name    dev

        page    60,132

        title   'DEV --- Report installed device drivers'



; DEV --- a utility to report device header information for

;         all installed device drivers

; 

; Requires PC-DOS or MS-DOS 2.0.

;

; Used in the form:

; A>DEV 

;

; version 1.0   December 12, 1984

; Copyright (c) 1984 by Ray Duncan



cr      equ     0dh             ;ASCII carriage return

lf      equ     0ah             ;ASCII line feed

blank	equ	20h		;ASCII space code

eom	equ	'$'		;end of string marker





cseg	segment	para public 'CODE'



	assume	cs:cseg,ds:data,es:data,ss:stack





dev 	proc    far             ;entry point from PC-DOS



        push    ds              ;save DS:0000 for final

        xor     ax,ax           ;return to PC-DOS

        push    ax

        mov     ax,data         ;make our data segment

	mov	ds,ax		;addressable via DS and ES.

	mov     es,ax 

        mov     ah,30h		;check version of PC-DOS.	

        int     21h

        cmp     al,2

        jae     dev1		;proceed, DOS 2.0 or greater.

        mov     dx,offset msg2  ;DOS 1.x --- print error message.

	jmp	dev6



dev1:	mov	cx,ax		;save DOS version number.

	mov	ah,15		;now try and open the "NUL" device.

	mov	dx,offset nulfcb

	int	21h

	or	al,al		;opened successfully?

	jz	dev2		;yes, jump.

	mov	dx,offset msg1	;no, print error msg and exit.

	jmp	dev6



dev2:				;Pick up double pointer to device 

				;driver chain out of reserved

				;area in fcb.  This area is mapped

				;differently in DOS 2.x and DOS 3.x.

	cmp	cl,2		;is this DOS 2.x?

	ja	dev3		;no, jump.

	mov	bx,word ptr nulfcb 25

	mov	es,word ptr nulfcb 27

	jmp	dev4



dev3:				;come here if DOS 3.0 or greater.

	mov	bx,word ptr nulfcb 26

	mov	es,word ptr nulfcb 28



dev4:	call	header		;print sign-on message and 

				;column headings.



dev5:				;trace through the device chain



	call	prdev		;print device header information

				;for driver pointed to by ES:BX.

				;pick up addr of next header.

	les	bx,dword ptr es:[bx]

	cmp	bx,-1		;found last one yet?

	jne	dev5		;no, try next.

	

      	mov	dx,offset msg3	;yes, print "end of device chain".



dev6: 	mov	ah,9		;print the string whose address

	int	21h		;is in DX.

	ret			;then return to DOS.



dev   	endp





header	proc	near		;print out headings for device

	mov	dx,offset hdr	;driver information.

	mov	ah,9

	int	21h

	ret

header	endp





prdev	proc	near		;print out device driver info.

				;ES:BX is pointer to device header,

				;which must be preserved.

	mov	ax,es		;convert segment of device header

	mov	di,offset inf1

	call	hexasc

	mov	ax,bx		;convert offset of device header.

	mov	di,offset inf2

	call	hexasc

	mov	ax,es:[bx 4]	;get attribute word, save a 

	push	ax		;copy of it, then convert it.

	mov	di,offset inf3

	call	hexasc

	mov	ax,es:[bx 6]	;convert ptr to device strategy.

	mov	di,offset inf4

	call	hexasc

	mov	ax,es:[bx 8]	;convert ptr to device int handler.

	mov	di,offset inf5

	call	hexasc



				;if not char device, clear out name

				;field and set number of units.

	pop	ax		;get back attribute word.

	test	ax,08000h	;is bit 15 = 1 ?

	jnz	prdev7		;yes, it's character dev, jump.

	              		;no, it's block device.

				;set flag to skip device name.

	mov 	byte ptr inf8,eom

	mov	al,es:[bx 10]	;pick up number of units.

	aam			;convert to ASCII decimal and

	add	ax,'00'		;store into output string.

	mov	byte ptr inf7 1,al

	mov	byte ptr inf7,ah

				;set type = B for Block

	mov	byte ptr inf6,'B'	

	jmp	prdev9



prdev7:				;if char device, move its 8-character

				;name into the output string.

	xor	si,si

prdev8:	mov	al,es:[si bx 10]

	mov	[si inf8],al

	inc	si

	cmp	si,8

	jne	prdev8

				;remove # of units field.

	mov	word ptr inf7,'  '

				;set type = C for Character.

	mov	byte ptr inf6,'C'



prdev9: mov	dx,offset inf	;now print device information

	mov	ah,9		;and exit.

	int	21h

	ret

prdev	endp



hexasc	proc	near		;convert binary word to hex ASCII.

				;call with AX=binary value

				;          DI=addr to store string 

				;returns AX, CX, DI destroyed.

	push	ax		;save copy of original value.

	mov	al,ah

	call	btoa		;convert upper byte.

	add	di,2		;increment output address.

	pop	ax

	call	btoa		;convert lower byte.

	ret			;return to caller.

hexasc	endp



btoa	proc	near		;convert binary byte to hex ASCII.

				;call with AL=binary value 

				;          DI=addr to store string

				;returns AX, CX destroyed.

	mov	ah,al		;save lower nibble.

	mov	cx,4		;shift right 4 positions

	shr	al,cl		;to get upper nibble.

	call	ascii		;convert 4 bits to ASCII equivalent

	mov	[di],al		;store into output string.

	mov	al,ah		;get back lower nibble.

	and	al,0fh

	call	ascii		;convert 4 bits to ASCII

	mov     [di 1],al	;and store into output string.

	ret			;back to caller.

btoa	endp



ascii	proc	near		;convert 4 lower bits of AL

	add	al,'0'		;into the equivalent ASCII char.

	cmp	al,'9'		;in the range {0...9,A...F}

	jle	ascii2		;and return char. in AL.

	add	al,'A'-'9'-1	;"fudge factor" for range A-F.

ascii2:	ret			;return to caller.

ascii	endp



cseg    ends





data    segment para public 'DATA'



msg1	db	cr,lf

	db	'Failed to open NUL device.'

	db	cr,lf,eom



msg2    db      cr,lf

        db      'Requires DOS version 2 or greater.'

        db      cr,lf,eom



msg3	db	cr,lf

	db	'End of device chain.'

	db	cr,lf,eom



hdr	db	cr,lf

	db	'Addr      Attr '

	db	'Str  Int   Type  Units  Name   '

	db	eom





inf 	db	cr,lf

inf1	db	'XXXX:'		;seg device header

inf2	db	'XXXX '		;offs device header

inf3	db	'XXXX '		;attribute

inf4	db	'XXXX '		;strategy

inf5	db	'XXXX   '	;interrupt handler

inf6	db	'X     '	;type (block or char)

inf7	db	'XX    '	;units (if block device)

inf8	db	'         '	;name  (if char device)

	db	eom



				;fcb to open NUL device

nulfcb	db	0		;drive

	db	'NUL'		;name of NUL device

	db	8 dup (' ')

	db	25 dup (0)

data    ends    





stack   segment para stack 'STACK'

        db      64 dup (?)

stack   ends



        end     dev