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ae7faed1 WJ |
1 | /* |
2 | * Copyright (c) 1988 Regents of the University of California. | |
3 | * All rights reserved. | |
4 | * | |
5 | * Redistribution and use in source and binary forms, with or without | |
6 | * modification, are permitted provided that the following conditions | |
7 | * are met: | |
8 | * 1. Redistributions of source code must retain the above copyright | |
9 | * notice, this list of conditions and the following disclaimer. | |
10 | * 2. Redistributions in binary form must reproduce the above copyright | |
11 | * notice, this list of conditions and the following disclaimer in the | |
12 | * documentation and/or other materials provided with the distribution. | |
13 | * 3. All advertising materials mentioning features or use of this software | |
14 | * must display the following acknowledgement: | |
15 | * This product includes software developed by the University of | |
16 | * California, Berkeley and its contributors. | |
17 | * 4. Neither the name of the University nor the names of its contributors | |
18 | * may be used to endorse or promote products derived from this software | |
19 | * without specific prior written permission. | |
20 | * | |
21 | * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
22 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
23 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
24 | * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
25 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
26 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
27 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
28 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
29 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
30 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
31 | * SUCH DAMAGE. | |
32 | */ | |
33 | ||
34 | #ifndef lint | |
35 | static char sccsid[] = "@(#)ring.c 5.2 (Berkeley) 3/1/91"; | |
36 | #endif /* not lint */ | |
37 | ||
38 | /* | |
39 | * This defines a structure for a ring buffer. | |
40 | * | |
41 | * The circular buffer has two parts: | |
42 | *((( | |
43 | * full: [consume, supply) | |
44 | * empty: [supply, consume) | |
45 | *]]] | |
46 | * | |
47 | */ | |
48 | ||
49 | #include <stdio.h> | |
50 | #include <errno.h> | |
51 | ||
52 | #ifdef size_t | |
53 | #undef size_t | |
54 | #endif | |
55 | ||
56 | #include <sys/types.h> | |
57 | #ifndef FILIO_H | |
58 | #include <sys/ioctl.h> | |
59 | #endif | |
60 | #include <sys/socket.h> | |
61 | ||
62 | #include "ring.h" | |
63 | #include "general.h" | |
64 | ||
65 | /* Internal macros */ | |
66 | ||
67 | #if !defined(MIN) | |
68 | #define MIN(a,b) (((a)<(b))? (a):(b)) | |
69 | #endif /* !defined(MIN) */ | |
70 | ||
71 | #define ring_subtract(d,a,b) (((a)-(b) >= 0)? \ | |
72 | (a)-(b): (((a)-(b))+(d)->size)) | |
73 | ||
74 | #define ring_increment(d,a,c) (((a)+(c) < (d)->top)? \ | |
75 | (a)+(c) : (((a)+(c))-(d)->size)) | |
76 | ||
77 | #define ring_decrement(d,a,c) (((a)-(c) >= (d)->bottom)? \ | |
78 | (a)-(c) : (((a)-(c))-(d)->size)) | |
79 | ||
80 | ||
81 | /* | |
82 | * The following is a clock, used to determine full, empty, etc. | |
83 | * | |
84 | * There is some trickiness here. Since the ring buffers are initialized | |
85 | * to ZERO on allocation, we need to make sure, when interpreting the | |
86 | * clock, that when the times are EQUAL, then the buffer is FULL. | |
87 | */ | |
88 | static u_long ring_clock = 0; | |
89 | ||
90 | ||
91 | #define ring_empty(d) (((d)->consume == (d)->supply) && \ | |
92 | ((d)->consumetime >= (d)->supplytime)) | |
93 | #define ring_full(d) (((d)->supply == (d)->consume) && \ | |
94 | ((d)->supplytime > (d)->consumetime)) | |
95 | ||
96 | ||
97 | ||
98 | ||
99 | ||
100 | /* Buffer state transition routines */ | |
101 | ||
102 | ring_init(ring, buffer, count) | |
103 | Ring *ring; | |
104 | unsigned char *buffer; | |
105 | int count; | |
106 | { | |
107 | memset((char *)ring, 0, sizeof *ring); | |
108 | ||
109 | ring->size = count; | |
110 | ||
111 | ring->supply = ring->consume = ring->bottom = buffer; | |
112 | ||
113 | ring->top = ring->bottom+ring->size; | |
114 | ||
115 | #if defined(ENCRYPT) | |
116 | ring->clearto = 0; | |
117 | #endif | |
118 | ||
119 | return 1; | |
120 | } | |
121 | ||
122 | /* Mark routines */ | |
123 | ||
124 | /* | |
125 | * Mark the most recently supplied byte. | |
126 | */ | |
127 | ||
128 | void | |
129 | ring_mark(ring) | |
130 | Ring *ring; | |
131 | { | |
132 | ring->mark = ring_decrement(ring, ring->supply, 1); | |
133 | } | |
134 | ||
135 | /* | |
136 | * Is the ring pointing to the mark? | |
137 | */ | |
138 | ||
139 | int | |
140 | ring_at_mark(ring) | |
141 | Ring *ring; | |
142 | { | |
143 | if (ring->mark == ring->consume) { | |
144 | return 1; | |
145 | } else { | |
146 | return 0; | |
147 | } | |
148 | } | |
149 | ||
150 | /* | |
151 | * Clear any mark set on the ring. | |
152 | */ | |
153 | ||
154 | void | |
155 | ring_clear_mark(ring) | |
156 | Ring *ring; | |
157 | { | |
158 | ring->mark = 0; | |
159 | } | |
160 | ||
161 | /* | |
162 | * Add characters from current segment to ring buffer. | |
163 | */ | |
164 | void | |
165 | ring_supplied(ring, count) | |
166 | Ring *ring; | |
167 | int count; | |
168 | { | |
169 | ring->supply = ring_increment(ring, ring->supply, count); | |
170 | ring->supplytime = ++ring_clock; | |
171 | } | |
172 | ||
173 | /* | |
174 | * We have just consumed "c" bytes. | |
175 | */ | |
176 | void | |
177 | ring_consumed(ring, count) | |
178 | Ring *ring; | |
179 | int count; | |
180 | { | |
181 | if (count == 0) /* don't update anything */ | |
182 | return; | |
183 | ||
184 | if (ring->mark && | |
185 | (ring_subtract(ring, ring->mark, ring->consume) < count)) { | |
186 | ring->mark = 0; | |
187 | } | |
188 | #if defined(ENCRYPT) | |
189 | if (ring->consume < ring->clearto && | |
190 | ring->clearto <= ring->consume + count) | |
191 | ring->clearto = 0; | |
192 | else if (ring->consume + count > ring->top && | |
193 | ring->bottom <= ring->clearto && | |
194 | ring->bottom + ((ring->consume + count) - ring->top)) | |
195 | ring->clearto = 0; | |
196 | #endif | |
197 | ring->consume = ring_increment(ring, ring->consume, count); | |
198 | ring->consumetime = ++ring_clock; | |
199 | /* | |
200 | * Try to encourage "ring_empty_consecutive()" to be large. | |
201 | */ | |
202 | if (ring_empty(ring)) { | |
203 | ring->consume = ring->supply = ring->bottom; | |
204 | } | |
205 | } | |
206 | ||
207 | ||
208 | ||
209 | /* Buffer state query routines */ | |
210 | ||
211 | ||
212 | /* Number of bytes that may be supplied */ | |
213 | int | |
214 | ring_empty_count(ring) | |
215 | Ring *ring; | |
216 | { | |
217 | if (ring_empty(ring)) { /* if empty */ | |
218 | return ring->size; | |
219 | } else { | |
220 | return ring_subtract(ring, ring->consume, ring->supply); | |
221 | } | |
222 | } | |
223 | ||
224 | /* number of CONSECUTIVE bytes that may be supplied */ | |
225 | int | |
226 | ring_empty_consecutive(ring) | |
227 | Ring *ring; | |
228 | { | |
229 | if ((ring->consume < ring->supply) || ring_empty(ring)) { | |
230 | /* | |
231 | * if consume is "below" supply, or empty, then | |
232 | * return distance to the top | |
233 | */ | |
234 | return ring_subtract(ring, ring->top, ring->supply); | |
235 | } else { | |
236 | /* | |
237 | * else, return what we may. | |
238 | */ | |
239 | return ring_subtract(ring, ring->consume, ring->supply); | |
240 | } | |
241 | } | |
242 | ||
243 | /* Return the number of bytes that are available for consuming | |
244 | * (but don't give more than enough to get to cross over set mark) | |
245 | */ | |
246 | ||
247 | int | |
248 | ring_full_count(ring) | |
249 | Ring *ring; | |
250 | { | |
251 | if ((ring->mark == 0) || (ring->mark == ring->consume)) { | |
252 | if (ring_full(ring)) { | |
253 | return ring->size; /* nothing consumed, but full */ | |
254 | } else { | |
255 | return ring_subtract(ring, ring->supply, ring->consume); | |
256 | } | |
257 | } else { | |
258 | return ring_subtract(ring, ring->mark, ring->consume); | |
259 | } | |
260 | } | |
261 | ||
262 | /* | |
263 | * Return the number of CONSECUTIVE bytes available for consuming. | |
264 | * However, don't return more than enough to cross over set mark. | |
265 | */ | |
266 | int | |
267 | ring_full_consecutive(ring) | |
268 | Ring *ring; | |
269 | { | |
270 | if ((ring->mark == 0) || (ring->mark == ring->consume)) { | |
271 | if ((ring->supply < ring->consume) || ring_full(ring)) { | |
272 | return ring_subtract(ring, ring->top, ring->consume); | |
273 | } else { | |
274 | return ring_subtract(ring, ring->supply, ring->consume); | |
275 | } | |
276 | } else { | |
277 | if (ring->mark < ring->consume) { | |
278 | return ring_subtract(ring, ring->top, ring->consume); | |
279 | } else { /* Else, distance to mark */ | |
280 | return ring_subtract(ring, ring->mark, ring->consume); | |
281 | } | |
282 | } | |
283 | } | |
284 | ||
285 | /* | |
286 | * Move data into the "supply" portion of of the ring buffer. | |
287 | */ | |
288 | void | |
289 | ring_supply_data(ring, buffer, count) | |
290 | Ring *ring; | |
291 | unsigned char *buffer; | |
292 | int count; | |
293 | { | |
294 | int i; | |
295 | ||
296 | while (count) { | |
297 | i = MIN(count, ring_empty_consecutive(ring)); | |
298 | memcpy(ring->supply, buffer, i); | |
299 | ring_supplied(ring, i); | |
300 | count -= i; | |
301 | buffer += i; | |
302 | } | |
303 | } | |
304 | ||
305 | #ifdef notdef | |
306 | ||
307 | /* | |
308 | * Move data from the "consume" portion of the ring buffer | |
309 | */ | |
310 | void | |
311 | ring_consume_data(ring, buffer, count) | |
312 | Ring *ring; | |
313 | unsigned char *buffer; | |
314 | int count; | |
315 | { | |
316 | int i; | |
317 | ||
318 | while (count) { | |
319 | i = MIN(count, ring_full_consecutive(ring)); | |
320 | memcpy(buffer, ring->consume, i); | |
321 | ring_consumed(ring, i); | |
322 | count -= i; | |
323 | buffer += i; | |
324 | } | |
325 | } | |
326 | #endif | |
327 | ||
328 | #if defined(ENCRYPT) | |
329 | void | |
330 | ring_encrypt(ring, encryptor) | |
331 | Ring *ring; | |
332 | void (*encryptor)(); | |
333 | { | |
334 | unsigned char *s, *c; | |
335 | ||
336 | if (ring_empty(ring) || ring->clearto == ring->supply) | |
337 | return; | |
338 | ||
339 | if (!(c = ring->clearto)) | |
340 | c = ring->consume; | |
341 | ||
342 | s = ring->supply; | |
343 | ||
344 | if (s <= c) { | |
345 | (*encryptor)(c, ring->top - c); | |
346 | (*encryptor)(ring->bottom, s - ring->bottom); | |
347 | } else | |
348 | (*encryptor)(c, s - c); | |
349 | ||
350 | ring->clearto = ring->supply; | |
351 | } | |
352 | ||
353 | void | |
354 | ring_clearto(ring) | |
355 | Ring *ring; | |
356 | { | |
357 | if (!ring_empty(ring)) | |
358 | ring->clearto = ring->supply; | |
359 | else | |
360 | ring->clearto = 0; | |
361 | } | |
362 | #endif |