dos33fsprogs/racebeam/gr_hline.s

41 lines
744 B
ArmAsm
Raw Normal View History

2019-03-06 17:44:31 +00:00
;==================================
; HLINE
;==================================
; Color in A
; Y has which line
hline:
pha ; 3
ldx gr_offsets,y ; 4+
stx hline_loop+1 ; 4
lda gr_offsets+1,y ; 4+
clc ; 2
adc DRAW_PAGE ; 3
sta hline_loop+2 ; 4
pla ; 4
ldx #39 ; 2
hline_loop:
sta $5d0,X ; 38 ; 5
dex ; 2
bpl hline_loop ; 2nt/3
rts ; 6
;==========================
; Clear gr screen
;==========================
; Color in A
clear_gr:
ldy #46
clear_page_loop:
jsr hline
dey
dey
bpl clear_page_loop
rts
gr_offsets:
.word $400,$480,$500,$580,$600,$680,$700,$780
.word $428,$4a8,$528,$5a8,$628,$6a8,$728,$7a8
.word $450,$4d0,$550,$5d0,$650,$6d0,$750,$7d0