?? rxdossft.asm
字號:
and ax, sftDrivemask
call getDPB ; get DPB address
mov cx, word ptr es:[ _dpbVolumeId. _High ][ bx ]
mov dx, word ptr es:[ _dpbVolumeId. _Low ][ bx ]
getdarg es, di, _sftPointer ; sft pointer
mov word ptr es:[ sftVolumeId. _High ][ di ], cx
mov word ptr es:[ sftVolumeId. _Low ][ di ], dx
clc
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; return
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
pop ds
Return
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Build Access Area from SFT ;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
; ;
; Input: ;
; es:di SFT entry ;
; ss:bx access block ;
;...............................................................;
buildAccessRef:
Entry
ddef _fileposAtBegCluster
def _clusterSize
saveRegisters si, cx
push es
push di
push bx
mov ax, word ptr es:[ sftDevInfo ][ di ]
and ax, sftDrivemask
push ax
mov dx, word ptr es:[ sftBegCluster ][ di ]
call initdiskAccess ; [ax] is drive, [dx] is cluster
pop ax ; restore drive
call getDPB ; gets a guaranteed init drive block
mov ax, word ptr es:[ _dpbBytesPerSector ][ bx ]
mov cl, byte ptr es:[ _dpbClusterSizeShift ][ bx ]
shl ax, cl ; bytes per cluster
storarg _clusterSize, ax
pop bx
pop di
pop es
mov cx, word ptr es:[ sftRelCluster ][ di ]
or cx, cx ; cluster zeroed out ?
jz buildAccessRef_08 ; can't use curr cluster -->
xor dx, dx
mul cx ; file position at start of cluster
stordarg _fileposAtBegCluster, dx, ax ; save
mov ax, word ptr es:[ sftFilePosition. _low ][ di ]
mov dx, word ptr es:[ sftFilePosition. _high ][ di ]
sub ax, word ptr [ _fileposAtBegCluster. _low ][ bp ]
sbb dx, word ptr [ _fileposAtBegCluster. _high ][ bp ]
jc buildAccessRef_08 ; can't use curr cluster -->
or dx, dx ; distance greater than 65k ?
jnz buildAccessRef_08 ; can't use curr cluster -->
cmp ax, word ptr [ _clusterSize ][ bp ] ; greater than cluster size ?
jge buildAccessRef_08 ; can't use curr cluster -->
; there's a bug here, so we'll just ignore it for now
; by ALWAYS exiting. This patch could be a problem
; for larger files, so it needs to be fixed !
jmp buildAccessRef_08 ; can't use curr cluster -->
mov dx, word ptr es:[ sftCurCluster ][ di ]
mov word ptr ss:[ diskAcCurCluster ][ bx ], dx ; ok, within cluster
getdarg dx, ax, _fileposAtBegCluster ; offset at start of cluster
mov word ptr ss:[ diskAcOffAtBegBuffer. _low ][ bx ], ax
mov word ptr ss:[ diskAcOffAtBegBuffer. _high ][ bx ], dx
mov word ptr ss:[ diskAcOffAtBegCluster. _low ][ bx ], ax
mov word ptr ss:[ diskAcOffAtBegCluster. _high ][ bx ], dx
buildAccessRef_08:
restoreRegisters cx, si
Return
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Set Relative Cluster Number From SFT FilePosition ;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
; ;
; Input: ;
; es:di SFT entry ;
; ;
; Preserved: ;
; CX, ES, DI ;
;...............................................................;
_computeRelativeCluster:
push cx
push es
push di
mov ax, word ptr es:[ sftDevInfo ][ di ]
and ax, sftDrivemask
call getAddrDPB ; es:bx
mov ax, word ptr es:[ _dpbBytesPerSector ][ bx ]
mov cl, byte ptr es:[ _dpbClusterSizeShift ][ bx ]
shl ax, cl ; bytes per cluster
mov cx, ax
pop di
pop es
mov ax, word ptr es:[ sftFilePosition. _low ][ di ]
mov dx, word ptr es:[ sftFilePosition. _high ][ di ]
call _div32
mov word ptr es:[ sftRelCluster ][ di ], ax
pop cx
ret
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Open SFT ;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
; ;
; Input: ;
; es:dx unexpanded filename ;
; ax open mode ;
; ;
; Output: ;
; es:di sft pointer ;
; zr means end of file or wrong address ;
;...............................................................;
_SFTOpenFile:
Entry
def _handle, -1
def _openMode, ax
ddef _filename, es, dx ; arg passed internally as es:dx
ddef _sftPointer ; sft reserved pointer
defbytes _dirAccess, sizeDIRACCESS
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; does file exist ?
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
mov ax, (FILE_ORDEVICE + FILECANNOT_BEDIRECTORY)
mov si, dx ; name from caller (es: si )
lea di, offset _dirAccess [ bp ] ; work dir access block
call LocateFile ; if can't locate, then
ifc _SFTOpenFile_50 ; error code already set
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; name is valid. populate sft.
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
call FindAvailableSFTHandle ; find an available file handle
ifc _SFTOpenFile_50 ; if none available -->
mov word ptr [ _handle ][ bp ], ax
stordarg _sftPointer, es, bx ; sft reserved pointer
call InitSFTEntry ; clear entry
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; if file opened is a device
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
getdarg dx, ax, _dirAccess.fileAcDevicePtr
or dx, dx ; _segment
jz _SFTOpenFile_22 ; if not a device -->
or word ptr es:[ sftDevInfo ][ bx ], sftIsDevice
mov word ptr es:[ sftDCB. _segment ][ bx ], dx
mov word ptr es:[ sftDCB. _pointer ][ bx ], ax ; device address
push ds
setDS ss
mov si, word ptr [ _dirAccess.fileAcNameOffset ][ bp ]
les di, dword ptr [ _sftPointer ][ bp ] ; get sft pointer
lea di, offset sftFileName [ di ]
call convFilenametoFCBString ; convert to a match template
pop ds
jmp short _SFTOpenFile_42
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; if open is to file
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
_SFTOpenFile_22:
push word ptr [ _dirAccess.fileAcBufferPtr. _segment ][ bp ]
mov ax, word ptr [ _dirAccess.fileAcBufferPtr. _pointer ][ bp ]
add ax, word ptr [ _dirAccess.fileAcDirOffset ][ bp ]
push ax
push word ptr [ _sftPointer. _segment ][ bp ]
push word ptr [ _sftPointer. _pointer ][ bp ]
call initSFTfromDirEntry
mov al, byte ptr [ _openMode ][ bp ]
mov byte ptr es:[ sftMode ][ di ], al ; set mode.
test al, OPEN_ACCESS_NOINHERIT
jz _SFTOpenFile_42 ; if inherit not used -->
or word ptr es:[ sftDevInfo ][ di ], sftNoInherit
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; return
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
_SFTOpenFile_42:
mov ax, word ptr [ _handle ][ bp ]
clc
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; if error, release locked sft
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
_SFTOpenFile_50:
getdarg es, di, _sftPointer ; sft reserved pointer
Return
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Create SFT File ;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
; ;
; Input: ;
; es:dx unexpanded filename ;
; cx attributes ;
; ;
; Output: ;
; es:di sft pointer ;
; zr means end of file or wrong address ;
;...............................................................;
_SFTCreateFile:
Entry
def _attributes, cx ; attributes
defbytes _dirAccess, sizeDIRACCESS
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; see if path is valid
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
mov ax, (FILE_NODEVICENAME + FILEMAY_EXIST + FILECANNOT_BEDIRECTORY)
mov si, dx ; name from caller
lea di, offset _dirAccess [ bp ] ; work dir access block
call LocateFile
jc _SFTCreateFile_42 ; if path invalid -->
lea di, offset _dirAccess [ bp ] ; work dir access block
mov cx, word ptr [ _attributes ][ bp ] ; get attributes
call createSFTEntry ; create/init SFT entry
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
; return
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
_SFTCreateFile_42:
Return
;''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''';
; Read From SFT ;
;- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -;
; ;
; Input: ;
; cx bytes to read ;
; es:di sft pointer ;
; stack buffer address ;
; ;
; Output: ;
; cx bytes actually read ;
; zr means end of file or wrong address ;
;...............................................................;
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