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A2osX/ProDOS.FX/ProDOS.S.XRW.txt
burniouf e65065228c ProDOS.FX 8M (required for KRNL8M)
2023-11-04 15:42:28 +01:00

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NEW
AUTO 3,1
*--------------------------------------
* If Called by ProDOS : SEI
* If Called directly from GP.DEVPTRS vectors : ????
*--------------------------------------
XRW.START .PH XRW
XRW.START1 cld $D8 to flag language card bank 1 (main)
lda ZP.UNITNUM get unit number.
pha
lsr
lsr
lsr
lsr
sta XRW.UnitIndex
tax
lda XRW.D2SeekTime-1,x
bne .10
lda #IO.D2.SeekTimeP
.10 sta XRW.SeekTime
stz XRW.montimel
pla
and #$7F mask off high bit.
sta ZP.A2L 0SSS0000 for IO indexing
* make sure other drives in other slots are stopped
eor XRW.LastUnitUsed same slot as last ?
asl
beq XRW.Blk2TS
lda #$01
sta XRW.montimeh
.1 lda XRW.LastUnitUsed
and #$70
tax
beq XRW.Blk2TS branch if no previous ever (boot only).
jsr XRW.CheckMotorOnX check if previous drive running.
beq XRW.Blk2TS branch if stopped.
jsr XRW.Wait100usec
lda XRW.montimeh
bne .1
*--------------------------------------
XRW.Blk2TS lda ZP.BLKNUM
sta XRW.ReqTrack
and #7
cmp #4
php
and #3
asl
plp
rol
sta XRW.ReqSector
lda ZP.BLKNUM+1
ldx #3
.1 lsr
ror XRW.ReqTrack
dex
bne .1
*--------------------------------------
ldx ZP.A2L
jsr XRW.ReadMode
jsr XRW.CheckMotorOn
php SAVE IRQ STATE
php save motor on state : NZ if on
lda #$E8 24 up to 0
sta XRW.montimeh
lda ZP.UNITNUM determine drive 1 or 2.
cmp XRW.LastUnitUsed same slot/drive used before ?
sta XRW.LastUnitUsed save it for next time.
php keep results of compare.
asl get drive # into carry.
bcc .3 branch if drive 1 selected.
inx select drive 2.
.3 lda IO.D2.DrvSel1,x
ldx ZP.A2L
lda IO.D2.DrvOn,x turn on the drive.
plp was it the same drive ?
beq .5 yes.
plp NZ: indicate drive off by setting z-flag.
ldy #6
.4 jsr XRW.Wait25600usec 150 ms delay before stepping.
dey
bne .4
php Z set
.5 plp was motor on ?
bne XRW.Cmd if so, don't wait.
* motor was off, wait for it to speed up
.6 jsr XRW.Wait100usec wait 100us for each count in montime
lda XRW.montimeh
bmi .6 count up to 0000
* motor should be up to speed,
* if it looks stopped then the drive is not present
jsr XRW.CheckMotorOn is drive present ?
beq XRW.E.ND
*--------------------------------------
XRW.Cmd lda ZP.CMDNUM get command #
bne .1
jsr XRW.TestWP 0 = status
bcs XRW.E.WP
bcc XRW.E.OK
.1 cmp #4 3 = format
bcs XRW.E.IO
cmp #2 2 = Write, 1 = Read
ror XRW.bWrite b7 = 1 if Write
bpl .2
jsr XRW.TestWP
bcs XRW.E.WP
*--------------------------------------
.2 sei DISABLE IRQ
lda #2
sta XRW.RecalibrateCnt
.3 jsr XRW.TrackSelect
bcs XRW.E.IO
jsr XRW.SectorIO
bcc .4
jsr XRW.Recalibrate
bcc .3
bcs XRW.E.IO
.4 inc ZP.BUFPTR+1
inc XRW.ReqSector
inc XRW.ReqSector
jsr XRW.SectorIO get 2nd half of block
dec ZP.BUFPTR+1
bcc XRW.E.OK
XRW.E.IO lda #MLI.E.IO
.HS 2C BIT ABS
XRW.E.WP lda #MLI.E.WRTPROT
.HS 2C BIT ABS
XRW.E.ND lda #MLI.E.NODEV
plp RESTORE IRQ STATE
sec
bra XRW.E.EXIT
XRW.E.OK plp RESTORE IRQ STATE
clc
lda #0
XRW.E.EXIT ldx ZP.A2L
bit IO.D2.DrvOff,x
rts
*--------------------------------------
XRW.SectorIO bit XRW.bWrite
bpl .1
jsr XRW.PreNibble
.1 stz XRW.RetryCnt
.2 jsr XRW.ReadAddr (..14)
bcs .3 (2)
lda XRW.AddrField.S (4)
cmp XRW.ReqSector (4)
bne .3 (2)
bit XRW.bWrite (4)
bpl XRW.Read (2)
jmp XRW.Write (3)
.3 inc XRW.RetryCnt
bpl .2
sec
.9 rts
*--------------------------------------
* read subroutine (16-sector format)
*
* reads encoded bytes into nbuf1 and nbuf2.
* first reads nbuf2 high to low, then nbuf1 low to high.
* on entry: x=slot# times $10, read mode
* on exit: carry set if error, else if no error:
* acc=$AA, x=unchanged, y=0, carry clear.
* observe 'no page cross' on some branches !!
*--------------------------------------
.LIST ON
XRW.Read txa get slot #
.LIST OFF
ora #$8C prepare mods to read routine.
sta rd4+1 warning: the read routine is
sta rd5+1 self modified !!
sta rd6+1
sta rd7+1
sta rd8+1
lda ZP.BUFPTR modify storage addresses also
ldy ZP.BUFPTR+1
sta ref3+1
sty ref3+2
sec
sbc #$54
bcs L571F branch if no borrow
dey
L571F sta ref2+1
sty ref2+2
sec
sbc #$57
bcs L572B branch if no borrow
dey
L572B sta ref1+1
sty ref1+2
ldy #$20 32 tries to find
L5733 dey
beq L576D branch if can't find data header marks
L5736 lda IO.D2.RData,x
bpl L5736
L573B eor #$D5 1st data mark
bne L5733
nop delay
L5740 lda IO.D2.RData,x
bpl L5740
cmp #$AA 2nd data mark.
bne L573B if not, check for 1st again
nop
L574A lda IO.D2.RData,x
bpl L574A
cmp #$AD 3rd data mark
bne L573B if not, check for data mark 1 again
ldy #$AA
lda #$00
L5757 sta ZP.PCL use z-page for keeping checksum
rd4 ldx IO.D2.RData+$60 warning: self modified
bpl rd4
lda XRW.Nib2FC-$96,x
sta nbuf2-$AA,y save the two-bit groups in nbuf.
eor ZP.PCL update checksum.
iny next position in nbuf.
bne L5757 loop for all $56 two-bit groups.
ldy #$AA now read directly into user buffer.
bne rd5 always taken.
L576D sec error
rts
ref1 sta $1000,y warning: self modified
rd5 ldx IO.D2.RData+$60 warning: self modified
bpl rd5
eor XRW.Nib2FC-$96,x get actual 6-bit data from dnib table.
ldx nbuf2-$AA,y get associated two-bit pattern
eor dnibl2,x and combine to form whole byte.
iny
bne ref1 loop for $56 bytes.
pha save for now, no time to store...
and #$FC strip low bits.
ldy #$AA prepare for next $56 bytes
rd6 ldx IO.D2.RData+$60 warning: self modified
bpl rd6
eor XRW.Nib2FC-$96,x
ldx nbuf2-$AA,y
eor dnibl3,x
ref2 sta $1000,y warning: self modified
iny
bne rd6 loop unil this group of $56 read
rd7 ldx IO.D2.RData+$60 warning: self modified
bpl rd7
and #$FC
ldy #$AC last group is $54 long
L57A5 eor XRW.Nib2FC-$96,x
ldx nbuf2-$AC,y
eor dnibl4,x combine to form full byte
ref3 sta $1000,y warning: self modified
rd8 ldx IO.D2.RData+$60 warning: self modified
bpl rd8
iny
bne L57A5
and #$FC
eor XRW.Nib2FC-$96,x checksum ok ?
bne L57CC error if not.
ldx ZP.A2L test end marks.
L57C2 lda IO.D2.RData,x
bpl L57C2
cmp #$DE
clc
beq L57CD branch if good trailer
L57CC sec
L57CD pla place last byte into user buffer
ldy #$55
sta (ZP.BUFPTR),y
.LIST ON
XRW.Read.RTS rts
.LIST OFF
*--------------------------------------
XRW.TestWP ldx ZP.A2L
lda IO.D2.ReadProt,x test for write protected
lda IO.D2.ReadMode,x
rol write protect-->carry-->bit 0=1
lda IO.D2.RData,x keep in read mode
rts
*--------------------------------------
* write subroutine (16 sector format)
*
* writes data from nbuf1 and buf. first nbuf2, high to low then direct
* from (buf), low to high. assumes 1 usec cycle time. self modified code !!
*
* on entry: x = slotnum times 16 (35us since read $DE)
*--------------------------------------
.LIST ON
XRW.Write lda IO.D2.ReadProt,x (4) PREWRITE MODE
.LIST OFF
lda IO.D2.ReadMode,x (4)
jsr XRW.Write.RTS (12)
nop (2)
lda #$FF (2)
sta IO.D2.WriteMode,x (5) goto write mode
ora IO.D2.WShift,x (4)
ldy nbuf2 (4)
sty ZP.PCL (3)
ldy #6 (2)
nop (2)
.1 pha (3) exact timing.
pla (4) exact timing.
jsr wnibl7 (18..10) write sync.
dey (2)
bne .1 (3) must not cross page !
nop (2)
nop (2)
lda #$D5 (2) 1st data mark
jsr wnibl9 (20..10)
lda #$AA (2) 2nd data mark
jsr wnibl9 (20..10)
lda #$AD (2) 3rd data mark
jsr wnibl9 (20..10)
tya (2) zero checksum
ldy #$56 (2) nbuf2 index
bne L583D (3) branch always
* total time in this write byte loop must = 32us !!!
L583A lda nbuf2,y (4) prior 6-bit nibl
*L583D eor nbuf2-1,y (5) xor with current (4+1 : PAGE CROSS)
L583D eor nbuf2-1,y (4) xor with current (NO MORE PAGE CROSS)
tax (2) index to 7-bit nibl
lda XRW.FC2Nib,x (4) must not cross page boundary
* ldx ZP.A2L (3) restore slot index
ldx >ZP.A2L (4) absolute reference to zero page
sta IO.D2.WLoad,x (5) store encoded byte
lda IO.D2.WShift,x (4) handshake
dey (2)
bne L583A (3-) must not cross page boundary
* end of write byte loop
lda ZP.PCL (3) get prior nibl (from nbuf2)
wrefd1 ldy #$00 (2) warning: load value modified by prenib.
wrefa1 eor $1000,y (4) warning: address modified by prenib.
and #$FC (2) strip low 2 bits
tax (2) index to nibl table
lda XRW.FC2Nib,x (4)
wrefd2 ldx #$60 (2) warning: value modified by prenib.
sta IO.D2.WLoad,x (5) write nibl
lda IO.D2.WShift,x (4) handshake
wrefa2 lda $1000,y (4) prior nibl. warning: address modified by prenib.
iny (2) all done with this page ?
bne wrefa1 (3-) loop until page end.
lda ZP.PCH (3) get next (precalculated & translated) nibl.
beq L58C0 (2+) branch if code written was page aligned.
lda ZP.A2H (3) get byte address of last byte to be written.
beq L58B3 (2+) branch if only 1 byte left to write.
lsr (2) test for odd or even last byte (carry set/clear)
lda ZP.PCH (3) restore nibl to acc.
sta IO.D2.WLoad,x (5)
lda IO.D2.WShift,x (4)
lda ZP.A1L (3) = byte 0 of 2nd page xor'd with byte 1 if
nop (2) above test set carry.
iny (2) y=1
bcs L5899 (2+) branch if last byte to be odd.
wrefa3 eor $1100,y (4) warning: address modified by prenib.
and #$FC (2) strip low 2 bits.
tax (2) index to nibl table
lda XRW.FC2Nib,x (4) get nibl
wrefd3 ldx #$60 (2) restore slot index. warning: modified by prenib
sta IO.D2.WLoad,x (5)
lda IO.D2.WShift,x (4)
wrefa4 lda $1100,y (4) warning: modified by prenib
iny (2) got prior nibl, point to next
wrefa5 eor $1100,y (4) warning: modified by prenib
L5899 cpy ZP.A2H (3) set carry if this is the last nibl
and #$FC (2) strip low 2 bits
tax (2)
lda XRW.FC2Nib,x (4)
wrefd4 ldx #$60 (2) restore slot. warning: modified by prenib
sta IO.D2.WLoad,x (5)
lda IO.D2.WShift,x (4)
wrefa6 lda $1100,y (4) get prior nibl. warning: modified by prenib
iny (2)
bcc wrefa3 (3-) branch if not the last.
bcs L58B1 (3) waste 3 cycles, branch always.
L58B1 bcs L58C0 (3) branch always.
L58B3 lda >ZP.PCH (4) absolute reference to zero page
sta IO.D2.WLoad,x (5)
lda IO.D2.WShift,x (4)
pha (3) waste 14 micro-seconds total
pla (4)
pha (3)
pla (4)
L58C0 ldx ZP.A1H (3) use last nibl (anded with $FC) for checksum
lda XRW.FC2Nib,x (4)
wrefd5 ldx #$60 (2) restore slot. warning: modified by prenib
sta IO.D2.WLoad,x (5)
lda IO.D2.WShift,x (4)
ldy #2 (2) set y = index end mark table.
pha (3) waste another 11 micro-seconds
pla (4)
nop (2)
.1 clc (2)
lda XRW.EndMark,y (4) DE AA EB
jsr wnibl (11..10) write it
dey (2)
bpl .1 (3) if not.
bmi .2 (3)
.2 nop (2)
tya (2) Y = $FF from DEY BMI
jsr wnibl (11..10) write turn off byte.
XRW.ReadMode lda IO.D2.ReadMode,x (4) out of write mode
lda IO.D2.WShift,x (4) to read mode.
rts return from write.
* 7-bit nibl write subroutines
wnibl9 clc (2) 9 cycles, then write.
wnibl7 pha (3) 7 cycles, then write.
pla (4)
wnibl sta IO.D2.WLoad,x (5) nibl write
ora IO.D2.WShift,x (4) clobbers acc, not carry
.LIST ON
XRW.Write.RTS rts (6)
.LIST OFF
*--------------------------------------
XRW.Wait25600usec
lda #0
.HS 2C BIT ABS
XRW.Wait100usec lda #1
XRW.Wait100usecA
phx
.1 ldx #17 (2)
.2 dex (2)
bne .2 (3)
inc XRW.montimel (6)
bne .3 (3)
inc XRW.montimeh (6)
.3 dec (2)
bne .1 (3)
plx
rts
*--------------------------------------
XRW.CheckMotorOn
ldx ZP.A2L
XRW.CheckMotorOnX
ldy #0 init loop counter.
.1 lda IO.D2.RData,x read the shift register.
jsr .9 delay
pha
pla more delay.
cmp IO.D2.RData,x has shift reg changed ?
bne .9 yes, motor is moving.
dey no, dec retry counter
bne .1 and try 256 times.
.9 rts Z if motor OFF
*--------------------------------------
.LIST ON
XRW.ReadAddr ldy #$FC
.LIST OFF
sty XRW.CheckSum init nibble counter to $FCFC
ldx ZP.A2L get slot #
.1 iny
bne .2 counter LO
inc XRW.CheckSum counter HI
beq .99
.2 lda IO.D2.RData,x read nibl
bpl .2
.3 cmp #$D5 address mark 1 ?
bne .1
nop
.4 lda IO.D2.RData,x
bpl .4
cmp #$AA address mark 2 ?
bne .3 if not, is it address mark 1 ?
ldy #3 index for 4 byte read
.5 lda IO.D2.RData,x
bpl .5
cmp #$96 address mark 3 ?
bne .3 if not, is it address mark 1
lda #0 init Chksum
.6 sta XRW.CheckSum
.7 lda IO.D2.RData,x read 'odd bit' nibl
bpl .7
rol align odd bits, '1' into lsb.
sta XRW.Temp4x4 save them.
.8 lda IO.D2.RData,x read 'even bit' nibl
bpl .8
and XRW.Temp4x4 merge odd and even bits.
sta XRW.AddrField.C,y store data byte.
eor XRW.CheckSum
dey
bpl .6 loop on 4 data bytes.
tay if final checksum non-zero,
bne .99 (2) then error.
.9 lda IO.D2.RData,x (4)
bpl .9 (2)
eor #$DE (2)
bne .99 (2)
clc (2)
rts (6)
.99 sec
.LIST ON
XRW.ReadAddr.RTS
rts
.LIST OFF
*--------------------------------------
XRW.TrackSelect lda #2
sta XRW.BadSeekCnt
.1 stz XRW.RetryCnt
.2 jsr XRW.ReadAddr
bcc .4
.3 inc XRW.RetryCnt
bpl .2
jsr XRW.Recalibrate
bcc .1
rts
*--------------------------------------
.4 ldx XRW.UnitIndex
lda XRW.AddrField.V
sta XRW.D2VolNum-1,x
lda XRW.AddrField.T
sta XRW.D2Trk-1,x
eor XRW.ReqTrack
beq .8
lda XRW.AddrField.V
asl
bcc .5 single sided
bmi .5 > 192 ????
lda XRW.ReqTrack
and #1
rol A = 0/2
ora ZP.A2L
tay y = n0/n2
lda IO.D2.Ph0On,y PhOn 0/2 for Head0 or 1/3 for Head1
lda IO.D2.Ph0On+4,y
jsr XRW.Wait100usec
jsr XRW.AllPhOff
lda XRW.AddrField.T
sta XRW.D2Trk-1,x
bra .1
.5 lda XRW.AddrField.T
cmp XRW.ReqTrack
beq .8
lda XRW.BadSeekCnt
beq .6 2 bad seeks, already
dec XRW.BadSeekCnt
bne .7
.6 lda XRW.SeekTime
clc
adc #IO.D2.SeekTimeI
bmi .7 seektime > 128
sta XRW.SeekTime
sta XRW.D2SeekTime-1,x
.7 ldy XRW.D2Trk-1,x From actual Pos...
lda XRW.ReqTrack ....to Req
jsr XRW.SeekYA X = XRW.UnitIndex
bra .3
.8 clc
XRW.TrackSelect.RTS
rts
*--------------------------------------
XRW.Recalibrate sec
dec XRW.RecalibrateCnt
beq XRW.TrackSelect.RTS
ldx XRW.UnitIndex
ldy #40 from 40... (4/4)
lda #0 ....to 0
sta XRW.D2VolNum-1,x reset volnum for seeking 40->0 4/4 tracks
*--------------------------------------
XRW.SeekYA sta XRW.D2Trk-1,x will be current track at the end
jsr XRW.Trk2Qtrk
sta XRW.TargetQTrack
tya
jsr XRW.Trk2Qtrk
sta XRW.CurrentQTrack
bit #1 A = Current QT
beq .2 we are on 0/4 or 2/4 track
pha
cmp XRW.TargetQTrack we are on 1/4 or 3/4 track
bcc .1 if CC, C < T, must move in
inc move out: X = Ph(N+1)
.1 jsr XRW.SeekPhOnY move in : X = Ph(N)
tya
tax
pla
bcs .2 if CS, C > T, must move out
inc move in : Y = Ph(N+1)
.2 jsr XRW.SeekPhOnY move out: Y = Ph(N)
bra .9 Ph ON to go to 0/4 or 2/4, no wait
*--------------------------------------
.3 bcs .4 if CS, C > T, must move out
inc CC: C < T, ON next PH
.HS B0 BCS
.4 dec CS: C > T, ON prev PH
sta XRW.CurrentQTrack
bit #1 C = xxxxxxx1 ?
bne .5 yes, 2 PhOn required
lda IO.D2.Ph0Off,x we must go to 0/4 or 2/4 : PhX Off
bra .8 go wait....
.5 phy we must go on 1/4 or 3/4
plx Y already ON, -> X for Ph0Off,x
bcs .6 if CS, C > T, must move out
inc CC: C < T, ON next PH
.6 jsr XRW.SeekPhOnY now X and Y on
.8 lda XRW.SeekTime
jsr XRW.Wait100usecA ...wait...
.9 lda XRW.CurrentQTrack
cmp XRW.TargetQTrack
bne .3
* lsr CS if X,Y on
jsr XRW.Wait25600usec
XRW.AllPhOff ldy ZP.A2L
lda IO.D2.Ph0Off,y
lda IO.D2.Ph0Off+2,y
lda IO.D2.Ph0Off+4,y
lda IO.D2.Ph0Off+6,y
* lda IO.D2.Ph0Off,y
* bcc .10
* lda IO.D2.Ph0Off,x
clc Exit wit CC (recalibrate)
* lda IO.D2.Ph0Off,y
.10 rts
*--------------------------------------
XRW.SeekPhOnY and #6
ora ZP.A2L
tay
lda IO.D2.Ph0On,y
rts
*--------------------------------------
* In:
* A = Logical Track 0 -> 159,
* X = XRW.UnitIndex
* D2VolNum : d0000sss
* Out:
* A =
*--------------------------------------
XRW.Trk2Qtrk sta ZP.PCH
lda XRW.D2VolNum-1,x
bne .1
.10 lda ZP.PCH standard SS 4 qtrack stepping
asl
asl
rts
.1 bpl .2
cmp #$85
bcs .10 > 192 ? must be a buggy 254
lsr ZP.PCH 2 sides
.2 phx
and #%00000111 stepping
tax
lda #0
clc
.3 adc ZP.PCH
dex
bne .3
plx
.8 rts
*--------------------------------------
* preniblize subroutine (16 sector format)
*
* converts 256 bytes of user data in (buf) into 6 bit nibls in nbuf2.
* high 6 bits are translated directly by the write routines.
*
* on entry: buf is 2-byte pointer to 256 bytes of user data.
*
* on exit: a,x,y undefined. write routine modified to do direct conversion
* of high 6 bits of user's buffer data.
*--------------------------------------
XRW.PreNibble lda ZP.BUFPTR self-modify the addresses because of
ldy ZP.BUFPTR+1 the fast timing required.
clc all offsets are minus $AA.
adc #$02 the highest set is buf+$AC.
bcc L58FA branch if no carry,
iny otherwise add carry to high address.
L58FA sta prn3+1 self mod 3
sty prn3+2
sec
sbc #$56 middle set is buf+$56.
bcs L5906 branch if no borrow,
dey otherwise deduct from high.
L5906 sta prn2+1 self mod 2
sty prn2+2
sec
sbc #$56 low set is exactly buf
bcs L5912
dey
L5912 sta prn1+1 self mod 1
sty prn1+2
ldy #$AA count up to 0.
prn1 lda $1000,y warning: self modified. get byte from lowest group.
and #$03 strip high 6 bits.
tax index to 2 bit equivalent.
lda XRW.0000XX00,x
pha save pattern
prn2 lda $1056,y warning: self modified. get byte from middle group.
and #$03
tax
pla restore pattern.
ora XRW.00XX0000,x combine 2nd group with 1st.
pha save new pattern.
prn3 lda $10AC,y warning: self modified. get byte from highest group.
and #$03
tax
pla restore new pattern
ora XRW.XX000000,x and form final nibl.
pha
tya
eor #$FF
tax
pla
sta nbuf2,x save in nibl buffer.
iny inc to next set.
bne prn1 loop until all $56 nibls formed.
ldy ZP.BUFPTR now prepare data bytes for write16 subr.
dey prepare end address.
sty ZP.A2H
lda ZP.BUFPTR
sta wrefd1+1 warning: the following storage addresses
beq L595F starting with 'wref' are refs into code
eor #$FF space, changed by this routine.
tay index to last byte of page in (buf).
lda (ZP.BUFPTR),y pre-niblize the last byte of the page
iny with the first byte of the next page.
eor (ZP.BUFPTR),y
and #$FC
tax
lda XRW.FC2Nib,x get disk 7-bit nible equivalent.
L595F sta ZP.PCH
beq L596F branch if data to be written is page aligned.
lda ZP.A2H check if last byte is even
lsr or odd address. shift even/odd -> carry.
lda (ZP.BUFPTR),y if even, then leave intact.
bcc L596D branch if odd.
iny if even, then pre-xor with byte 1.
eor (ZP.BUFPTR),y
L596D sta ZP.A1L save result for write routine.
L596F ldy #$FF index to last byte of data to write.
lda (ZP.BUFPTR),y to be used as a checksum.
and #$FC strip extra bits
sta ZP.A1H and save it.
ldy ZP.BUFPTR+1 now modify address references to
sty wrefa1+2 user data.
sty wrefa2+2
iny
sty wrefa3+2
sty wrefa4+2
sty wrefa5+2
sty wrefa6+2
ldx ZP.A2L and lastly, index references to
stx wrefd2+1 controller.
stx wrefd3+1
stx wrefd4+1
stx wrefd5+1
rts
*--------------------------------------
.LIST ON
XRW.FREE .EQ $D540-*
.LIST OFF
.BS $D540-*
*--------------------------------------
* nibl buffer 'nbuf2' must fit in a page
*--------------------------------------
nbuf2 .BS $56 nibl buffer for read/write of low 2-bits of each byte.
*--------------------------------------
* 7-bit to 6-bit 'deniblize' table (16-sector format)
*
* valid codes are $96 to $FF only. codes with more than one pair of
* adjacent zeroes or with no adjacent ones (except bit 7) are excluded.
*
* nibbles in the ranges of $A0-$A3, $C0-$C7, $E0-$E3 are used for
* other tables since no valid nibbles are in these ranges.
* aligned to page boundary + $96
*--------------------------------------
XRW.Nib2FC .HS 0004
* .HS FFFF
XRW.UnitIndex .HS 00
XRW.LastUnitUsed .HS 00
.HS 080C
* .HS FF
XRW.RecalibrateCnt .HS 00
.HS 101418
XRW.XX000000 .HS 008040C0 used in fast prenib as lookup for 2-bit quantities.
* .HS FFFF
XRW.montimel .HS 00
XRW.montimeh .HS 00
.HS 1C20
.HS FFFFFF
.HS 24282C3034
* .HS FFFF
XRW.ReqTrack .HS 00
XRW.ReqSector .HS 00
.HS 383C4044484C
* .HS FF
XRW.BadSeekCnt .HS 00
.HS 5054585C606468
XRW.00XX0000 .HS 00201030 used in fast prenib.
XRW.EndMark .HS EBAADE table using 'unused' nibbles ($C4,$C5,$C6,$C7)
* .HS FFFFFFFF
XRW.AddrField.C .HS 00 AddrField Checksum
XRW.AddrField.S .HS 00 AddrField Sector
XRW.AddrField.T .HS 00 AddrField Track
XRW.AddrField.V .HS 00 AddrField Volume
.HS 6C
XRW.SeekTime .HS 00
*ibstat .HS 00
.HS 707478
.HS FFFFFF
.HS 7C
* .HS FFFF
XRW.Temp4x4 .HS 00
XRW.CheckSum .HS 00 used for address header cksum
.HS 8084
.HS FF
.HS 888C9094989CA0
XRW.0000XX00 .HS 0008040C used in fast prenib.
* .HS FF
XRW.CurrentQTrack .HS 00
.HS A4A8AC
* .HS FF
XRW.TargetQTrack .HS 00
.HS B0B4B8BCC0C4C8
* .HS FFFF
XRW.RetryCnt .HS 00
.HS 00
.HS CCD0D4D8DCE0
XRW.bWrite .HS 00
.HS E4E8ECF0F4F8FC
*--------------------------------------
* 6-bit to 2-bit conversion tables:
*
* origin = $D600 (page boundary)
*
* dnibl2 abcdef-->0000FE
* dnibl3 abcdef-->0000DC
* dnibl4 abcdef-->0000BA
* page align the following tables:
*--------------------------------------
* FC-bits to nibble conversion table (256 bytes)
*
* codes with more than one pair of adjacent zeroes
* or with no adjacent ones (except B7) are excluded.
*--------------------------------------
dnibl2 .HS 00
dnibl3 .HS 00
dnibl4 .HS 00
XRW.FC2Nib .HS 96
.HS 02000097
.HS 0100009A
.HS 0300009B
.HS 0002009D
.HS 0202009E
.HS 0102009F
.HS 030200A6
.HS 000100A7
.HS 020100AB
.HS 010100AC
.HS 030100AD
.HS 000300AE
.HS 020300AF
.HS 010300B2
.HS 030300B3
.HS 000002B4
.HS 020002B5
.HS 010002B6
.HS 030002B7
.HS 000202B9
.HS 020202BA
.HS 010202BB
.HS 030202BC
.HS 000102BD
.HS 020102BE
.HS 010102BF
.HS 030102CB
.HS 000302CD
.HS 020302CE
.HS 010302CF
.HS 030302D3
.HS 000001D6
.HS 020001D7
.HS 010001D9
.HS 030001DA
.HS 000201DB
.HS 020201DC
.HS 010201DD
.HS 030201DE
.HS 000101DF
.HS 020101E5
.HS 010101E6
.HS 030101E7
.HS 000301E9
.HS 020301EA
.HS 010301EB
.HS 030301EC
.HS 000003ED
.HS 020003EE
.HS 010003EF
.HS 030003F2
.HS 000203F3
.HS 020203F4
.HS 010203F5
.HS 030203F6
.HS 000103F7
.HS 020103F9
.HS 010103FA
.HS 030103FB
.HS 000303FC
.HS 020303FD
.HS 010303FE
.HS 030303FF
*--------------------------------------
.EP
*--------------------------------------
.LIST ON
XRW.LEN .EQ *-XRW.START
.LIST OFF
*--------------------------------------
MAN
SAVE usr/src/prodos.fx/prodos.s.xrw
LOAD usr/src/prodos.fx/prodos.s
ASM
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