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 static char sccsid[] = "@(#)ring.c      8.1 (Berkeley) 6/6/93";
  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, buffer, count)
 103 Ring *ring;
 104     unsigned char *buffer;
 105     int count;
 106 {
 107         (void) memset(ring, 0, sizeof (*ring));
 108
 109         ring->size = count;
 110
 111         ring->supply = ring->consume = ring->bottom = buffer;
 112
 113         ring->top = ring->bottom+ring->size;
 114
 115         ring->clearto = 0;
 116
 117         return (1);
 118 }
 119
 120 /* Mark routines */
 121
 122 /*
 123  * Mark the most recently supplied byte.
 124  */
 125
 126 void
 127 ring_mark(ring)
 128         Ring *ring;
 129 {
 130         ring->mark = ring_decrement(ring, ring->supply, 1);
 131 }
 132
 133 /*
 134  * Is the ring pointing to the mark?
 135  */
 136
 137 int
 138 ring_at_mark(ring)
 139         Ring *ring;
 140 {
 141         if (ring->mark == ring->consume) {
 142                 return (1);
 143         } else {
 144                 return (0);
 145         }
 146 }
 147
 148 /*
 149  * Clear any mark set on the ring.
 150  */
 151
 152 void
 153 ring_clear_mark(ring)
 154         Ring *ring;
 155 {
 156         ring->mark = 0;
 157 }
 158
 159 /*
 160  * Add characters from current segment to ring buffer.
 161  */
 162     void
 163 ring_supplied(ring, count)
 164     Ring *ring;
 165     int count;
 166 {
 167     ring->supply = ring_increment(ring, ring->supply, count);
 168     ring->supplytime = ++ring_clock;
 169 }
 170
 171 /*
 172  * We have just consumed "c" bytes.
 173  */
 174 void
 175 ring_consumed(ring, count)
 176         Ring *ring;
 177         int count;
 178 {
 179         if (count == 0) /* don't update anything */
 180                 return;
 181
 182         if (ring->mark &&
 183             (ring_subtract(ring, ring->mark, ring->consume) < count)) {
 184                 ring->mark = 0;
 185         }
 186
 187         if (ring->consume < ring->clearto &&
 188             ring->clearto <= ring->consume + count)
 189                 ring->clearto = 0;
 190         else if (ring->consume + count > ring->top &&
 191             ring->bottom <= ring->clearto &&
 192             ring->bottom + ((ring->consume + count) - ring->top))
 193                 ring->clearto = 0;
 194
 195         ring->consume = ring_increment(ring, ring->consume, count);
 196         ring->consumetime = ++ring_clock;
 197         /*
 198          * Try to encourage "ring_empty_consecutive()" to be large.
 199          */
 200         if (ring_empty(ring)) {
 201                 ring->consume = ring->supply = ring->bottom;
 202         }
 203 }
 204
 205
 206
 207 /* Buffer state query routines */
 208
 209
 210 /* Number of bytes that may be supplied */
 211 int
 212 ring_empty_count(ring)
 213         Ring *ring;
 214 {
 215         if (ring_empty(ring)) { /* if empty */
 216                 return (ring->size);
 217         } else {
 218                 return (ring_subtract(ring, ring->consume, ring->supply));
 219         }
 220 }
 221
 222 /* number of CONSECUTIVE bytes that may be supplied */
 223 int
 224 ring_empty_consecutive(ring)
 225         Ring *ring;
 226 {
 227         if ((ring->consume < ring->supply) || ring_empty(ring)) {
 228                 /*
 229                  * if consume is "below" supply, or empty, then
 230                  * return distance to the top
 231                  */
 232                 return (ring_subtract(ring, ring->top, ring->supply));
 233         } else {
 234                 /*
 235                  * else, return what we may.
 236                  */
 237                 return (ring_subtract(ring, ring->consume, ring->supply));
 238         }
 239 }
 240
 241 /*
 242  * Return the number of bytes that are available for consuming
 243  * (but don't give more than enough to get to cross over set mark)
 244  */
 245
 246 int
 247 ring_full_count(ring)
 248         Ring *ring;
 249 {
 250         if ((ring->mark == 0) || (ring->mark == ring->consume)) {
 251                 if (ring_full(ring)) {
 252                         return (ring->size);    /* nothing consumed, but full */
 253                 } else {
 254                         return (ring_subtract(ring, ring->supply,
 255                             ring->consume));
 256                 }
 257         } else {
 258                 return (ring_subtract(ring, ring->mark, ring->consume));
 259         }
 260 }
 261
 262 /*
 263  * Return the number of CONSECUTIVE bytes available for consuming.
 264  * However, don't return more than enough to cross over set mark.
 265  */
 266 int
 267 ring_full_consecutive(ring)
 268         Ring *ring;
 269 {
 270         if ((ring->mark == 0) || (ring->mark == ring->consume)) {
 271                 if ((ring->supply < ring->consume) || ring_full(ring)) {
 272                         return (ring_subtract(ring, ring->top, ring->consume));
 273                 } else {
 274                         return (ring_subtract(ring, ring->supply,
 275                             ring->consume));
 276                 }
 277         } else {
 278                 if (ring->mark < ring->consume) {
 279                         return (ring_subtract(ring, ring->top, ring->consume));
 280                 } else {        /* Else, distance to mark */
 281                         return (ring_subtract(ring, ring->mark, ring->consume));
 282                 }
 283         }
 284 }
 285
 286 /*
 287  * Move data into the "supply" portion of of the ring buffer.
 288  */
 289 void
 290 ring_supply_data(ring, buffer, count)
 291         Ring *ring;
 292         unsigned char *buffer;
 293         int count;
 294 {
 295         int i;
 296
 297         while (count) {
 298                 i = MIN(count, ring_empty_consecutive(ring));
 299                 (void) memcpy(ring->supply, buffer, i);
 300                 ring_supplied(ring, i);
 301                 count -= i;
 302                 buffer += i;
 303         }
 304 }
 305
 306 #ifdef notdef
 307
 308 /*
 309  * Move data from the "consume" portion of the ring buffer
 310  */
 311 void
 312 ring_consume_data(ring, buffer, count)
 313         Ring *ring;
 314         unsigned char *buffer;
 315         int count;
 316 {
 317         int i;
 318
 319         while (count) {
 320                 i = MIN(count, ring_full_consecutive(ring));
 321                 memcpy(buffer, ring->consume, i);
 322                 ring_consumed(ring, i);
 323                 count -= i;
 324                 buffer += i;
 325         }
 326 }
 327 #endif
 328
 329 void
 330 ring_encrypt(ring, encryptor)
 331         Ring *ring;
 332         void (*encryptor)();
 333 {
 334         unsigned char *s, *c;
 335
 336         if (ring_empty(ring) || ring->clearto == ring->supply)
 337                 return;
 338
 339         if ((c = ring->clearto) == NULL)
 340                 c = ring->consume;
 341
 342         s = ring->supply;
 343
 344         if (s <= c) {
 345                 (*encryptor)(c, ring->top - c);
 346                 (*encryptor)(ring->bottom, s - ring->bottom);
 347         } else
 348                 (*encryptor)(c, s - c);
 349
 350         ring->clearto = ring->supply;
 351 }
 352
 353     void
 354 ring_clearto(ring)
 355     Ring *ring;
 356 {
 357     if (!ring_empty(ring))
 358         ring->clearto = ring->supply;
 359     else
 360         ring->clearto = 0;
 361 }