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Applecorn
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Implemented ADSR release 'hold' feature

This commit is contained in:
Bobbi Webber-Manners 2022-10-31 17:48:52 -04:00
parent 7fece994bc
commit 43e429d4df
3 changed files with 40 additions and 19 deletions
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BIN
applecorn.po
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2
auxmem.init.s
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@ -209,7 +209,7 @@ BYTE00 BEQ BYTE00A ; OSBYTE 0,0 - generate error
RTS ; %000x1xxx host type, 'A'pple
BYTE00A BRK
DB $F7
HELLO ASC 'Applecorn MOS 2022-10-25'
HELLO ASC 'Applecorn MOS 2022-10-31-BOO!'
DB $00 ; Unify MOS messages
* TO DO: Move into RAM
GSSPEED DB $00 ; $80 if GS is fast, $00 for slow

57
mainmem.audio.s
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@ -389,26 +389,18 @@ ENSQISR INC COUNTER+0 ; Increment centisecond timer
:PEEK JSR PEEKAUDIO ; Inspect byte at head of queue
BCS :NEXT ; Nothing in queue
; NOTE: A contains HS byte of &HSFC
TAY ; Stash for later
AND #$0F ; Mask out hold nybble
BNE :SYNCSET ; Do not play if sync != 0
TYA ; HS byte
AND #$F0 ; Mask out sync nybble
BNE :HOLDSET ; Handle hold function
* The following is paranoid maybe. Perhaps can be removed once I am debugged. ***
PHX
INX ; Convert audio channel to buf num
INX
INX
INX
CLV ; Ask to count buffer
CLC ; Ask for space used
JSR CNP ; Go count it
TXA
PLX
CMP #3 ; At least 4 bytes used?
BMI :NEXT
* End paranoid section. ***
JSR CHECK4BYTES ; Check queue has a note
BCS :NEXT ; Less than 4 bytes, skip
JSR REMAUDIO ; Remove byte from queue
JSR REMAUDIO ; Remove byte from queue
JSR REMAUDIO ; Remove HS byte from queue
JSR REMAUDIO ; Remove amplitude byte from queue
TYA ; Amplitude or envelope -> A
DEC A
@ -433,9 +425,9 @@ ENSQISR INC COUNTER+0 ; Increment centisecond timer
LDA #$00 ; Initial amplitude is zero
PHA ; Zero amplitude to stack
:S2 JSR REMAUDIO ; Remove byte from queue
:S2 JSR REMAUDIO ; Remove freq byte from queue
PHY ; Frequency
JSR REMAUDIO ; Remove byte from queue
JSR REMAUDIO ; Remove dur byte from queue
TYA ; Duration
STA CHANTIMES,X
PLA ; Recover frequency
@ -457,6 +449,13 @@ ENSQISR INC COUNTER+0 ; Increment centisecond timer
BPL :L2 ; Next audio queue
CLC
RTL
:HOLDSET LDA CURRAMP,X ; Get current amplitude
BNE :NEXT ; If non zero, hold
JSR REMAUDIO ; Dequeue four bytes
JSR REMAUDIO
JSR REMAUDIO
JSR REMAUDIO
BRA :NEXT
:SYNCSET JSR CHORD ; See if chord can be released
BRA :NEXT
:CNT DB $05 ; Used to determine 20Hz cycles
@ -477,6 +476,28 @@ NONOTE LDA CHANENV,X ; See if envelope is in effect
RTS
* Helper function for ENSQISR
* On entry: X is audio channel #
* On return: CS if there are <= 4 bytes in queue, CC otherwise
* X is preserved
CHECK4BYTES PHX
INX ; Convert audio channel to buf num
INX
INX
INX
CLV ; Ask to count buffer
CLC ; Ask for space used
JSR CNP ; Go count it
TXA
PLX
CMP #3 ; At least 4 bytes used?
BMI :NO
CLC
RTS
:NO SEC
RTS
* Handle envelope tick counter
* On entry: X is audio channel #
* On return: CS if this cycle is an envelope tick, CC otherwise.