1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
|
name vxdstub
;************************************************************************
;
; (C) Copyright MICROSOFT Corp., 1990-1991
;
; Title: VXDSTUB.ASM
;
; Date: 1-Jun-1991
;
; Author: Neil Sandlin
;
;************************************************************************
INCLUDE INT2FAPI.INC
;----------------------------- M A C R O S ------------------------------
Writel MACRO addr
push ax
push bx
push cx
push dx
mov dx,offset &addr ;Print
mov cx,&addr&l
mov bx,1 ;stdout
mov ah,40h ;write
int 21h
pop dx
pop cx
pop bx
pop ax
ENDM
;----------------------------- E Q U A T E S -----------------------------
cr equ 0dh
lf equ 0ah
_TEXT segment word public 'CODE'
assume cs:_TEXT,ds:_DATA
;*----------------------- TSR Data Area ---------------------*
InstData Win386_Startup_Info_Struc <>
oldint dd 0
;*----------------------- TSR Code --------------------------*
handle2f proc
cmp ax,1605h
jnz @f
push di
lea di,InstData
mov word ptr cs:[di].SIS_Next_Ptr,bx
mov word ptr cs:[di][2].SIS_Next_Ptr,es
pop di
push cs
pop es
lea bx,InstData
@@:
jmp DWORD PTR [oldint]
handle2f endp
ALIGN 16
init_fence:
_TEXT ends
;*---------------------- Initialization Data ------------------------*
_DATA segment word public 'DATA'
TSR_rsv dw ?
intmsg db cr,lf,'Hooking interrupt '
intmsgx dd ?
db cr,lf
intmsgl equ $-intmsg
hndmsg db cr,lf,'ISR entry point: '
hndmsga dd ?
db ':'
hndmsgb dd ?
db ', length='
hndmsgc dd ?
db 'h bytes'
db cr,lf
hndmsgl equ $-hndmsg
tsrmsg db 'TSR; reserving '
tsrmsgx dd ?
db ' paragraphs'
db cr,lf
tsrmsgl equ $-tsrmsg
_DATA ends
_TEXT segment word public 'CODE'
;*-------------------------- Initialization Code ----------------------*
vxdstub proc far
mov ax, _DATA
mov ds, ax
; get a pointer to the name of the load file in the environment seg.
mov ah,62h
int 21h ;bx -> psp
mov es,bx
mov bx,2ch ;environment segment
mov es,es:[bx]
xor di,di
mov cx,-1 ;big number
xor al,al ;search for a null
cld
@@:
repne scasb ;get past one null and stop
cmp byte ptr es:[di],0 ;another null
jnz @b ;no.
add di,3 ;skip the word before the name.
; prepare part of the instance data list. Stuff in pointer to the file name
; and refernce data
lea si,InstData
mov word ptr CS:[si].SIS_Version,3
mov word ptr CS:[si].SIS_Virt_Dev_File_Ptr,di
mov word ptr CS:[si][2].SIS_Virt_Dev_File_Ptr,es
mov word ptr cs:[si].SIS_Instance_Data_Ptr,0
mov word ptr cs:[si][2].SIS_Instance_Data_Ptr,0
; Write message and hook interrupt 2f
mov ax, 2fh
mov bx, offset intmsgx
call hexasc
Writel intmsg
mov ah, 35h
mov al, 2fh
int 21h ; get old vector
mov WORD PTR cs:oldint,bx ; save old vector here
mov WORD PTR cs:oldint+2,es
push ds
mov dx, offset handle2f
push cs ; get current code segment
pop ds
mov ah, 25h
mov al, 2fh ; vector to hook
int 21h ; hook that vector
pop ds
; Print out some information about the handler
push cs ; code segment
pop ax
mov bx, offset hndmsga
call hexasc
mov ax, offset handle2f ; offset of ISR
mov bx, offset hndmsgb
call hexasc
mov ax, offset init_fence ; length in bytes of handler
mov bx, offset hndmsgc
call hexasc
Writel hndmsg
; Compute size of TSR area
mov dx, offset init_fence ; start of initialization code
add dx, 15 ; round it off to paragraph
shr dx, 1 ; divide by 16
shr dx, 1
shr dx, 1
shr dx, 1
add dx, 32 ; add in PSP
mov TSR_rsv, dx ; save it
mov ax, dx
mov bx, offset tsrmsgx
call hexasc
Writel tsrmsg
; Terminate and stay resident
mov ax, 3100h ; TSR
mov dx, TSR_rsv ; # of paragraphs to reserve
int 21h ; TSR
vxdstub endp
;************************************************************************
;
; HEXASC
;
; This subroutine formats hex values into ASCII
; (utility routine from Advanced MS-DOS Programming)
;
;
;************************************************************************
hexasc proc near ; converts word to hex ASCII
; call with AX = value,
; DS:BX = address for string
; returns AX, BX destroyed
push cx ; save registers
push dx
mov dx,4 ; initialize character counter
hexasc1:
mov cx,4 ; isolate next four bits
rol ax,cl
mov cx,ax
and cx,0fh
add cx,'0' ; convert to ASCII
cmp cx,'9' ; is it 0-9?
jbe hexasc2 ; yes, jump
add cx,'A'-'9'-1 ; add fudge factor for A-F
hexasc2: ; store this character
mov [bx],cl
inc bx ; bump string pointer
dec dx ; count characters converted
jnz hexasc1 ; loop, not four yet
pop dx ; restore registers
pop cx
ret ; back to caller
hexasc endp
_TEXT ends
end vxdstub
|
