8bitfiles.net/archives/archives.tar/archives/genie-commodore-file-library/Information/HACK5C.SFX/hack5-6

Text File | 1990-02-12 | 16.5 KB | 801 lines

%    JSR TOGGLE├LOCK
%    JSR SERIAL╫AIT
%    LDX CIA─ATA
%    JSR TOGGLE├LOCK
%    TXA
%    STA ERRNO
%    AND #$0F
%    CMP #2
%    CLI
%    RTS
%

╘HIS NEXT LEVEL OF ROUTINES DEALS WITH LOGICAL SECTORS AND THE TRACK CACHE
RATHER THAN WITH HARDWARE.

% ;====LOGICAL SECTOR LEVEL====
%

╔NVALIDATE THE TRACK CACHE IF THE ═╙-─╧╙ DRIVE NUMBER IS CHANGED OR IF A NEW
DISK IS INSERTED.  ╘HIS ROUTINE HAS TO ESTABLISH A ╥┴═ CONFIGURATION OF $0┼
SINCE IT WILL BE CALLED FROM ╥┴═0.  ├ONFIGURATION $0┼ GIVES ╥┴═0 FROM $0000 TO
$┬╞╞╞, ╦ERNAL ╥╧═ FROM $├000 TO $╞╞╞╞, AND THE ╔/╧ SPACE OVER THE ╦ERNAL FROM
$─000 TO $─╞╞╞.  ╘HIS CONFIGURATION IS SET BY ALL APPLICATION INTERFACE
SUBROUTINES.

% INIT╨ACKAGE = *
%    LDA #$0E
%    STA $FF00
%    LDA #$FF
%    STA BUF├YLINDER
%    STA BUF╙IDE
%    LDX #7
% -  STA DIR─IRTY,X
%    DEX
%    BPL -
%    STA FAT─IRTY
%    CLC
%    RTS
%

╠OCATE A SECTOR (BLOCK) IN THE TRACK CACHE, OR READ THE CORRESPONDING PHYSICAL
TRACK INTO THE TRACK CACHE IF NECESSARY.  ╘HIS ROUTINE ACCEPTS THE CYLINDER,
SIDE, AND SECTOR NUMBERS OF THE BLOCK.

% SECTOR╙AVE = 5
%
% READ┬LOCK = *  ;( .┴=CYLINDER,.╪=SIDE,.┘=SECTOR ) : .┴┘=BLK╨TR,.├╙=ERR

├HECK IF THE CORRECT TRACK IS IN THE TRACK CACHE.

%    CMP BUF├YLINDER
%    BNE READ┬LOCK╨HYSICAL
%    CPX BUF╙IDE
%    BNE READ┬LOCK╨HYSICAL

╔F SO, THEN LOCATE THE SECTOR'S ADDRESS AND RETURN THAT.

%    DEY
%    TYA
%    ASL
%    CLC
%    ADC #>TRACKBUF
%    TAY
%    LDA #<TRACKBUF
%    CLC
%    RTS
%

╚ERE, WE HAVE TO READ THE PHYSICAL TRACK INTO THE TRACK CACHE.  ╫E SAVE THE
INPUT PARAMETERS AND CALL THE HARDWARE-LEVEL TRACK-READING ROUTINE.

%    READ┬LOCK╨HYSICAL = *
%    STA BUF├YLINDER
%    STX BUF╙IDE
%    STY SECTOR╙AVE
%    JSR READ╘RACK

├HECK FOR ERRORS.

%    BCC READ┬LOCK╨HYSICAL╧K
%    LDA ERRNO
%    AND #$0F
%    CMP #11    ;DISK CHANGE
%    BEQ +
%    SEC
%    RTS

╔F THE ERROR THAT HAPPENED IS A "─ISK ├HANGE" ERROR, THEN MOUNT THE DISK AND
TRY TO READ THE PHYSICAL TRACK AGAIN.

% +  JSR MOUNT─ISK
%    LDA BUF├YLINDER
%    LDX BUF╙IDE
%    LDY SECTOR╙AVE
%    BCC READ┬LOCK╨HYSICAL
%    RTS
%

╚ERE, THE PHYSICAL TRACK HAS BEEN READ INTO THE TRACK CACHE OK, SO WE RECOVER
THE ORIGINAL INPUT PARAMETERS AND TRY THE TOP OF THE ROUTINE AGAIN.

%    READ┬LOCK╨HYSICAL╧K = *
%    LDA BUF├YLINDER
%    LDX BUF╙IDE
%    LDY SECTOR╙AVE
%    JMP READ┬LOCK
%

─IVIDE THE GIVEN NUMBER BY 18.  ╘HIS IS NEEDED FOR THE CALCULATIONS TO CONVERT
A LOGICAL SECTOR NUMBER TO THE CORRESPONDING PHYSICAL CYLINDER, SIDE, AND
SECTOR NUMBERS THAT THE LOWER-LEVEL ROUTINES REQUIRE.  ╘HE METHOD OF REPEATED
SUBTRACTION IS USED.  ╘HIS ROUTINE WOULD PROBABLY WORK FASTER IF WE TRIED TO
REPEATEDLY SUBTRACT 360 (18*20) AT THE TOP, BUT ╔ DIDN'T BOTHER.

% DIVIDE┬Y18 = *  ;( .┴┘=NUMBER ) : .┴=QUOTIENT, .┘=REMAINDER
%    ;** COULD REPEATEDLY SUBTRACT 360 HERE
%    LDX #$FF
% -  INX
%    SEC
%    SBC #18
%    BCS -
%    DEY
%    BPL -
%    CLC
%    ADC #18
%    INY
%    TAY
%    TXA
%    RTS
%

├ONVERT THE GIVEN LOGICAL BLOCK NUMBER TO THE CORRESPONDING PHYSICAL CYLINDER,
SIDE, AND SECTOR NUMBERS.  ╘HIS ROUTINE FOLLOWS THE FORMULAE GIVEN IN THE
PREVIOUS ARTICLE WITH A FEW SIMPLIFYING TRICKS.

% CONVERT╠OGICAL┬LOCK╬UM = *  ;( .┴┘=BLOCK╬UM ) : .┴=CYL, .╪=SIDE,.┘=SEC
%    JSR DIVIDE┬Y18
%    LDX #0
%    CPY #9
%    BCC +
%    PHA
%    TYA
%    SBC #9
%    TAY
%    PLA
%    LDX #1
% +  INY
%    RTS
%

├OPY A SEQUENTIAL GROUP OF LOGICAL SECTORS INTO MEMORY.  ╘HIS ROUTINE IS USED
BY THE DIRECTORY LOADING ROUTINE TO LOAD THE ╞┴╘ AND ╥OOT ─IRECTORY, AND IS
USED BY THE CLUSTER READING ROUTINE TO RETRIEVE ALL OF THE BLOCKS OF A
CLUSTER.  ┴FTER THE GIVEN STARTING LOGICAL SECTOR NUMBER IS CONVERTED INTO ITS
PHYSICAL CYLINDER, SIDE, AND SECTOR EQUIVALENT, THE PHYSICAL VALUES ARE
INCREMENTED TO GET THE ADDRESS OF SUCCESSIVE SECTORS OF THE GROUP.  ╘HIS
AVOIDS THE OVERHEAD OF THE LOGICAL TO PHYSICAL CONVERSION.  ╤UITE A NUMBER OF
TEMPORARIES ARE NEEDED.

% DEST╨TR = 6
% CUR├YLINDER = 8
% CUR╙IDE = 9
% CUR╙ECTOR = 10
% BLOCK├OUNTDOWN = 11
% SOURCE╨TR = 12
%
% COPY┬LOCKS = *  ;( .┴┘=START┬LOCK, .╪=BLOCK├OUNT, ($6)=DEST ) : .├╙=ERR
%    STX BLOCK├OUNTDOWN
%    JSR CONVERT╠OGICAL┬LOCK╬UM
%    STA CUR├YLINDER
%    STX CUR╙IDE
%    STY CUR╙ECTOR
%
%    COPY┬LOCK╠OOP = *
%    LDA CUR├YLINDER
%    LDX CUR╙IDE
%    LDY CUR╙ECTOR
%    JSR READ┬LOCK
%    BCC +
%    RTS
% +  STA SOURCE╨TR
%    STY SOURCE╨TR+1
%    LDX #2
%    LDY #0

╚ERE ╔ UNROLL THE COPYING LOOP A LITTLE BIT TO CUT THE OVERHEAD OF THE BRANCH
INSTRUCTION IN HALF.  (┴ CYCLE SAVED... YOU KNOW).

% -  LDA (SOURCE╨TR),Y
%    STA (DEST╨TR),Y
%    INY
%    LDA (SOURCE╨TR),Y
%    STA (DEST╨TR),Y
%    INY
%    BNE -
%    INC SOURCE╨TR+1
%    INC DEST╨TR+1
%    DEX
%    BNE -

╔NCREMENT THE CYLINDER, SIDE, SECTOR VALUES.

%    INC CUR╙ECTOR
%    LDA CUR╙ECTOR
%    CMP #10
%    BCC +
%    LDA #1
%    STA CUR╙ECTOR
%    INC CUR╙IDE
%    LDA CUR╙IDE
%    CMP #2
%    BCC +
%    LDA #0
%    STA CUR╙IDE
%    INC CUR├YLINDER
% +  DEC BLOCK├OUNTDOWN
%    BNE COPY┬LOCK╠OOP
%    CLC
%    RTS
%

├ONVERT A GIVEN CLUSTER NUMBER INTO THE FIRST CORRESPONDING LOGICAL BLOCK
NUMBER.

% CONVERT├LUSTER╬UM = *  ;( .┴┘=CLUSTER╬UM ) : .┴┘=LOGICAL┬LOCK╬UM
%    SEC
%    SBC #2
%    BCS +
%    DEY
% +  LDX CLUSTER┬LOCK├OUNT
%    CPX #1
%    BEQ +
%    ASL
%    STY 7
%    ROL 7
%    LDY 7
% +  CLC
%    ADC FIRST╞ILE┬LOCK
%    BCC +
%    INY
% +  RTS
%

╥EAD A CLUSTER INTO THE ├LUSTER ┬UFFER, GIVEN THE CLUSTER NUMBER.  ╘HE CLUSTER
NUMBER IS CONVERTED TO A LOGICAL SECTOR NUMBER AND THEN THE SECTOR COPYING
ROUTINE IS CALLED.  ╘HE FORMULA GIVEN IN THE PREVIOUS ARTICLE IS USED.

% READ├LUSTER = *  ;( .┴┘=CLUSTER╬UMBER ) : CLUSTER┬UF, .├╙=ERR
%    JSR CONVERT├LUSTER╬UM
%
%    ;** READ LOGICAL BLOCKS COMPRISING CLUSTER
%    LDX #<CLUSTER┬UF
%    STX 6
%    LDX #>CLUSTER┬UF
%    STX 7
%    LDX CLUSTER┬LOCK├OUNT
%    JMP COPY┬LOCKS
%

╫RITE A LOGICAL BLOCK OUT TO DISK.  ╘HE REAL PURPOSE OF THIS ROUTINE IS TO
INVALIDATE THE READ-TRACK CACHE IF THE BLOCK TO BE WRITTEN IS CONTAINED IN
THE CACHE.

% WRITE╠OGICAL┬LOCK = *  ;( .┴┘=LOGICAL┬LOCK╬UMBER, BUFPTR ) : .├╙=ERR
%    JSR CONVERT╠OGICAL┬LOCK╬UM
%    CMP BUF├YLINDER
%    BNE +
%    CPX BUF╙IDE
%    BNE +
%    PHA
%    LDA #$FF
%    STA BUF├YLINDER
%    STA BUF╙IDE
%    PLA
% +  JSR WRITE╙ECTOR
%    RTS
%
% WRITE├LUSTER╙AVE .BUF 2
%

╫RITE A CLUSTER-FUL OF DATA OUT TO DISK FROM THE CLUSTER BUFFER.  ╘HIS ROUTINE
SIMPLY CALLS THE WRITE LOGICAL BLOCK ROUTINE ONCE OR TWICE, DEPENDING ON THE
CLUSTER SIZE OF THE DISK INVOLVED.

% WRITE├LUSTER = *  ;( .┴┘=CLUSTER╬UMBER, CLUSTER┬UF ) : .├╙=ERR
%    JSR CONVERT├LUSTER╬UM
%    LDX #<CLUSTER┬UF
%    STX BUFPTR
%    LDX #>CLUSTER┬UF
%    STX BUFPTR+1
%    STA WRITE├LUSTER╙AVE
%    STY WRITE├LUSTER╙AVE+1
%    JSR WRITE╠OGICAL┬LOCK
%    BCC +
%    RTS
% +  LDA CLUSTER┬LOCK├OUNT
%    CMP #2
%    BCS +
%    RTS
% +  LDA WRITE├LUSTER╙AVE
%    LDY WRITE├LUSTER╙AVE+1
%    CLC
%    ADC #1
%    BCC +
%    INY
% +  JSR WRITE╠OGICAL┬LOCK
%    RTS
%

╘HIS NEXT LEVEL OF ROUTINES DEAL WITH THE DATA STRUCTURES OF THE ═╙-─╧╙ DISK
FORMAT.

% ;====═╙-─╧╙ FORMAT LEVEL====
%
% BOOT┬LOCK = 2
%

╥EAD THE DISK FORMAT PARAMETERS, DIRECTORY, AND ╞┴╘ INTO MEMORY.

% MS─IR = *  ;( ) : .┴┘=DIRBUF, .╪=DIR┼NTRIES, .├╙=ERR
%    LDA #$0E
%    STA $FF00
%

╥EAD THE BOOT SECTOR AND EXTRACT THE PARAMETERS.

%    ;** GET PARAMETERS FROM BOOT SECTOR
%    LDA #0
%    LDY #0
%    JSR CONVERT╠OGICAL┬LOCK╬UM
%    JSR READ┬LOCK
%    BCC +
%    RTS
% +  STA BOOT┬LOCK
%    STY BOOT┬LOCK+1
%    LDY #13              ;GET CLUSTER SIZE
%    LDA (BOOT┬LOCK),Y
%    STA CLUSTER┬LOCK├OUNT
%    CMP #3
%    BCC +
%

╔F A DISK PARAMETER IS FOUND TO EXCEED THE LIMITS OF ╠╥╥, ERROR CODE #60 IS
RETURNED.

%    INVALID╨ARMS = *
%    LDA #60
%    STA ERRNO
%    SEC
%    RTS
%
% +  LDY #16              ;CHECK ╞┴╘ REPLICATION COUNT, MUST BE 2
%    LDA (BOOT┬LOCK),Y
%    CMP #2
%    BNE INVALID╨ARMS
%    LDY #22              ;GET ╞┴╘ SIZE IN SECTORS
%    LDA (BOOT┬LOCK),Y
%    STA FAT┬LOCKS
%    CMP #4
%    BCS INVALID╨ARMS
%    LDY #17              ;GET DIRECTORY SIZE
%    LDA (BOOT┬LOCK),Y
%    STA ROOT─IR┼NTRIES
%    CMP #129
%    BCS INVALID╨ARMS
%    LSR
%    LSR
%    LSR
%    LSR
%    STA ROOT─IR┬LOCKS
%    LDY #19              ;GET TOTAL SECTOR COUNT
%    LDA (BOOT┬LOCK),Y
%    STA TOTAL╙ECTORS
%    INY
%    LDA (BOOT┬LOCK),Y
%    STA TOTAL╙ECTORS+1
%    LDY #24              ;CHECK SECTORS PER TRACK, MUST BE 9
%    LDA (BOOT┬LOCK),Y
%    CMP #9
%    BNE INVALID╨ARMS
%    LDY #26
%    LDA (BOOT┬LOCK),Y
%    CMP #2               ;CHECK NUMBER OF SIDES, MUST BE 2
%    BNE INVALID╨ARMS
%    LDY #14              ;CHECK NUMBER OF BOOT SECTORS, MUST BE 1
%    LDA (BOOT┬LOCK),Y
%    CMP #1
%    BNE INVALID╨ARMS
%

├ALCULATE THE DERIVED PARAMETERS.

%    ;** GET DERIVED PARAMETERS
%    LDA FAT┬LOCKS        ;FIRST ROOT DIRECTORY SECTOR
%    ASL
%    CLC
%    ADC #1
%    STA FIRST╥OOT─IR┬LOCK
%    CLC                  ;FIRST FILE SECTOR
%    ADC ROOT─IR┬LOCKS
%    STA FIRST╞ILE┬LOCK
%    LDA TOTAL╙ECTORS     ;NUMBER OF FILE CLUSTERS
%    LDY TOTAL╙ECTORS+1
%    SEC
%    SBC FIRST╞ILE┬LOCK
%    BCS +
%    DEY
% +  STA FILE├LUSTER├OUNT
%    STY FILE├LUSTER├OUNT+1
%    LDA CLUSTER┬LOCK├OUNT
%    CMP #2
%    BNE +
%    LSR FILE├LUSTER├OUNT+1
%    ROR FILE├LUSTER├OUNT
% +  CLC
%    LDA FILE├LUSTER├OUNT
%    ADC #2
%    STA LAST╞AT┼NTRY
%    LDA FILE├LUSTER├OUNT+1
%    ADC #0
%    STA LAST╞AT┼NTRY+1
%
%    ;** LOAD ╞┴╘
%    LDA #<FATBUF
%    LDY #>FATBUF
%    STA 6
%    STY 7
%    LDA #1
%    LDY #0
%    LDX FAT┬LOCKS
%    JSR COPY┬LOCKS
%    BCC +
%    RTS
%
%    ;** LOAD ACTUAL DIRECTORY
% +  LDA #<DIRBUF
%    LDY #>DIRBUF
%    STA 6
%    STY 7
%    LDA FIRST╥OOT─IR┬LOCK
%    LDY #0
%    LDX ROOT─IR┬LOCKS
%    JSR COPY┬LOCKS
%    BCC +
%    RTS
% +  LDA #<DIRBUF
%    LDY #>DIRBUF
%    LDX ROOT─IR┼NTRIES
%    CLC
%    RTS
%

╘HIS ROUTINE LOCATES THE GIVEN ╞┴╘ TABLE ENTRY NUMBER AND RETURNS THE VALUE
STORED IN IT.  ╙OME WORK IS NEEDED TO DEAL WITH THE 12-BIT COMPRESSED DATA
STRUCTURE.

% ENTRY┴DDR = 2
% ENTRY╫ORK = 4
% ENTRY┬ITS = 5
% ENTRY─ATA0 = 6
% ENTRY─ATA1 = 7
% ENTRY─ATA2 = 8
%
% LOCATE╞AT┼NTRY = *  ;( .┴┘=FAT┼NTRY╬UMBER ) : ENTRY┴DDR, ENTRY┬ITS%1

─IVIDE THE ╞┴╘ ENTRY NUMBER BY TWO AND MULTIPLY BY THREE BECAUSE TWO ╞┴╘
ENTRIES ARE STORED IN THREE BYTES.  ╘HEN ADD THE ╞┴╘ BASE ADDRESS AND WE HAVE
THE ADDRESS OF THE THREE BYTES THAT CONTAIN THE ╞┴╘ ENTRY WE ARE INTERESTED
IN.  ╔ RETRIEVE THE THREE BYTES INTO ZERO-PAGE MEMORY FOR EASY MANIPULATION.

%    STA ENTRY┬ITS
%    ;** DIVIDE BY TWO
%    STY ENTRY┴DDR+1
%    LSR ENTRY┴DDR+1
%    ROR
%
%    ;** TIMES THREE
%    STA ENTRY╫ORK
%    LDX ENTRY┴DDR+1
%    ASL
%    ROL ENTRY┴DDR+1
%    CLC
%    ADC ENTRY╫ORK
%    STA ENTRY┴DDR
%    TXA
%    ADC ENTRY┴DDR+1
%    STA ENTRY┴DDR+1
%
%    ;** ADD BASE, GET DATA
%    CLC
%    LDA ENTRY┴DDR
%    ADC #<FATBUF
%    STA ENTRY┴DDR
%    LDA ENTRY┴DDR+1
%    ADC #>FATBUF
%    STA ENTRY┴DDR+1
%    LDY #2
% -  LDA (ENTRY┴DDR),Y
%    STA ENTRY─ATA0,Y
%    DEY
%    BPL -
%    RTS
%
% GET╞AT┼NTRY = *  ;( .┴┘=FAT┼NTRY╬UMBER ) : .┴┘=FAT┼NTRY╓ALUE
%    JSR LOCATE╞AT┼NTRY
%    LDA ENTRY┬ITS
%    AND #1
%    BNE +
%

╔F THE ORIGINAL GIVEN ╞┴╘ ENTRY NUMBER IS EVEN, THEN WE WANT THE FIRST 12-BIT
COMPRESSED FIELD.  ╘HE NYBBLES ARE EXTRACTED ACCORDING TO THE DIAGRAM SHOWN
EARLIER.

%    ;** CASE 1: FIRST 12-BIT CLUSTER
%    LDA ENTRY─ATA1
%    AND #$0F
%    TAY
%    LDA ENTRY─ATA0
%    RTS
%

╧THERWISE, WE WANT THE SECOND 12-BIT FIELD.

%    ;** CASE 2: SECOND 12-BIT CLUSTER
% +  LDA ENTRY─ATA1
%    LDX #4
% -  LSR ENTRY─ATA2
%    ROR
%    DEX
%    BNE -
%    LDY ENTRY─ATA2
%    RTS
%
% FAT╓ALUE = 9
%

├HANGE THE VALUE IN A ╞┴╘ ENTRY.  ╘HIS ROUTINE IS QUITE SIMILAR TO THE GET
ROUTINE.

% SET╞AT┼NTRY = *  ;( .┴┘=FAT┼NTRY╬UMBER, (FAT╓ALUE) )
%    JSR LOCATE╞AT┼NTRY
%    LDA FAT╓ALUE+1
%    AND #$0F
%    STA FAT╓ALUE+1
%    LDA ENTRY┬ITS
%    AND #1
%    BNE +
%
%    ;** CASE 1: FIRST 12-BIT CLUSTER
%    LDA FAT╓ALUE
%    STA ENTRY─ATA0
%    LDA ENTRY─ATA1
%    AND #$F0
%    ORA FAT╓ALUE+1
%    STA ENTRY─ATA1
%    JMP SET╞AT┼XIT
%
%    ;** CASE 2: SECOND 12-BIT CLUSTER
% +  LDX #4
% -  ASL FAT╓ALUE
%    ROL FAT╓ALUE+1
%    DEX
%    BNE -
%    LDA FAT╓ALUE+1
%    STA ENTRY─ATA2
%    LDA ENTRY─ATA1
%    AND #$0F
%    ORA FAT╓ALUE
%    STA ENTRY─ATA1
%
%    SET╞AT┼XIT = *
%    LDY #2
% -  LDA ENTRY─ATA0,Y
%    STA (ENTRY┴DDR),Y
%    DEY
%    BPL -
%    STY FAT─IRTY
%    RTS
%

═ARK THE DIRECTORY SECTOR CORRESPONDING TO THE GIVEN DIRECTORY ENTRY AS BEING
DIRTY SO IT WILL BE WRITTEN OUT TO DISK THE NEXT TIME THE MS╞LUSH ROUTINE IS
CALLED.

% DIRTY─IRENT = *  ;( WRITE─IRENT )
%    SEC
%    LDA WRITE─IRENT
%    SBC #<DIRBUF
%    LDA WRITE─IRENT+1
%    SBC #>DIRBUF
%    LSR
%    AND #$07
%    TAX
%    LDA #$FF
%    STA DIR─IRTY,X
%    RTS
%
% DEL├LUSTER = 14
%

─ELETE THE ═╙-─╧╙ FILE WHOSE DIRECTORY ENTRY IS GIVEN.  ╨UT THE $┼5 INTO
ITS FILENAME, GET ITS STARTING CLUSTER AND FOLLOW THE CHAIN OF CLUSTERS
ALLOCATED TO THE FILE IN THE ╞┴╘, MARKING THEM AS UNALLOCATED (VALUE $000)
AS WE GO.  ┼XIT BY MARKING THE DIRECTORY ENTRY AS "DIRTY".

% MS─ELETE = *  ;( WRITE─IRENT )
%    LDY #$0E
%    STY $FF00
%    LDA WRITE─IRENT
%    LDY WRITE─IRENT+1
%    STA 2
%    STY 3
%    LDA #$E5
%    LDY #0
%    STA (2),Y
%    LDY #26
%    LDA (2),Y
%    STA DEL├LUSTER
%    INY
%    LDA (2),Y
%    STA DEL├LUSTER+1
% -  LDA DEL├LUSTER+1
%    CMP #5
%    BCC +
%    JMP DIRTY─IRENT
% +  TAY
%    LDA DEL├LUSTER
%    JSR GET╞AT┼NTRY
%    PHA
%    TYA
%    PHA
%    LDA #0
%    STA FAT╓ALUE
%    STA FAT╓ALUE+1
%    LDA DEL├LUSTER
%    LDY DEL├LUSTER+1
%    JSR SET╞AT┼NTRY
%    PLA
%    STA DEL├LUSTER+1
%    PLA
%    STA DEL├LUSTER
%    JMP -
%
% FLUSH┬LOCK = 14
% FLUSH├OUNTDOWN = $60
% FLUSH╥EPEATS = $61
% FLUSH─IR╔NDEX = $61
%

╫RITE THE ╞┴╘ AND DIRECTORY SECTORS FROM MEMORY TO DISK, IF THEY ARE DIRTY.

% MS╞LUSH = *  ;( MS─EVICE, MS╘YPE ) : .├╙=ERROR
%    LDA #$0E
%    STA $FF00
%    LDA FAT─IRTY
%    BEQ FLUSH─IRECTORY
%    LDA #0
%    STA FAT─IRTY
%
%    ;** FLUSH FAT

╞LUSH BOTH COPIES OF THE ╞┴╘, IF THERE ARE TWO; OTHERWISE, ONLY FLUSH THE ONE.

%    LDA #2
%    STA FLUSH╥EPEATS
%    LDA #1
%    STA FLUSH┬LOCK
%
%    MASTER╞LUSH = *
%    LDA FAT┬LOCKS
%    STA FLUSH├OUNTDOWN
%    LDA #<FATBUF
%    LDY #>FATBUF
%    STA BUFPTR
%    STY BUFPTR+1
% -  LDA FLUSH┬LOCK
%    LDY #0
%    JSR WRITE╠OGICAL┬LOCK
%    BCC +
%    RTS
% +  INC FLUSH┬LOCK
%    DEC FLUSH├OUNTDOWN
%    BNE -
%    DEC FLUSH╥EPEATS
%    BNE MASTER╞LUSH
%
%    ;** FLUSH DIRECTORY
%    FLUSH─IRECTORY = *
%    LDA FIRST╥OOT─IR┬LOCK
%    STA FLUSH┬LOCK
%    LDA ROOT─IR┬LOCKS
%    STA FLUSH├OUNTDOWN
%    LDA #0
%    STA FLUSH─IR╔NDEX
%    LDA #<DIRBUF
%    LDY #>DIRBUF
%    STA BUFPTR
%    STY BUFPTR+1
% -  LDX FLUSH─IR╔NDEX
%    LDA DIR─IRTY,X
%    BEQ +
%    LDA #0
%    STA DIR─IRTY,X
%    LDA FLUSH┬LOCK
%    LDY #0
%    JSR WRITE╠OGICAL┬LOCK
%    DEC BUFPTR+1
%    DEC BUFPTR+1
% +  INC FLUSH┬LOCK
%    INC FLUSH─IR╔NDEX
%    INC BUFPTR+1
%    INC BUFPTR+1
%    DEC FLUSH├OUNTDOWN
%    BNE -
%    CLC
%    RTS
%
% BF╞AT┼NTRY = 14
% BF┬LOCKS = $60
%

├OUNT THE NUMBER OF FREE ╞┴╘ ENTRIES (VALUE $000) FROM ENTRY 2 UP TO THE
HIGHEST ╞┴╘ ENTRY AVAILABLE FOR CLUSTER ALLOCATION.  ╘HEN MULTIPLY THIS
BY THE NUMBER OF BYTES PER CLUSTER (EITHER 512 OR 1024).

% MS┬YTES╞REE = *  ;( ) : .┴┘╪=FILE┬YTES╞REE
%    LDY #$0E
%    STY $FF00
%    LDA #2
%    LDY #0
%    STA BF╞AT┼NTRY
%    STY BF╞AT┼NTRY+1
%    STY BF┬LOCKS
%    STY BF┬LOCKS+1
% -  LDA BF╞AT┼NTRY
%    LDY BF╞AT┼NTRY+1
%    JSR GET╞AT┼NTRY
%    STY 2
%    ORA 2
%    BNE +
%    INC BF┬LOCKS
%    BNE +
%    INC BF┬LOCKS+1
% +  INC BF╞AT┼NTRY
%    BNE +
%    INC BF╞AT┼NTRY+1
% +  LDA BF╞AT┼NTRY
%    CMP LAST╞AT┼NTRY
%    LDA BF╞AT┼NTRY+1
%    SBC LAST╞AT┼NTRY+1
%    BCC -
%    LDX CLUSTER┬LOCK├OUNT
% -  ASL BF┬LOCKS
%    ROL BF┬LOCKS+1
%    DEX
%    BNE -
%    LDA #0
%    LDY BF┬LOCKS
%    LDX BF┬LOCKS+1
%    RTS
%

╘HIS IS THE FILE COPYING LEVEL.  ╔T DEALS WITH READING/WRITING THE CLUSTERS OF
═╙-─╧╙ FILES AND COPYING THE DATA THEY CONTAIN TO/FROM THE ALREADY-OPEN ├┬═
╦ERNAL FILE, POSSIBLY WITH ┴╙├╔╔/╨┼╘╙├╔╔ TRANSLATION.

% ;====FILE COPY LEVEL====
%
% TRANS═ODE = 14
% LFN = 15
% CBM─ATA╨TR = $60
% CBM─ATA╠EN = $62
% CLUSTER = $64
%

├OPY THE GIVEN CLUSTER TO THE ├┬═ OUTPUT FILE.  ╘HIS ROUTINE FETCHES THE NEXT
CLUSTER OF THE FILE FOR THE NEXT TIME THIS ROUTINE IS CALLED, AND IF IT HITS
THE ╬╒╠╠ POINTER OF THE LAST CLUSTER OF A FILE, IT ADJUSTS THE NUMBER OF VALID
FILE DATA BYTES THE CURRENT CLUSTER CONTAINS TO ╞ILE╠ENGTH % ├LUSTER╠ENGTH
(SEE NOTE BELOW).

% COPY╞ILE├LUSTER = *  ;( CLUSTER, LFN, TRANS═ODE ) : .├╙=ERR

╥EAD THE CLUSTER AND SETUP TO COPY THE WHOLE CLUSTER TO THE ├┬═ FILE.

%    LDA CLUSTER
%    LDY CLUSTER+1
%    JSR READ├LUSTER
%    BCC +
%    RTS
% +  LDA #<CLUSTER┬UF
%    LDY #>CLUSTER┬UF
%    STA CBM─ATA╨TR
%    STY CBM─ATA╨TR+1
%    LDA #0
%    STA CBM─ATA╠EN
%    LDA CLUSTER┬LOCK├OUNT
%    ASL
%    STA CBM─ATA╠EN+1