dos33fsprogs/vertical_scroll/gr_unrle_large.s
2020-02-17 13:41:01 -05:00

91 lines
1.7 KiB
ArmAsm

;======================
; load large RLE image
;======================
; Output is A:00 (assume page aligned)
; Input is in GBASH/GBASL
; format: first byte=xsize
; A0,X,Y means run of X bytes of Y color
; A1 means end of file
; A2-AF,X means run of low nibble, X color
; if high nibble not A: just display color
; CV = current Y
; CH = max X xsize (usually 40)
; TEMP = page
; TEMPY= current X
load_rle_large:
sta OUTH
ldy #0
sty OUTL
sty CV ; init Y to 0
jsr load_and_increment ; load xsize, increment
sta CH
rle_large_loop:
jsr load_and_increment ; load next value from
tax
cmp #$A1 ; if 0xa1
beq rle_large_done ; we are done
and #$f0 ; mask
cmp #$a0 ; see if special AX
beq rle_large_decompress_special
; not special, just color
txa ; put color back in A
ldx #$1 ; only want to print 1
bne rle_large_decompress_run
rle_large_decompress_special:
txa ; put read value back in A
and #$0f ; check if was A0
bne rle_large_decompress_color ; if A0 need to read run, color
rle_large_decompress_large:
jsr load_and_increment ; run length now in A
rle_large_decompress_color:
tax ; put runlen into X
jsr load_and_increment ; get color into A
rle_large_decompress_run:
rle_large_run_loop:
sta (OUTL),y ; write out the value
inc OUTL
bne rle_large_inc_done
inc OUTH ; handle 16-bit
rle_large_inc_done:
dec TEMPY
bne rle_large_not_eol ; if less then keep going
rle_large_not_eol:
dex
bne rle_large_run_loop ; if not zero, keep looping
beq rle_large_loop ; and branch always
rle_large_done:
lda #$15 ; move the cursor somewhere sane
sta CV
rts
;load_and_increment:
; lda (GBASL),Y
; inc GBASL
; bne lai_no_oflo
; inc GBASH
;lai_no_oflo:
; rts