dos33fsprogs/demos/xmas_2019/gr_unrle.s
Vince Weaver b1238af49d re-arranged the entire directory structure
this will probably upset people
2021-01-05 15:29:31 -05:00

138 lines
2.7 KiB
ArmAsm

;=================
; load 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 xsize (usually 40)
; TEMP = page
; TEMPY= current X
; RECALC, I changed gr_offsets
; 82 + 10 +
; special short: 38+7+ 27+ 27*run +5+2
; special long: 38+7+24+27+ 27*run +5+2
; nospecial: 38+6+19+(cross line*58)+5+2
load_rle_gr:
sec ; 2
sbc #4 ; adjust page to write to ; 2
; to match gr_offsets
sta TEMP ; 3
ldy #$0 ; init Y to 0 ; 2
sty CV ; 3
jsr load_and_increment ; load xsize ; 6+19
sta CH ; 3
jsr unrle_new_y ; 6+36
;============
; 82
rle_loop:
jsr load_and_increment ; 6+19
tax ; 2
cmp #$A1 ; if 0xa1 ; 2
beq rle_done ; we are done ; 3
; -1
and #$f0 ; mask ; 2
cmp #$a0 ; see if special AX ; 2
beq decompress_special ; 3
;===========
; 38
; -1
; not special, just color
txa ; put color back in A ; 2
ldx #$1 ; only want to print 1 ; 2
bne decompress_run ; bra ; 3
decompress_special:
txa ; put read value back in A ; 2
and #$0f ; check if was A0 ; 2
bne decompress_color ; if A0 need to read run, color ; 3
;===
; 7
decompress_large: ; -1
jsr load_and_increment ; run length now in A ; 6+19
decompress_color:
tax ; put runlen into X ; 2
jsr load_and_increment ; get color into A ; 6+19
decompress_run:
rle_run_loop:
sta (BASL),y ; write out the value ; 6
inc BASL ; 5
dec TEMPY ; 5
bne rle_not_eol ; if less then keep going ; 3
;====
; 19
; -1
; if here, we are > max_X
inc CV ; 5
pha ; 3
jsr unrle_new_y ; 6+36
pla ; 4
;===
;53
rle_not_eol:
dex ; 2
bne rle_run_loop ; if not zero, keep looping ; 3
;==
; 5
; -1
beq rle_loop ; and branch always ; 3
rle_done:
lda #$15 ; move cursor somewhere sane ; 2
sta CV ; 3
rts ; 6
;========================
; common case = 19
load_and_increment:
lda (GBASL),Y ; 5+
inc GBASL ; 5
bne lai_no_oflo ; 3
; -1
inc GBASH ; 5
lai_no_oflo:
rts ; 6
;========================
; common case = 36
unrle_new_y:
ldy CV ; 3
lda gr_offsets_l,Y ; 4+
sta BASL ; 3
lda gr_offsets_h,Y ; 4+
clc ; 2
adc TEMP ; adjust for page ; 3
sta BASH ; 3
lda CH ; 3
sta TEMPY ; 3
ldy #0 ; 2
rts ; 6
;===========
; 36