;-------------------------------
; IsF7
; check for a specific nibble sequence
; ("F7 F6 EF EE AB") that is used by a
; whole-track protection scheme
;
; in  slot 6, drive 1 is on track to test
; out C clear if sequence was found
;     C set if sequence was not found
;-------------------------------
IsF7
         lda   $C0E9
         lda   #$00
         jsr   WAIT
         lda   #$20
         sta   nibcount
         ldy   #$00
-        lda   $C0EC
         bpl   -
         cmp   #$F7
         beq   +
restart  iny
         bne   -
         dec   nibcount
         bne   -
         beq   F7fail
-
+        lda   $C0EC
         bpl   -
         cmp   #$F6
         bne   restart
-        lda   $C0EC
         bpl   -
         cmp   #$EF
         bne   restart
-        lda   $C0EC
         bpl   -
         cmp   #$EE
         bne   restart
-        lda   $C0EC
         bpl   -
         cmp   #$AB
         bne   restart
         clc
         !byte $24        ; hides SEC
F7fail   sec
         lda   $C0E8
         rts

;-------------------------------
; IsSyncBytes
; check if track is mostly $FF bytes
;
; in  slot 6, drive 1 is on track to test
; out C clear if track is mostly just $FF bytes
;     C set otherwise
;-------------------------------
IsSyncBytes
         lda   #$FD
         sta   nibtableff
         jsr   IsUnformatted
         lda   #$3F
         sta   nibtableff
         rts

;-------------------------------
; IsUnformatted
; check if track is unformatted
;
; in  slot 6, drive 1 is on track to test
; out C clear if track is unformatted
;     C set if track is formatted
;-------------------------------
IsUnformatted
         lda   $C0E9
         lda   #$00
         sta   unform
         sta   unform+1
         jsr   WAIT
         lda   #$20
         sta   nibcount
         ldy   #$00
nibloop  ldx   $C0EC
         bpl   nibloop
         lda   nibtable,x
         bpl   +
         inc   unform
         bne   +
         inc   unform+1
+        iny
         bne   nibloop
         dec   nibcount
         bne   nibloop
         lda   $C0E8
         lda   #$18
         cmp   unform+1
         rts

;-------------------------------
; xHeredityDog
; check for a protection check at $BB00
; which implies an unreadable T00,S0A
;
; in:  $0800..$08FF contains boot0
;      $B600..$BFFF contains boot1
; out: C clear if protection code was found
;      C set if protection code was not found
;-------------------------------
xHeredityDog
         lda   $08FE
         clc
         adc   #$04
         pha
         ldx   #$16
         ldy   #$0B
         jsr   CompareMemory
         !byte $F0,05,$A2,$B2,$4C,$F0,$BB,$BD,$8C,$C0,$A9
         pla
         bcc   analyze_maybe
         jmp   no1

; don't check byte at $BB21 because it can vary

analyze_maybe
         ldx   #$22
         ldy   #$3E
         jsr   CompareMemory
         !byte $8D,00,02,$BD,$8C,$C0,$10,$FB,$C9,$EB,$D0,$F7,$BD,$8C
         !byte $C0,$10,$FB,$C9,$D5,$D0,$EE,$BD,$8C,$C0,$10,$FB,$C9,$AA,$D0,$E5
         !byte $A9,$4C,$A0,00,$99,00,$95,$88,$D0,$FA,$CE,$46,$BB,$AD,$46,$BB
         !byte $C9,07,$D0,$EC,$A9,$18,$8D,$42,$B9,$A9,$0A,$8D,$ED,$B7,$D0,05
         bcs   no1
yes1
         lda   #$80
         sta   T00S0A
no1
         rts

;-------------------------------
; xSunburst
; check for a Sunburst RWTS
; which implies an unreadable T11,S0F
;
; in:  $0800..$08FF contains boot0
;      $B600..$BFFF contains boot1
; out: C clear if Sunburst RWTS was found
;      C set otherwise
;-------------------------------
xSunburst
         lda   $08FE
         clc
         adc   #$03
         ldx   #$69
         ldy   #$2C
         jsr   CompareMemory
         !byte $48,$A5,$2A,$4A,$A8,$B9,$29,$BA
         !byte $8D,$6A,$B9,$8D,$84,$BC,$B9,$34
         !byte $BA,$8D,$FC,$B8,$8D,$5D,$B8,$C0
         !byte $11,$D0,03,$A9,02,$AC,$A9,$0E
         !byte $8D,$C0,$BF,$68,$69,00,$48,$AD
         !byte $78,04,$90,$2B
         bcs   no2
yes2
         lda   #$80
         sta   T11S0F
no2
         rts

;-------------------------------
; xOptimumRes
; check if disk has Optimum Resource bootloader
; which implies an unreadable T01,S0F
;
; in:  $0800..$08FF contains boot0
;      $B600..$BFFF contains boot1
; out: C clear if OptimumRes bootloader was found
;      C set otherwise
;-------------------------------
xOptimumRes
         lda   #$08
         ldx   #$5D
         ldy   #$0C
         jsr   CompareMemory
         !byte $68,$85,$F0,$68,$85,$F1,$A0,01
         !byte $B1,$F0,$85,$54
         bcc   yes3
         lda   #$08
         ldx   #$5D
         ldy   #$0C
         jsr   CompareMemory
         !byte $68,$85,$A0,$68,$85,$A1,$A0,01
         !byte $B1,$A0,$85,$54
         bcs   no3
yes3
         lda   #$80
         sta   T01S0F
no3
         rts

;-------------------------------
; xB4BB
; check if disk changes RWTS in
; late boot after a nibble check
;
; in:  $0800..$08FF contains boot0
;      $B600..$BFFF contains boot1
; out: C clear if RWTS was modified in this routine
;      C set otherwise
;-------------------------------
xB4BB
         lda   gTrack
         pha
         lda   gSector
         pha
b4bbcompare
         lda   #$FF       ; modified at runtime (in Inspect1)
         ldx   #$00
         ldy   #$20
         jsr   CompareMemory
         !byte $D8,$A9,$DF,$48,$A9,$FF,$48,$A9
         !byte 08,$85,$3D,$85,$43,$A9,$BF,$85
         !byte $3F,$A9,00,$85,$3C,$85,$42,$E6
         !byte $42,$A9,$FE,$85,$3E,$A0,00,$AD
         bcs   _b4bbexit
         lda   #$00
         sta   gTrack
         sta   gAddress
         lda   #$0C
         sta   gSector
         lda   #$0C
         clc
         adc   #BASEPAGE
         sta   gAddress+1
         jsr   ReadSector
         bcs   _b4bbexit
         lda   #$0C
         ldx   #$84
         ldy   #$03
         jsr   compare
         !byte $4C,$BB,$B4
         bcs   _b4bbexit
         lda   #$02
         sta   gTrack
         sta   gSector
         jsr   ReadSector
         bcs   _b4bbexit
         lda   #$0C
         clc
         adc   #BASEPAGE
         sta   x0+2
x0       lda   $FFC2      ; modified at runtime (above)
b4bbmodify
         sta   $FF55      ; modified at runtime (in Inspect1)
         lda   #$DE
b4bbmodify2
         sta   $FF91      ; modified at runtime (in Inspect1)
_b4bbexit
         pla
         sta   gSector
         pla
         sta   gTrack
         rts

;-------------------------------
; xB660
; Check if RWTS calls an extra routine at $B660
; after matching the first two data prologue
; nibbles. This routine can hang in an infinite
; loop if it's used to read an unprotected sector,
; so we need to force-switch to the built-in RWTS
; after reading all the protected sectors.
; (T00,S00-S09 are unprotected because they are
; read by the drive firmware.)
;
; in:  $0800..$08FF contains boot0
; out: C clear if $B660 routine was found
;      C set otherwise
;-------------------------------
xB660
         lda   #$08
         ldx   #$60
         ldy   #$1A
         jsr   CompareMemory
         !byte $BD,$8C,$C0,$10,$FB,$C9,$AD,$D0
         !byte $F4,$A9,$F8,$3D,$8C,$C0,$D0,02
         !byte $EA,$EA,$EA,$EA,$BD,$8C,$C0,$2A
         !byte $30,02
         bcs   no4
yes4
         lda   #$FE
         sta   T00S09
no4
         rts