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41 lines
1.0 KiB
ArmAsm
41 lines
1.0 KiB
ArmAsm
; void __fastcall__ bios_playsound (void *a, unsigned char b);
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.export _bios_playsound
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.import popax
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.include "creativision.inc"
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songptr := $00 ; Points to current tune data
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volptr := $04 ; Points to current volume table
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;* Creativision Sound Player
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;* Based on BIOS song player.
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;*
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;* Pass a pointer to a set of note triples, terminated with a tempo byte;
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;* and pass the length of the triples and tempo (max 255).
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;*
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;* Note: tune data must be stored backwards.
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_bios_playsound:
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php
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pha ; Save tune length
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sei
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lda #<$FCD5 ; BIOS decreasing-volume table
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ldx #>$FCD5
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sta volptr
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stx volptr+1
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jsr popax ; Get tune array pointer
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sta songptr
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stx songptr+1
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pla
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tay
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dey ; Point to tempo byte
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jmp BIOS_PLAY_SONG ; Let BIOS do its thing
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