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1.1 root 1:
2: ; dynlib3.asm
3: ;
4: ; Created 17 August 1987 by Kevin Ruddell, Microsoft Corp
5: ;
6: ;
7: ; Demonstrates the use of shared and non-shared data segments.
8: ; When each process attaches, the contents of "count" (in a shared segment)
9: ; is incremented and assigned to "id" (in a non-shared segment).
10: ; "count" is used to detect the first time the initialization routine
11: ; is invoked.
12: ; When a process makes a call to PRINTDATA, the current values of
13: ; "count" and "id" are displayed on the screen. They will be different for
14: ; all but the last process to attach to the dll.
15:
16:
17: TITLE dynlib3
18:
19: .286p
20:
21: EXTRN DOSWRITE:FAR
22:
23: ;-----------------------------------------------------------------------------
24: ;A fresh copy of this segment is created for each process attaching to the dll.
25:
26: ETHEL SEGMENT WORD PUBLIC 'FAR_DATA'
27: id DW 00H ;unique to each attached process
28: ETHEL ENDS
29:
30: ;---------------------------------------
31: ;This segment is shared by all processes attached to the dll.
32:
33: FRED SEGMENT WORD PUBLIC 'FAR_DATA'
34: First DB 'First time initialization.', 0aH, 0dH, 00H
35: NotFirst DB 'Not first time initialization.', 0aH, 0dH, 00H
36: msg_beg DB 'I am number ', 00H
37: ORG $+1 ;to line up on word boundaries
38: const_1 DB '.', 0aH, 0dH, 00H
39: msg_mid DB '. There are ', 00H
40: count DW 00H ;number of processes which have attached
41: msg_end DB ' processes attached.', 0dH, 00H
42: written DW 00H ;bytes written
43: c DW 00H ;temporary variable
44: FRED ENDS
45:
46: ;-----------------------------------------------------------------------------
47: ;-----------------------------------------------------------------------------
48: ASSUME CS: _TEXT, DS: FRED, ES: ETHEL
49: ;---------------------------------------
50: _TEXT SEGMENT BYTE PUBLIC 'CODE'
51: ;---------------------------------------
52: ; START
53: ; Initialization routine.
54: ; Called for each process when the process attaches to the dll.
55: ;
56: ; count is initialized to 0 in its definition, and so can be used as a first-
57: ; time switch. A First/NotFirst message is sent to the screen and count is
58: ; incremented to reflect the number of processes which have attached to
59: ; the dll. The freshly-incremented count is copied to the non-shared
60: ; location id and is unique among the attached processes. Actually,
61: ; accesses to count should be synchronized, but this is omitted for simplicity.
62: ; The unique id is sent to the screen.
63:
64:
65: START PROC FAR
66:
67: push di ;save registers
68: push si
69: push ds
70: push es
71:
72: mov ax,SEG FRED ;set up segment registers
73: mov ds,ax ;ds points to global segment
74: mov ax,SEG ETHEL
75: mov es,ax ;es points to non-shared segment
76:
77: mov ax,count
78: inc WORD PTR count ;bump shared count of attached processes
79: cmp ax,0 ;test for first time through
80: jne START_NOT
81:
82: push 1 ;write to standard output (screen)
83: push ds
84: push OFFSET First ;address of "First time initialization."
85: push 28 ;number of bytes to write
86: push ds
87: push OFFSET written ;address to hold # bytes written
88: call FAR PTR DOSWRITE ;synchronous write
89: jmp START_ID
90:
91: START_NOT:
92: push 1 ;write to standard output
93: push ds
94: push OFFSET NotFirst ;addr of "Not first time initialization."
95: push 32 ;number of bytes to write
96: push ds
97: push OFFSET written ;address to hold # bytes written
98: call FAR PTR DOSWRITE ;synchronous write
99:
100: START_ID:
101: mov ax,count ;non-shared id = shared count
102: mov es:id,ax
103:
104: push 1 ;write to standard output
105: push ds
106: push OFFSET msg_beg ;addr of "I am number "
107: push 12 ;number of bytes to write
108: push ds
109: push OFFSET written ;address to hold # bytes written
110: call FAR PTR DOSWRITE ;synchronous write
111:
112: mov al,BYTE PTR count
113: add al,'0' ;c = count + '0'
114: mov BYTE PTR c,al
115:
116: push 1 ;write to standard output
117: push ds
118: push OFFSET c ;@c
119: push 1 ;number of bytes to write
120: push ds
121: push OFFSET written ;address to hold # bytes written
122: call FAR PTR DOSWRITE ;synchronous write
123:
124: push 1 ;write to standard output
125: push ds
126: push OFFSET const_1 ;addr of ".<cr><lf>"
127: push 3 ;number of bytes to write
128: push ds
129: push OFFSET written ;address to hold # bytes written
130: call FAR PTR DOSWRITE ;synchronous write
131:
132: mov ax,1 ;indicates success
133: pop es ;restore registers
134: pop ds
135: pop si
136: pop di
137: ret
138:
139: START ENDP
140: ;---------------------------------------
141: ; PRINTDATA
142: ; Called by the attached process to display on the screen the current values
143: ; of the shared "count" and the non-shared "id".
144:
145:
146: PUBLIC PRINTDATA ;entry point
147: PRINTDATA PROC FAR
148:
149: push di ;save registers
150: push si
151: push ds
152: push es
153:
154: mov ax,SEG FRED ;set up segment registers
155: mov ds,ax ;ds points to global segment
156: mov ax,SEG ETHEL
157: mov es,ax ;es points to non-shared segment
158:
159: push 1 ;write to standard output
160: push ds
161: push OFFSET msg_beg ;addr of "I am number "
162: push 12 ;number of bytes to write
163: push ds
164: push OFFSET written ;address to hold # bytes written
165: call FAR PTR DOSWRITE ;synchronous write
166:
167: mov al,BYTE PTR es:id
168: add al,'0' ;c = id + '0'
169: mov BYTE PTR c,al
170:
171: push 1 ;write to standard output
172: push ds
173: push OFFSET c ;@c
174: push 1 ;number of bytes to write
175: push ds
176: push OFFSET written ;address to hold # bytes written
177: call FAR PTR DOSWRITE ;synchronous write
178:
179: push 1 ;write to standard output
180: push ds
181: push OFFSET msg_mid ;addr of ". There are "
182: push 13 ;number of bytes to write
183: push ds
184: push OFFSET written ;address to hold # bytes written
185: call FAR PTR DOSWRITE ;synchronous write
186:
187: mov al,BYTE PTR count
188: add al,'0' ;c = count + '0'
189: mov BYTE PTR c,al
190:
191: push 1 ;write to standard output
192: push ds
193: push OFFSET c ;@c
194: push 1 ;number of bytes to write
195: push ds
196: push OFFSET written ;address to hold # bytes written
197: call FAR PTR DOSWRITE ;synchronous write
198:
199: push 1 ;write to standard output
200: push ds
201: push OFFSET msg_end ;addr of " processes attached.<cr>"
202: push 21 ;number of bytes to write
203: push ds
204: push OFFSET written ;address to hold # bytes written
205: call FAR PTR DOSWRITE ;synchronous write
206:
207: pop es ;restore registers
208: pop ds
209: pop si
210: pop di
211: ret
212:
213: PRINTDATA ENDP
214: ;---------------------------------------
215: _TEXT ENDS
216: ;-----------------------------------------------------------------------------
217: END START ;defines auto-initialization entry point
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