Category : Dbase (Clipper, FoxBase, etc) Languages Source Code
Archive   : ASMFLS.ZIP
Filename : DRV_STAT.ASM

;
;****************************************************************
; *
; CLIPPER ROUTINE - DISK DRIVE STATUS *
; By Kelly Mc Tiernan *
; *
;****************************************************************
;
;
; This routine uses the lowest level BIOS interupt for disk
; I/O to determine status of the drive in question, bypassing
; the DOS error routines. Thus disk drive errors such as
; non - dos disk, drive door open, and write protected can
; be handled at the application level. Call with a single
; byte parameter containing the drive letter (CAPS!).
; Returned in second variable parameter is status, e.g.->
;
; DR = "A"
; ST = "0"
; CALL DRSTAT WITH DR,ST
;
; ST | ERROR DESCRIPTION
; ---+-------------------------------------
; 0 | DRIVE READY - READ / WRITE
; 1 | DRIVE READY - WRITE PROTECTED
; 2 | DRIVE NOT READY - DOOR OPEN
; 3 | DRIVE NOT READY - NON - DOS DISK
; 4 | DRIVE NOT READY - MISC. ERROR
; |
;
;
;
PUBLIC drstat
;
dskint EQU 13h ; BIOS disk drive int.
read EQU 02h ; disk read command
write EQU 03h ; disk write command
dskrst EQU 00h ; disk reset command
wrprot EQU 03h ; write protect status bits
door EQU 80h ; T.O. error, usually door open
nondos EQU 02h ; address mark, not formatted
;
_PROG SEGMENT BYTE
ASSUME CS:_PROG
;
drstat PROC FAR
push bp ; standard setup, param's
mov bp,sp ;
push es ; save seg.'s need for ptr.'s
push ds ;
lds si,dword ptr [bp + 6] ; address of drive select byte
push cs ; read buffer is here in DS
pop es ; ES:BX is buff. ptr.
mov bx,offset cs:buffer ;
lodsb ; get drive specifier
sub al,'A' ; A - A = 0, B - A = 1 .. etc.
mov dl,al ; for interupt

mov dh,0 ; always use head 0
mov cx,1 ; track 0, sector 1
mov al,1 ; read 1 sector
mov ah,read ; read command
int dskint ;
jc error ; cy = error, report and process
mov ah,write ; write same back, write prot. chk.
mov al,1 ; same number of sectors
int dskint ;
jc error ; cy = error, report and process
mov al,'0' ; return all O.K.
jmp done ;
error:
mov al,'1' ; first error condition
cmp ah,wrprot ; write protected disk ?
jz reset ;
inc al ; next error condition
cmp ah,door ; door open ?
jz reset ;
inc al ;
cmp ah,nondos ; non - dos disk ?
jz reset ;
inc al ; fall through, general error
reset:
push ax ; save, need to issue reset
mov ah,dskrst ; reset disk controller
int dskint ;
pop ax ; get back return value
done:
les di,dword ptr [bp + 10] ; address of status return byte
stosb ; set return code
pop ds ; restore state
pop es ;
pop bp ;
ret
drstat ENDP
;
buffer DB 1024 DUP(0) ; 1K buffer ( 512 bytes = 1 sector )
;
_PROG ENDS
END