; DRIVESEX.ASM - Drive existence detection July 6th, 1994; Code by : Lee Hamel (hamell@cs.pdx.edu); Partial credit: Paul Schlyter;; Goes through drives A-Z and determines if they:; 1) Exist; 2) Are removable or fixed; 3) Are local, remote, or shared; 4) Are a floppy, hard, RAM, subst, or CD-ROM drive;; Callable from C as: void Drives_Exist(void);.model small.286DRIVEEXIST EQU 1REMOVEDRV EQU 0FIXEDDRV EQU 1LOCALDRV EQU 0REMOTEDRV EQU 1SHAREDRV EQU 2FLOPPY EQU 0HARD EQU 1RAM EQU 2SUBST EQU 3CDROM EQU 4.dataPUBLIC _drives _drives db 26 dup(0,1,0,1) ; default to not exist, fixed, local, hard drive.code PUBLIC _Drives_Exist_Drives_Exist PROC NEAR pusha push es mov ah,19h int 21h ; get start drive push ax ; save start drive mov ax,40h mov es,ax mov bh,es:[10h] ; 40:10h is # of floppies-1 shr bh,6 inc bh ; # of actual floppy drives mov bl,1 mov di,offset _drivesnextchkfloppy: mov ax,4409h ; check if drive exists int 21h jc nextsetfloppy test dh,10000000b ; check if SUBST drive jz chkfloppy dec bh ; dec actual drive count mov byte ptr [di+3],SUBSTsetfloppyexist: mov byte ptr [di],DRIVEEXIST jmp nextsetfloppychkfloppy: dec bh ; dec actual drive count js nextsetfloppy mov byte ptr [di+1],REMOVEDRV mov byte ptr [di+3],FLOPPY jmp setfloppyexistnextsetfloppy: add di,4 inc bl cmp bl,2 ; if B then jump back je nextchkfloppy mov ch,24 ; loop 24 times (drives C - Z) mov cl,3 ; start at C:drivechkloop: mov ax,4409h ; check if drive exists mov bl,cl ; set drive letter int 21h ; 0 = default, 1 = A:, etc. jc nextsetdrv mov byte ptr [di],DRIVEEXIST mov ax,4408h ; check if removable int 21h mov byte ptr [di+1],al ; set REMOVABLE or FIXED mov bx,dx mov dl,dh shr dl,7 and dh,00010000b shr dh,4 mov byte ptr [di+2],dh ; set REMOTE or LOCAL or dl,dl ; if not SUBST, then jump jz chkremote mov byte ptr [di+3],SUBST jmp nextsetdrvchkremote: cmp dh,REMOTEDRV ; if REMOTE, then check for CD ROM je chkcdrom test bh,00000010b ; sharable? jz drivenoshare mov byte ptr [di+2],SHAREDRVdrivenoshare: test bl,00000010b ; RAM drive? jnz nextsetdrv mov byte ptr [di+3],RAM jmp nextsetdrvchkcdrom: push cx mov ax,1500h xor bx,bx int 2fh pop cx or bx,bx ; MSCDEX driver found? jz nextsetdrv ; if not, jump to next drive setup mov ax,150bh dec cl ; 0=A:, etc. int 2fh inc cl or ax,ax jz nextsetdrv ; drive supported by MSCDEX? mov byte ptr [di+3],CDROMnextsetdrv: add di,4 inc cl dec ch jnz drivechkloop pop dx mov ah,0eh int 21h ; reset start drive pop es popa ret_Drives_Exist ENDP END
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