1 /* $NetBSD: ring.c,v 1.9 2000/06/22 06:47:48 thorpej Exp $ */ 2 3 /* 4 * Copyright (c) 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 #include <sys/cdefs.h> 37 #ifndef lint 38 #if 0 39 static char sccsid[] = "@(#)ring.c 8.2 (Berkeley) 5/30/95"; 40 #else 41 __RCSID("$NetBSD: ring.c,v 1.9 2000/06/22 06:47:48 thorpej Exp $"); 42 #endif 43 #endif /* not lint */ 44 45 /* 46 * This defines a structure for a ring buffer. 47 * 48 * The circular buffer has two parts: 49 *((( 50 * full: [consume, supply) 51 * empty: [supply, consume) 52 *]]] 53 * 54 */ 55 56 #include <stdio.h> 57 #ifndef NO_STRING_H 58 #include <string.h> 59 #endif 60 #include <strings.h> 61 #include <errno.h> 62 63 #ifdef size_t 64 #undef size_t 65 #endif 66 67 #include <sys/types.h> 68 #ifndef FILIO_H 69 #include <sys/ioctl.h> 70 #endif 71 #include <sys/socket.h> 72 73 #include "ring.h" 74 #include "general.h" 75 76 /* Internal macros */ 77 78 #if !defined(MIN) 79 #define MIN(a,b) (((a)<(b))? (a):(b)) 80 #endif /* !defined(MIN) */ 81 82 #define ring_subtract(d,a,b) (((a)-(b) >= 0)? \ 83 (a)-(b): (((a)-(b))+(d)->size)) 84 85 #define ring_increment(d,a,c) (((a)+(c) < (d)->top)? \ 86 (a)+(c) : (((a)+(c))-(d)->size)) 87 88 #define ring_decrement(d,a,c) (((a)-(c) >= (d)->bottom)? \ 89 (a)-(c) : (((a)-(c))-(d)->size)) 90 91 92 /* 93 * The following is a clock, used to determine full, empty, etc. 94 * 95 * There is some trickiness here. Since the ring buffers are initialized 96 * to ZERO on allocation, we need to make sure, when interpreting the 97 * clock, that when the times are EQUAL, then the buffer is FULL. 98 */ 99 static u_long ring_clock = 0; 100 101 102 #define ring_empty(d) (((d)->consume == (d)->supply) && \ 103 ((d)->consumetime >= (d)->supplytime)) 104 #define ring_full(d) (((d)->supply == (d)->consume) && \ 105 ((d)->supplytime > (d)->consumetime)) 106 107 108 109 110 111 /* Buffer state transition routines */ 112 113 int 114 ring_init(ring, buffer, count) 115 Ring *ring; 116 unsigned char *buffer; 117 int count; 118 { 119 memset((char *)ring, 0, sizeof *ring); 120 121 ring->size = count; 122 123 ring->supply = ring->consume = ring->bottom = buffer; 124 125 ring->top = ring->bottom+ring->size; 126 127 #ifdef ENCRYPTION 128 ring->clearto = 0; 129 #endif /* ENCRYPTION */ 130 131 return 1; 132 } 133 134 /* Mark routines */ 135 136 /* 137 * Mark the most recently supplied byte. 138 */ 139 140 void 141 ring_mark(ring) 142 Ring *ring; 143 { 144 ring->mark = ring_decrement(ring, ring->supply, 1); 145 } 146 147 /* 148 * Is the ring pointing to the mark? 149 */ 150 151 int 152 ring_at_mark(ring) 153 Ring *ring; 154 { 155 if (ring->mark == ring->consume) { 156 return 1; 157 } else { 158 return 0; 159 } 160 } 161 162 /* 163 * Clear any mark set on the ring. 164 */ 165 166 void 167 ring_clear_mark(ring) 168 Ring *ring; 169 { 170 ring->mark = 0; 171 } 172 173 /* 174 * Add characters from current segment to ring buffer. 175 */ 176 void 177 ring_supplied(ring, count) 178 Ring *ring; 179 int count; 180 { 181 ring->supply = ring_increment(ring, ring->supply, count); 182 ring->supplytime = ++ring_clock; 183 } 184 185 /* 186 * We have just consumed "c" bytes. 187 */ 188 void 189 ring_consumed(ring, count) 190 Ring *ring; 191 int count; 192 { 193 if (count == 0) /* don't update anything */ 194 return; 195 196 if (ring->mark && 197 (ring_subtract(ring, ring->mark, ring->consume) < count)) { 198 ring->mark = 0; 199 } 200 #ifdef ENCRYPTION 201 if (ring->consume < ring->clearto && 202 ring->clearto <= ring->consume + count) 203 ring->clearto = 0; 204 else if (ring->consume + count > ring->top && 205 ring->bottom <= ring->clearto && 206 ring->bottom + ((ring->consume + count) - ring->top)) 207 ring->clearto = 0; 208 #endif /* ENCRYPTION */ 209 ring->consume = ring_increment(ring, ring->consume, count); 210 ring->consumetime = ++ring_clock; 211 /* 212 * Try to encourage "ring_empty_consecutive()" to be large. 213 */ 214 if (ring_empty(ring)) { 215 ring->consume = ring->supply = ring->bottom; 216 } 217 } 218 219 220 221 /* Buffer state query routines */ 222 223 224 /* Number of bytes that may be supplied */ 225 int 226 ring_empty_count(ring) 227 Ring *ring; 228 { 229 if (ring_empty(ring)) { /* if empty */ 230 return ring->size; 231 } else { 232 return ring_subtract(ring, ring->consume, ring->supply); 233 } 234 } 235 236 /* number of CONSECUTIVE bytes that may be supplied */ 237 int 238 ring_empty_consecutive(ring) 239 Ring *ring; 240 { 241 if ((ring->consume < ring->supply) || ring_empty(ring)) { 242 /* 243 * if consume is "below" supply, or empty, then 244 * return distance to the top 245 */ 246 return ring_subtract(ring, ring->top, ring->supply); 247 } else { 248 /* 249 * else, return what we may. 250 */ 251 return ring_subtract(ring, ring->consume, ring->supply); 252 } 253 } 254 255 /* Return the number of bytes that are available for consuming 256 * (but don't give more than enough to get to cross over set mark) 257 */ 258 259 int 260 ring_full_count(ring) 261 Ring *ring; 262 { 263 if ((ring->mark == 0) || (ring->mark == ring->consume)) { 264 if (ring_full(ring)) { 265 return ring->size; /* nothing consumed, but full */ 266 } else { 267 return ring_subtract(ring, ring->supply, ring->consume); 268 } 269 } else { 270 return ring_subtract(ring, ring->mark, ring->consume); 271 } 272 } 273 274 /* 275 * Return the number of CONSECUTIVE bytes available for consuming. 276 * However, don't return more than enough to cross over set mark. 277 */ 278 int 279 ring_full_consecutive(ring) 280 Ring *ring; 281 { 282 if ((ring->mark == 0) || (ring->mark == ring->consume)) { 283 if ((ring->supply < ring->consume) || ring_full(ring)) { 284 return ring_subtract(ring, ring->top, ring->consume); 285 } else { 286 return ring_subtract(ring, ring->supply, ring->consume); 287 } 288 } else { 289 if (ring->mark < ring->consume) { 290 return ring_subtract(ring, ring->top, ring->consume); 291 } else { /* Else, distance to mark */ 292 return ring_subtract(ring, ring->mark, ring->consume); 293 } 294 } 295 } 296 297 /* 298 * Move data into the "supply" portion of of the ring buffer. 299 */ 300 void 301 ring_supply_data(ring, buffer, count) 302 Ring *ring; 303 unsigned char *buffer; 304 int count; 305 { 306 int i; 307 308 while (count) { 309 i = MIN(count, ring_empty_consecutive(ring)); 310 memmove(ring->supply, buffer, i); 311 ring_supplied(ring, i); 312 count -= i; 313 buffer += i; 314 } 315 } 316 317 #ifdef notdef 318 319 /* 320 * Move data from the "consume" portion of the ring buffer 321 */ 322 void 323 ring_consume_data(ring, buffer, count) 324 Ring *ring; 325 unsigned char *buffer; 326 int count; 327 { 328 int i; 329 330 while (count) { 331 i = MIN(count, ring_full_consecutive(ring)); 332 memmove(buffer, ring->consume, i); 333 ring_consumed(ring, i); 334 count -= i; 335 buffer += i; 336 } 337 } 338 #endif 339 340 #ifdef ENCRYPTION 341 void 342 ring_encrypt(ring, encryptor) 343 Ring *ring; 344 void (*encryptor) P((unsigned char *, int)); 345 { 346 unsigned char *s, *c; 347 348 if (ring_empty(ring) || ring->clearto == ring->supply) 349 return; 350 351 if (!(c = ring->clearto)) 352 c = ring->consume; 353 354 s = ring->supply; 355 356 if (s <= c) { 357 (*encryptor)(c, ring->top - c); 358 (*encryptor)(ring->bottom, s - ring->bottom); 359 } else 360 (*encryptor)(c, s - c); 361 362 ring->clearto = ring->supply; 363 } 364 365 void 366 ring_clearto(ring) 367 Ring *ring; 368 { 369 370 if (!ring_empty(ring)) 371 ring->clearto = ring->supply; 372 else 373 ring->clearto = 0; 374 } 375 #endif /* ENCRYPTION */ 376