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https://github.com/cc65/cc65.git
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116 lines
2.1 KiB
ArmAsm
116 lines
2.1 KiB
ArmAsm
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; Written by Groepaz/Hitmen <groepaz@gmx.net>
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; Cleanup by Ullrich von Bassewitz <uz@cc65.org>
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;
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.export ppubuf_waitempty
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.export ppubuf_wait
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.export ppubuf_put
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.export ppubuf_flush
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.include "nes.inc"
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.code
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; ------------------------------------------------------------------------
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; ppubuf_waitempty
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; Wait until buffer is empty
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.proc ppubuf_waitempty
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@wait: lda ringcount
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bne @wait
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rts
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.endproc
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; ------------------------------------------------------------------------
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; ppubuf_wait
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; Wait until buffer is full
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.proc ppubuf_wait
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lda #$ff ; (($0100/3)*1)
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@wait: cmp ringcount
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beq @wait
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rts
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.endproc
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; ------------------------------------------------------------------------
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; Put a PPU-Memory write to buffer
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; called from main program (not necessary when in vblank irq)
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.proc ppubuf_put
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sta ppuval
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sty ppuhi
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stx ppulo
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jsr ppubuf_wait ; wait if buffer is full
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ldy ringwrite
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lda ppuhi
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sta ringbuff,y
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lda ppulo
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sta ringbuff+$0100,y
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lda ppuval
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sta ringbuff+$0200,y
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iny
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sty ringwrite
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inc ringcount
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rts
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.endproc
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; ------------------------------------------------------------------------
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; Flush PPU-Memory write buffer
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; called from vblank interupt
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.proc ppubuf_flush
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ldy ringcount
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bne @doloop
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rts
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@doloop:
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ldx ringread
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lda #$0e
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sta temp
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@loop:
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.repeat 5
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lda ringbuff,x
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sta $2006
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lda ringbuff+$0100,x
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sta $2006
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lda ringbuff+$0200,x
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sta $2007
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inx
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dey
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beq @end
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.endrepeat
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dec temp
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bne @loop
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@end: stx ringread
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sty ringcount
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rts
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.endproc
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; ------------------------------------------------------------------------
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; Data
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.bss
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temp: .res 1
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