mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-11-01 01:06:33 +00:00
169 lines
3.6 KiB
ArmAsm
169 lines
3.6 KiB
ArmAsm
;=============================================
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; put_sprite_mask
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;=============================================
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; put an outline of the sprite, using non-transparent ($AA)
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; pixels with a solid color in COLOR
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; Sprite to display in INH,INL
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; Location is XPOS,YPOS
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; Note, only works if YPOS is multiple of two
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; transparent color is $A (grey #2)
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; this means we can have black ($0) in a sprite
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; FIXME: force YPOS to be even?
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; A, X, Y trashed
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put_sprite_mask:
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ldy #0 ; byte 0 is xsize ; 2
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lda (INL),Y ; 5
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sta CH ; xsize is in CH ; 3
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iny ; 2
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clc
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adc XPOS
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sta XMAX
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lda (INL),Y ; byte 1 is ysize ; 5
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sta CV ; ysize is in CV ; 3
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iny ; 2
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lda 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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; 28
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psm_put_sprite_loop:
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sty TEMP ; save sprite pointer ; 3
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ldy TEMPY ; 3
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bpl psm_put_sprite_pos ; if < 0, skip to next
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clc ; skip line in sprite too
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lda TEMP
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adc CH
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tay
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bne psm_increment_y
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psm_put_sprite_pos:
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psm_smc1:
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cpy #48 ; bge if >= 48, done sprite
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bcs psm_sprite_done
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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 XPOS ; add in xpos ; 3
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sta OUTL ; store out low byte of addy ; 3
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clc ; never wraps, handle negative
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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 XPOS ; load xposition into x ; 3
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;===========
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; 34
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psm_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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cpx #0 ; if off-screen left, skip draw
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bmi psm_skip_drawing
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cpx #40
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bcs psm_skip_drawing ; if off-screen right, skip draw
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ldy #$0 ; 2
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; check if completely transparent
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; if so, skip
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cmp #$AA ; if all zero, transparent ; 2
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beq psm_put_sprite_done_draw ; don't draw it ; 2nt/3
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;==============
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; 16/17
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sta COLOR2 ; save color for later ; 3
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; check if top pixel transparent
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and #$f0 ; check if top nibble zero ; 2
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cmp #$a0
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bne psm_put_sprite_bottom ; if not skip ahead ; 2nt/3
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;==============
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; 7/8
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lda COLOR
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and #$0f
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sta COLOR2
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lda #$f0 ; setup mask ; 2
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sta MASK ; 3
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bmi psm_put_sprite_mask ; always? ; 3
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;=============
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; 8
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psm_put_sprite_bottom:
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lda COLOR2 ; re-load color ; 3
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and #$0f ; check if bottom nibble zero ; 2
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cmp #$0a
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bne psm_put_sprite_all ; if not, skip ahead ; 2nt/3
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;=============
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; 7/8
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lda COLOR
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and #$f0
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sta COLOR2
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lda #$0f ; 2
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sta MASK ; setup mask ; 3
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;===========
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; 5
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psm_put_sprite_mask:
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lda (OUTL),Y ; get color at output ; 5
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and MASK ; mask off unneeded part ; 3
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ora COLOR2 ; or the color in ; 3
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sta (OUTL),Y ; store it back ; 6
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jmp psm_put_sprite_done_draw ; we are done ; 3
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;===========
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; 20
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psm_put_sprite_all:
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lda COLOR ; load color ; 3
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sta (OUTL),Y ; and write it out ; 6
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;============
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; 9
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psm_put_sprite_done_draw:
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psm_skip_drawing:
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ldy TEMP ; restore sprite pointer ; 3
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inc OUTL ; increment output pointer ; 5
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inx ; increment x counter ; 2
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cpx XMAX
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bne psm_put_sprite_pixel ; if not done, keep looping ; 2nt/3
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;==============
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; 12/13
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psm_increment_y:
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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 psm_put_sprite_loop ; loop if not done ; 2nt/3
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;==============
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; 17/18
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psm_sprite_done:
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rts ; return ; 6
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