dos33fsprogs/games/mist/qkumba_popwr.s

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; popwr -- code provided by qkumba
frombuff=$d00 ; sector data to write
; note these must be contiguous
encbuf=$e00 ; nibble buffer must be page alined
bit2tbl=$f00
readnib = $1001
readd5aa:
try_again:
jsr readnib
try_for_d5:
cmp #$d5
bne try_again
jsr readnib
cmp #$aa
bne try_for_d5
jsr readnib
rts
;================================
; set up the self-modifying code
; to point to the proper slot
;================================
; slot number is in high nibble of A
popwr_init:
and #$70 ; the slot number is in the top here
sta slotpatchw1+1 ; self modify the code
sta slotpatchw2+1
sta slotpatchw3+1
sta slotpatchw4+1
rts
;================================
; write a sector
;================================
sector_write:
; convert the input to nibbles
ldy #2 ; why start at 2?
aa:
ldx #$aa
b1:
dey
frombuff_smc:
lda frombuff, y
lsr
rol bit2tbl-$aa, x
lsr
rol bit2tbl-$aa, x
sta encbuf, y
lda bit2tbl-$aa, x
and #$3f
sta bit2tbl-$aa, x
inx
bne b1
tya
bne aa
jmp cmpsecwr
.align $100
; look for the proper sector to write
cmpsecwr:
b2:
jsr readd5aa ; look for dd55aa marker
cmp #$96
bne b2
ldy #3 ; try getting the sector number
b3:
jsr readnib
rol
sta tmpsec
jsr readnib
and tmpsec ; and with prev nibble?
dey
bne b3
requested_sector:
cmp #$d1
bne cmpsecwr ; retry if not what we want?
;skip tail #$DE #$AA #$EB some #$FFs ...
ldy #$24
b4:
dey
bpl b4
; c0e0 slot 6 ph0 off
; c0e1 slot 6 ph0 on
; c0e2 slot 6 ph1 off
; c0e3 slot 6 ph1 on
; c0e4 slot 6 ph2 off
; c0e5 slot 6 ph2 on
; c0e6 slot 6 ph3 off
; c0e7 slot 6 ph3 on
; c0e8 slot 6 motor off
; c0e9 slot 6 motor on
; c0ea slot 6 drive 1
; c0eb slot 6 drive 2
; c0ec slot 6 q6 off \ Q6 Q7
; c0ed slot 6 q6 on |-- state machine 0 0 READ
; c0ee slot 6 q7 off | 0 1 WRITE
; c0ef slot 6 q7 on / 1 0 SENSE WRITE PROTECT
; 1 1 WRITE LOAD
; write sector data
slotpatchw1:
ldx #$d1 ; cycle num smc Q6 Q7
lda $c08d, x ; prime drive 1 X
lda $c08e, x ; required by Unidisk 1 0 ; senese wp?
tya
sta $c08f, x ; 1 1 ; write load
ora $c08c, x ; 0 1 ; write
; 40 cycles
ldy #4 ; 2 cycles
cmp $ea ; nop ; 3 cycles
cmp ($ea,x) ; nop ; 6 cycles
b5:
jsr writenib1 ; (29 cycles)
; +6 cycles
dey ; 2 cycles
bne b5 ; 3/2nt
; 36 cycles
; +10 cycles
ldy #(prolog_e-prolog)
; 2 cycles
cmp $ea ; nop ; 3 cycles
b6:
lda prolog-1, y ; 4 cycles
jsr writenib3 ; (17 cycles)
; 32 cycles if branch taken
; +6 cycles
dey ; 2 cycles
bne b6 ; 3/2nt
; 36 cycles on first pass
; +10 cycles
tya ; 2 cycles
ldy #$56 ; 2 cycles
b7:
eor bit2tbl-1, y ; 5 cycles
tax ; 2 cycles
lda xlattbl, x ; 4 cycles
slotpatchw2:
ldx #$d1 ; slot number smc ; 2 cycles
sta $c08d, x ; wp sense ; 5 cycles
lda $c08c, x ; read ; 4 cycles
; 32 cycles if branch taken
lda bit2tbl-1, y ; 5 cycles
dey ; 2 cycles
bne b7 ; 3/2nt
; 32 cycles
; +9 cycles
clc ; 2 cycles
b88:
eor encbuf, y ; 4 cycles
b8:
tax ; 2 cycles
lda xlattbl, x ; 4 cycles
slotpatchw3:
ldx #$d1 ; slot number smc ; 2 cycles
sta $c08d, x ; wp sense ; 5 cycles
lda $c08c, x ; read ; 4 cycles
bcs f1 ; 3/2nt
; 32 cycles if branch taken
lda encbuf, y ; 4 cycles
iny ; 2 cycles
bne b88 ; 3/2nt
; 32 cycles
; +10 cycles
sec ; 2 cycles
bcs b8 ; 3 cycles
; 32 cycles
; +3 cycles
f1:
ldy #(epilog_e-epilog)
; 2 cycles
cmp ($ea,x) ; nop ; 6 cycles
b9:
lda epilog-1, y ; 4 cycles
jsr writenib3 ; (17 cycles)
; 32 cycles if branch taken
; +6 cycles
dey ; 2 cycles
bne b9 ;3/2nt
lda $c08e, x ; read/wp
lda $c08c, x ; read
lda $c088, x ; motor off
rts ; 6 cycles
writenib1:
cmp ($ea,x) ; nop ; 6 cycles
cmp ($ea,x) ; nop ; 6 cycles
writenib3:
slotpatchw4:
ldx #$d1 ; slot number ; 2 cycles
writenib4:
sta $c08d, x ; wp sense? ; 5 cycles
ora $c08c, x ; read ; 4 cycles
rts ; 6 cycles
prolog: .byte $ad, $aa, $d5
prolog_e:
epilog: .byte $ff, $eb, $aa, $de
epilog_e:
xlattbl:
.byte $96,$97,$9A,$9B,$9D,$9E,$9F,$A6
.byte $A7,$AB,$AC,$AD,$AE,$AF,$B2,$B3
.byte $B4,$B5,$B6,$B7,$B9,$BA,$BB,$BC
.byte $BD,$BE,$BF,$CB,$CD,$CE,$CF,$D3
.byte $D6,$D7,$D9,$DA,$DB,$DC,$DD,$DE
.byte $DF,$E5,$E6,$E7,$E9,$EA,$EB,$EC
.byte $ED,$EE,$EF,$F2,$F3,$F4,$F5,$F6
.byte $F7,$F9,$FA,$FB,$FC,$FD,$FE,$FF