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better nibble count protection track detection (512 repeated nibbles instead of 256)

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4am 2018-01-04 16:12:16 -05:00
parent 1c5fdcfed3
commit 338e65caa5
1 changed files with 31 additions and 25 deletions
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56
src/analyze.a
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@ -15,10 +15,16 @@ SkipTrack
lda #s_eatrk6
bcc .print
;
; Nibble count track?
;
jsr JustTheSameDamnThingOverAndOver
lda #s_sync
bcc .print ; always branches
;
; Unformatted track?
;
jsr IsUnformatted
bcs +
bcs .donotskip
;
; $F7F6EFEAAB protection track?
; (initially presents as unformatted, needs separate test because it
@ -33,12 +39,7 @@ SkipTrack
bvc .print
; if we're in 'crack' mode, restart the scan to find the protection code
jmp SetupF7F6SecondRound
;
; Nibble count track?
;
+ jsr JustTheSameDamnThingOverAndOver
bcs .donotskip
lda #s_sync
.print
jsr PrintByID
;
@ -148,7 +149,7 @@ SetupF7F6SecondRound
;-------------------------------
; JustTheSameDamnThingOverAndOver
; check if track has a large sequence of repeated bytes
; check if track has 512 repeated nibbles
;
; in slot 6, drive 1 is on track to test
; out C clear if found
@ -156,26 +157,32 @@ SetupF7F6SecondRound
;-------------------------------
!zone {
JustTheSameDamnThingOverAndOver
lda $C0E9
jsr WAIT
lda $C0E9 ; turn on drive motor, but we assume it's already spun up from previous reads so no waiting
lda #$60
sta tmp
lda #$19
sta unform+1
ldx #$00
;
; Timing-sensitive code! Cycle counts in margin for worst case path
;
.reset ldy #$00 ; 2
.reset clv ; 2
ldy #$00 ; 2
sta .cmp+1 ; 4
.loop lda $C0EC
bpl .loop ; 3 when not taken
.loop lda $C0EC ; 4
bpl .loop ; 2 when not taken
dex ; 2
bne .cmp ; 3 when not taken
bne .cmp ; 2 when not taken
dec unform+1 ; 5
beq .notfound ; 3 when not taken
beq .notfound ; 2 when not taken
.cmp cmp #$d1 ; 2
bne .reset ; 3 when not taken
bne .reset ; 2 when not taken
iny ; 2
bne .loop ; 2 when taken
bne .loop ; 2 when not taken (3 when taken)
bvs .found ; 2 when not taken
bit tmp ; 3 (sets overflow flag)
bvs .loop ; 3 (always taken)
.found
clc
!byte $24
.notfound
@ -198,8 +205,7 @@ IsUnformatted
lda #$FD
sta gNIBTableFF
lda $C0E9
jsr WAIT
lda $C0E9 ; turn on drive motor, but we assume it's already spun up from previous reads so no waiting
lda #$00
sta unform
lda #$19
@ -208,16 +214,16 @@ IsUnformatted
; Timing-sensitive code! Cycle counts in margin for worst case path
;
.reset ldy #$00
.loop ldx $C0EC
bpl .loop ; 3 when not taken
.loop ldx $C0EC ; 4
bpl .loop ; 2 when not taken
dec unform ; 5
bne + ; 3 when not taken
bne + ; 2 when not taken
dec unform+1 ; 5
beq .unformatted;3 when not taken
beq .unformatted;2 when not taken
+ lda gNIBTable,x; 4
bmi .reset ; 3 when not taken
bmi .reset ; 2 when not taken
iny ; 2
bne .loop ; 2 when taken
bne .loop ; 3 when taken
sec
!byte $24
.unformatted