dos33fsprogs/another_myst/gr_hlin.s
2020-06-20 18:29:00 -04:00

35 lines
397 B
ArmAsm

;===============================
; hlin
;===============================
; Y = y position
; A = start
; X = length
hlin:
clc
adc gr_offsets,Y
sta hlin_smc1+1
sta hlin_smc2+1
lda gr_offsets+1,Y
clc
adc DRAW_PAGE
sta hlin_smc1+2
sta hlin_smc2+2
hlin_loop:
hlin_smc1:
lda $c00,X
hlin_mask_smc:
and #$f0
hlin_color_smc:
ora #$01
hlin_smc2:
sta $c00,X
dex
bpl hlin_loop
rts