📄 rxdosfil.asm
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defbytes _diskAccess, sizeDISKACCESS
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; init access
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setES ds
lea bx, offset _diskAccess [ bp ] ; pointer to access block
call initdiskAccess ; [ax] is drive, [dx] is cluster
call getAddrDPB ; see if drive initialized
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; search for empty entry
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mov word ptr [ _diskAccess. diskAcPosition. _low ][ bp ], -sizeDIRENTRY
mov word ptr [ _diskAccess. diskAcPosition. _high ][ bp ], -1
mov word ptr [ _diskAccess. diskAcOptions ][ bp ], (ccb_isDIR)
locateFreeDirSlot_12:
add word ptr [ _diskAccess. diskAcPosition. _low ][ bp ], sizeDIRENTRY
adc word ptr [ _diskAccess. diskAcPosition. _high ][ bp ], 0000
lea bx, offset _diskAccess [ bp ] ; pointer to access block
call _FATReadRandom ; read into buffer
stc ; just in case error,
jz locateFreeDirSlot_18 ; if no more data -->
cmp byte ptr es:[ deName ][ bx ], DIRENTRY_NEVERUSED
jz locateFreeDirSlot_16
cmp byte ptr es:[ deName ][ bx ], DIRENTRY_DELETED
jnz locateFreeDirSlot_12 ; if item not found -->
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; item found
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locateFreeDirSlot_16:
mov si, bx ; dir entry to si
or si, si ; no carry
Return
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; if not root directory, append a cluster
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locateFreeDirSlot_18:
cmp word ptr [ _diskAccess. diskAcBegCluster ][ bp ], 0000
stc ; just in case error,
jz locateFreeDirSlot_28 ; if root dir, can't extend -->
mov ax, word ptr [ _diskAccess. diskAcDrive ][ bp ]
mov dx, word ptr [ _diskAccess. diskAcCurCluster ][ bp ]
call AllocateInitCluster ; init a cluster
jc locateFreeDirSlot_28 ; if can't append -->
mov cx, dx ; cluster address to update
mov ax, word ptr [ _diskAccess. diskAcDrive ][ bp ]
mov dx, word ptr [ _diskAccess. diskAcCurCluster ][ bp ]
call updateClusterValue
lea si, offset ccbData [ di ] ; dir address to di
or si, si ; no carry
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; return
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locateFreeDirSlot_28:
Return
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Get Actual (Current Drive as a = 0, b = 1, ... ) ;
;...............................................................;
GetActualDrive:
Entry 1
Arg _drive
push ds
currSegment ds
mov al, byte ptr [ _drive ][ bp ]
and ax, 001fh
dec al
jge GetActualDrive_20
mov al, byte ptr [ _RxDOS_CurrentDrive ]
GetActualDrive_20:
mov dx, ax
cmp al, byte ptr [ _RxDOS_bLastDrive ]
jnc GetActualDrive_Error
clc
GetActualDrive_Return:
pop ds
Return
GetActualDrive_Error:
stc
mov ax, offset pexterrInvalidDrive
jmp GetActualDrive_Return
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Get Device from String ;
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; ;
; Input: ;
; es:si input string ;
; ;
; Output: ;
; es:bx pointer to device header ;
; cy device not found ;
;...............................................................;
getDevice:
Entry
defbytes _devicename, sizeTempFILENAME
push ds ; push these registers
push di
push si
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; get device name, if any.
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setDS es
setES ss
lea di, offset _devicename [ bp ]
mov cx, sizeTempFILENAME - 1
xor ax, ax
getDevice_08:
lodsb
cmp al, ' '+1 ; if space or control
jc getDevice_12
cmp al, '/' ; if slash
jz getDevice_12
cmp al, '\' ; if backslash
jz getDevice_12
cmp al, '.' ; if extension separator
jz getDevice_12
cmp al, ':' ; if colon break
jz getDevice_12
call upperCase
stosb ; store name
loop getDevice_08 ; continue -->
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; see if name is legitimate
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getDevice_12:
mov byte ptr es:[ di ], 0 ; zero terminate string
currSegment ds ; restore ds:
lea di, offset _devicename [ bp ]
call checkforDeviceName ; see if char device name
jc getDevice_26 ; if invalid -->
mov ax, es
or ax, ax ; nc character device
jmp short getDevice_Return ; exit with bad device error -->
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; if error
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getDevice_26:
mov ax, offset pexterrIllegalName
stc
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; return
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getDevice_Return:
push si
push di
push ds ; restore these registers
Return
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Get Drive from String ;
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; ;
; Input: ;
; es:si input string ;
; ;
; Output: ;
; es:si past ':', is any. ;
; ax current drive or drive named. ;
; cy error, invalid drive. ;
;...............................................................;
getDrive:
mov ax, word ptr es:[ si ] ; save drive info available
cmp ah, ':' ; drive break in string ?
jnz getDrive_14 ; no, return current -->
xor ah, ah ; clear carry
call upperCase ; convert drive to upper case
sub al, 'A' ; convert to a range
jc getDrive_12 ; if invalid, return valid drive with carry ->
cmp al, byte ptr ss:[ _RxDOS_bLastDrive ] ; within valid range ?
jge getDrive_12 ; yes -->
add si, 2 ; skip drive letter / colon
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; return valid drive.
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cbw ; valid drive
or ax, ax
ret
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; return valid drive.
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getDrive_12:
stc
mov al, byte ptr ss:[ _RxDOS_CurrentDrive ]
ret
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; return default drive.
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getDrive_14:
xor ax, ax ;clear carry
mov al, byte ptr ss:[ _RxDOS_CurrentDrive ]
ret
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Get Current Directory Cluster ;
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; ;
; Input: ;
; al drive ;
; ;
; Output: ;
; es:bx points to cds ;
; dx starting cluster address ;
;...............................................................;
getCurrDirCluster:
push ax
push cx
mov cl, sizeCDS
mul cl ; offset into cds table
les bx, dword ptr ss:[ _RxDOS_pCDS ] ; CDS start address
add bx, ax ; offset to proper drive
mov dx, word ptr es:[ _cdsStartClusterDir ][ bx ]
pop cx
pop ax
ret
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Read To App Buffer ;
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; ;
; Input: ;
; ss:bx Access Control Buffer ;
; es:di buffer address ;
; dx:ax file position to start reading ;
; cx bytes to read ;
; ;
; Output: ;
; ss:bx Access Contr⌨️ 快捷键说明
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