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Work-in-progress, noise channel for Ensoniq.

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Bobbi Webber-Manners 2022-11-25 19:19:09 -05:00
parent 5ccc5e47af
commit b2da3c705c
3 changed files with 108 additions and 6 deletions
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BIN
applecorn.po
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2
auxmem.init.s
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@ -290,7 +290,7 @@ BYTE00 BEQ BYTE00A ; OSBYTE 0,0 - generate error
RTS ; %000x1xxx host type, 'A'pple
BYTE00A BRK
DB $F7
HELLO ASC 'Applecorn MOS 2022-11-24'
HELLO ASC 'Applecorn MOS 2022-11-25'
DB $00 ; Unify MOS messages
* TO DO: Move into RAM
GSSPEED DB $00 ; $80 if GS is fast, $00 for slow

112
mainmem.ensq.s
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@ -20,24 +20,81 @@ ENSQINIT LDX #3
DEX
BNE :L0
* One cycle of square wave for 256 samples
* Starts at address $0000 in DOC RAM
LDA ENSQSNDCTL ; Get settings
ORA #$60 ; DOC RAM, autoincrement on
STA ENSQSNDCTL ; Set it
LDA #$00
STA ENSQADDRL ; DOC RAM addr $0000
STA ENSQADDRH ; DOC RAM addr $0000
LDA #120 ; High value of square wave
LDA #210 ; High value of square wave
LDX #$00
:L1 STA ENSQSNDDAT ; 128 cycles of high value
INX
CPX #128
BNE :L1
LDA #80 ; Low value of square wave
LDA #40 ; Low value of square wave
:L2 STA ENSQSNDDAT ; 128 cycles of low value
INX
CPX #0
BNE :L2
* One cycle of pulse wave for 256 samples
* Starts at $0100 in DOC RAM
LDA #210 ; High value of square wave
LDX #$00
:L3 STA ENSQSNDDAT ; 128 cycles of high value
INX
CPX #128
BNE :L3
LDA #40 ; Low value of square wave
:L4 STA ENSQSNDDAT ; 128 cycles of low value
INX
CPX #0
BNE :L4
* Random waveform for 256 samples
* Starts at $0200 in DOC RAM
LDY #$00
:L5 LDA $E000,Y ; Read ROM code as 'random' data
BNE :S1 ; Filter out zeros
LDA #$01 ; Change 0 -> 1
:S1 STA ENSQSNDDAT
INY
CPY #0
BNE :L5
* One cycle of pulse wave for 4096 samples
** Starts at address $1000 in DOC RAM
* LDA ENSQSNDCTL ; Get settings
* ORA #$60 ; DOC RAM, autoincrement on
* STA ENSQSNDCTL ; Set it
* LDA #$00
* STA ENSQADDRL ; DOC RAM addr $1000
* LDA #$10
* STA ENSQADDRH ; DOC RAM addr $1000
* LDA #210 ; High value of pulse wave
* LDX #$00
*:L3 STA ENSQSNDDAT ; 128 cycles of high value
* INX
* CPX #128
* BNE :L3
* LDA #40 ; Low value of pulse wave
*:L4 STA ENSQSNDDAT ; 128 cycles of low value
* INX
* CPX #0
* BNE :L4
* LDY #$00
*:L6 LDX #$00
*:L5 STA ENSQSNDDAT ; 256 cycles of low value
* INX
* CPX #0
* BNE :L5
* INY
* CPY #16 ; Do it 15 times
* BNE :L6
LDA #$5C ; GS IRQ.SOUND initialization
STAL $E1002C
LDA #<ENSQISR
@ -85,6 +142,9 @@ ENSQNOTE PHA
PHY
STX OSCNUM ; Stash oscillator number 0-3
CPX #$00
BEQ :NOISE ; Oscillator 0 is noise channel
PHA ; Stash orig freq
TAY
LDA EFREQLOW,Y
@ -112,17 +172,59 @@ ENSQNOTE PHA
JSR ADDOSC ; Actual register in X
JSR ENSQWRTDOC
LDY #$00 ; For 256 byte wavetable, res 0
LDA #$C0 ; DOC register base $C0 (WT size)
JSR ADDOSC ; Actual register in X
JSR ENSQWRTDOC
LDY #$00 ; Free run, no IRQ, start
LDA #$A0 ; DOC register base $A0 (Control)
JSR ADDOSC ; Actual register in X
JSR ENSQWRTDOC
LDY #$00 ; For 256 byte wavetable
LDA #$C0 ; DOC register base $C0 (WT size)
JSR ADDOSC ; Actual register in X
BRA :DONE
:NOISE PHA ; Preserve value of parameter P
AND #$04 ; 'Periodic noise' or 'white noise'?
BEQ :S1
LDY #$02 ; DOC RAM $0200 - white noise
BRA :S2
:S1 LDY #$01 ; DOC RAM $0100 - periodic noise
:S2 LDX #$80 ; Wavetable pointer Register
JSR ENSQWRTDOC
PLA ; Restore P
AND #$03 ; Keep least significant 2 bits
TAX
LDA #$40
:L1 CPX #$00
BEQ :S3
LSR
DEX
BRA :L1
:S3 TAY ; Computed frequency value
LDX #$20 ; Freq Hi Register
JSR ENSQWRTDOC
LDX #$00 ; Freq Lo Register
LDY #$00 ; Value
JSR ENSQWRTDOC
LDX #$40 ; Amplitude Register
PLY
PHY
JSR ENSQWRTDOC
LDX #$C0 ; Wavetable size Register
LDY #$04 ; Size 256, resolution 4
JSR ENSQWRTDOC
LDX #$A0 ; Wavetable size Register
LDY #$00 ; Free run, no IRQ, start
JSR ENSQWRTDOC
:DONE PLY
PLX
PLA
RTS