mirror of
https://github.com/deater/dos33fsprogs.git
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76 lines
1.7 KiB
ArmAsm
76 lines
1.7 KiB
ArmAsm
;=============================================
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; put_sprite
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;=============================================
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; Sprite to display in INH,INL
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; Assumes sprite size is 3x2
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; Location is SPRITE_XPOS,SPRITE_YPOS
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; Note, only works if SPRITE_YPOS is multiple of two
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; NO TRANSPARENCY
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; 13+ Y*(33+17+X*(18+13) + 5
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; 18 + Y*(50+31*X)
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; so if 3*2 = 304 cycles??
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put_sprite:
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ldy #0 ; 2
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lda #2 ; ysize is 2 ; 2
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sta CV ; ysize is in CV ; 3
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lda SPRITE_YPOS ; make a copy of ypos ; 3
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sta TEMPY ; as we modify it ; 3
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;===========
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; 13
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put_sprite_loop:
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sty TEMP ; save sprite pointer ; 3
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ldy TEMPY ; 3
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lda gr_offsets,Y ; lookup low-res memory address ; 4
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clc ; 2
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adc SPRITE_XPOS ; add in xpos ; 3
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sta OUTL ; store out low byte of addy ; 3
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lda gr_offsets+1,Y ; look up high byte ; 4
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adc DRAW_PAGE ; ; 3
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sta OUTH ; and store it out ; 3
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ldy TEMP ; restore sprite pointer ; 3
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; OUTH:OUTL now points at right place
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ldx #3 ; load xsize into x ; 2
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;===========
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; 33
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put_sprite_pixel:
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lda (INL),Y ; get sprite colors ; 5
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iny ; increment sprite pointer ; 2
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sty TEMP ; save sprite pointer ; 3
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ldy #$0 ; 2
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sta (OUTL),Y ; and write it out ; 6
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;============
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; 18
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put_sprite_done_draw:
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ldy TEMP ; restore sprite pointer ; 3
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inc OUTL ; increment output pointer ; 5
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dex ; decrement x counter ; 2
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bne put_sprite_pixel ; if not done, keep looping ; 3
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;==============
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; 13
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; -1
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inc TEMPY ; each line has two y vars ; 5
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inc TEMPY ; 5
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dec CV ; decemenet total y count ; 5
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bne put_sprite_loop ; loop if not done ; 3
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;==============
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; 17
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; -1
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rts ; return ; 6
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