source: trunk/src/win32k/misc/buffer.asm@ 2838

Last change on this file since 2838 was 2838, checked in by bird, 26 years ago

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1; $Id: buffer.asm,v 1.5 2000-02-21 09:24:02 bird Exp $
2;
3; Simple resident buffer for use when overloading tkExecPgm.
4;
5; Copyright (c) 2000 knut st. osmundsen
6;
7; Project Odin Software License can be found in LICENSE.TXT
8;
9 .486p
10
11
12;
13; Defined Constants And Macros
14;
15NBR_BUFFERS EQU 20
16BUFFER_SIZE EQU 1536
17
18;
19; Include files
20;
21 include devsegdf.inc
22
23;
24; Exported symbols
25;
26 public AcquireBuffer
27 public ReleaseBuffer
28 public QueryBufferSegmentOffset
29 public QueryBufferPointerFromFilename
30
31
32;
33; Imported Functions
34;
35 extrn stricmp:PROC
36
37
38;
39; Global Variables
40;
41DATA16 SEGMENT
42aachBuffer db BUFFER_SIZE*NBR_BUFFERS dup(?) ; The buffer
43DATA16 ENDS
44
45DATA32 SEGMENT
46afBuffer db NBR_BUFFERS dup(0) ; Access "semaphore"
47 ; 0 - not in use
48 ; 1 - in use
49DATA32 ENDS
50
51
52CODE32 segment
53 assume CS:CODE32, DS:NOTHING, SS:NOTHING
54
55;;
56; Aquires a resident buffer. (intended use for tkExecPgm)
57; @cproto assembly only for time being.
58; @returns Pointer to buffer
59; @uses eax
60; @sketch if AfBuffer == 0 then
61; ok!
62; fBuffer <- 1
63; return pointer to buffer
64; else
65; fail
66; return NULL
67; endif
68; @status completely implemented.
69; @author knut st. osmundsen (knut.stange.osmundsen@pmsc.no)
70; @remark cbBuffer holds the size of the buffer.
71AcquireBuffer PROC NEAR
72 push ds
73 push ecx
74 push edx
75
76 ; make ds flat
77 mov ax, seg FLAT:DATA32
78 mov ds, ax
79 ASSUME DS:FLAT
80
81 ; loop thru all buffers and try reserve one
82 mov ah, 1 ; afBuffer[ecx] is set to this value (if equal to al)
83 mov ecx, NBR_BUFFERS ; interations.
84 mov edx, offset FLAT:afBuffer
85 add edx, ecx
86AcquireBuffer_loop:
87 dec edx
88 mov al, 0 ; afBuffer[ecx] should have this value
89 lock cmpxchg [edx], ah
90 je AcquireBuffer_ok
91 loop AcquireBuffer_loop
92
93 ; failure
94AcquireBuffer_nok:
95 xor eax,eax
96 jmp AcquireBuffer_ret
97
98 ;success - calc buffer pointer
99AcquireBuffer_ok:
100 mov eax, BUFFER_SIZE
101 dec ecx
102 imul eax, ecx ; ecx has the buffer number
103 add eax, offset FLAT:aachBuffer
104AcquireBuffer_ret:
105 pop edx
106 pop ecx
107 pop ds
108 ret
109AcquireBuffer ENDP
110
111;;
112; Release the resident buffer pointed to by eax from use.
113; @cproto assembly only for time being.
114; @returns 0 on success, 87 on error.
115; @param eax Pointer to buffer.
116; @uses eax
117; @equiv
118; @status
119; @author knut st. osmundsen (knut.stange.osmundsen@pmsc.no)
120; @remark
121ReleaseBuffer PROC NEAR
122 ASSUME DS:NOTHING
123 push ds
124 push ecx
125 push edx
126
127 ; make ds flat
128 push eax
129 mov ax, seg FLAT:DATA32
130 mov ds, ax
131 ASSUME DS:FLAT
132 pop eax
133 push eax
134
135 ; validate input and calc buffer number
136 cmp eax, offset FLAT:aachBuffer
137 jl ReleaseBuffer_nok ; if eax (buffer pointer) is less than the first buffer, then fail.
138 sub eax, offset FLAT:aachBuffer ; eax <- offset to buffer from aachBuffer
139 xor edx, edx
140 mov ecx, BUFFER_SIZE
141 div ecx ; eax <- buffer number, edx <- offset into buffer (should be NULL)
142 or edx, edx
143 jnz ReleaseBuffer_nok ; if offset into buffer not 0 the fail.
144 cmp eax, NBR_BUFFERS
145 jge ReleaseBuffer_nok ; if buffernumber >= number of buffers then fail.
146
147 ; unlock buffer - if locked
148 mov edx, eax
149 add edx, offset FLAT:afBuffer ; ds:edx points at buffer "semaphore"
150 mov al, 1
151 mov ah, 0
152 lock cmpxchg [edx], ah
153 jne ReleaseBuffer_nok ; fail if buffer was not locked
154
155ReleaseBuffer_ok:
156 ;swipe out buffer
157 pop eax
158 push edi
159 push es
160 mov edi, eax
161 mov ax, ds
162 mov es, ax
163 ASSUME es:FLAT
164 xor eax, eax ; ecx is allready BUFFER_SIZE
165 rep stosb
166 pop es
167 pop edi
168
169 ;return successfully
170 jmp ReleaseBuffer_ret
171
172ReleaseBuffer_nok:
173 ;failure
174 pop eax
175 mov eax, 87 ;some error
176
177ReleaseBuffer_ret:
178 pop edx
179 pop ecx
180 pop ds
181 ret
182ReleaseBuffer ENDP
183
184
185;;
186; Gets the 16-bit segment and offset for this buffer.
187; @cproto assembly only for time being.
188; @returns segment in es and offset in eax
189; On error high word of eax is 87.
190; @param eax Buffer pointer.
191; @uses eax, es
192; @status completely implemented.
193; @author knut st. osmundsen (knut.stange.osmundsen@pmsc.no)
194; @remark cbBuffer holds the size of the buffer.
195QueryBufferSegmentOffset PROC NEAR
196 ASSUME DS:NOTHING
197 push ds
198
199 ; make ds FLAT
200 push eax
201 mov ax, seg FLAT:DATA32
202 mov ds, ax
203 ASSUME DS:FLAT
204 pop eax
205
206 ; validate parameter and calc offset relative to aachBuffer
207 cmp eax, offset FLAT:aachBuffer
208 jl QueryBufferSegmentOffset_nok
209 sub eax, offset FLAT:aachBuffer
210 cmp eax, NBR_BUFFERS * BUFFER_SIZE
211 jge QueryBufferSegmentOffset_nok
212
213QueryBufferSegmentOffset_ok:
214 jmp far ptr CODE16:GetBufferSegmentOffset16
215QueryBufferSegmentOffset_Back::
216 pop ds
217 ret
218
219QueryBufferSegmentOffset_nok:
220 mov eax, 00570000h
221 pop ds
222 ret
223QueryBufferSegmentOffset ENDP
224
225
226;;
227; Special function which checks all used buffers for the string passed in in eax.
228; @cproto PCHAR _Optlink QueryBufferPointerFromFilename(const char *pszFilename)
229; @returns Pointer to Buffer. NULL on error/notfound.
230; @param ds:eax Pointer to filename. The filename will later be compared to the string at buffer start.
231; Currently this parameter is not used, since there is only one buffer.
232; @uses eax.
233; @sketch
234; @status completely implemented
235; @author knut st. osmundsen (knut.stange.osmundsen@pmsc.no)
236; @remark assumes ds flat on call.
237QueryBufferPointerFromFilename PROC NEAR
238 ASSUME cs:CODE32, ds:FLAT
239 push ecx
240 push edx
241 push ebx
242
243 ; loop thru all buffers until found or non left
244 mov ecx, NBR_BUFFERS
245 mov edx, BUFFER_SIZE
246 imul edx, ecx ; edx <- sizeof(aachBuffer)
247 add edx, offset FLAT:aachBuffer ; edx points at the first byte after the buffers.
248 mov ebx, offset FLAT:afBuffer
249 add ebx, ecx ; edx points at the first byte after the "semaphore" array (afBuffer).
250QueryBufferPointerFromFilename_loop:
251 sub edx, BUFFER_SIZE ; edx points at the buffer being concidered.
252 dec ebx ; ebx points at the "semaphore" for the buffer being concidered.
253 cmp byte ptr [ebx], 1 ; Is buffer in use?
254 jne QueryBufferPointerFromFilename_next
255
256 ; buffer is active - lets compare
257 push eax
258 push ecx
259 push edx
260 sub esp, 8
261 call stricmp
262 add esp, 8
263 pop edx
264 pop ecx
265 or eax, eax
266 jz QueryBufferPointerFromFilename_found
267 pop eax
268
269QueryBufferPointerFromFilename_next:
270 loop QueryBufferPointerFromFilename_loop
271 ; when we exit this loop we have failed!
272
273QueryBufferPointerFromFilename_nok:
274 ; The buffer was not found, return NULL pointer.
275 xor eax, eax
276 pop ebx
277 pop edx
278 pop ecx
279 ret
280
281QueryBufferPointerFromFilename_found:
282 ; The buffer was found, return the pointer to it!
283 pop eax
284 pop ebx
285 mov eax, edx
286 pop edx
287 pop ecx
288 ret
289
290QueryBufferPointerFromFilename ENDP
291
292
293
294
295CODE32 ENDS
296
297
298CODE16 SEGMENT
299;;
300; Gets the segment(->es) and offset(+ax -> ax) of the achBuffer.
301; @param ax offset to buffer relative to aachBuffer
302; Jumps back to GetBufferOffset32
303GetBufferSegmentOffset16:
304 ASSUME CS:CODE16, DS:NOTHING
305 push ax
306 mov ax, seg aachBuffer
307 mov es, ax
308 pop ax
309 add ax, offset aachBuffer
310 jmp far ptr FLAT:QueryBufferSegmentOffset_Back
311CODE16 ENDS
312
313END
314
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