dos33fsprogs/megademo/gr_pageflip.s
Vince Weaver d208ea0cd3 megademo: add in mode7 code
this might be ill-advised
2018-10-02 23:04:51 -04:00

25 lines
503 B
ArmAsm

;==========
; page_flip
;==========
page_flip:
lda DISP_PAGE ; 3
beq page_flip_show_1 ; 2nt/3
page_flip_show_0:
bit PAGE0 ; 4
lda #4 ; 2
sta DRAW_PAGE ; DRAW_PAGE=1 ; 3
lda #0 ; 2
sta DISP_PAGE ; DISP_PAGE=0 ; 3
rts ; 6
page_flip_show_1:
bit PAGE1 ; 4
sta DRAW_PAGE ; DRAW_PAGE=0 ; 3
lda #1 ; 2
sta DISP_PAGE ; DISP_PAGE=1 ; 3
rts ; 6
;====================
; DISP_PAGE=0 26
; DISP_PAGE=1 24