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|
name mscdexnt
;
; MSCDEXNT
;
; Author: Neil Sandlin (neilsa)
;
; Description:
;
; This TSR implements the v86 mode portion of MSCDEX support under
; NT. Basically, all this piece does is hook INT2F and watch for
; MSCDEX calls. When the first one occurs, it tries to load VCDEX.DLL.
; If that succeeds, it passes the call (and all subsequent calls)
; to VCDEX for processing.
;
include isvbop.inc
include mscdexnt.inc
_TEXT segment word public 'CODE'
assume cs:_TEXT,ds:_TEXT,es:_TEXT
;*----------------------- TSR Code --------------------------*
DrvStrat proc far ; Strategy Routine
ret
DrvStrat endp
DrvIntr proc far ; INterrupt routine
ret
DrvIntr endp
;******************************************************************************
;
; Int2FHook
;
;
;******************************************************************************
Int2FHook proc near
cmp ah, MSCDEX_ID ;MSCDEX?
jnz int2fchain ;no
cmp al, MAX_MSCDEX_CMD ;command too high?
ja int2fchain ;yes
cmp word ptr cs:[hVDD], 0 ;zero is an invalid module handle
jnz callvdd ;registered ok
cmp byte ptr cs:[fVDDChecked],1
jz vddfailed
call RegisterVDD
jc vddfailed ;didn't get it
callvdd:
push ax ;put ax on stack
mov ax, word ptr cs:[hVDD]
DispatchCall
add sp, 2 ;vdd has set ax accordingly
iret ;svc handled, return to caller
vddfailed:
or al,al
jnz try_0b
xor bx,bx
jmp short int2f_done
try_0b:
cmp al,0bh
jne int2f_done
;; williamh - June 1 1993 - if unable to load VDD, we should tell
;; the caller that the drive is NOT a cd rom.
xor ax, ax
mov bx,0adadh
int2f_done:
iret
int2fchain:
jmp dword ptr cs:[oldint]
Int2FHook endp
;****************************************************************************
;
; RegisterVDD
;
;****************************************************************************
RegisterVDD proc near
push ax
push bx
push cx
push dx
push si
push di
push ds
push es
mov ax, cs
mov ds, ax
mov es, ax
; Load vcdex.dll
mov si, offset DllName ; ds:si = dll name
mov di, offset InitFunc ; es:di = init routine
mov bx, offset DispFunc ; ds:bx = dispatch routine
push cs ; pass far pointer to headers
pop cx ; in cx:dx
mov dx, offset drive_header
RegisterModule
jc errorexit ; jif error
mov cs:[hVDD],ax ; save handle
errorexit:
mov byte ptr cs:[fVDDChecked],1
pop es
pop ds
pop di
pop si
pop dx
pop cx
pop bx
pop ax
ret
RegisterVDD endp
;*----------------------- TSR Data Area ---------------------*
oldint dd 0
hVDD DW 0
fVDDChecked DB 0 ; 0 - VDD never called. 1 - VDD once called.
DllName DB "VCDEX.DLL",0
InitFunc DB "VDDRegisterInit",0
DispFunc DB "VDDDispatch",0
ALIGN 16
drive_header:
DrvHd 'MSCDEX00'
ALIGN 16
Init_Fence:
;*-------------------------- Initialization Code ----------------------*
mscdexnt proc far
; at this point es,ds -> PSP
; SS:SP points to stack
; first check that we are running under NT
mov ax, GET_NT_VERSION
int 21h
cmp bl, NT_MAJOR_VERSION
je cdx_chk_more
jmp cdx_badver
cdx_chk_more:
cmp bh, NT_MINOR_VERSION
je cdx_ver_ok
jmp cdx_badver
cdx_ver_ok:
; Now check that this TSR is'nt already installed
mov ah,MSCDEX_ID
mov al,0bh ; call function 0b
int MPX_INT ; int 2f
cmp bx,0adadh
jne cdx_chks_done
jmp cdx_installed
cdx_chks_done:
; free the env segment
push es
push ds
mov es, es:[2ch]
mov ah, 49h
int 21h
mov ah, DOS_GET_VECTOR
mov al, MPX_INT ; 2f
int 21h ; get old vector
mov WORD PTR cs:oldint,bx ; save old vector here
mov WORD PTR cs:oldint+2,es
mov dx, offset Int2FHook
push cs ; get current code segment
pop ds
mov ah, DOS_SET_VECTOR
mov al, MPX_INT ; vector to hook
int 21h ; hook that vector
;
; Compute size of TSR area
;
pop ds
pop es
mov dx, offset Init_Fence ; end of fixed TSR code
mov cl, 4 ; divide by 16
shr dx, cl
add dx, 16 ; add in PSP
;
; Terminate and stay resident
;
mov ah, DOS_TSR ; TSR
mov al, 0
int 21h ; TSR
cdx_badver:
mov dx, offset Message1
push cs
pop ds
mov ah,09h
int 21h
jmp short cdx_exit
cdx_installed:
mov dx, offset Message2
push cs
pop ds
mov ah,09h
int 21h
cdx_exit:
mov ax,4c00h ; Exit
int 21h
mscdexnt endp
include messages.inc
_TEXT ends
InitStack segment para stack 'STACK'
dw 256 dup (?)
top_of_stack equ $
InitStack ends
end mscdexnt
|
