mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-11-04 05:05:13 +00:00
99 lines
1.9 KiB
ArmAsm
99 lines
1.9 KiB
ArmAsm
;=================
|
|
; load RLE image
|
|
;=================
|
|
; Output is BASH/BASL
|
|
; Input is in GBASH/GBASL
|
|
load_rle_gr:
|
|
lda #$0
|
|
tax
|
|
tay ; init X and Y to 0
|
|
|
|
sta CV ; ycoord=0
|
|
|
|
lda (GBASL),y ; load xsize
|
|
sta CH
|
|
iny ; (we should check if we had
|
|
; bad luck and overflows page)
|
|
|
|
iny ; skip ysize
|
|
|
|
rle_loop:
|
|
lda (GBASL),y ; load run value
|
|
cmp #$ff ; if 0xff
|
|
beq rle_done ; we are done
|
|
sta RUN
|
|
iny ; point to next value
|
|
bne rle_yskip1 ; if overflow, increment address
|
|
inc GBASH
|
|
rle_yskip1:
|
|
lda (GBASL),y ; load value to write
|
|
iny
|
|
bne rle_yskip2
|
|
inc GBASH
|
|
rle_yskip2:
|
|
sty TEMP2 ; save y for later
|
|
pha
|
|
lda #$0
|
|
tay
|
|
pla ; convoluted way to set y to 0
|
|
|
|
rle_run_loop:
|
|
sta (BASL),y ; write out the value
|
|
inc BASL ; increment the pointer
|
|
bne rle_skip3 ; if wrapped
|
|
inc BASH ; then increment the high value
|
|
rle_skip3:
|
|
inx ; increment the X value
|
|
cpx CH ; compare against the image width
|
|
bcc rle_not_eol ; if less then keep going
|
|
|
|
pha ; save out value on stack
|
|
|
|
lda BASL ; cheat to avoid a 16-bit add
|
|
cmp #$a7 ; we are adding 0x58 to get
|
|
bcc rle_add_skip ; to the next line
|
|
inc BASH
|
|
rle_add_skip:
|
|
clc
|
|
adc #$58 ; actually do the 0x58 add
|
|
sta BASL ; and store it back
|
|
|
|
inc CV ; add 2 to ypos
|
|
inc CV ; each "line" is two high
|
|
|
|
lda CV ; load value
|
|
cmp #15 ; if it's greater than 14 it wraps
|
|
bcc rle_no_wrap ; Thanks Woz
|
|
|
|
lda #$0 ; we wrapped, so set to zero
|
|
sta CV
|
|
|
|
; when wrapping have to sub 0x3d8
|
|
sec ; this is a 16-bit subtract routine
|
|
lda BASL
|
|
sbc #$d8 ; LSB
|
|
sta BASL
|
|
lda BASH ; MSB
|
|
sbc #$3 ;
|
|
sta BASH
|
|
|
|
rle_no_wrap:
|
|
lda #$0 ; set X value back to zero
|
|
tax
|
|
pla ; restore value to write from stack
|
|
|
|
rle_not_eol:
|
|
dec RUN ; decrement run value
|
|
bne rle_run_loop ; if not zero, keep looping
|
|
|
|
ldy TEMP2 ; restore the input pointer
|
|
sec
|
|
bcs rle_loop ; and branch always
|
|
|
|
rle_done:
|
|
lda #$15 ; move the cursor somewhere sane
|
|
sta CV
|
|
rts
|
|
|
|
|