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1 | /* |
2 | * Copyright (c) 1988 Regents of the University of California. | |
3 | * All rights reserved. | |
4 | * | |
cb956e54 | 5 | * %sccs.include.redist.c% |
897ce52e KB |
6 | */ |
7 | ||
8 | #ifndef lint | |
8832c633 | 9 | static char sccsid[] = "@(#)ring.c 5.3 (Berkeley) %G%"; |
897ce52e KB |
10 | #endif /* not lint */ |
11 | ||
cde671b6 | 12 | /* |
8b6750f5 | 13 | * This defines a structure for a ring buffer. |
cde671b6 | 14 | * |
8b6750f5 | 15 | * The circular buffer has two parts: |
cde671b6 | 16 | *((( |
8b6750f5 GM |
17 | * full: [consume, supply) |
18 | * empty: [supply, consume) | |
cde671b6 GM |
19 | *]]] |
20 | * | |
cde671b6 GM |
21 | */ |
22 | ||
23 | #include <stdio.h> | |
24 | #include <errno.h> | |
25 | ||
26 | #ifdef size_t | |
27 | #undef size_t | |
28 | #endif | |
29 | ||
30 | #include <sys/types.h> | |
4a8a7128 | 31 | #ifndef FILIO_H |
cde671b6 | 32 | #include <sys/ioctl.h> |
4a8a7128 | 33 | #endif |
cde671b6 GM |
34 | #include <sys/socket.h> |
35 | ||
36 | #include "ring.h" | |
37 | #include "general.h" | |
38 | ||
39 | /* Internal macros */ | |
40 | ||
115a5494 GM |
41 | #if !defined(MIN) |
42 | #define MIN(a,b) (((a)<(b))? (a):(b)) | |
43 | #endif /* !defined(MIN) */ | |
cde671b6 | 44 | |
6055a9f6 | 45 | #define ring_subtract(d,a,b) (((a)-(b) >= 0)? \ |
115a5494 | 46 | (a)-(b): (((a)-(b))+(d)->size)) |
cde671b6 GM |
47 | |
48 | #define ring_increment(d,a,c) (((a)+(c) < (d)->top)? \ | |
49 | (a)+(c) : (((a)+(c))-(d)->size)) | |
50 | ||
218b1a4c GM |
51 | #define ring_decrement(d,a,c) (((a)-(c) >= (d)->bottom)? \ |
52 | (a)-(c) : (((a)-(c))-(d)->size)) | |
53 | ||
cde671b6 GM |
54 | |
55 | /* | |
56 | * The following is a clock, used to determine full, empty, etc. | |
57 | * | |
58 | * There is some trickiness here. Since the ring buffers are initialized | |
59 | * to ZERO on allocation, we need to make sure, when interpreting the | |
8b6750f5 | 60 | * clock, that when the times are EQUAL, then the buffer is FULL. |
cde671b6 GM |
61 | */ |
62 | static u_long ring_clock = 0; | |
63 | ||
64 | ||
8b6750f5 GM |
65 | #define ring_empty(d) (((d)->consume == (d)->supply) && \ |
66 | ((d)->consumetime >= (d)->supplytime)) | |
67 | #define ring_full(d) (((d)->supply == (d)->consume) && \ | |
68 | ((d)->supplytime > (d)->consumetime)) | |
cde671b6 GM |
69 | |
70 | ||
71 | ||
72 | ||
73 | ||
74 | /* Buffer state transition routines */ | |
75 | ||
15d31b7e | 76 | ring_init(ring, buffer, count) |
115a5494 | 77 | Ring *ring; |
15d31b7e DB |
78 | unsigned char *buffer; |
79 | int count; | |
115a5494 GM |
80 | { |
81 | memset((char *)ring, 0, sizeof *ring); | |
82 | ||
83 | ring->size = count; | |
84 | ||
8b6750f5 | 85 | ring->supply = ring->consume = ring->bottom = buffer; |
115a5494 GM |
86 | |
87 | ring->top = ring->bottom+ring->size; | |
88 | ||
8832c633 | 89 | #if defined(ENCRYPTION) |
15d31b7e DB |
90 | ring->clearto = 0; |
91 | #endif | |
92 | ||
115a5494 GM |
93 | return 1; |
94 | } | |
cde671b6 | 95 | |
218b1a4c GM |
96 | /* Mark routines */ |
97 | ||
98 | /* | |
99 | * Mark the most recently supplied byte. | |
100 | */ | |
101 | ||
15d31b7e | 102 | void |
218b1a4c | 103 | ring_mark(ring) |
15d31b7e | 104 | Ring *ring; |
218b1a4c GM |
105 | { |
106 | ring->mark = ring_decrement(ring, ring->supply, 1); | |
107 | } | |
108 | ||
109 | /* | |
110 | * Is the ring pointing to the mark? | |
111 | */ | |
112 | ||
15d31b7e | 113 | int |
218b1a4c | 114 | ring_at_mark(ring) |
15d31b7e | 115 | Ring *ring; |
218b1a4c GM |
116 | { |
117 | if (ring->mark == ring->consume) { | |
118 | return 1; | |
119 | } else { | |
120 | return 0; | |
121 | } | |
122 | } | |
123 | ||
124 | /* | |
125 | * Clear any mark set on the ring. | |
126 | */ | |
127 | ||
15d31b7e | 128 | void |
218b1a4c | 129 | ring_clear_mark(ring) |
15d31b7e | 130 | Ring *ring; |
218b1a4c GM |
131 | { |
132 | ring->mark = 0; | |
133 | } | |
134 | ||
cde671b6 GM |
135 | /* |
136 | * Add characters from current segment to ring buffer. | |
137 | */ | |
15d31b7e | 138 | void |
8b6750f5 | 139 | ring_supplied(ring, count) |
15d31b7e DB |
140 | Ring *ring; |
141 | int count; | |
cde671b6 | 142 | { |
8b6750f5 GM |
143 | ring->supply = ring_increment(ring, ring->supply, count); |
144 | ring->supplytime = ++ring_clock; | |
cde671b6 GM |
145 | } |
146 | ||
147 | /* | |
8b6750f5 | 148 | * We have just consumed "c" bytes. |
cde671b6 | 149 | */ |
15d31b7e | 150 | void |
8b6750f5 | 151 | ring_consumed(ring, count) |
15d31b7e DB |
152 | Ring *ring; |
153 | int count; | |
cde671b6 | 154 | { |
ad1c581e GM |
155 | if (count == 0) /* don't update anything */ |
156 | return; | |
157 | ||
218b1a4c GM |
158 | if (ring->mark && |
159 | (ring_subtract(ring, ring->mark, ring->consume) < count)) { | |
160 | ring->mark = 0; | |
161 | } | |
8832c633 | 162 | #if defined(ENCRYPTION) |
15d31b7e DB |
163 | if (ring->consume < ring->clearto && |
164 | ring->clearto <= ring->consume + count) | |
165 | ring->clearto = 0; | |
166 | else if (ring->consume + count > ring->top && | |
167 | ring->bottom <= ring->clearto && | |
168 | ring->bottom + ((ring->consume + count) - ring->top)) | |
169 | ring->clearto = 0; | |
170 | #endif | |
8b6750f5 GM |
171 | ring->consume = ring_increment(ring, ring->consume, count); |
172 | ring->consumetime = ++ring_clock; | |
8166d918 GM |
173 | /* |
174 | * Try to encourage "ring_empty_consecutive()" to be large. | |
175 | */ | |
176 | if (ring_empty(ring)) { | |
177 | ring->consume = ring->supply = ring->bottom; | |
178 | } | |
cde671b6 GM |
179 | } |
180 | ||
e8507c1e | 181 | |
cde671b6 GM |
182 | |
183 | /* Buffer state query routines */ | |
184 | ||
185 | ||
8b6750f5 | 186 | /* Number of bytes that may be supplied */ |
15d31b7e | 187 | int |
cde671b6 | 188 | ring_empty_count(ring) |
15d31b7e | 189 | Ring *ring; |
cde671b6 | 190 | { |
8b6750f5 | 191 | if (ring_empty(ring)) { /* if empty */ |
cde671b6 GM |
192 | return ring->size; |
193 | } else { | |
8b6750f5 | 194 | return ring_subtract(ring, ring->consume, ring->supply); |
cde671b6 GM |
195 | } |
196 | } | |
197 | ||
8b6750f5 | 198 | /* number of CONSECUTIVE bytes that may be supplied */ |
15d31b7e | 199 | int |
cde671b6 | 200 | ring_empty_consecutive(ring) |
15d31b7e | 201 | Ring *ring; |
cde671b6 | 202 | { |
8b6750f5 GM |
203 | if ((ring->consume < ring->supply) || ring_empty(ring)) { |
204 | /* | |
205 | * if consume is "below" supply, or empty, then | |
206 | * return distance to the top | |
207 | */ | |
208 | return ring_subtract(ring, ring->top, ring->supply); | |
cde671b6 GM |
209 | } else { |
210 | /* | |
211 | * else, return what we may. | |
212 | */ | |
8b6750f5 | 213 | return ring_subtract(ring, ring->consume, ring->supply); |
cde671b6 GM |
214 | } |
215 | } | |
216 | ||
218b1a4c GM |
217 | /* Return the number of bytes that are available for consuming |
218 | * (but don't give more than enough to get to cross over set mark) | |
219 | */ | |
220 | ||
15d31b7e | 221 | int |
8b6750f5 | 222 | ring_full_count(ring) |
15d31b7e | 223 | Ring *ring; |
cde671b6 | 224 | { |
218b1a4c GM |
225 | if ((ring->mark == 0) || (ring->mark == ring->consume)) { |
226 | if (ring_full(ring)) { | |
227 | return ring->size; /* nothing consumed, but full */ | |
228 | } else { | |
229 | return ring_subtract(ring, ring->supply, ring->consume); | |
230 | } | |
cde671b6 | 231 | } else { |
218b1a4c | 232 | return ring_subtract(ring, ring->mark, ring->consume); |
cde671b6 GM |
233 | } |
234 | } | |
235 | ||
218b1a4c GM |
236 | /* |
237 | * Return the number of CONSECUTIVE bytes available for consuming. | |
238 | * However, don't return more than enough to cross over set mark. | |
239 | */ | |
15d31b7e | 240 | int |
8b6750f5 | 241 | ring_full_consecutive(ring) |
15d31b7e | 242 | Ring *ring; |
cde671b6 | 243 | { |
218b1a4c GM |
244 | if ((ring->mark == 0) || (ring->mark == ring->consume)) { |
245 | if ((ring->supply < ring->consume) || ring_full(ring)) { | |
246 | return ring_subtract(ring, ring->top, ring->consume); | |
247 | } else { | |
248 | return ring_subtract(ring, ring->supply, ring->consume); | |
249 | } | |
cde671b6 | 250 | } else { |
218b1a4c GM |
251 | if (ring->mark < ring->consume) { |
252 | return ring_subtract(ring, ring->top, ring->consume); | |
253 | } else { /* Else, distance to mark */ | |
254 | return ring_subtract(ring, ring->mark, ring->consume); | |
255 | } | |
cde671b6 GM |
256 | } |
257 | } | |
258 | ||
cde671b6 | 259 | /* |
8b6750f5 | 260 | * Move data into the "supply" portion of of the ring buffer. |
cde671b6 | 261 | */ |
15d31b7e | 262 | void |
8b6750f5 | 263 | ring_supply_data(ring, buffer, count) |
15d31b7e DB |
264 | Ring *ring; |
265 | unsigned char *buffer; | |
266 | int count; | |
cde671b6 GM |
267 | { |
268 | int i; | |
269 | ||
270 | while (count) { | |
115a5494 | 271 | i = MIN(count, ring_empty_consecutive(ring)); |
8b6750f5 GM |
272 | memcpy(ring->supply, buffer, i); |
273 | ring_supplied(ring, i); | |
cde671b6 GM |
274 | count -= i; |
275 | buffer += i; | |
276 | } | |
277 | } | |
278 | ||
4a8a7128 | 279 | #ifdef notdef |
cde671b6 GM |
280 | |
281 | /* | |
8b6750f5 | 282 | * Move data from the "consume" portion of the ring buffer |
cde671b6 | 283 | */ |
15d31b7e | 284 | void |
8b6750f5 | 285 | ring_consume_data(ring, buffer, count) |
15d31b7e DB |
286 | Ring *ring; |
287 | unsigned char *buffer; | |
288 | int count; | |
cde671b6 GM |
289 | { |
290 | int i; | |
291 | ||
292 | while (count) { | |
8b6750f5 GM |
293 | i = MIN(count, ring_full_consecutive(ring)); |
294 | memcpy(buffer, ring->consume, i); | |
295 | ring_consumed(ring, i); | |
cde671b6 GM |
296 | count -= i; |
297 | buffer += i; | |
298 | } | |
299 | } | |
4a8a7128 | 300 | #endif |
15d31b7e | 301 | |
8832c633 | 302 | #if defined(ENCRYPTION) |
15d31b7e DB |
303 | void |
304 | ring_encrypt(ring, encryptor) | |
305 | Ring *ring; | |
306 | void (*encryptor)(); | |
307 | { | |
308 | unsigned char *s, *c; | |
309 | ||
310 | if (ring_empty(ring) || ring->clearto == ring->supply) | |
311 | return; | |
312 | ||
313 | if (!(c = ring->clearto)) | |
314 | c = ring->consume; | |
315 | ||
316 | s = ring->supply; | |
317 | ||
318 | if (s <= c) { | |
319 | (*encryptor)(c, ring->top - c); | |
320 | (*encryptor)(ring->bottom, s - ring->bottom); | |
321 | } else | |
322 | (*encryptor)(c, s - c); | |
323 | ||
324 | ring->clearto = ring->supply; | |
325 | } | |
326 | ||
327 | void | |
328 | ring_clearto(ring) | |
329 | Ring *ring; | |
330 | { | |
331 | if (!ring_empty(ring)) | |
332 | ring->clearto = ring->supply; | |
333 | else | |
334 | ring->clearto = 0; | |
335 | } | |
336 | #endif |