dos33fsprogs/megademo/disk/rts.s

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;read any file slot 6 version
;copyright (c) Peter Ferrie 2013
;!cpu 65c02
;!to "trk",plain
;*=$800
adrlo = $26 ;constant from boot prom
adrhi = $27 ;constant from boot prom
tmpsec = $3c ;constant from boot prom
reqsec = $3d ;constant from boot prom
A1L = $3c ;constant from ROM
A1H = $3d ;constant from ROM
A2L = $3e ;constant from ROM
A2H = $3f ;constant from ROM
curtrk = $40
niblo = $41
nibhi = $42
A4L = $42 ;constant from ROM
A4H = $43 ;constant from ROM
sizelo = $44
sizehi = $45
secsize = $46
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TEMPX = $f9
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
reloc = $bc00
dirbuf = $bf00
MOVE = $fe2c
;unhook DOS and build nibble table
init: jsr $fe93
jsr $fe89
lda #<unreloc
sta A1L
lda #>unreloc
sta A1H
lda #<(unreloc+(codeend-opendir)-1)
sta A2L
lda #>(unreloc+(codeend-opendir)-1)
sta A2H
ldy #0
sty A4L
lda #>reloc
sta A4H
jsr MOVE
ldx #3
L1: stx $3c
txa
asl
bit $3c
beq L3
ora $3c
eor #$ff
and #$7e
L2: bcs L3
lsr
bne L2
tya
sta nibtbl, x
iny
L3: inx
bpl L1
rts
unreloc:
;!pseudopc reloc {
;turn on drive and read volume table of contents
opendir:
lda $c0e9
ldx #0
stx adrlo
stx secsize
lda #$11
jsr readdirsec
firstent:
lda dirbuf+1
;lock if entry not found
beq *
;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
ldx dirbuf+1, y
sty TEMPY ; ** was phy **
jsr seekread1
ldy TEMPY ; ** 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
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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
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:
ldy #>dirbuf
seekread:
sty adrhi
seekread1:
sta phase
lda sectbl, x
sta reqsec
jsr readadr
; if track does not match, then seek
lda curtrk
cmp phase
beq checksec
jsr seek
; [re-]read sector
L8:
jsr readadr
checksec:
cmp reqsec
bne L8
; read sector data
readdata:
ldy $c0ec
bpl readdata
L9:
cpy #$d5
bne readdata
L10:
ldy $c0ec
bpl L10
cpy #$aa ;we need Y=#$AA later
bne L9
L11:
lda $c0ec
bpl L11
eor #$ad ;zero A if match
bne * ;lock if read failure
L12:
ldx $c0ec
bpl L12
eor nibtbl-$80, x
sta bit2tbl-$aa, y
iny
bne L12
L13:
ldx $c0ec
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:
lda $c0ec
bpl readadr
L16:
cmp #$d5
bne readadr
L17:
lda $c0ec
bpl L17
cmp #$aa
bne L16
L18:
lda $c0ec
bpl L18
cmp #$96
bne L16
ldy #3
L19:
sta curtrk
L20:
lda $c0ec
bpl L20
rol
sta tmpsec
L21:
lda $c0ec
bpl L21
and tmpsec
dey
bne L19
rts
;=====================
; Stepper motor delay
;=====================
stepdelay:
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stx TEMPX ; was **phx**
and #3
rol
tax
lda $c0e0, x
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lda TEMPX ; was **pla**
L22:
ldx #$13
L23:
dex
bne L23
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sec
sbc #1 ; was **dec**
bne L22
seekret:
rts
;================
; SEEK
;================
seek:
asl curtrk
lda #0
sta step ; *** WAS *** stz step
asl phase
copy_cur:
lda curtrk
sta tmptrk
sec
sbc phase
beq seekret
bcs L24
eor #$ff
inc curtrk
bcc L25
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L24:
sec
sbc #1 ; *** WAS *** dec
dec curtrk
L25:
cmp step
bcc L26
lda step
L26:
cmp #8
bcs L27
tay
sec
L27:
lda curtrk
ldx step1, y
jsr stepdelay
lda tmptrk
ldx step2, y
jsr stepdelay
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 0, $0d, $0b, 9, 7, 5, 3, 1, $0e, $0c, $0a, 8, 6, 4, 2, $0f
codeend = *
nibtbl = *
bit2tbl = nibtbl+128
filbuf = bit2tbl+86
dataend = filbuf+4
;hack to error out when code is too large for current address
;!if ((dirbuf-(dataend-opendir))&$ff00)<reloc {
;1=1
;}
;}