Stacken/c64-livecoding
6
0
Fork 0
Code Issues 1 Pull requests Projects Releases Packages Wiki Activity Actions

rewrote the circle code to use relative position for pixel draw. This made it 2 orders of magnitudes faster!

Browse source
This commit is contained in:
hugova 2025-06-28 22:25:55 +02:00
parent 484bafa828
commit c2a5af481f
1 changed files with 31 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

35
wip-hugo/routines/circle/circle.s
View file

@ -18,12 +18,29 @@
LSR LSR
LSR LSR
STA t1 STA t1
;; We only draw the first pixel using absolute position.
;; After that we use relative position.
JSR pixel_draw
;; This sets byte_to_paint, btp_mem_pos and Y
while_x_bigger_then_y: while_x_bigger_then_y:
JSR pixel_draw LDA byte_to_paint ;A byte containing a single 1. Coresponds to X position in the chunk.
ORA (btp_mem_pos), Y
STA (btp_mem_pos), Y
INC Y_pos ; y++ increment_y_pos:
INC Y_rel INC Y_rel ; y++
INY
CPY #$08
BNE increment_y_pos_end
move_8px_down:
LDY #$00
;; Switch to chunk bellow
; So we subtract #$4000
Add_16 btp_mem_pos, btp_mem_pos + 1, #$40, #$01 ;+320
increment_y_pos_end:
;;t1 += y ;;t1 += y
CLC CLC
@ -39,8 +56,18 @@ while_x_bigger_then_y:
CMP #$00 CMP #$00
BMI endif BMI endif
if: if:
DEC X_pos ; x-- decrement_x_pos:
DEC X_rel DEC X_rel
ASL byte_to_paint
BCC decrement_x_pos_end
move_8px_left:
;; Next chunk is 8 addresses away. Look in pixel_draw for more detail.
;; -8.
Sub_16 btp_mem_pos, btp_mem_pos + 1, #$08, #$00
;; Restores byte to paint
LDA #%00000001
STA byte_to_paint
decrement_x_pos_end:
LDA t2 LDA t2
STA t1 ; t1 = t2 STA t1 ; t1 = t2
endif: endif: