00
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DB $00
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DB $00
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DB $00
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* Envelope step counter for current note.
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CHANCTR DB $00
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DB $00
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DB $00
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DB $00
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@ -209,7 +221,7 @@ CNP PHP ; Preserve flags
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RTS
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:PURGE LDA ENDINDICES,X ; Eat all buffer contents
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STA STARTINDICES,X
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STZ OSCTIMES-4,X ; Set to zero time remaining
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STZ CHANTIMES-4,X ; Set to zero time remaining
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PLP ; Recover flags
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RTS
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@ -293,14 +305,14 @@ ENSQISR INC COUNTER+0 ; Increment centisecond timer
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BNE :S1
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INC COUNTER+1
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:S1 DEC :CNT ; Find every 5th cycle
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BNE :NOT20HZ
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BNE :AT100HZ
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LDA #5
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STA :CNT
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LDX #3 ; Process four audio queues
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:L1 LDA OSCTIMES,X ; Time remaining on current note
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:L1 LDA CHANTIMES,X ; Time remaining on current note
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BEQ :NONOTE ; No note playing
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DEC OSCTIMES,X
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DEC CHANTIMES,X
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BRA :NEXT
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:NONOTE LDY #$00 ; Zero volume
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LDA #$00 ; Zero freq
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@ -312,7 +324,7 @@ ENSQISR INC COUNTER+0 ; Increment centisecond timer
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AND #$0F ; Mask out hold nybble
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BNE :SYNCSET ; Do not play if sync != 0
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* The following is paranoid maybe. Perhaps can be removed once I am debugged.
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* The following is paranoid maybe. Perhaps can be removed once I am debugged. ***
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PHX
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PHY
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INX ; Convert audio channel to buf num
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@ -327,25 +339,51 @@ ENSQISR INC COUNTER+0 ; Increment centisecond timer
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PLX
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CMP #3 ; At least 4 bytes used?
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BMI :NEXT
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* End paranoid section.
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* End paranoid section. ***
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JSR REMAUDIO ; Remove byte from queue
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JSR REMAUDIO ; Remove byte from queue
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PHY ; Amplitude
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JSR REMAUDIO ; Remove byte from queue
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TYA ; Amplitude or envelope -> A
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DEC A
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BPL :HASENV ; If +ve, value was 1,2,3..
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INC A
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EOR #$FF ; Negate A
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INC A ; ..
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ASL ; Multiply by 16
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ASL
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ASL
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ASL
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PHA ; Amplitude to stack
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LDA #$FF ; $FF means 'no envelope'
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STA CHANENV,X
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BRA :S2
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:HASENV STA CHANENV,X ; Store envelope number
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STZ CHANCTR,X ; Reset envelope step counter
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LDA #$00 ; Initial amplitude is zero
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PHA ; Zero amplitude to stack
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:S2 JSR REMAUDIO ; Remove byte from queue
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PHY ; Frequency
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JSR REMAUDIO ; Remove byte from queue
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TYA ; Duration
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STA OSCTIMES,X
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STA CHANTIMES,X
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PLA ; Recover frequency
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PLY ; Recover amplitude
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JSR ENSQNOTE ; Start note playing
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:NEXT DEX
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BPL :L1 ; Next audio queue
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:NOT20HZ
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*
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* TODO: Envelope processing on all cycles (AT 100Hz)
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*
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:AT100HZ ; Here on every call (100Hz)
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LDX #3 ; Iterate through channels
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:L2 LDA CHANENV,X ; Envelope for this channel?
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BMI :NOENV ; $FF means no envelope
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JSR ENVTICKS ; Handle envelope tick counter
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BCC :NOENV ; This cycle is not a tick
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JSR PITCHENV ; Process pitch envelope
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JSR ADSRENV ; Process amplitude envelope
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:NOENV DEX
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BPL :L2 ; Next audio queue
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CLC
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RTL
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:SYNCSET JSR CHORD ; See if chord can be released
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@ -353,6 +391,42 @@ ENSQISR INC COUNTER+0 ; Increment centisecond timer
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:CNT DB $05 ; Used to determine 20Hz cycles
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* Handle envelope tick counter
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* On entry: X is audio channel #
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* On exit: CS if this cycle is a tick, CC otherwise.
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ENVTICKS DEC CHANCTR,X ; Decrement counter
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BEQ :ZERO ; Expired
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CLC ; Not expired
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RTS
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:ZERO JSR RSTTICKS ; Reset counter
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SEC ; Counter had expired
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RTS
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* Reset envelope tick counter
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* On entry: X is audio channel #
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RSTTICKS LDA CHANENV,X ; Get envelope number
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* TODO: Just assume ENV0 for now ... need some indexing
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LDA ENVBUF0+ENVT ; Length of each step
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AND #$7F ; Mask out MSB
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STA CHANCTR,X ; Reset counter
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RTS
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* Process pitch envelope
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PITCHENV
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RTS
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* Process amplitude envelope
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ADSRENV
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RTS
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*****************************************************************************
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* Ensoniq DOC Driver for Apple IIGS Follows ...
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*****************************************************************************
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* Ensoniq control registers
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ENSQSNDCTL EQU $C03C
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ENSQSNDDAT EQU $C03D
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@ -412,7 +486,7 @@ ENSQSILENT LDY #$00 ; Amplitude
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LDA #$80 ; Frequency
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LDX #$03
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:L1 JSR ENSQNOTE ; Initialize channel Y
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STZ OSCTIMES,X ; No note playing
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STZ CHANTIMES,X ; No note playing
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DEX
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BPL :L1
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RTS
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