c2d/asm/bar.s

168 lines
2.9 KiB
ArmAsm

;bar.s
;
; moves itself to another page memory,
; then reads binary from disk using params at end,
; then jumps to binary
;
; apple params/vectors
warm = $FF69 ; back to monitor
bell = $FBDD ; ding
preg = $48 ; mon p reg
ch = $24 ; cursor horizontal
movecur = $FB5B ; move cursor to ch,a
cout = $FDED ; character out sub
; dos params/vectors
rwtsprm = $B7E8 ; looked at dos 3.3 disk, not using $3E3 to find
rwts = $B7B5 ; rwts jsr
; vars
stage1 = $800
stage2 = $300 ; $300 looks open
invsp = $20 ; inverse space for draw
;;;run time
trkcnt = $00 ; track counter
segcnt = $01 ; loop var
buffer = $02 ; MSB of RWTS buffer
secnum = $03 ; loop var
trknum = $04 ; loop var
barcnt = $05 ; bar counter
barptr = $06 ; bar pointer
.org stage1
init:
lda #0 ; reset pointer and counter
sta barcnt
sta barptr
lda #1 ; read(1)/write(2) command
ldy #$0C ; offset in RWTS
sta rwtsprm,y ; write it to RWTS
lda #0 ; buffer LSB
ldy #8 ; offset in RWTS
sta rwtsprm,y ; write it to RWTS
lda #2
sta trknum ; start with track 2
start:
ldx #0 ; move code to stage2
move:
lda moved,x
sta loader,x
inx
cpx #$D0
bne move ; move 208 bytes
jmp loader
moved:
.org stage2
loader:
lda loadpage ; where to dump the tracks
sta buffer
ldx lasttrack
dex ; because data starts at track 2
dex
stx trkcnt ; number of complete and partial tracks
;;;begin track loop
trkloop:
lda trknum ; track number
ldy #4 ; offset in RWTS
sta rwtsprm,y ; write it to RWTS
;;;begin sector loop (16), backwards is faster, much faster
lda trkcnt ; check if last track
bne fulltrack ; if not then full track
lda lastsector ; if so, get last sector number
bpl subtrack
fulltrack:
lda #$F
subtrack:
sta secnum
secloop:
lda secnum ; sector number
ldy #5 ; offset in RWTS
sta rwtsprm,y ; write it to RWTS
lda buffer ; buffer MSB
clc
adc secnum ; compute page load address
ldy #9 ; offset in RWTS
sta rwtsprm,y ; write it to RWTS
ldy #<rwtsprm ; load rwts paramlist B7E8
lda #>rwtsprm
jsr rwts ; do it!
bcs diskerror
lda #0
sta preg ; fix p reg so mon is happy
;;;draw code
inc barcnt ; sectors read
ldx barptr ; get current pointer value
lda bar,x
cmp barcnt ; is bar,x = barcnt?
bne nodraw ; if bar,x = barcnt draw bar
lda barptr ; get position
;clc
;adc #5 ; intend
sta ch
lda #19 ; row 19
jsr movecur
lda #invsp
jsr cout
inc barptr ; move pointer to next bar position
nodraw:
;;;end draw code
dec secnum
bpl secloop
;;;end sector loop
lda buffer ; buffer += $10
clc
adc #$10
sta buffer
inc trknum ; next track
dec trkcnt ;
bpl trkloop ; 0, all done with tracks
;;;end track loop
done:
jmp (nextjump) ; down with load, run it
diskerror:
jmp warm
lasttrack:
.org *+1
lastsector:
.org *+1
loadpage:
.org *+1
nextjump:
.org *+2
bar:
.org *+40
;;; used for debug
;trkcnt:
; .org *+1
;segcnt:
; .org *+1
;buffer:
; .org *+1
;secnum:
; .org *+1
;trknum:
; .org *+1