usr/src/cmd/cmd-inet/usr.bin/telnet/ring.c

   1 /*
   2  * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
   3  * Use is subject to license terms.
   4  */
   5
   6 #pragma ident   "%Z%%M% %I%     %E% SMI"
   7
   8 /*
   9  * usr/src/cmd/cmd-inet/usr.bin/telnet/ring.c
  10  */
  11
  12 /*
  13  * Copyright (c) 1988, 1993
  14  *      The Regents of the University of California.  All rights reserved.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  * 1. Redistributions of source code must retain the above copyright
  20  *    notice, this list of conditions and the following disclaimer.
  21  * 2. Redistributions in binary form must reproduce the above copyright
  22  *    notice, this list of conditions and the following disclaimer in the
  23  *    documentation and/or other materials provided with the distribution.
  24  * 3. All advertising materials mentioning features or use of this software
  25  *    must display the following acknowledgement:
  26  *      This product includes software developed by the University of
  27  *      California, Berkeley and its contributors.
  28  * 4. Neither the name of the University nor the names of its contributors
  29  *    may be used to endorse or promote products derived from this software
  30  *    without specific prior written permission.
  31  *
  32  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  33  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  34  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  35  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  36  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  37  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  38  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  39  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  40  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  41  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  42  * SUCH DAMAGE.
  43  */
  44
  45 #ifndef lint
  46 static char sccsid[] = "@(#)ring.c      8.1 (Berkeley) 6/6/93";
  47 #endif /* not lint */
  48
  49 /*
  50  * This defines a structure for a ring buffer.
  51  *
  52  * The circular buffer has two parts:
  53  * (((
  54  *      full:   [consume, supply)
  55  *      empty:  [supply, consume)
  56  * ]]]
  57  *
  58  */
  59
  60 #include        <stdio.h>
  61 #include        <errno.h>
  62 #include        <string.h>
  63
  64 #include        <sys/types.h>
  65 #include        <sys/socket.h>
  66 #include        <sys/sysmacros.h>
  67
  68 #include        "ring.h"
  69 #include        "general.h"
  70
  71
  72 #define ring_subtract(d, a, b)  (((a)-(b) >= 0)? \
  73                                         (a)-(b): (((a)-(b))+(d)->size))
  74
  75 #define ring_increment(d, a, c) (((a)+(c) < (d)->top)? \
  76                                         (a)+(c) : (((a)+(c))-(d)->size))
  77
  78 #define ring_decrement(d, a, c) (((a)-(c) >= (d)->bottom)? \
  79                                         (a)-(c) : (((a)-(c))-(d)->size))
  80
  81
  82 /*
  83  * The following is a clock, used to determine full, empty, etc.
  84  *
  85  * There is some trickiness here.  Since the ring buffers are initialized
  86  * to ZERO on allocation, we need to make sure, when interpreting the
  87  * clock, that when the times are EQUAL, then the buffer is FULL.
  88  */
  89 ulong_t ring_clock = 0;
  90
  91
  92 #define ring_empty(d) (((d)->consume == (d)->supply) && \
  93                                 ((d)->consumetime >= (d)->supplytime))
  94 #define ring_full(d) (((d)->supply == (d)->consume) && \
  95                                 ((d)->supplytime > (d)->consumetime))
  96
  97
  98
  99
 100
 101 /* Buffer state transition routines */
 102
 103 int
 104     ring_init(ring, buffer, count)
 105 Ring *ring;
 106     unsigned char *buffer;
 107     int count;
 108 {
 109         (void) memset(ring, 0, sizeof (*ring));
 110
 111         ring->size = count;
 112
 113         ring->supply = ring->consume = ring->bottom = buffer;
 114
 115         ring->top = ring->bottom+ring->size;
 116
 117         ring->clearto = 0;
 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
 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
 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 /*
 244  * Return the number of bytes that are available for consuming
 245  * (but don't give more than enough to get to cross over set mark)
 246  */
 247
 248 int
 249 ring_full_count(ring)
 250         Ring *ring;
 251 {
 252         if ((ring->mark == 0) || (ring->mark == ring->consume)) {
 253                 if (ring_full(ring)) {
 254                         return (ring->size);    /* nothing consumed, but full */
 255                 } else {
 256                         return (ring_subtract(ring, ring->supply,
 257                             ring->consume));
 258                 }
 259         } else {
 260                 return (ring_subtract(ring, ring->mark, ring->consume));
 261         }
 262 }
 263
 264 /*
 265  * Return the number of CONSECUTIVE bytes available for consuming.
 266  * However, don't return more than enough to cross over set mark.
 267  */
 268 int
 269 ring_full_consecutive(ring)
 270         Ring *ring;
 271 {
 272         if ((ring->mark == 0) || (ring->mark == ring->consume)) {
 273                 if ((ring->supply < ring->consume) || ring_full(ring)) {
 274                         return (ring_subtract(ring, ring->top, ring->consume));
 275                 } else {
 276                         return (ring_subtract(ring, ring->supply,
 277                             ring->consume));
 278                 }
 279         } else {
 280                 if (ring->mark < ring->consume) {
 281                         return (ring_subtract(ring, ring->top, ring->consume));
 282                 } else {        /* Else, distance to mark */
 283                         return (ring_subtract(ring, ring->mark, ring->consume));
 284                 }
 285         }
 286 }
 287
 288 /*
 289  * Move data into the "supply" portion of of the ring buffer.
 290  */
 291 void
 292 ring_supply_data(ring, buffer, count)
 293         Ring *ring;
 294         unsigned char *buffer;
 295         int count;
 296 {
 297         int i;
 298
 299         while (count) {
 300                 i = MIN(count, ring_empty_consecutive(ring));
 301                 (void) memcpy(ring->supply, buffer, i);
 302                 ring_supplied(ring, i);
 303                 count -= i;
 304                 buffer += i;
 305         }
 306 }
 307
 308 #ifdef notdef
 309
 310 /*
 311  * Move data from the "consume" portion of the ring buffer
 312  */
 313 void
 314 ring_consume_data(ring, buffer, count)
 315         Ring *ring;
 316         unsigned char *buffer;
 317         int count;
 318 {
 319         int i;
 320
 321         while (count) {
 322                 i = MIN(count, ring_full_consecutive(ring));
 323                 memcpy(buffer, ring->consume, i);
 324                 ring_consumed(ring, i);
 325                 count -= i;
 326                 buffer += i;
 327         }
 328 }
 329 #endif
 330
 331 void
 332 ring_encrypt(ring, encryptor)
 333         Ring *ring;
 334         void (*encryptor)();
 335 {
 336         unsigned char *s, *c;
 337
 338         if (ring_empty(ring) || ring->clearto == ring->supply)
 339                 return;
 340
 341         if ((c = ring->clearto) == NULL)
 342                 c = ring->consume;
 343
 344         s = ring->supply;
 345
 346         if (s <= c) {
 347                 (*encryptor)(c, ring->top - c);
 348                 (*encryptor)(ring->bottom, s - ring->bottom);
 349         } else
 350                 (*encryptor)(c, s - c);
 351
 352         ring->clearto = ring->supply;
 353 }
 354
 355     void
 356 ring_clearto(ring)
 357     Ring *ring;
 358 {
 359     if (!ring_empty(ring))
 360         ring->clearto = ring->supply;
 361     else
 362         ring->clearto = 0;
 363 }