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Applecorn
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Ensoniq noise channel is now feature-complete.

This commit is contained in:
Bobbi Webber-Manners 2022-11-25 23:09:40 -05:00
parent ec02d0cc41
commit 56883335b5
4 changed files with 10 additions and 3 deletions
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BIN
applecorn.po
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3
mainmem.audio.s
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@ -732,7 +732,6 @@ ADSRPHASE STX OSCNUM
:S1 TYA ; Change/step -> A
CLC
ADC CURRAMP,X ; Add change to current amp
* BCS :CLAMP ; If overflow, clamp to target
CMP :TARGET ; Compare with target
BCS :CLAMP ; If target < sum, clamp to target
BRA :UPDATE
@ -743,7 +742,7 @@ ADSRPHASE STX OSCNUM
:S2 TYA ; Change/step -> A
CLC
ADC CURRAMP,X ; Add change to current amp
BCS :CLAMP ; If overflow, clamp to target
BCS :CLAMP ; If overflow (-ve), clamp to target
CMP :TARGET ; Compare with target
BCC :CLAMP ; If target >= sum, clamp to target
BRA :UPDATE

10
mainmem.ensq.s
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@ -2,6 +2,7 @@
* (c) Bobbi 2022 GPLv3
*
* Ensoniq DOC Driver for Apple IIGS.
* Simulates Hitachi SN76489 sound generator chip found in BBC Micro.
*
* Ensoniq control registers
@ -145,7 +146,13 @@ ENSQNOTE PHA
CPX #$00
BEQ :NOISE ; Oscillator 0 is noise channel
PHA ; Stash orig freq
CPX #$01 ; Oscillator 1 controls noise freq
BNE :S0 ; Not 1? Skip
CMP #$00 ; If frequency is zero ..
BEQ :S0 ; .. skip
STA :CH1NOTE ; Store frequency for noise gen
:S0 PHA ; Stash orig freq
TAY
LDA EFREQLOW,Y
TAY ; Frequency value LS byte
@ -232,6 +239,7 @@ ENSQNOTE PHA
:NOISENOTE DB 149 ; BBC Micro note P=0 or 4
DB 101 ; BBC Micro note P=1 or 5
DB 53 ; BBC Micro note P=2 or 6
:CH1NOTE DB 00 ; Note on channel 1
* Adjust frequency of note already playing

0
mame_applecorn Normal file → Executable file
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