mirror of
https://github.com/deater/dos33fsprogs.git
synced 2025-01-08 03:31:10 +00:00
73 lines
781 B
ArmAsm
73 lines
781 B
ArmAsm
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; Soft Switches
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KEYPRESS= $C000
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KEYRESET= $C010
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SPEAKER= $C030
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WAIT = $FCA8 ; delay 1/2(26+27A+5A^2) us
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; zero page use
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HALF_PERIOD = $FF
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test_sound:
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jsr tiny_sound_effect
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wait_until_keypress:
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lda KEYPRESS
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bpl wait_until_keypress
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bit KEYRESET
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jmp test_sound
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tiny_sound_effect:
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ldy #0
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freq_smc:
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lda #$40
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sta HALF_PERIOD
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play_note:
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loop_half_period:
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lda $C030 ; 4 cycles
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ldx HALF_PERIOD ; 3 cycles
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loop_nops:
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pha ; 4 cycles
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plp ; 4 cycles
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dex ; 2 cycles
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bne loop_nops ; 3 cycles
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; Testing duration loop
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dey ; 2 cycles
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bne loop_half_period ; 3 cycles
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lsr freq_smc+1
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lsr pattern
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beq end
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bcc skip_wait
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wait_smc:
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lda #80
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jsr WAIT
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skip_wait:
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beq tiny_sound_effect ; bra
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end:
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rts
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pattern:
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.byte $13
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