1 /*
2 * Copyright 2005 Sun Microsystems, Inc. All rights reserved.
3 * Use is subject to license terms.
4 */
5
6 /*
7 * usr/src/cmd/cmd-inet/usr.bin/telnet/ring.c
8 */
9
10 /*
11 * Copyright (c) 1988, 1993
12 * The Regents of the University of California. All rights reserved.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
22 * 3. All advertising materials mentioning features or use of this software
23 * must display the following acknowledgement:
24 * This product includes software developed by the University of
25 * California, Berkeley and its contributors.
26 * 4. Neither the name of the University nor the names of its contributors
27 * may be used to endorse or promote products derived from this software
28 * without specific prior written permission.
29 *
30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
31 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
32 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
33 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
34 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
35 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
36 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
37 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
38 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
39 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
40 * SUCH DAMAGE.
41 */
42
43 #ifndef lint
44 static char sccsid[] = "@(#)ring.c 8.1 (Berkeley) 6/6/93";
45 #endif /* not lint */
46
47 /*
48 * This defines a structure for a ring buffer.
49 *
50 * The circular buffer has two parts:
51 * (((
52 * full: [consume, supply)
53 * empty: [supply, consume)
54 * ]]]
55 *
56 */
57
58 #include <stdio.h>
59 #include <errno.h>
60 #include <string.h>
61
62 #include <sys/types.h>
63 #include <sys/socket.h>
64 #include <sys/sysmacros.h>
65
66 #include "ring.h"
67 #include "general.h"
68
69
70 #define ring_subtract(d, a, b) (((a)-(b) >= 0)? \
71 (a)-(b): (((a)-(b))+(d)->size))
72
73 #define ring_increment(d, a, c) (((a)+(c) < (d)->top)? \
74 (a)+(c) : (((a)+(c))-(d)->size))
75
76 #define ring_decrement(d, a, c) (((a)-(c) >= (d)->bottom)? \
77 (a)-(c) : (((a)-(c))-(d)->size))
78
79
80 /*
81 * The following is a clock, used to determine full, empty, etc.
82 *
83 * There is some trickiness here. Since the ring buffers are initialized
84 * to ZERO on allocation, we need to make sure, when interpreting the
85 * clock, that when the times are EQUAL, then the buffer is FULL.
86 */
87 ulong_t ring_clock = 0;
88
89
90 #define ring_empty(d) (((d)->consume == (d)->supply) && \
91 ((d)->consumetime >= (d)->supplytime))
92 #define ring_full(d) (((d)->supply == (d)->consume) && \
93 ((d)->supplytime > (d)->consumetime))
94
95
96
97
98
99 /* Buffer state transition routines */
100
101 int
ring_init(Ring * ring,unsigned char * buffer,int count)102 ring_init(Ring *ring, unsigned char *buffer, int count)
103 {
104 (void) memset(ring, 0, sizeof (*ring));
105
106 ring->size = count;
107
108 ring->supply = ring->consume = ring->bottom = buffer;
109
110 ring->top = ring->bottom+ring->size;
111
112 ring->clearto = 0;
113
114 return (1);
115 }
116
117 /* Mark routines */
118
119 /*
120 * Mark the most recently supplied byte.
121 */
122
123 void
ring_mark(Ring * ring)124 ring_mark(Ring *ring)
125 {
126 ring->mark = ring_decrement(ring, ring->supply, 1);
127 }
128
129 /*
130 * Is the ring pointing to the mark?
131 */
132
133 int
ring_at_mark(Ring * ring)134 ring_at_mark(Ring *ring)
135 {
136 if (ring->mark == ring->consume) {
137 return (1);
138 } else {
139 return (0);
140 }
141 }
142
143 /*
144 * Clear any mark set on the ring.
145 */
146
147 void
ring_clear_mark(Ring * ring)148 ring_clear_mark(Ring *ring)
149 {
150 ring->mark = 0;
151 }
152
153 /*
154 * Add characters from current segment to ring buffer.
155 */
156 void
ring_supplied(Ring * ring,int count)157 ring_supplied(Ring *ring, int count)
158 {
159 ring->supply = ring_increment(ring, ring->supply, count);
160 ring->supplytime = ++ring_clock;
161 }
162
163 /*
164 * We have just consumed "c" bytes.
165 */
166 void
ring_consumed(Ring * ring,int count)167 ring_consumed(Ring *ring, int count)
168 {
169 if (count == 0) /* don't update anything */
170 return;
171
172 if (ring->mark &&
173 (ring_subtract(ring, ring->mark, ring->consume) < count)) {
174 ring->mark = 0;
175 }
176
177 if (ring->consume < ring->clearto &&
178 ring->clearto <= ring->consume + count)
179 ring->clearto = 0;
180 else if (ring->consume + count > ring->top &&
181 ring->bottom <= ring->clearto)
182 ring->clearto = 0;
183
184 ring->consume = ring_increment(ring, ring->consume, count);
185 ring->consumetime = ++ring_clock;
186 /*
187 * Try to encourage "ring_empty_consecutive()" to be large.
188 */
189 if (ring_empty(ring)) {
190 ring->consume = ring->supply = ring->bottom;
191 }
192 }
193
194
195
196 /* Buffer state query routines */
197
198
199 /* Number of bytes that may be supplied */
200 int
ring_empty_count(Ring * ring)201 ring_empty_count(Ring *ring)
202 {
203 if (ring_empty(ring)) { /* if empty */
204 return (ring->size);
205 } else {
206 return (ring_subtract(ring, ring->consume, ring->supply));
207 }
208 }
209
210 /* number of CONSECUTIVE bytes that may be supplied */
211 int
ring_empty_consecutive(Ring * ring)212 ring_empty_consecutive(Ring *ring)
213 {
214 if ((ring->consume < ring->supply) || ring_empty(ring)) {
215 /*
216 * if consume is "below" supply, or empty, then
217 * return distance to the top
218 */
219 return (ring_subtract(ring, ring->top, ring->supply));
220 } else {
221 /*
222 * else, return what we may.
223 */
224 return (ring_subtract(ring, ring->consume, ring->supply));
225 }
226 }
227
228 /*
229 * Return the number of bytes that are available for consuming
230 * (but don't give more than enough to get to cross over set mark)
231 */
232
233 int
ring_full_count(Ring * ring)234 ring_full_count(Ring *ring)
235 {
236 if ((ring->mark == 0) || (ring->mark == ring->consume)) {
237 if (ring_full(ring)) {
238 return (ring->size); /* nothing consumed, but full */
239 } else {
240 return (ring_subtract(ring, ring->supply,
241 ring->consume));
242 }
243 } else {
244 return (ring_subtract(ring, ring->mark, ring->consume));
245 }
246 }
247
248 /*
249 * Return the number of CONSECUTIVE bytes available for consuming.
250 * However, don't return more than enough to cross over set mark.
251 */
252 int
ring_full_consecutive(Ring * ring)253 ring_full_consecutive(Ring *ring)
254 {
255 if ((ring->mark == 0) || (ring->mark == ring->consume)) {
256 if ((ring->supply < ring->consume) || ring_full(ring)) {
257 return (ring_subtract(ring, ring->top, ring->consume));
258 } else {
259 return (ring_subtract(ring, ring->supply,
260 ring->consume));
261 }
262 } else {
263 if (ring->mark < ring->consume) {
264 return (ring_subtract(ring, ring->top, ring->consume));
265 } else { /* Else, distance to mark */
266 return (ring_subtract(ring, ring->mark, ring->consume));
267 }
268 }
269 }
270
271 /*
272 * Move data into the "supply" portion of of the ring buffer.
273 */
274 void
ring_supply_data(Ring * ring,unsigned char * buffer,int count)275 ring_supply_data(Ring *ring, unsigned char *buffer, int count)
276 {
277 int i;
278
279 while (count) {
280 i = MIN(count, ring_empty_consecutive(ring));
281 (void) memcpy(ring->supply, buffer, i);
282 ring_supplied(ring, i);
283 count -= i;
284 buffer += i;
285 }
286 }
287
288 #ifdef notdef
289
290 /*
291 * Move data from the "consume" portion of the ring buffer
292 */
293 void
ring_consume_data(Ring * ring,unsigned char * buffer,int count)294 ring_consume_data(Ring *ring, unsigned char *buffer, int count)
295 {
296 int i;
297
298 while (count) {
299 i = MIN(count, ring_full_consecutive(ring));
300 memcpy(buffer, ring->consume, i);
301 ring_consumed(ring, i);
302 count -= i;
303 buffer += i;
304 }
305 }
306 #endif
307
308 void
ring_encrypt(Ring * ring,void (* encryptor)())309 ring_encrypt(Ring *ring, void (*encryptor)())
310 {
311 unsigned char *s, *c;
312
313 if (ring_empty(ring) || ring->clearto == ring->supply)
314 return;
315
316 if ((c = ring->clearto) == NULL)
317 c = ring->consume;
318
319 s = ring->supply;
320
321 if (s <= c) {
322 (*encryptor)(c, ring->top - c);
323 (*encryptor)(ring->bottom, s - ring->bottom);
324 } else
325 (*encryptor)(c, s - c);
326
327 ring->clearto = ring->supply;
328 }
329
330 void
ring_clearto(Ring * ring)331 ring_clearto(Ring *ring)
332 {
333 if (!ring_empty(ring))
334 ring->clearto = ring->supply;
335 else
336 ring->clearto = 0;
337 }
338