dos33fsprogs/games/keen/text_drawbox.s
2024-03-10 00:44:20 -05:00

85 lines
1007 B
ArmAsm

; draw inverse box on text screen
; we could use HLIN/VLIN instead?
; note Y should be in text coords (0..23) not GR (0..47)
drawbox:
lda drawbox_y1
jsr text_hlin
lda drawbox_y2
jsr text_hlin
jsr text_vlins
rts
;========================
; text hlin
;========================
; draw from x1,A to x2,A
text_hlin:
asl
tay
lda gr_offsets,Y
sta OUTL
lda gr_offsets+1,Y
clc
adc DRAW_PAGE
sta OUTH
lda #' '
ldy drawbox_x1
drawbox_hlin_loop:
sta (OUTL),Y
iny
cpy drawbox_x2
bne drawbox_hlin_loop
rts
;========================
; text vlin
;========================
; draw from A,y1 to A,y2
text_vlins:
ldx drawbox_y1
text_vlins_loop:
txa
asl
tay
lda gr_offsets,Y
sta OUTL
lda gr_offsets+1,Y
clc
adc DRAW_PAGE
sta OUTH
lda #' '
ldy drawbox_x1
sta (OUTL),Y
ldy drawbox_x2
sta (OUTL),Y
inx
cpx drawbox_y2
bcc text_vlins_loop
beq text_vlins_loop ; ble
rts
drawbox_x1: .byte $00
drawbox_x2: .byte $00
drawbox_y1: .byte $00
drawbox_y2: .byte $00