dos33fsprogs/demos/mode7_demo/gr_hlin_double.s
Vince Weaver b1238af49d re-arranged the entire directory structure
this will probably upset people
2021-01-05 15:29:31 -05:00

68 lines
1.4 KiB
ArmAsm

;=====================================================================
;= ROUTINES
;=====================================================================
;================================
; hlin_setup
;================================
; put address in GBASL/GBASH
; Ycoord in A, Xcoord in Y
hlin_setup:
sty TEMPY ; 3
tay ; y=A ; 2
lda gr_offsets,Y ; lookup low-res memory address ; 4
clc ; 2
adc TEMPY ; 3
sta GBASL ; 3
iny ; 2
lda gr_offsets,Y ; 4
adc DRAW_PAGE ; add in draw page offset ; 3
sta GBASH ; 3
rts ; 6
;===========
; 35
;================================
; hlin_double:
;================================
; HLIN Y, V2 AT A
; Y, X, A trashed
; start at Y, draw up to and including X
hlin_double:
;int hlin_double(int page, int x1, int x2, int at) {
jsr hlin_setup ; 41
sec ; 2
lda V2 ; 3
sbc TEMPY ; 3
tax ; 2
inx ; 2
;===========
; 53
; fallthrough
;=================================
; hlin_double_continue: width
;=================================
; GBASL has correct offset for row/col
; width in X
hlin_double_continue:
ldy #0 ; 2
lda COLOR ; 3
hlin_double_loop:
sta (GBASL),Y ; 6
inc GBASL ; 5
dex ; 2
bne hlin_double_loop ; 2nt/3
rts ; 6
;=============
; 53+5+X*16+5