mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-12-27 02:31:00 +00:00
54 lines
1.4 KiB
ArmAsm
54 lines
1.4 KiB
ArmAsm
;=========================================================
|
|
; gr_copy_to_current
|
|
;=========================================================
|
|
; copy 0xc00 to DRAW_PAGE
|
|
; ORIGINAL: 2 + 8*38 + 4*80*23 + 4*120*26 + 13 = 20,159 = 20ms = 50Hz
|
|
;
|
|
; OPTIMIZED: 2+ 8*38 + 9*4 + 7*4 + 14*120*4 + 14*80*4 + 9*8 + 6 =
|
|
; 11,648 = 11ms = 90Hz
|
|
gr_copy_to_current:
|
|
|
|
ldx #0 ; set ypos to zero ; 2
|
|
|
|
gr_copy_loop:
|
|
lda gr_offsets,X ; lookup low byte for line addr ; 4+
|
|
|
|
sta gr_copy_line+1 ; out and in are the same ; 4
|
|
sta gr_copy_line+4 ; 4
|
|
|
|
lda gr_offsets+1,X ; lookup high byte for line addr ; 4+
|
|
clc ; 2
|
|
adc DRAW_PAGE ; 3
|
|
sta gr_copy_line+5 ; 4
|
|
|
|
lda gr_offsets+1,X ; lookup high byte for line addr ; 4+
|
|
adc #$8 ; for now, fixed 0xc ; 2
|
|
sta gr_copy_line+2 ; 4
|
|
|
|
ldy #0 ; set xpos counter to 0 ; 2
|
|
|
|
|
|
cpx #$8 ; don't want to copy bottom 4*40 ; 2
|
|
bcs gr_copy_above4 ; 2nt/3
|
|
|
|
gr_copy_below4:
|
|
ldy #119 ; for early ones, copy 120 bytes ; 2
|
|
bcc gr_copy_line ; ; 3
|
|
|
|
gr_copy_above4: ; for last four, just copy 80 bytes
|
|
ldy #79 ; 2
|
|
|
|
gr_copy_line:
|
|
lda $ffff,Y ; load a byte (self modified) ; 4+
|
|
sta $ffff,Y ; store a byte (self modified) ; 5
|
|
dey ; decrement pointer ; 2
|
|
bpl gr_copy_line ; ; 2nt/3
|
|
|
|
gr_copy_line_done:
|
|
inx ; increment ypos value ; 2
|
|
inx ; twice, as address is 2 bytes ; 2
|
|
cpx #16 ; there are 8*2 of them ; 2
|
|
bne gr_copy_loop ; if not, loop ; 3
|
|
rts ; 6
|
|
|