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DOSSEG .MODEL LARGE
include disk.inc
.DATA? public DiskList DiskList dd ?
.CODE ASSUME ds:NOTHING
extrn InitializeInt13DiskList:far extrn OpenInt13Disk:far extrn CloseInt13Disk:far extrn Int13DiskIo:far extrn GetInt13DiskInfo:far
.386
;++;; UINT; _far; InitializeDiskList(; VOID; );;; Routine Description:;; This routine initializes internal data structures necessary so that; other disk-related routines in this module can be called.;; A data structure for each disk (currently int13 units only) is built; and saved away. The structure contains various info such as; drive geometry.;; This routine may be called multiple times. Subsequent calls after; the first simply return the disk count.;; Arguments:;; None.;; Return Value:;; Total count of all hard drives that we can deal with.; 0 if an error occurs.;;--
public _InitializeDiskList_InitializeDiskList proc far
push ds push si
; ; See if we're initialized yet by counting items in the DiskList ; linked list. If 0, then assume not initialized yet. ; mov ax,DGROUP mov ds,ax mov si,OFFSET DGROUP:DiskList
mov ax,0
idl1: .errnz DiskInfoNextl
mov cx,[si].DiskInfoNextl or cx,[si].DiskInfoNexth jz idl2 inc ax lds si,[si].DiskInfoNext jmp short idl1idl2: cmp ax,0 jne idl3
; ; Currently we deal with int13 disks only. ; push ax ; disk ids start at 0 call InitializeInt13DiskList add sp,2
idl3: pop si pop ds retf
_InitializeDiskList endp
;++;; HDISK; _far; OpenDisk(; IN UINT DiskId; );;; Routine Description:;; This routine "opens" a disk so that i/o can be performed to it.; Housekeeping such as locking, etc, is performed.; A disk can be opened only once at a time.;; Arguments:;; DiskId - supplies an ordinal value for the disk to be opened.; Range is 0 - n-1, where n is the value returned by; InitializeDiskList().;; Return Value:;; Handle, or 0 if an error occurs.;;--
DiskId equ word ptr [bp+6]
public _OpenDisk_OpenDisk proc far
push bp mov bp,sp
push ds push si
; ; Locate the disk record corresponding to this disk id. ; mov ax,DiskId call far ptr pLocateDiskRecord mov cx,si or cx,dx mov ax,0 jz od_done ; dx:ax already 0 for error return
od_gotrec: ; ; Make sure disk is not already open ; cmp [si].DiskInfoDiskOpen,al jz @f mov dx,ax ; dx:ax = 0 jnz od_done ; disk already open, error.@@: ; ; Int13 disks only for now. ; push ds push si call OpenInt13Disk pop si pop ds
cmp ax,0 jnz @f mov dx,ax jz od_done ; error, dx:ax set for return
@@: inc [si].DiskInfoDiskOpen mov dx,ds mov ax,si ; dx:ax = handle for return
od_done: pop si pop ds
leave retf
_OpenDisk endp
;++;; VOID; _far; CloseDisk(; IN HDISK DiskHandle; );;; Routine Description:;; This routine "closes" a disk previously opened by OpenDisk().; Housekeeping such as unlocking, etc, is performed.;; Arguments:;; DiskHandle - supplies the handle of the disk to be closed,; as previously opened by OpenDisk().;; Return Value:;; None.;;--
DiskHandle equ dword ptr [bp+6]
public _CloseDisk_CloseDisk proc far
push bp mov bp,sp
push ds push si
lds si,DiskHandle
cmp [si].DiskInfoDiskOpen,0 jz cd_done ; not open, nothing to do
; ; Int13 disks only for now ; push ds push si call CloseInt13Disk pop si pop ds ; ds:si -> disk record
dec [si].DiskInfoDiskOpen
cd_done: pop si pop ds leave retf
_CloseDisk endp
;++;; BOOL; _far; GetDiskInfoByHandle(; IN HDISK DiskHandle,; OUT FPBYTE Int13UnitNumber,; OUT FPBYTE SectorsPerTrack,; OUT FPUSHORT Heads,; OUT FPUSHORT Cylinders,; OUT FPULONG ExtendedSectorCount,; OUT FPUINT DiskId; );;; BOOL; _far; GetDiskInfoById(; IN UINT DiskId,; IN UINT Reserved,; OUT FPBYTE Int13UnitNumber,; OUT FPBYTE SectorsPerTrack,; OUT FPUSHORT Heads,; OUT FPUSHORT Cylinders,; OUT FPULONG ExtendedSectorCount; );;; Routine Description:;; These routines fetch information about a disk.;; Arguments:;; Return Value:;; non-0 - success; 0 - failure;;--
DiskHandle equ dword ptr [bp+6]DiskId equ word ptr [bp+6]Int13UnitNumber equ dword ptr [bp+10]SectorsPerTrack equ dword ptr [bp+14]Heads equ dword ptr [bp+18]Cylinders equ dword ptr [bp+22]ExtendedSecCnt equ dword ptr [bp+26]pDiskId equ dword ptr [bp+30]
public _GetDiskInfoById_GetDiskInfoById proc far
push bp mov bp,sp
push ds push si
; ; Locate the disk record. ; mov ax,DiskId call far ptr pLocateDiskRecord cmp dx,0 jnz gdi_do_it cmp si,0 jnz gdi_do_it mov ax,dx jz gdi_done
gdi_do_it: ; ; Int13 disks are the only ones supported now so we can ; just call the int13-specific disk info routine. ; push ExtendedSecCnt push Cylinders push Heads push SectorsPerTrack push Int13UnitNumber push ds push si call GetInt13DiskInfo add sp,24 mov ax,1
gdi_done: pop si pop ds leave retf
_GetDiskInfoById endp
public _GetDiskInfoByHandle_GetDiskInfoByHandle proc far
push bp mov bp,sp
push ds push si
; ; Make sure the disk is open. ; lds si,DiskHandle cmp [si].DiskInfoDiskOpen,0 jz @f
; ; Set disk id in caller's variable ; mov ax,[si].DiskInfoDiskId lds si,pDiskId mov [si],ax lds si,DiskHandle jmp short gdi_do_it
@@: mov ax,0 jz gdi_done
_GetDiskInfoByHandle endp
;++;; BOOL; _far; ReadDisk(; IN HDISK DiskHandle,; IN ULONG StartSector,; IN BYTE SectorCount,; OUT PVOID Buffer; );;; BOOL; _far; WriteDisk(; IN HDISK DiskHandle,; IN ULONG StartSector,; IN BYTE SectorCount,; IN PVOID Buffer; );;; Routine Description:;; These routines perform i/o to a disk previously opened with; OpenDisk().;; Arguments:;; DiskHandle - supplies the handle of the disk to be read/written,; as previously opened by OpenDisk().;; StartSector - supplies the physical start sector where the read/write; is to begin.;; SectorCount - supplies the number of sectors to be read/written.;; Buffer - supplies a buffer for the transfer.;; Return Value:;; non-0 - success; 0 - failure;;--
DiskHandle equ dword ptr [bp+6]StartSector equ dword ptr [bp+10]SectorCount equ word ptr [bp+14]Buffer equ dword ptr [bp+16]
public _WriteDisk_WriteDisk label far
mov ax,1 jmp short DiskIo
public _ReadDisk_ReadDisk label far
mov ax,0
DiskIo proc far
push bp mov bp,sp
push ds push si
lds si,DiskHandle cmp [si].DiskInfoDiskOpen,0 jnz @f mov ax,0 ; not open, error out jz rd_done
; ; Int13 disks only for now ;@@: push ax push Buffer push SectorCount push StartSector ; only care about low byte push ds push si call Int13DiskIo add sp,16
rd_done: pop si pop ds leave retf
DiskIo endp
;++;; PVOID; _far; pLocateDiskRecord(; IN UINT DiskId; );;; Routine Description:;; Internal routine.;; This routine locates a disk record in the linked list; of all disk records as prepared by InitializeDiskList().;; Arguments:;; DiskId - supplies an ordinal value identifying the disk.; Valid range is 0 - n-1, where n is the number returned; from InitializeDiskList().;; This parameter is passed in ax, not on the stack.;; Return Value:;; NULL if record not located.; Otherwise fills ds:si and dx:si with a far pointer to the; disk record.;;--pLocateDiskRecord proc far
mov dx,DGROUP mov ds,dx mov si,offset DGROUP:[DiskList] ; ds:si = &DiskList
; ; Note that this code depends on the link field in the ; disk record structure being first! ; .errnz DiskInfoNextldr_loop: lds si,[si].DiskInfoNext mov dx,ds cmp dx,0 jz ldr_done ; end of list, we're done cmp [si].DiskInfoDiskId,ax jz ldr_done jmp short ldr_loop
ldr_done: retf
pLocateDiskRecord endp
end
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