Apple-2-SW/dos33fsprogs
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dos33fsprogs/demosplash/loader.s

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; Loader for Demosplash
nibtbl = $300 ; nothing uses the bottom 128 bytes of $300, do they?
bit2tbl = $380 ; bit2tbl: .res 86 ; = nibtbl+128
filbuf = $3D6 ; filbuf: .res 4 ; = bit2tbl+86
; read any file slot 6 version
; based on FASTLD6 and RTS copyright (c) Peter Ferrie 2011-2013,2018
; modified to assembled with ca64 -- vmw
; added code to patch it to run from current disk slot -- vmw
adrlo = $26 ; constant from boot prom
adrhi = $27 ; constant from boot prom
tmpsec = $3c ; constant from boot prom
reqsec = $3d ; constant from boot prom
sizelo = $44
sizehi = $45
secsize = $46
TEMPY = $fa
namlo = $fb
namhi = $fc
step = $fd ; state for stepper motor
tmptrk = $fe ; temporary copy of current track
phase = $ff ; current phase for /seek
OUTL = $fe ; for picking filename
OUTH = $ff
dirbuf = $c00
; note, don't put this immediately below
; the value being read as destaddr-4
; is temporarily overwritten during read
; process
; note also, can't load file bigger than $8000 (32k) in size?
; seems to break things?
start:
jsr init ; unhook DOS, init nibble table
;======================
which_load_loop:
ldy #0 ; load first filename
lda filenames_low,Y
sta OUTL
lda filenames_high,Y
sta OUTH
opendir_filename:
; clear out the filename with $A0 (space)
lda #<filename
sta namlo
lda #>filename
sta namhi
ldy #29
wipe_filename_loop:
lda #$A0
sta (namlo),Y
dey
bpl wipe_filename_loop
ldy #0
copy_filename_loop:
lda (OUTL),Y
beq copy_filename_done
ora #$80
sta (namlo),Y
iny
bne copy_filename_loop
copy_filename_done:
jsr opendir ; open and read entire file into memory
jsr $1400 ; jump to common entry point
; hope they updated the WHICH_LOAD value
jmp which_load_loop
; filename to open is 30-character Apple text, must be padded with space ($A0)
filename:
.byte $A0,$A0,$A0,$A0,$A0,$A0,$A0,$A0,$A0,$A0
.byte $A0,$A0,$A0,$A0,$A0,$A0,$A0,$A0,$A0,$A0
.byte $A0,$A0,$A0,$A0,$A0,$A0,$A0,$A0,$A0,$A0
filenames_low:
.byte <demosplash_filename
filenames_high:
.byte >demosplash_filename
demosplash_filename:
.byte "DEMOSPLASH",0
;unhook DOS and build nibble table
init:
; patch to use current drive
; locate input paramater list
jsr $3E3
; result is in A:Y
sta $FF
sty $FE
ldy #1
lda ($FE),y
; list+1 should have slot<<8
ora #$80 ; add in $80
; c0e0
sta mlsmc06+1
; c0e8
clc
adc #8
sta mlsmc02+1
; c0e9
clc
adc #1
sta mlsmc01+1
; c0ec
clc
adc #3
sta mlsmc03+1
sta mlsmc04+1
sta mlsmc05+1
jsr $fe93 ; clear COUT
jsr $fe89 ; clear KEYIN
;========================
; Create nibble table
; Note: the table starts 16 bytes in, and is sparse
; so it doesn't entirely look like the DOS33 table at
ldy #0
ldx #3
L1: stx $3c ; store tempx (3?)
txa ; a=x (a=3)
asl ; a*=2 (a=6)
bit $3c ; a&tempx, set N/V (a=6)
beq L3 ; if 0, skip to L3
ora $3c ; a|=tempx (a=7)
eor #$ff ; a=~a (a=f8)
and #$7e ; a&=0x7e 0111 1110 (a=78)
L2: bcs L3 ; this set way back at asl??
lsr ; a>>1 a=3c c=0
; a=1e c=0
; a=0f c=0
; a=07 c=1
bne L2 ; if a!=0 goto l2
tya ; if a==0, a=y
sta nibtbl, x ; write out to table
iny ; increment y
L3: inx ; increment x x=4, a=0f
bpl L1 ; loop while high bit not set
rts
;===========================
; opendir
;===========================
; turn on drive and read volume table of contents
opendir:
mlsmc01:lda $c0e9 ; turn slot#6 drive on
ldx #0
stx adrlo ; zero out adrlo
stx secsize ; zero out secsize
lda #$11 ; a=$11 (VTOC)
jsr readdirsec
firstent:
lda dirbuf+1
; lock if entry not found
entry_not_found:
beq entry_not_found
; read directory sector
ldx dirbuf+2
jsr seekread1
ldy #7 ;number of directory entries in a sector
ldx #$2b ;offset of filename in directory entry
nextent:
tya
pha ; was **phy**
txa
pha ; was **phx**
ldy #$1d
; match name backwards (slower but smaller)
L4:
lda (namlo), y
cmp dirbuf, x
beq foundname
pla
; move to next directory in this block, if possible
clc
adc #$23
tax
pla
tay ; was **ply**
dey
bne nextent
beq firstent ; was **bra**
foundname:
dex
dey
bpl L4
pla
tay ; was **ply**
pla
; read track/sector list
lda dirbuf-32, y
ldx dirbuf-31, y
jsr seekread1
; read load offset and length info only, initially
lda #<filbuf
sta adrlo
lda #4
sta secsize
lda dirbuf+12
ldx dirbuf+13
ldy #>filbuf
jsr seekread
; reduce load offset by 4, to account for offset and length
sec
lda filbuf
sbc #4
sta adrlo
lda filbuf+1
sbc #0
sta adrhi
; save on stack bytes that will be overwritten by extra read
ldy #3
L5:
lda (adrlo), y
pha
dey
bpl L5
lda adrhi
pha
lda adrlo
pha
; increase load size by 4, to account for offst and length
lda filbuf+2
adc #3
sta sizelo
sta secsize
lda filbuf+3
adc #0
sta sizehi
beq readfirst
lda #0 ; was **stz secsize**
sta secsize
readfirst:
ldy #$0c
; read a file sector
readnext:
tya
pha
lda dirbuf, y ; A = track
ldx dirbuf+1, y ; x = sector
jsr seekread1
pla
tay
; if low count is non-zero then we are done
; (can happen only for partial last block)
lda secsize
bne readdone
; continue if more than $100 bytes left
dec sizehi
bne L6
; set read size to min(length, $100)
lda sizelo
beq readdone
sta secsize
L6:
inc adrhi
iny
iny
bne readnext
; save current address for after t/s read
lda adrhi
pha
lda adrlo
pha
lda #0
sta adrlo ; was **stz adrlo**
; read next track/sector sector
lda dirbuf+1
ldx dirbuf+2
jsr readdirsec
clc
; restore current address
readdone:
pla
; sta adrhi
; pla
sta adrlo ; code originally had this backwards
pla
sta adrhi
bcc readfirst
mlsmc02:lda $c0e8
; restore from stack bytes that were overwritten by extra read
ldx #3
ldy #0
L7:
pla
sta (adrlo), y
iny
dex
bpl L7
rts
;======================
; readdirsec
;======================
; a = track?
; x = sector?
readdirsec:
ldy #>dirbuf
seekread:
sty adrhi
seekread1:
sta phase
lda sectbl, x
sta reqsec
jsr readadr
; if track does not match, then seek
cpx phase
beq checksec
jsr seek
;=========================================
; re merge in with qkumba's recent changes
; to fix seek problem?
;=========================================
; [re-]read sector
re_read_addr:
jsr readadr
checksec:
cmp reqsec
bne re_read_addr
;=========================
; read sector data
;=========================
readdata:
jsr readd5aa
eor #$ad ; zero A if match
bne re_read_addr
L12:
mlsmc03:ldx $c0ec ; read until valid data (high bit set)
bpl L12
eor nibtbl-$80, x
sta bit2tbl-$aa, y
iny
bne L12
L13:
mlsmc04:ldx $c0ec ; read until valid data (high bit set)
bpl L13
eor nibtbl-$80, x
sta (adrlo), y ; the real address
iny
cpy secsize
bne L13
ldy #0
L14:
ldx #$a9
L15:
inx
beq L14
lda (adrlo), y
lsr bit2tbl-$aa, x
rol
lsr bit2tbl-$aa, x
rol
sta (adrlo), y
iny
cpy secsize
bne L15
rts
; no tricks here, just the regular stuff
;=======================
; readaddr -- read the address field
;=======================
; Find address field, put track in cutrk, sector in tmpsec
readadr:
jsr readd5aa
cmp #$96
bne readadr
ldy #3 ; three?
; first read volume/volume
; then track/track
; then sector/sector?
adr_read_two_bytes:
tax
jsr readnib
rol
sta tmpsec
jsr readnib
and tmpsec
dey
bne adr_read_two_bytes
rts
;========================
; make sure we see the $D5 $AA pattern
readd5aa:
L16:
jsr readnib
L17:
cmp #$d5
bne L16
jsr readnib
cmp #$aa
bne L17
tay ; we need Y=#$AA later
readnib:
mlsmc05:lda $c0ec ; read until valid (high bit set)
bpl readnib
seekret:
rts
;=====================
; SEEK
;=====================
; current track in X?
; desired track in phase
seek:
ldy #0
sty step
asl phase ; multiply by two
txa ; current track?
asl ; mul by two
copy_cur:
tax
sta tmptrk
sec
sbc phase
beq L22
bcs L18
eor #$ff
inx
bcc L19
L18:
sbc #1
dex
L19:
cmp step
bcc L20
lda step
L20:
cmp #8
bcs L21
tay
sec
L21:
txa
pha
ldx step1, y
L22:
php
bne L24
L23:
clc
lda tmptrk
ldx step2, y
L24:
stx tmpsec
and #3
rol
tax
lsr
mlsmc06:lda $c0e0, x
L25:
ldx #$12
L26:
dex
bpl L26
dec tmpsec
bne L25
bcs L23
plp
beq seekret
pla
inc step
bne copy_cur
.if 0
;==============================
; old code
; [re-]read sector
re_read_addr:
jsr readadr
repeat_until_right_sector:
cmp reqsec
bne re_read_addr
;==========================
; read sector data
;==========================
;
readdata:
mlsmc07:
ldy $c0ec ; read data until valid
bpl readdata
find_D5:
cpy #$d5 ; if not D5, repeat
bne readdata
find_AA:
mlsmc08:
ldy $c0ec ; read data until valid, should be AA
bpl find_AA
cpy #$aa ; we need Y=#$AA later
bne find_D5
find_AD:
mlsmc09:lda $c0ec ; read data until high bit set (valid)
bpl find_AD
eor #$ad ; should match $ad
bne * ; lock if didn't find $ad (failure)
L12:
mlsmc0A:ldx $c0ec ; read data until high bit set (valid)
bpl L12
eor nibtbl-$80, x
sta bit2tbl-$aa, y
iny
bne L12
L13:
mlsmc0B:ldx $c0ec ; read data until high bit set (valid)
bpl L13
eor nibtbl-$80, x
sta (adrlo), y ; the real address
iny
cpy secsize
bne L13
ldy #0
L14:
ldx #$a9
L15:
inx
beq L14
lda (adrlo), y
lsr bit2tbl-$aa, x
rol
lsr bit2tbl-$aa, x
rol
sta (adrlo), y
iny
cpy secsize
bne L15
rts
; no tricks here, just the regular stuff
;=================
; readadr -- read address field
;=================
; Find address field, put track in cutrk, sector in tmpsec
readadr:
mlsmc0C:lda $c0ec ; read data until we find a $D5
bpl readadr
adr_d5:
cmp #$d5
bne readadr
adr_aa:
mlsmc0D:lda $c0ec ; read data until we find a $AA
bpl adr_aa
cmp #$aa
bne adr_d5
adr_96:
mlsmc0E:lda $c0ec ; read data until we find a $96
bpl adr_96
cmp #$96
bne adr_d5
ldy #3 ; three?
; first read volume/volume
; then track/track
; then sector/sector?
adr_read_two_bytes:
sta curtrk ; store out current track
tax
L20:
mlsmc0F:lda $c0ec ; read until full value
bpl L20
rol
sta tmpsec
L21:
mlsmc10:lda $c0ec ; read until full value
bpl L21 ; sector value is (v1<<1)&v2????
and tmpsec
dey ; loop 3 times
bne adr_read_two_bytes
seekret:
rts ; return
;================
; SEEK
;================
; current track in curtrk
; desired track in phase
seek:
asl curtrk ; multiply by 2
asl phase ; multiply by 2
lda #0
sta step
copy_cur:
lda curtrk ; load current track
sta tmptrk ; store as temptrk
sec ; calc current-desired
sbc phase
beq seekret ; if they match, we are done!
bcs seek_neg ; if negative, skip ahead
eor #$ff ; ones-complement the distance
inc curtrk ; increment current (make it 2s comp?)
bcc L114 ; skip ahead
seek_neg:
adc #$fe
dec curtrk
L114:
cmp step
bcc L115
lda step
L115:
cmp #8
bcs L116
tay
sec
L116:
lda curtrk
ldx step1, y
bne L118
L117:
clc
lda tmptrk
ldx step2, y
L118:
stx tmpsec
and #3
rol
tax
mlsmc11:sta $c0e0, x
L119:
ldx #$13
L120:
dex
bne L120
dec tmpsec
bne L119
lsr
bcs L117
inc step
bne copy_cur
.endif
step1: .byte $01, $30, $28, $24, $20, $1e, $1d, $1c
step2: .byte $70, $2c, $26, $22, $1f, $1e, $1d, $1c
sectbl: .byte $00,$0d,$0b,$09,$07,$05,$03,$01,$0e,$0c,$0a,$08,$06,$04,$02,$0f
; From $BA96 of DOS33
;nibtbl: .res 128 ; = *
; .byte $00,$01,$98,$99,$02,$03,$9C,$04 ; $BA96 ; 00
; .byte $05,$06,$A0,$A1,$A2,$A4,$A4,$A5 ; $BA9E ; 08
; .byte $07,$08,$A8,$A9,$AA,$09,$0A,$0B ; $BAA6 ; 10
; .byte $0C,$0D,$B0,$B1,$0E,$0F,$10,$11 ; $BAAE ; 18
; .byte $12,$13,$B8,$14,$15,$16,$17,$18 ; $BAB6 ; 20
; .byte $19,$1A,$C0,$C1,$C2,$C3,$C4,$C5 ; $BABE ; 28
; .byte $C6,$C7,$C8,$C9,$CA,$1B,$CC,$1C ; $BAC6 ; 30
; .byte $1D,$1E,$D0,$D1,$D2,$1E,$D4,$D5 ; $BACE ; 38
; .byte $20,$21,$D8,$22,$23,$24,$25,$26 ; $BAD6 ; 40
; .byte $27,$28,$E0,$E1,$E2,$E3,$E4,$29 ; $BADE ; 48
; .byte $2A,$2B,$E8,$2C,$2D,$2E,$2F,$30 ; $BAE6 ; 50
; .byte $31,$32,$F0,$F1,$33,$34,$35,$36 ; $BAEE ; 58
; .byte $37,$38,$F8,$39,$3A,$3B,$3C,$3D ; $BAF6 ; 60
; .byte $3E,$3F,$13,$00,$01,$02,$01,$00 ; $BAFE ; 68
; .byte $00,$00,$00,$00,$00,$00,$00,$00
; .byte $00,$00,$00,$00,$00,$00,$00,$00
;bit2tbl: .res 86 ; = nibtbl+128
;filbuf: .res 4 ; = bit2tbl+86
;dataend = filbuf+4
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