516 lines
9.1 KiB
ArmAsm
516 lines
9.1 KiB
ArmAsm
; read any file slot 6 version
|
|
; based on FASTLD6 and RTS copyright (c) Peter Ferrie 2011-2013,2018
|
|
|
|
; TODO:
|
|
; non-slot6? self modfiy code?
|
|
|
|
adrlo = $26 ; constant from boot prom
|
|
adrhi = $27 ; constant from boot prom
|
|
tmpsec = $3c ; constant from boot prom
|
|
reqsec = $3d ; constant from boot prom
|
|
curtrk = $40
|
|
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
|
|
|
|
dirbuf = $1e00 ; 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
|
|
|
|
; open and read a file
|
|
lda #<megademo_filename
|
|
sta namlo
|
|
lda #>megademo_filename
|
|
sta namhi
|
|
jsr opendir ; open and read entire file into memory
|
|
|
|
; open and read a file
|
|
; lda #<half_filename
|
|
; sta namlo
|
|
; lda #>half_filename
|
|
; sta namhi
|
|
; jsr opendir ; open and read entire file into memory
|
|
|
|
jmp $4000 ; jump to entry point
|
|
|
|
|
|
; filename to open is 30-character Apple text:
|
|
megademo_filename: ;.byte "MEGAMUSIC "
|
|
.byte 'M'|$80,'E'|$80,'G'|$80,'A'|$80,'M'|$80,'U'|$80,'S'|$80,'I'|$80
|
|
.byte 'C'|$80,$A0,$A0,$A0,$A0,$A0,$A0,$A0
|
|
.byte $A0,$A0,$A0,$A0,$A0,$A0,$A0,$A0
|
|
.byte $A0,$A0,$A0,$A0,$A0,$A0
|
|
|
|
half_filename: ;.byte "HALFMUSIC "
|
|
.byte 'H'|$80,'A'|$80,'L'|$80,'F'|$80,'M'|$80,'U'|$80,'S'|$80,'I'|$80
|
|
.byte 'C'|$80,$A0,$A0,$A0,$A0,$A0,$A0,$A0
|
|
.byte $A0,$A0,$A0,$A0,$A0,$A0,$A0,$A0
|
|
.byte $A0,$A0,$A0,$A0,$A0,$A0
|
|
|
|
|
|
;unhook DOS and build nibble table
|
|
|
|
init:
|
|
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:
|
|
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
|
|
ldy #0 ; was **stz secsize**
|
|
sty secsize
|
|
|
|
readfirst:
|
|
ldy #$0c
|
|
|
|
; read a file sector
|
|
|
|
readnext:
|
|
lda dirbuf, y ; A = track
|
|
ldx dirbuf+1, y ; x = sector
|
|
sty TEMPY ; save t/s ptr ** was phy **
|
|
jsr seekread1
|
|
ldy TEMPY ; restore t/s ptr ** was ply **
|
|
|
|
; 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
|
|
|
|
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
|
|
|
|
; lda curtrk ; BUG fixed recently
|
|
; cmp phase
|
|
|
|
cpx phase
|
|
beq repeat_until_right_sector
|
|
jsr seek
|
|
|
|
; [re-]read sector
|
|
|
|
re_read_addr:
|
|
jsr readadr
|
|
|
|
repeat_until_right_sector:
|
|
cmp reqsec
|
|
bne re_read_addr
|
|
|
|
;==========================
|
|
; read sector data
|
|
;==========================
|
|
;
|
|
|
|
readdata:
|
|
ldy $c0ec ; read data until valid
|
|
bpl readdata
|
|
find_D5:
|
|
cpy #$d5 ; if not D5, repeat
|
|
bne readdata
|
|
find_AA:
|
|
ldy $c0ec ; read data until valid, should be AA
|
|
bpl find_AA
|
|
cpy #$aa ; we need Y=#$AA later
|
|
bne find_D5
|
|
find_AD:
|
|
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:
|
|
ldx $c0ec ; read data until high bit set (valid)
|
|
bpl L12
|
|
eor nibtbl-$80, x
|
|
sta bit2tbl-$aa, y
|
|
iny
|
|
bne L12
|
|
L13:
|
|
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:
|
|
lda $c0ec ; read data until we find a $D5
|
|
bpl readadr
|
|
adr_d5:
|
|
cmp #$d5
|
|
bne readadr
|
|
|
|
adr_aa:
|
|
lda $c0ec ; read data until we find a $AA
|
|
bpl adr_aa
|
|
cmp #$aa
|
|
bne adr_d5
|
|
|
|
adr_96:
|
|
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:
|
|
lda $c0ec ; read until full value
|
|
bpl L20
|
|
rol
|
|
sta tmpsec
|
|
L21:
|
|
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
|
|
sta $c0e0, x
|
|
L119:
|
|
ldx #$13
|
|
L120:
|
|
dex
|
|
bne L120
|
|
dec tmpsec
|
|
bne L119
|
|
lsr
|
|
bcs L117
|
|
inc step
|
|
bne copy_cur
|
|
|
|
|
|
|
|
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
|
|
|