mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-12-28 09:30:41 +00:00
49 lines
987 B
ArmAsm
49 lines
987 B
ArmAsm
; Based on redbook_sound.s
|
|
|
|
; it's originally by Paul Lutus, from the Apple II Red Book p45
|
|
; which can only do roughly 194Hz to 2000Hz+
|
|
|
|
; this makes things twice as long, which allows lower notes, but
|
|
; loses some precision on high notes
|
|
|
|
; also modified so "0" means no sound
|
|
|
|
|
|
;=====================================================
|
|
; speaker tone
|
|
;=====================================================
|
|
; A,X,Y trashed
|
|
; duration also trashed
|
|
|
|
; more exactly, it is (4+10F)+(13+10F) = 20F+17
|
|
|
|
speaker_tone:
|
|
ldy #0 ; 3
|
|
speaker_tone_loop:
|
|
lda $C030 ; click speaker ; 4
|
|
speaker_loop:
|
|
nop
|
|
nop
|
|
nop
|
|
nop
|
|
nop
|
|
|
|
dey ; ; 2
|
|
bne freq_loop ; ; 2/3
|
|
dec speaker_duration ; (Duration) ; 6
|
|
beq done_tone ; 2/3
|
|
freq_loop:
|
|
dex ; 2
|
|
bne speaker_loop ; 2/3
|
|
ldx speaker_frequency ; (Frequency) ; 4
|
|
beq speaker_loop ; play nothing if 0 ; 2/3
|
|
jmp speaker_tone_loop ; 3
|
|
done_tone:
|
|
rts
|
|
|
|
speaker_duration:
|
|
.byte $00
|
|
speaker_frequency:
|
|
.byte $00
|
|
|