diff --git a/megademo/gr_putsprite.s b/megademo/gr_putsprite.s new file mode 100644 index 00000000..a81ac0c6 --- /dev/null +++ b/megademo/gr_putsprite.s @@ -0,0 +1,137 @@ + + ;============================================= + ; put_sprite + ;============================================= + ; Sprite to display in INH,INL + ; Location is XPOS,YPOS + ; Note, only works if YPOS is multiple of two + + + ; time= 28 setup + ; Y*outerloop + ; outerloop = 34 setup + ; X*innerloop + ; innerloop = 30 if $00 17+13(done) + ; 64 if $0X 16+7+8+20(put_sprite_mask)+13(done) + ; 69 if $X0 16+8+7+5+20(put_sprite_mask)+13(done) + ; 54 if if $XX 16+8+8+9(put_all)+13(done) + + + ; -1 for last iteration + ; 18 (-1 for last) + ; 6 return + + ; so cost = 28 + Y*(34+18)+ (INNER-Y) -1 + 6 + ; = 33 + Y*(52)+(INNER-Y) + ; = 33 + Y*(52)+ [30A + 64B + 69C + 54D]-Y + +put_sprite: + + ldy #0 ; byte 0 is xsize ; 2 + lda (INL),Y ; 5 + sta CH ; xsize is in CH ; 3 + iny ; 2 + + lda (INL),Y ; byte 1 is ysize ; 5 + sta CV ; ysize is in CV ; 3 + iny ; 2 + + lda YPOS ; make a copy of ypos ; 3 + sta TEMPY ; as we modify it ; 3 + ;=========== + ; 28 +put_sprite_loop: + sty TEMP ; save sprite pointer ; 3 + ldy TEMPY ; 3 + lda gr_offsets,Y ; lookup low-res memory address ; 4 + clc ; 2 + adc XPOS ; add in xpos ; 3 + sta OUTL ; store out low byte of addy ; 3 + lda gr_offsets+1,Y ; look up high byte ; 4 + adc DRAW_PAGE ; ; 3 + sta OUTH ; and store it out ; 3 + ldy TEMP ; restore sprite pointer ; 3 + + ; OUTH:OUTL now points at right place + + ldx CH ; load xsize into x ; 3 + ;=========== + ; 34 +put_sprite_pixel: + lda (INL),Y ; get sprite colors ; 5 + iny ; increment sprite pointer ; 2 + + sty TEMP ; save sprite pointer ; 3 + ldy #$0 ; 2 + + ; check if completely transparent + ; if so, skip + + cmp #$0 ; if all zero, transparent ; 2 + beq put_sprite_done_draw ; don't draw it ; 2nt/3 + ;============== + ; 16/17 + + sta COLOR ; save color for later ; 3 + + ; check if top pixel transparent + + and #$f0 ; check if top nibble zero ; 2 + bne put_sprite_bottom ; if not skip ahead ; 2nt/3 + ;============== + ; 7/8 + + lda #$f0 ; setup mask ; 2 + sta MASK ; 3 + bmi put_sprite_mask ; always? ; 3 + ;============= + ; 8 + +put_sprite_bottom: + lda COLOR ; re-load color ; 3 + and #$0f ; check if bottom nibble zero ; 2 + bne put_sprite_all ; if not, skip ahead ; 2nt/3 + ;============= + ; 7/8 + + lda #$0f ; 2 + sta MASK ; setup mask ; 3 + ;=========== + ; 5 + +put_sprite_mask: + lda (OUTL),Y ; get color at output ; 5 + and MASK ; mask off unneeded part ; 3 + ora COLOR ; or the color in ; 3 + sta (OUTL),Y ; store it back ; 6 + + jmp put_sprite_done_draw ; we are done ; 3 + ;=========== + ; 20 + +put_sprite_all: + lda COLOR ; load color ; 3 + sta (OUTL),Y ; and write it out ; 6 + ;============ + ; 9 + +put_sprite_done_draw: + + ldy TEMP ; restore sprite pointer ; 3 + + inc OUTL ; increment output pointer ; 5 + dex ; decrement x counter ; 2 + bne put_sprite_pixel ; if not done, keep looping ; 2nt/3 + ;============== + ; 12/13 + + inc TEMPY ; each line has two y vars ; 5 + inc TEMPY ; 5 + dec CV ; decemenet total y count ; 5 + bne put_sprite_loop ; loop if not done ; 2nt/3 + ;============== + ; 17/18 + + rts ; return ; 6 + +