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 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 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 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 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 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 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 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 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 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 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 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 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 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 331 ring_clearto(Ring *ring) 332 { 333 if (!ring_empty(ring)) 334 ring->clearto = ring->supply; 335 else 336 ring->clearto = 0; 337 } 338