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PROGRAM
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AMISL082
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UNINSTAL.ASM
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Assembly Source File
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1992-04-19
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8KB
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308 lines
;-----------------------------------------------------------------------
; Alternate Multiplex Interrup Specification Library
; AMIS.ASM Public Domain 1992 Ralf Brown
; You may do with this software whatever you want, but
; common courtesy dictates that you not remove my name
; from it.
;
; Version 0.80
; LastEdit: 4/19/92
;-----------------------------------------------------------------------
INCLUDE AMIS.MAC
;-----------------------------------------------------------------------
_TEXT SEGMENT PUBLIC BYTE 'CODE'
ASSUME CS:_TEXT
;-----------------------------------------------------------------------
resident_seg dw 0 ; location of TSR code after relocation
alloc_strat dw 0
link_state db 0 ; are UMBs part of memory chain?
;-----------------------------------------------------------------------
; Call the XMS driver
;
; entry: all registers as needed for XMS call
; exit: registers as returned by XMS driver
; ZF set if successful, ZF clear if failure
;
XMS proc near
db 09Ah ; FAR CALL
xms_entry dd 0 ; XMS driver's entry point
cmp ax,1
ret
XMS endp
;-----------------------------------------------------------------------
; Determine entry point of XMS driver and initialize procedure XMS to call
; that entry point
;
; exit: CF set if no XMS driver or other failure
; CF clear if initialization successful
;
get_XMS_entry proc near
push es
mov ax,352Fh
int 21h ; find out whether INT 2F is valid
mov ax,es
or ax,bx ; don't try XMS if INT 2F is NULL
jz no_XMS_driver ; (could be case under DOS 2.x)
mov ax,4300h ; see if XMS is installed
int 2Fh
cmp al,80h ; did XMS respond?
jnz no_XMS_driver
mov ax,4310h ; if XMS present, get its entry point
int 2Fh
mov word ptr xms_entry,bx
mov word ptr xms_entry+2,es ; and store entry point for call
pop es
clc
ret
no_XMS_driver:
pop es
stc
ret
get_XMS_entry endp
;-----------------------------------------------------------------------
; entry: nothing
; exit: CF set if not available, clear if available
; AX,BX,CX,DX destroyed
; if available, DOS5 UMBs have been linked into the memory chain
;
check_if_DOS5_UMBs proc near
mov ax,5800h
int 21h ; get current allocation strategy
mov alloc_strat,ax ; and remember it for later restore
mov ax,5802h ; get current state of UMB linkage
int 21h
mov link_state,al
mov ax,3000h ; get DOS version
int 21h
cmp al,5 ; DOS 5.0 or higher?
jb no_DOS5_UMBs
cmp al,10 ; but make sure not OS/2 penalty box
jae no_DOS5_UMBs
mov ax,2B01h
mov cx,4445h
mov dx,5351h
int 21h ; check if DESQview running
cmp al,0FFh ; if yes, no UMB's to be allocated
jne no_DOS5_UMBs
mov ax,5803h
mov bx,1 ; try to link in UMBs
int 21h
mov ax,5802h ; get new link state
int 21h
cmp al,1
jne no_DOS5_UMBs
clc ; yes, we have UMBs
ret
no_DOS5_UMBs:
stc
ret
check_if_DOS5_UMBs endp
;-----------------------------------------------------------------------
; entry: DS:SI -> hooked interrupt list
; exit: AX, BX, CX, DX destroyed
; CF set if unable to unhook all vectors
; CF clear if successful
;
public unhook_interrupts
unhook_interrupts proc DIST
push es
push ds
push di
push si
cld
chk_unhook_loop:
lodsb
mov dx,[si] ; get offset of interrupt handler
inc si ; and skip that field in the hook
inc si ; list
cmp al,2Dh
je all_unhookable
mov ah,35h
int 21h ; get interrupt vector
mov ax,es
mov cx,ds
cmp ax,cx ; check segment agains of vectors
jne chk_isp_loop
cmp dx,bx ; check offset of vector against ours
je chk_unhook_loop ; this int is unhookable if same
chk_isp_loop:
cmp word ptr es:[bx],10EBh ; handler starts with JMP SHORT $+12 ?
jne not_unhookable
cmp word ptr es:[bx+6],424Bh ; valid signature?
jne not_unhookable
cmp byte ptr es:[bx+9],0EBh ; hardware reset must also be JMP SHORT
jne not_unhookable
cmp cx,word ptr es:[bx+4] ; check segment of next ptr against ours
jne chk_next_isp
cmp dx,word ptr es:[bx+2] ; check offset of next ptr against ours
je chk_unhook_loop ; this int is unhookable if same
chk_next_isp:
les bx,es:[bx+2] ; advance to next ISP header
jmp chk_isp_loop ; and test it
not_unhookable:
stc
unhook_ints_done:
pop di
pop si
pop ds
pop es
ret
all_unhookable:
pop si ; get back start of hook list
push si ; and preserve SI for return
unhook_loop:
lodsb
mov dx,[si]
inc si
inc si
push ds
push ax
mov ah,35h
int 21h ; get interrupt vector
mov ax,es
mov cx,ds
cmp ax,cx ; check segments of vectors
jne isp_loop
cmp dx,bx ; check offsets of vectors
jne isp_loop
lds dx,[bx+2] ; get our old_int?? pointer
pop ax
push ax
mov ah,25h ; set interrupt vector
int 21h
jmp short unhooked_interrupt
isp_next:
les bx,es:[bx+2] ; advance to next ISP header
isp_loop:
;
; no need to check for a valid ISP header, as we already know all chains reach
; our header before non-ISP code
;
cmp cx,es:[bx+4] ; check segment of 'previous' ptr
jne isp_next
cmp dx,es:[bx+2] ; check offset of 'previous' ptr
jne isp_next
xchg bx,dx
lds bx,[bx+2]
xchg bx,dx ; ES:BX -> previous ISP
; DS:DX -> next ISP
mov es:[bx+2],dx ; prev->next = curr->next
mov es:[bx+4],ds ; thus, we are now unhooked
unhooked_interrupt:
pop ax
pop ds
cmp al,2Dh
jne unhook_loop
clc ; indicate success
jmp unhook_ints_done
unhook_interrupts endp
;-----------------------------------------------------------------------
; entry: AX = segment of TSR code within the calling executable
; exit: CF clear if successful
; CF set on error
;
public _AMIS_uninstall
_AMIS_uninstall proc DIST
push bp
mov bp,sp
ifidni <DIST>,<FAR>
@mpx_number = byte ptr [bp+6]
ELSE
@mpx_number = byte ptr [bp+4]
ENDIF
;
; first, see whether the TSR can uninstall itself
;
mov ah,@mpx_number
mov al,2
mov dx,cs ; load return address for success
mov bx,offset _TEXT:uninstall_successful
int 2Dh
cmp al,0FFh ; successful?
je uninstall_successful
cmp al,02h ; unsupp, unsucc, or unable to remove?
jbe uninstall_done
cmp al,05h ; unknown return code?
jae uninstall_failed
;
; TSR said it is safe to uninstall, but not able to do so itself,
; so now we unhook its interrupts and free its memory
;
mov resident_seg,bx ; remember which memory block to free
mov ah,@mpx_number
mov al,4
mov bl,0 ; start with INT 00h
int 2Dh
cmp al,1 ; function unsupported or can't determine?
jbe uninstall_failed
cmp al,4
jne uninstall_failed ; sorry, can't handle returns 02h/03h yet
go_uninstall:
push ds
push si
mov ds,dx ; DS:SI -> hook list
mov si,bx
call unhook_interrupts
pop si
pop ds
jc uninstall_failed
cmp resident_seg,0B000h ; regular DOS memblk if below video
jae uninstall_highmem
mov es,resident_seg
mov ah,49h ; free memory block
int 21h
uninstall_successful:
mov al,0FFh ; indicate success
jmp short uninstall_done
uninstall_failed:
mov al,1 ; status = unsuccessful
uninstall_done:
mov ah,0 ; return AX=uninstall status code
pop bp
ret
uninstall_highmem:
call check_if_DOS5_UMBs ; check if UMBs, and link them in
jc uninstall_XMS
mov es,resident_seg ; free the memory block
mov ah,49h
int 21h
restore_link_state:
mov ax,5801h
mov bx,alloc_strat ; restore allocation strategy
int 21h
mov ax,5803h ; and restore UMB link status
mov bh,0
mov bl,link_state
int 21h
jmp uninstall_successful
uninstall_XMS:
call get_XMS_entry
jc uninstall_failed ; no XMS driver!?!?!
mov ah,11h ; release UMB
mov dx,resident_seg
call XMS
jne uninstall_failed ; we deallocation successful?
jmp uninstall_successful
_AMIS_uninstall endp
;-----------------------------------------------------------------------
_TEXT ENDS
END